publications

* denotes equal contribution

preprint

1. Padezhki, I., Linde-Domingo, J. & Gonzalez-Garcia, C. (2025). Dynamic prioritization reshapes neural geometries for action in human working memory. bioRxiv. https://doi.org/10.1101/2025.07.18.665374

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   Prior work has shown that control brain regions encode upcoming novel instructed actions. Similarly, visual working memory (WM) representations can reflect different priority states. However, it remains unknown whether the priority status of WM-guided novel actions similarly modulates their neural coding format, and how such dynamics unfold over time. We addressed these questions using EEG while human participants performed two consecutive choice reaction tasks. At the start of each trial, participants encoded two novel stimulus-response (S-R) mappings. A cue then indicated whether these mappings would be relevant immediately ("current" condition), later after an intervening task ("prospective"), or after a free delay ("delayed"). Using multivariate pattern analysis, we found that the S-R category was decodable in all conditions during relevant time windows. Critically, pattern similarity analyses revealed that while mere maintenance demands allow for temporary preservation of neural codes (i.e., between current and delayed trials), shielding from interference (i.e., prospective trials) induced significant alterations to the neural code. Further exploration of the representational geometry revealed that priority status gained prominence dynamically over S-R category coding when preparing for such shielding demands. Importantly, some of these changes emerged anticipatorily, prior to target onset. Overall, our results show that, similar to visual WM, the priority of intended actions dynamically and anticipatorily reshapes their neural format. They further reveal how different demands induce content geometries compatible with previously proposed coding schemes, and that such representational changes can be implemented flexibly in time.Competing Interest StatementThe authors have declared no competing interest.MCIN/AEI/10.13039/501100011033, PID2020-116342GA-I00, RYC2021-033536-I, PID2023-151104NA-I00, RYC2021-033940-I, CEX2023-001312-MUniversity of Granada, https://ror.org/04njjy449, UCE-PP2023-11

2. Linde-Domingo*, J., Ortiz-Tudela*, J., Voeller, J., Hebart, M. & González-García, C. (2025). Determinants of Visual Ambiguity Resolution. bioRxiv. https://doi.org/10.1101/2025.05.28.656283

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   Visual inputs during natural perception are highly ambiguous: objects are frequently occluded, lighting conditions vary, and object identification depends significantly on prior experiences. However, why do certain images remain unidentifiable while others can be recognized immediately, and what visual features drive subjective clarification? To address these critical questions, we developed a unique dataset of 1,854 ambiguous images and collected more than 100,000 participant ratings evaluating their identifiability before and after seeing undistorted versions of the images. Relating the representations of a brain-inspired neural network model in response to our images with human ratings, we show that subjective identification depends largely on the extent to which higher-level visual features from the original images are preserved in their ambiguous counterparts. Notably, the predominance of higher-level features over lower-level ones softens after participants disambiguate the images. In line with these results, an image-level regression analysis showed that the subjective identification of ambiguous images was best explained by high-level visual dimensions. Moreover, we found that the process of ambiguity resolution was accompanied by a notable decrease in semantic distance and a greater consistency in object naming among participants. However, the relationship between information gained after disambiguation and subjective identification was non-linear, indicating that acquiring more information does not necessarily enhance subjective clarity. Instead, we observed a U-shaped relationship, suggesting that subjective identification improves when the acquired information either strongly matches or mismatches prior predictions. Collectively, these findings highlight fundamental principles underlying the mapping between human visual perception and memory, advancing our understanding on how we resolve ambiguity and extract meaning from incomplete visual information.

2025

1. Vermeylen, L., Braem, S., Ivanchei, I., Desender, K., García-Román, J., González-García, C., et al. (2025). The Temporal Dynamics of Metacognitive Experiences Track Rational Adaptations in Task Performance. Communications Psychology, 3, 96. https://doi.org/10.1101/2023.09.26.559523

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   Human task performance elicits diverse subjective metacognitive experiences, such as boredom, effort, fatigue and frustration, which are thought to play important roles in the monitoring and regulation of cognitive processes. Yet, their specific contributions to task performance remain poorly understood. Therefore, we investigated temporal dynamics between these metacognitive experiences and the cognitive processes supporting task performance. We used a time-on-task design using a conflict Flanker task, and analyzed the data using a multi-methodological approach involving behavioral, model-based, subjective, and neural measures. We show that the temporal dynamics supporting task performance can be understood as a rational attempt to optimize behavior and that distinct metacognitive experiences track distinct aspects of this rational endeavor: frustration signals the need to adapt the decision boundary which is experienced as fatiguing. These findings demonstrate that metacognitive experiences might act as tools for humans to gain insights into the optimality of their cognitive performance.

2. Ponce, R., Lupiáñez, J., González-García, C., Casagrande, M. & Marotta, A. (2025). Investigating the gaze-driven reversed congruency effect in the spatial Stroop task: A distributional approach. British Journal of Psychology, 00, 1-21. https://doi.org/10.1111/bjop.70004

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   Abstract This study investigated how social (faces and eyes) and non-social (arrows) stimuli modulate attentional orienting in a spatial Stroop task, using a distributional approach. Data from 11 studies (N = 705) were analysed through cumulative distribution functions (CDF), delta functions, and polynomial trend analyses. Three models were applied: (1) a reaction time (RT) model comparing social (faces and eyes) vs. non-social stimuli under congruent and incongruent conditions, (2) a delta model assessing conflict effects across quantiles, and (3) a trend model identifying specific delta function patterns. Non-social targets produced a standard congruency effect (SCE), with faster responses in congruent trials but no consistent conflict reduction across the distribution. In contrast, social stimuli exhibited a reversed congruency effect (RCE), with faster responses in incongruent trials, emerging from the second quantile onward and minimal conflict among the fastest responses. Social targets exhibited comparable reaction times in the RT model and similar early delta plot patterns, suggesting shared initial perceptual and attentional mechanisms between faces and eyes. However, faces eventually induced a larger RCE, possibly due to their more complex configuration. These findings highlight distinctive patterns between social and non-social processing in the spatial Stroop task.

3. Fuentes-Guerra Toral, Á., Botta, F., Lupiáñez, J., González-García*, C. & Martín-Arévalo*, E. (2025). Exogenous attention and its relationship with working memory contents: beyond spatial selection. Acta Psychologica, 256, 105003. https://doi.org/10.1016/j.actpsy.2025.105003

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   To successfully perform everyday activities, cognitive functions such as working memory (WM) and selective attention are necessary. Specifically, when environmental demands are dynamic, exogenous attention is crucial. However, its ability to select and prioritize not only perceptual spatial locations, but also novel stimulus-response (S-R) bindings held in WM remains largely unexplored. By implementing a retro-cueing paradigm on a task that capitalized on WM, the present experiment’s aim was two-fold: i) to evaluate whether exogenous cueing effects would not only impact spatial processing but also WM content, and ii) to explore how meta-control states induced by the manipulation of an intervening event (IE) would modulate these effects. We observed (N = 50) that exogenous attention led to selection of space, as it is usually observed in spatial exogenous attention paradigms, but also the content associated with that location. Moreover, space selection was modulated by the IE manipulation, which was thought to induce two meta-control states (persistent vs. flexible). As such, the presence of the IE also modulated participants’ performance regarding novel vs. repeated stimulus-response mappings, again hinting at an important role of content in this task. This pattern of findings fits well with the concept of event file; a mental representation of all relevant components assembled at the beginning of a trial (i.e., cue, target, lateralization, meta-control state, etc.), which are retrieved together once one or more of its elements are encountered. Although preliminary, this evidence of exogenous attentional selection of WM through event file activation paves the way for a promising research line.

4. Pena, P., Palenciano, A., González-García, C. & Ruz, M. (2025). Novel verbal instructions recruit abstract neural patterns of time-variable information dimensionality. Journal of Neuroscience. https://doi.org/10.1523/JNEUROSCI.1964-24.2025

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   Human performance is endowed by neural representations of information that is relevant for behavior, some of which are also activated in a preparatory fashion to optimize later execution. Most studies to date have focused on highly practiced actions, leaving largely unaddressed the novel re-configuration of information to generate unique whole task-sets. Using electroencephalography (EEG), this study investigated the dynamics of the content and geometry reflected on the neural patterns of control representations during re-configuration of information. We designed a verbal instruction paradigm where each trial involved novel combinations of multi-component task information. By manipulating three task-relevant factors in a sample of 40 participants (26 females, 14 males), we observed complex coding schemes throughout the trial, during both preparation and implementation stages. The temporal profiles were consistent with a hierarchical structure: whereas task information was active in a sustained manner, the coding of more concrete stimulus features was more transient. Data showed both high dimensionality and abstraction, particularly during instruction encoding and target processing. Our results suggest that whenever task content could be recovered from neural patterns of activity, there was evidence of abstract coding, with an underlying geometry that favored generalization. During target processing, where potential interference across stimulus and response factors increased, orthogonal configurations also appeared. Overall, our findings uncover the dynamic manner with which control representations operate during novel recombination unique scenarios, with changes in dimensionality and abstraction adjusting along processing stages.Significance Statement The neural mechanisms that support task performance in novel contexts have been largely overlooked. Cognitive control is thought to enable complex behavior through the active maintenance of task sets, containing essential information for execution. However, how novel whole combinations of information are organized in neural patterns and their temporal dependencies remain unknown. Here, using a novel complex instruction paradigm, we observed that coding of informational content and its underlying geometry followed a dynamic temporal pattern. Our results reveal varying dimensionality and abstraction throughout the trial, with neural codes generally structured in a geometry favoring generalization of relevant information across task demands. These findings provide a first glimpse into the temporal computations engaged by the brain when encountering novel recombination settings.

5. Fuentes-Guerra, Á., Botta, F., Lupiáñez, J., Talavera, P., Martín-Arévalo*, E. & González-García*, C. (2025). Exogenous spatial attention selects associated novel bindings in working memory. Journal of Memory and Language, 140, 104571. https://doi.org/10.1016/j.jml.2024.104571

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   Real-world environments are complex, demanding a diverse set of cognitive functions such as attention and working memory (WM) to perform adaptive behaviors. However, exogenous attention, characterized as automatic and involuntary, has primarily been studied by focusing on spatial perception. In particular, the ability of pure exogenous retro-cues to select and prioritize not only spatial locations, but also novel stimulus–response (S-R) bindings held in WM remains largely unexplored. Here, in two experimental series, we provide evidence that pure exogenous non-predictive retro-cues can select not only space, but also associated S-R bindings held in WM. Additional evidence from a drift–diffusion model hinted at the possibility that the mechanisms through which exogenous attention selects and prioritizes WM contents depend, at least partially, on the hierarchical relevance of the different dimensions encoded within a specific representation. These results highlight the relationship between pure exogenous attention and complex WM contents and shed light on current theoretical debates about the interaction of attention, memory, and action.

2024

1. Cipriani, G., González-García, C., Martín-Arévalo, E., Lupiáñez, J. & Botta, F. (2024). Competing working memory contents: perceptual over semantic prioritization and voluntary retrieval following retro-cueing. Visual Cognition, 0(0), 1–20. https://doi.org/10.1080/13506285.2024.2435652

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   This study investigated how voluntary and involuntary retrospective attention prioritize working memory (WM) representations of low-level visual features (perceptual dimension) and high-level categories (semantic dimension) using real-world objects. Reaction time and accuracy from two retro-cueing experiments were analyzed with a hierarchical drift-diffusion model to assess impacts on representation quality (drift rate) and retrieval time (non-decision time). Voluntariness of attention did not differentially affect perceptual and semantic WM contents. Drift rates showed stronger retro-cueing effects on perceptual compared to semantic contents, while non-decision times revealed retro-cueing effects only for voluntary attention. These findings suggest: (1) voluntariness does not differentiate between perceptual and semantic contents competing in WM; (2) attention prioritizes perceptual over semantic contents; and (3) voluntariness is critical for retrieving WM contents in advance of decision-making. This work highlights how WM content type and attentional voluntariness independently shape the effects of retrospective attention.

2. Peñalver, J., González-García, C., Palenciano, A., López-García, D. & Ruz, M. (2024). Context-dependent neural preparation for information relevance vs. probability. Imaging Neuroscience. https://doi.org/10.1101/2024.05.20.594985

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   Preparation is a top-down phenomenon known to improve performance across different situations. In light of recent electrophysiological findings that suggest that anticipatory neural preactivations linked to preparation are context-specific and do not generalize across domains, in the current study we used fMRI to investigate the brain regions involved in these differential patterns. We applied multivariate decoding to data obtained in a paradigm where, in different blocks, cues provided information about the relevance or probability of incoming target stimuli. Results showed that the anticipated stimulus category was pre-activated in both conditions, mostly in different brain regions within the ventral visual cortex and with differential overlap with actual target perception. Crucially, there was little cross-classification across attention and expectation contexts, indicating lack of common neural coding across relevance and probability contexts. Finally, a model-based fMRI-EEG fusion showed that these regions differentially code for specific conditions during preparation, as well as specifically preparing for category anticipation in a ramping-up manner. Overall, our results stress the specificity of anticipatory neural processing depending on its informative role.Competing Interest StatementThe authors have declared no competing interest.

3. Ponce, R., Lupiáñez, J., González-García, C., Casagrande, M. & Marotta, A. (2024). Exploring the spatial interference effects elicited by social and non-social targets: A conditional accuracy function approach. British Journal of Psychology. https://doi.org/10.1111/bjop.12735

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   Recent studies employing the spatial interference paradigm reveal qualitative differences in congruency effects between gaze and arrow targets. Typically, arrows produce a standard congruency effect (SCE), with faster responses when target direction aligns with its location. Conversely, gaze targets often lead to a reversed congruency effect (RCE), where responses are slower in similar conditions. We explored this dissociation using the Conditional Accuracy Function (CAF) to assess accuracy across reaction time bins. Using a hierarchical linear mixed modelling approach to compare cropped eyes, and full faces as social stimuli, and arrows as non-social stimuli, we synthesized findings from 11 studies, which led to three distinct models. The results showed that with non-social targets, incongruent trials exhibited lower accuracy rates in the first bin than in subsequent bins, while congruent trials maintained stable accuracy throughout the distribution. Conversely, social targets revealed a dissociation within the fastest responses; alongside a general reduction in accuracy for both congruency conditions, congruent trials resulted in even lower accuracy rates than incongruent ones. These results suggest with gaze targets that additional information, perhaps social, in addition to the automatic capture by the irrelevant target location, is being processed during the earlier stages of processing.

4. Engelmann, N., Hannikainen, I., González-García, C. & Ruz, M. (2024). Understanding Rule Enforcement Using Drift Diffusion Models. Proceedings of the Annual Meeting of the Cognitive Science Society, 46(0).

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   Since their inception, drift diffusion models have been applied across a wide range of disciplines within psychology to uncover the mental processes that underlie perception, attention, and cognitive control. Our studies contribute to ongoing efforts to extend these models to abstract, social reasoning processes like moral or legal judgment. We presented participants with a set of social rules, while manipulating whether various behaviors violated the rule’s letter and/or its purpose – two independent standards by which to decide what constitutes a transgression. In this framework, cases that violate or comply with both a rule’s text and its purpose can be seen as congruent or ’easy’ cases, and cases that elicit opposing verdicts as incongruent or ’hard’ cases – in a manner analogous to widely-studied conflict tasks in cognitive psychology. We recorded 34,573 decisions made by 364 participants under soft time pressure, and investigated whether hierarchical drift diffusion modeling could explain various behavioral patterns in our data. This approach yielded three key insights: (1) judgments of conviction were faster than judgments of acquittal owing to an overall bias (z parameter) toward conviction; (2) incongruent cases produced longer reaction times than congruent cases (an interference effect), due to differences in the rate of evidence accumulation (v parameter) across case-types; and (3) increases in the ratio of congruent-to-incongruent cases amplified the interference effect on reaction times, by fostering greater response caution‚Äîrevealed by a larger threshold (or a parameter). Thus, our studies document dissociable effects of the drift diffusion components on rule-based decision-making, and illustrate how the cognitive processes that subserve abstract and social decision-making tasks, such as the enforcement of communal and legal rules, may be illuminated through the drift diffusion framework.

5. Palenciano, A., González-García, C., Houwer, J., Liefooghe, B. & Brass, M. (2024). Concurrent response and action effect representations across the somatomotor cortices during novel task preparation.. Cortex. https://doi.org/10.1016/j.cortex.2024.05.003

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   Instructions allow us to fulfill novel and complex tasks on the first try. This skill has been linked to preparatory brain signals that encode upcoming demands in advance, facilitating novel performance. To deepen insight into these processes, we aimed to explore whether instructions pre-activated task-relevant motoric and perceptual neural states. Critically, we addressed whether these representations anticipated activity patterns guiding overt sensorimotor processing, which could reflect that internally simulating the novel task facilitates the preparation. To do so, we collected functional magnetic resonance imaging data while participants encoded and implemented novel stimulus-response associations. Participants also completed localizer tasks designed to isolate the neural representations of the mappings-relevant motor responses, perceptual consequences, and stimulus categories. Using canonical template tracking, we identified whether and where these sensorimotor representations were pre-activated. We found that response-related templates were encoded in advance in regions linked with action control, entailing not only the instructed responses but also their action effects. This result was particularly robust in primary motor and somatosensory cortices. While, following our predictions, we found a systematic decrease in the irrelevant stimulus templates’ representational strength compared to the relevant ones, this difference was due to below-zero estimates linked to the irrelevant category activity patterns. Overall, our findings reflect that instruction processing relies on the sensorimotor cortices to anticipate motoric and kinesthetic representations of prospective action plans, suggesting the engagement of motor imagery during novel task preparation. More generally, they stress that the somatomotor system could participate with higher-level frontoparietal regions during anticipatory task control.Competing Interest StatementThe authors have declared no competing interest.

6. Formica, S., Palenciano, A., Vermeylen, L., Myers, N., Brass, M. & González-García, C. (2024). Internal attention modulates the functional state of novel stimulus-response associations in working memory. Cognition, 245, 105739. https://doi.org/10.1016/j.cognition.2024.105739

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   Information in working memory (WM) is crucial for guiding behavior. However, not all WM representations are equally relevant simultaneously. Current theoretical frameworks propose a functional dissociation between ‘latent’ and ‘active’ states, in which relevant representations are prioritized into an optimal (active) state to face current demands, while relevant information that is not immediately needed is maintained in a dormant (latent) state. In this context, task demands can induce rapid and flexible prioritization of information from latent to active state. Critically, these functional states have been primarily studied using simple visual memories, with attention selecting and prioritizing relevant representations to serve as templates to guide subsequent behavior. It remains unclear whether more complex WM representations, such as novel stimulus-response associations, can also be prioritized into different functional states depending on their task relevance, and if so how these different formats relate to each other. In the present study, we investigated whether novel WM-guided actions can be brought into different functional states depending on current task demands. Our results reveal that planned actions can be flexibly prioritized when needed and show how their functional state modulates their influence on ongoing behavior. Moreover, they suggest the representations of novel actions of different functional states are maintained in WM via a non-orthogonal coding scheme, thus are prone to interference.

2023

1. Wisniewski, D., Braem, S., González-García, C., Houwer, J. & Brass, M. (2023). Effects of experiencing CS-US pairings on instructed fear reversal. Journal of Neuroscience. https://doi.org/10.1101/2022.04.05.487162

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   Fear learning allows us to identify and anticipate aversive events, and adapt our behavior accordingly. This is often thought to rely on associative learning mechanisms where an initially neutral conditioned stimulus (CS) is repeatedly paired with an aversive unconditioned stimulus (US), eventually leading to the CS also being perceived as aversive and threatening. Importantly, however, humans also show verbal fear learning. Namely, they have the ability to change their responses to stimuli rapidly through verbal instructions about CS-US pairings. Past research on the link between experience-based and verbal fear learning indicated that verbal instructions about a reversal of CS-US pairings can fully override the effects of previously experienced CS-US pairings, as measured through fear ratings, skin conductance, and fear-potentiated startle. However, it remains an open question whether such instructions can also annul memory traces in the brain. Here, we used a fear reversal paradigm in conjunction with representational similarity analysis of fMRI data to test whether verbal instructions fully override the effects of experienced CS-US pairings in fear-related brain regions or not. Previous research suggests that only the right amygdala should show lingering representations of previously experienced threat (a so-called “Pavlovian trace”). Unexpectedly, we found evidence for the residual effect of prior CS-US experience to be much more widespread than anticipated, in the amygdala but also cortical regions like the dorsal anterior cingulate or dorso-lateral prefrontal cortex. This finding shines a new light on the interaction of different fear learning mechanisms, at times with unexpected consequences.

2. Ortiz-Tudela, J. & González-García, C. (2023). Exploring the conceptual structure of Spanish Experimental Psychology. Psicologica, 44(2), e15275. https://doi.org/10.31234/osf.io/rvtby

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   The recent incursion of experimental psychology into the arena of cognitive neuroscience has brought attention back to its conceptual foundations. As we embark on more multidisciplinary enterprises, some authors have called to rethink the taxonomy of psychology and cognitive neuroscience in order to build stronger theories. While some claim that, compared to other disciplines, the ontology of psychology precedes scientific work and has minimally departed from “folksy” terminology, others argue psychology’s explanandum confers a special status to folk insight. Here, we examine which psychological constructs are prevalent in the abstracts of five editions of the SEPEX meeting and compare them with those present in William James’ seminal Principles of Psychology. Additionally, we assess aspects where Spanish’ experimental psychology might fall behind to identify promising, relatively unexplored research avenues. Together, this initial exploration aims at characterizing the current conceptual status of Experimental Psychology in Spain. In a broader sense, we expect to raise awareness on the importance of a robust and up-to-date ontology given the increasingly multidisciplinary field in which our discipline now plays.

3. Wisniewski, D., González-García, C., Formica, S., Woolgar, A. & Brass, M. (2023). Adaptive coding of stimulus information in human frontoparietal cortex during visual classification. NeuroImage, 120150. https://doi.org/10.1016/j.neuroimage.2023.120150

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   The neural mechanisms of how frontal and parietal brain regions support flexible adaptation of behavior remain poorly understood. Here, we used functional magnetic resonance imaging (fMRI) and representational similarity analysis (RSA) to investigate frontoparietal representations of stimulus information during visual classification under varying task demands. Based on prior research, we predicted that increasing perceptual task difficulty should lead to adaptive changes in stimulus coding: task-relevant category information should be stronger, while task-irrelevant exemplar-level stimulus information should become weaker, reflecting a focus on the behaviorally relevant category information. Counter to our expectations, however, we found no evidence for adaptive changes in category coding. We did find weakened coding at the exemplar-level within categories however, demonstrating that task-irrelevant information is de-emphasized in frontoparietal cortex. These findings reveal adaptive coding of stimulus information at the exemplar-level, highlighting how frontoparietal regions might support behavior even under challenging conditions.

4. Peñalver, J., López-García, D., González-García, C., Aguado-López, B., Górriz, J. & Ruz, M. (2023). Top-down specific preparatory activations for Selective Attention and Perceptual Expectations. NeuroImage, 271, 119960. https://doi.org/10.1016/j.neuroimage.2023.119960

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   Proactive cognition brain models are mainstream nowadays. Within these, preparation is understood as an endogenous, top-down function that takes place prior to the actual perception of a stimulus and improves subsequent behavior. Neuroimaging has shown the existence of such preparatory activity separately in different cognitive domains, however no research to date has sought to uncover their potential similarities and differences. Two of these, often confounded in the literature, are Selective Attention (information relevance) and Perceptual Expectation (information probability). We used EEG to characterize the mechanisms that pre-activate specific contents in Attention and Expectation. In different blocks, participants were cued to the relevance or to the probability of target categories, faces vs. names, in a gender discrimination task. Multivariate Pattern (MVPA) and Representational Similarity Analyses (RSA) during the preparation window showed that both manipulations led to a significant, ramping-up prediction of the relevant or expected target category. However, classifiers trained with data from one condition did not generalize to the other, indicating the existence of unique anticipatory neural patterns. In addition, a Canonical Template Tracking procedure showed that there was stronger anticipatory perceptual reinstatement for relevance than for expectation blocks. Overall, the results indicate that preparation during attention and expectation acts through distinguishable neural mechanisms. These findings have important implications for current models of brain functioning, as they are a first step towards characterizing and dissociating the neural mechanisms involved in top-down anticipatory processing.

5. Palenciano, A., Senoussi, M., Formica, S. & González-García, C. (2023). Canonical template tracking: measuring the activation state of specific neural representations. Frontiers in Neuroimaging, 1,. https://doi.org/10.3389/fnimg.2022.974927

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   Multivariate analyses of neural data have become increasingly influential in cognitive neuroscience since they allow to address questions about the representational signatures of neurocognitive phenomena. Here, we describe Canonical Template Tracking: a multivariate approach that employs independent localizer tasks to assess the activation state of specific representations during the execution of cognitive paradigms. We illustrate the benefits of this methodology in characterizing the particular content and format of task-induced representations, comparing it with standard (cross-)decoding and representational similarity analyses. Then, we discuss relevant design decisions for experiments using this analysis approach, focusing on the nature of the localizer tasks from which the canonical templates are derived. We further provide a step-by-step tutorial of this method, stressing the relevant analysis choices for functional magnetic resonance imaging and magneto/electroencephalography data. Importantly, we point out the potential pitfalls linked to canonical template tracking implementation and interpretation of the results, together with recommendations to mitigate them. To conclude, we provide some examples from previous literature that highlight the potential of this analysis to address relevant theoretical questions in cognitive neuroscience.

2022

1. Sobrado, A., Palenciano, A., González-García, C. & Ruz, M. (2022). The effect of task demands on the neural patterns generated by novel instruction encoding. Cortex, 149, 59-72.

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   Verbal instructions allow fast and optimal implementation of novel behaviors. Previous research has shown that different control-related variables structure neural activity in frontoparietal regions during the encoding of novel instructed tasks. However, it is uncertain whether different task goals modulate the organizing effect of these variables. In this study, we investigated whether the neural encoding of three task-relevant variables (dimension integration, response set complexity and target category) is modulated by implementation and memorization demands. To do so, we combined functional Magnetic Resonance Imaging (fMRI), an instruction-following paradigm and multivariate analyses. We addressed how and where distributed activity patterns encoded the instructions’ variables and the impact of the implementation and memorization demands on the fidelity of these representations. We further explored the nature of the neural code underpinning this process. Our results reveal, first, that the content of to-be-implemented and to-be-memorized instructions is represented in overlapping brain regions, flexibly using a common neural code across tasks. Importantly, they also suggest that preparing to implement the instructions increases the decodability of task-relevant information in frontoparietal areas, in comparison with memorization demands. Overall, our work emphasizes both similarities and differences in task coding under the two contextual demands. These findings qualify the previous understanding of novel instruction processing, suggesting that representing task attributes in a generalizable code, together with the increase in encoding fidelity induced by the implementation goals, could be key mechanisms for proactive control in novel scenarios.

2. Formica, S., González-García, C., Senoussi, M., Marinazzo, D. & Brass, M. (2022). Theta-Phase Connectivity between Medial Prefrontal and Posterior Areas Underlies Novel Instructions Implementation. eNeuro, 9(4).

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   Implementing novel instructions is a complex and uniquely human cognitive ability, which requires the rapid and flexible conversion of symbolic content into a format that enables the execution of the instructed behavior. Preparing to implement novel instructions, as opposed to their mere maintenance, involves the activation of the instructed motor plans, and the binding of the action information to the specific context in which this should be executed. Recent evidence and prominent computational models suggest that this efficient configuration of the system might involve a central role of frontal theta oscillations in establishing top-down long-range synchronization between distant and task-relevant brain areas. In the present EEG study (human subjects, 30 females, 4 males), we demonstrate that proactively preparing for the implementation of novels instructions, as opposed to their maintenance, involves a strengthened degree of connectivity in the theta frequency range between medial prefrontal and motor/visual areas. Moreover, we replicated previous results showing oscillatory features associated specifically with implementation demands, and extended on them demonstrating the role of theta oscillations in mediating the effect of task demands on behavioral performance. Taken together, these findings support our hypothesis that the modulation of connectivity patterns between frontal and task-relevant posterior brain areas is a core factor in the emergence of a behavior-guiding format from novel instructions.

3. Wisniewski, D., Cracco, E., González-García, C. & Brass, M. (2022). Relating free will beliefs and attitudes. Royal Society Open Science, 9(2), 202018. https://doi.org/10.1098/rsos.202018

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   Most people believe in free will, which is foundational for our sense of agency and responsibility. Past research demonstrated that such beliefs are dynamic, and can be manipulated experimentally. Much less is known about free will attitudes (FWAs; do you value free will?), whether they are equally dynamic, and about their relation to free will beliefs (FWBs). If FWAs were strongly positive, people might be reluctant to revise their beliefs even in the face of strong evidence to do so. In this registered report, we developed a novel measure of FWAs and directly related FWBs and attitudes for the first time. We found FWBs and attitudes to be positively related, although to a lesser degree than determinism or dualism beliefs/attitudes. Nevertheless, an experimental manipulation technique aimed at reducing FWBs (Crick text) showed remarkably specific effects on FWBs only, and no effects on FWAs. Overall, these results provide valuable new insights into laypeople’s views on free will by including a novel measure of FWAs. They also provide evidence for the validity of a common experimental technique that has been rightfully criticized in the literature lately.

2021

1. Desender*, K., Teuchies*, M., González-García, C., De Baene, W., Demanet, J. & Brass, M. (2021). Metacognitive Awareness of Difficulty in Action Selection: The Role of the Cingulo-opercular Network. Journal of Cognitive Neuroscience, 33(12), 2512-2522. https://doi.org/10.1162/jocn_a_01773

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   The question whether and how we are able to monitor our own cognitive states (metacognition) has been a matter of debate for decades. Do we have direct access to our cognitive processes, or can we only infer them indirectly based on their consequences? In the current study, we wanted to investigate the brain circuits that underlie the metacognitive experience of fluency in action selection. To manipulate action-selection fluency, we used a subliminal response priming paradigm. On each trial, both male and female human participants additionally engaged in the metacognitive process of rating how hard they felt it was to respond to the target stimulus. Despite having no conscious awareness of the prime, results showed that participants rated incompatible trials (during which subliminal primes interfered with the required response) to be more difficult than compatible trials (where primes facilitated the required response), reflecting metacognitive awareness of difficulty. This increased sense of subjective difficulty was mirrored by increased activity in the rostral cingulate zone and the anterior insula, two regions that are functionally closely connected. Importantly, this reflected activations that were unique to subjective difficulty ratings and were not explained by RTs or prime–response compatibility. We interpret these findings in light of a possible grounding of the metacognitive judgment of fluency in action selection in interoceptive signals resulting from increased effort.

2. Formica, S., González-García, C., Senoussi, M. & Brass, M. (2021). Neural oscillations track the maintenance and proceduralization of novel instructions. NeuroImage, 232, 117870. https://doi.org/10.1016/j.neuroimage.2021.117870

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   Humans are capable of flexibly converting symbolic instructions into novel behaviors. Previous evidence and theoretical models suggest that the implementation of a novel instruction requires the reformatting of its declarative content into an action-oriented code optimized for the execution of the instructed behavior. While neuroimaging research focused on identifying the brain areas involved in such a process, the temporal and electrophysiological mechanisms remain poorly understood. These mechanisms, however, can provide information about the specific cognitive processes that characterize the proceduralization of information. In the present study, we recorded EEG activity while we asked participants to either simply maintain declaratively the content of novel S-R mappings or to proactively prepare for their implementation. By means of time-frequency analyses, we isolated the oscillatory features specific to the proceduralization of instructions. Implementation of the instructed mappings elicited stronger theta activity over frontal electrodes and suppression in mu and beta activity over central electrodes. On the contrary, activity in the alpha band, which has been shown to track the attentional deployment to task-relevant items, showed no differences between tasks. Together, these results support the idea that proceduralization of information is characterized by specific component processes such as orchestrating complex task settings and configuring the motor system that are not observed when instructions are held in a declarative format.

3. Palenciano, A., González-García, C., Houwer, J., Brass, M. & Liefooghe, B. (2021). Exploring the Link between Novel Task Proceduralization and Motor Simulation. Journal of Cognition, 4(1), 57. https://doi.org/10.5334/joc.190

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   Our ability to generate efficient behavior from novel instructions is critical for our adaptation to changing environments. Despite the absence of previous experience, novel instructed content is quickly encoded into an action-based or procedural format, facilitating automatic task processing. In the current work, we investigated the link between proceduralization and motor simulation, specifically, whether the covert activation of the task-relevant responses is used during the assembly of action-based instructions representations. Across three online experiments, we used a concurrent finger-tapping task to block motor simulation during the encoding of novel stimulus-response (S-R) associations. The overlap between the mappings and the motor task at the response level was manipulated. We predicted a greater impairment at mapping implementation in the overlapping condition, where the mappings’ relevant response representations were already loaded by the motor demands, and thus, could not be used in the upcoming task simulation. This hypothesis was robustly supported by the three datasets. Nonetheless, the overlapping effect was not modulated by further manipulations of proceduralization-related variables (preparation demands in Exp.2, mapping novelty in Exp.3). Importantly, a fourth control experiment ruled out that our results were driven by alternative accounts as fatigue or negative priming. Overall, we provided strong evidence towards the involvement of motor simulation during anticipatory task reconfiguration. However, this involvement was rather general, and not restricted to novelty scenarios. Finally, these findings can be also integrated into broader models of anticipatory task control, stressing the role of the motor system during preparation.

4. González-García, C. & He, B. (2021). A Gradient of Sharpening Effects by Perceptual Prior across the Human Cortical Hierarchy. Journal of Neuroscience, 41(1), 167–178. https://doi.org/10.1523/JNEUROSCI.2023-20.2020

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   Prior knowledge profoundly influences perceptual processing. Previous studies have revealed consistent suppression of predicted stimulus information in sensory areas, but how prior knowledge modulates processing higher up in the cortical hierarchy remains poorly understood. In addition, the mechanism leading to suppression of predicted sensory information remains unclear, and studies thus far have revealed a mixed pattern of results in support of either the “sharpening” or “dampening” model. Here, using 7T fMRI in humans (both sexes), we observed that prior knowledge acquired from fast, one-shot perceptual learning sharpens neural representation throughout the ventral visual stream, generating suppressed sensory responses. In contrast, the frontoparietal and default mode networks exhibit similar sharpening of content-specific neural representation, but in the context of unchanged and enhanced activity magnitudes, respectively: a pattern we refer to as “selective enhancement.” Together, these results reveal a heretofore unknown macroscopic gradient of prior knowledge’s sharpening effect on neural representations across the cortical hierarchy. SIGNIFICANCE STATEMENT A fundamental question in neuroscience is how prior knowledge shapes perceptual processing. Perception is constantly informed by internal priors in the brain acquired from past experiences, but the neural mechanisms underlying this process are poorly understood. To date, research on this question has focused on early visual regions, reporting a consistent downregulation when predicted stimuli are encountered. Here, using a dramatic one-shot perceptual learning paradigm, we observed that prior knowledge results in sharper neural representations across the cortical hierarchy of the human brain through a gradient of mechanisms. In visual regions, neural responses tuned away from internal predictions are suppressed. In frontoparietal regions, neural activity consistent with priors is selectively enhanced. These results deepen our understanding of how prior knowledge informs perception.

5. González-García, C., Formica, S., Wisniewski, D. & Brass, M. (2021). Frontoparietal action-oriented codes support novel instruction implementation. NeuroImage, 226, 117608. https://doi.org/10.1016/j.neuroimage.2020.117608

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   A key aspect of human cognitive flexibility concerns the ability to convert complex symbolic instructions into novel behaviors. Previous research proposes that this transformation is supported by two neurocognitive states: an initial declarative maintenance of task knowledge, and an implementation state necessary for optimal task execution. Furthermore, current models predict a crucial role of frontal and parietal brain regions in this process. However, whether declarative and procedural signals independently contribute to implementation remains unknown. We report the results of an fMRI experiment in which participants executed novel instructed stimulus-response associations. We then used a pattern-tracking procedure to quantify the contribution of format-unique signals during instruction implementation. This revealed independent procedural and declarative representations of novel S-Rs in frontoparietal areas, prior to execution. Critically, the degree of procedural activation predicted subsequent behavioral performance. Altogether, our results suggest an important contribution of frontoparietal regions to the neural architecture that regulates cognitive flexibility.

2020

1. González-García, C., García-Carrión, B., López-Benítez, R., Sobrado, A., Acosta, A. & Ruz, M. (2020). Induced affective states do not modulate effort avoidance. Psychological Research, 85(3), 1016–1028. https://doi.org/10.1007/s00426-020-01300-9

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   Recent research reveals that when faced with alternative lines of action, humans tend to choose the less cognitively demanding one, suggesting that cognitive control is intrinsically registered as costly. This idea is further supported by studies showing that the exertion of cognitive control evokes negative affective states. Despite extensive evidence for mood-induced modulations on control abilities, the impact of affective states on the avoidance of cognitive demand is still unknown. Across two well-powered experiments, we tested the hypothesis that negative affective states would increase the avoidance of cognitively demanding tasks. Contrary to our expectations, induced affective states did not modulate the avoidance of demand, despite having an effect on task performance and subjective experience. Altogether, our results indicate that there are limits to the effect of affective signals on cognitive control and that such interaction might depend on specific affective and control settings.

2. Botvinik-Nezer, R., Holzmeister, F., Camerer, C., Dreber, A., Huber, J., Johannesson, M., et al. (2020). Variability in the analysis of a single neuroimaging dataset by many teams. Nature, 582(7810), 84-88.

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   Data analysis workflows in many scientific domains have become increasingly complex and flexible. Here we assess the effect of this flexibility on the results of functional magnetic resonance imaging by asking 70 independent teams to analyse the same dataset, testing the same 9 ex-ante hypotheses1. The flexibility of analytical approaches is exemplified by the fact that no two teams chose identical workflows to analyse the data. This flexibility resulted in sizeable variation in the results of hypothesis tests, even for teams whose statistical maps were highly correlated at intermediate stages of the analysis pipeline. Variation in reported results was related to several aspects of analysis methodology. Notably, a meta-analytical approach that aggregated information across teams yielded a significant consensus in activated regions. Furthermore, prediction markets of researchers in the field revealed an overestimation of the likelihood of significant findings, even by researchers with direct knowledge of the dataset2,3,4,5. Our findings show that analytical flexibility can have substantial effects on scientific conclusions, and identify factors that may be related to variability in the analysis of functional magnetic resonance imaging. The results emphasize the importance of validating and sharing complex analysis workflows, and demonstrate the need for performing and reporting multiple analyses of the same data. Potential approaches that could be used to mitigate issues related to analytical variability are discussed.

3. Vermeylen, L., Wisniewski, D., González-Garcı́a, C., Hoofs, V., Notebaert, W. & Braem, S. (2020). Shared Neural Representations of Cognitive Conflict and Negative Affect in the Medial Frontal Cortex. Journal of Neuroscience, 40(45), 8715–8725. https://doi.org/10.1523/JNEUROSCI.1744-20.2020

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   Influential theories of Medial Frontal Cortex (MFC) function suggest that the MFC registers cognitive conflict as an aversive signal, but no study directly tested this idea. Instead, recent studies suggested that nonoverlapping regions in the MFC process conflict and affect. In this preregistered human fMRI study (male and female), we used MVPAs to identify which regions respond similarly to conflict and aversive signals. The results reveal that, of all conflict- and value-related regions, only the ventral pre-supplementary motor area (or dorsal anterior cingulate cortex) showed a shared neural pattern response to different conflict and affect tasks. These findings challenge recent conclusions that conflict and affect are processed independently, and provide support for integrative views of MFC function.SIGNIFICANCE STATEMENT Multiple theories propose that the MFC, and the dorsal ACC in particular, integrates information related to suboptimal outcomes from different psychological domains (e.g., cognitive control and negative affect) with the aim of adaptively steering behavior. In contrast to recent studies in the field, we provide evidence for the idea that cognitive control and negative affect are integrated in the MFC by showing that a classification algorithm trained on discerning cognitive control (conflict vs no conflict) can predict affect (negative vs positive) in the voxel pattern response of the dorsal ACC/pre-SMA.

4. Cracco*, E., González-García*, C., Hussey, I., Braem, S. & Wisniewski, D. (2020). Cultural pressure and biased responding in free will attitudes. Royal Society Open Science, 7(8), 191824. https://doi.org/10.1098/rsos.191824

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   Whether you believe free will exists has profound effects on your behaviour, across different levels of processing, from simple motor action to social cognition. It is therefore important to understand which specific lay theories are held in the general public and why. Past research largely focused on investigating free will beliefs (FWB, ‘Do you think free will exists?’), but largely ignored a second key aspect: free will attitudes (FWA, ‘Do you like/value will?’). Attitudes are often independently predictive of behaviour, relative to beliefs, yet we currently know very little about FWAs in the general public. One key issue is whether such attitudes are subject to biased, socially desirable responding. The vast majority of the general public strongly believes in the existence of free will, which might create cultural pressure to value free will positively as well. In this registered report, we used a very large (N = 1100), open available dataset measuring implicit and explicit attitudes towards free will and determinism to address this issue. Our results indicate that both explicit and implicit attitudes towards free will are more positive than attitudes towards determinism. We also show that people experience cultural pressure to value free will, and to devalue determinism. Yet, we found no strong evidence that this cultural pressure affected either implicit or explicit attitudes in this dataset.

5. Díaz-Gutiérrez, P., Arco, J., Alguacil, S., González-García, C. & Ruz, M. (2020). Neural representations of social valence bias economic interpersonal choices. Neuropsychologia, 147, 107584. https://doi.org/10.1016/j.neuropsychologia.2020.107584

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   Prior personal information is highly relevant during social interactions. Such knowledge aids in the prediction of others, and it affects choices even when it is unrelated to actual behaviour. In this investigation, we aimed to study the neural representation of positive and negative personal expectations, how these impact subsequent choices, and the effect of mismatches between expectations and encountered behaviour. We employed functional Magnetic Resonance Imaging in combination with a version of the Ultimatum Game (UG) where participants were provided with information about their partners’ moral traits previous to receiving their fair or unfair offers. Univariate and multivariate analyses revealed the implication of the supplementary motor area (SMA) and inferior frontal gyrus (IFG) in the representation of expectations about the partners in the game. Further, these regions also represented the valence of these expectations, together with the ventromedial prefrontal cortex (vmPFC). Importantly, the performance of multivariate classifiers in these clusters correlated with a behavioural choice bias to accept more offers following positive descriptions, highlighting the impact of the valence of the expectations on participants’ economic decisions. Altogether, our results suggest that expectations based on social information guide future interpersonal decisions and that the neural representation of such expectations in the vmPFC is related to their influence on behaviour.

6. Formica, S., González-García, C. & Brass, M. (2020). The effects of declaratively maintaining and proactively proceduralizing novel stimulus-response mappings. Cognition, 201, 104295. https://doi.org/10.1016/j.cognition.2020.104295

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   Working memory (WM) allows for the maintenance and manipulation of information when carrying out ongoing tasks. Recent models propose that representations in WM can be either in a declarative format (as content of thought) or in a procedural format (in an action-oriented state that drives the cognitive operation to be performed). Current views on the implementation of novel instructions also acknowledge this distinction, assuming these are first encoded as declarative content, and then reformatted into an action-oriented procedural representation upon task demands. Although it is widely accepted that WM has a limited capacity, little is known about the reciprocal costs of maintaining instructions in a declarative format and transforming them in an action code. In a series of three experiments, we asked participants to memorize two or four S-R mappings (i.e., declarative load), and then selected a subset of them by means of a retro-cue to trigger their reformatting into an action-oriented format (i.e., procedural load). We measured the performance in the implementation of the proceduralized mapping and in the declarative recall of the entire set of memorized mappings, to test how the increased load on one component affected the functioning of the other. Our results showed a strong influence of declarative load on the processing of the procedural component, but no effects in the opposite direction. This pattern of results suggests an asymmetry in the costs of maintenance and manipulation in WM, at least when procedural representations cannot be retrieved from long term memory and need to be reformatted online. The available resources seem to be first deployed for the maintenance of all the task-relevant declarative content, and proceduralization takes place to the extent the system can direct attention to the relevant instruction.

7. Van der Biest, M., Cracco, E., Wisniewski, D., Brass, M. & González-García, C. (2020). Investigating the effect of trustworthiness on instruction-based reflexivity. Acta Psychologica, 207, 103085. https://doi.org/10.1016/j.actpsy.2020.103085

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   Unlike other species, humans are capable of rapidly learning new behavior from a single instruction. While previous research focused on the cognitive processes underlying the rapid, automatic implementation of instructions, the fundamentally social nature of instruction following has remained largely unexplored. Here, we investigated whether instructor trustworthiness modulates instruction implementation using both explicit and reflexive measures. In a first preregistered study, we validated a new paradigm to manipulate the perceived trustworthiness of two different virtual characters and showed that such a manipulation reliably induced implicit associations between the virtual characters and trustworthiness attributes. Moreover, we show that trustworthy instructors are followed more frequently and faster. In two additional preregistered experiments, we tested if trustworthiness towards the instructor influenced the cognitive processes underlying instruction implementation. While we show that verbally conveyed instructions led to automatic instruction implementation, this effect was not modulated by the trustworthiness of the instructor. Thus, we succeeded to design and validate a novel trustworthiness manipulation (Experiment 1) and to create a social variant of the instruction-based reflexivity paradigm (Experiments 2 and 3). However, this instruction-based reflexivity effect was not modulated by the instructors’ trustworthiness.

8. Kostandyan, M., Park, H., Bundt, C., González-García, C., Wisniewski, D., Krebs, R., et al. (2020). Are all behavioral reward benefits created equally? An EEG-fMRI study. NeuroImage, 215, 116829. https://doi.org/10.1016/j.neuroimage.2020.116829

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   Reward consistently boosts performance in cognitive tasks. Although many different reward manipulations exist, systematic comparisons are lacking. Reward effects on cognitive control are usually studied using monetary incentive delay (MID; cue-related reward information) or stimulus-reward association (SRA; target-related reward information) tasks. While for MID tasks, evidence clearly implicates reward-triggered global increases in proactive control, it is unclear how reward effects arise in SRA tasks, and in how far such mechanisms overlap during task preparation and target processing. Here, we address these questions with simultaneous EEG-fMRI using a Stroop task with four different block types. In addition to MID and SRA blocks, we used an SRA-task modification with reward-irrelevant cues (C-SRA) and regular reward-neutral Stroop-task blocks. Behaviorally, we observed superior performance for all reward conditions compared to Neutral, and more pronounced reward effects in the SRA and C-SRA blocks, compared to MID blocks. The fMRI data showed similar reward effects in value-related areas for events that signaled reward availability (MID cues and (C-)SRA targets), and comparable reward modulations in cognitive-control regions for all targets regardless of block type. This result pattern was echoed by the EEG data, showing clear markers of valuation and cognitive control, which only differed during task preparation, whereas reward-related modulations during target processing were again comparable across block types. Yet, considering only cue-related fMRI data, C-SRA cues triggered preparatory control processes beyond reward-unrelated MID cues, without simultaneous modulations in typical reward areas, implicating enhanced task preparation that is not directly driven by a concurrent neural reward-anticipation response.

9. González-García, C., Formica, S., Liefooghe, B. & Brass, M. (2020). Attentional prioritization reconfigures novel instructions into action-oriented task sets. Cognition, 194, 104059. https://doi.org/10.1016/j.cognition.2019.104059

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   An astonishing aspect of human cognitive flexibility concerns the ability to efficiently convert complex symbolic instructions into novel behaviors. In such ability, the rapid transformation of relevant content into action plans is particularly crucial as it allows for reflexive, automatic-like execution of merely instructed task sets. However, little is known about the mechanisms that give rise to this transformation. In the current study, we test the hypothesis that novel instructions held in working memory are reformatted into action-oriented representations when selective attention prioritizes their content. To do so, we devised a paradigm in which participants first encoded 4 S-R mappings and later, a retro-cue selected two of them. We first found that participants can benefit from retro-cues during the implementation of novel task-sets. Then, across two preregistered experiments, we observed that cued mappings (but not uncued ones) induced intention-based reflexivity, suggesting that only these entered an action-oriented state. Altogether, our results reveal that selective attention prioritizes relevant novel instructed content, playing an important role in its prospective reformatting into an action-bound task set.

2019

1. Palenciano, A., González-García, C., Arco, J. & Ruz, M. (2019). Transient and Sustained Control Mechanisms Supporting Novel Instructed Behavior. Cerebral Cortex, 29(9), 3948-3960. https://doi.org/10.1093/cercor/bhy273

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   The success of humans in novel environments is partially supported by our ability to implement new task procedures via instructions. This complex skill has been associated with the activity of control-related brain areas. Current models link fronto-parietal and cingulo-opercular networks with transient and sustained modes of cognitive control, based on observations during repetitive task settings or rest. The current study extends this dual model to novel instructed tasks. We employed a mixed design and an instruction-following task to extract phasic and tonic brain signals associated with the encoding and implementation of novel verbal rules. We also performed a representation similarity analysis to capture consistency in task-set encoding within trial epochs. Our findings show that both networks are involved while following novel instructions: transiently, during the implementation of the instruction, and in a sustained fashion, across novel trials blocks. Moreover, the multivariate results showed that task representations in the cingulo-opercular network were more stable than in the fronto-parietal one. Our data extend the dual model of cognitive control to novel demanding situations, highlighting the high flexibility of control-related regions in adopting different temporal profiles.

2. Flounders, M., González-García, C., Hardstone, R. & He, B. (2019). Neural dynamics of visual ambiguity resolution by perceptual prior. eLife, 8, e41861. https://doi.org/10.7554/eLife.41861

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   Past experiences have enormous power in shaping our daily perception. Currently, dynamical neural mechanisms underlying this process remain mysterious. Exploiting a dramatic visual phenomenon, where a single experience of viewing a clear image allows instant recognition of a related degraded image, we investigated this question using MEG and 7 Tesla fMRI in humans. We observed that following the acquisition of perceptual priors, different degraded images are represented much more distinctly in neural dynamics starting from \textasciitilde500 ms after stimulus onset. Content-specific neural activity related to stimulus-feature processing dominated within 300 ms after stimulus onset, while content-specific neural activity related to recognition processing dominated from 500 ms onward. Model-driven MEG-fMRI data fusion revealed the spatiotemporal evolution of neural activities involved in stimulus, attentional, and recognition processing. Together, these findings shed light on how experience shapes perceptual processing across space and time in the brain.

3. Palenciano, A., González-García, C., Arco, J., Pessoa, L. & Ruz, M. (2019). Representational Organization of Novel Task Sets during Proactive Encoding. Journal of Neuroscience, 39(42), 8386–8397. https://doi.org/10.1523/JNEUROSCI.0725-19.2019

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   Recent multivariate analyses of brain data have boosted our understanding of the organizational principles that shape neural coding. However, most of this progress has focused on perceptual visual regions (Connolly et al., 2012), whereas far less is known about the organization of more abstract, action-oriented representations. In this study, we focused on humans’ remarkable ability to turn novel instructions into actions. While previous research shows that instruction encoding is tightly linked to proactive activations in frontoparietal brain regions, little is known about the structure that orchestrates such anticipatory representation. We collected fMRI data while participants (both males and females) followed novel complex verbal rules that varied across control-related variables (integrating within/across stimuli dimensions, response complexity, target category) and reward expectations. Using representational similarity analysis (Kriegeskorte et al., 2008), we explored where in the brain these variables explained the organization of novel task encoding, and whether motivation modulated these representational spaces. Instruction representations in the lateral PFC were structured by the three control-related variables, whereas intraparietal sulcus encoded response complexity and the fusiform gyrus and precuneus organized its activity according to the relevant stimulus category. Reward exerted a general effect, increasing the representational similarity among different instructions, which was robustly correlated with behavioral improvements. Overall, our results highlight the flexibility of proactive task encoding, governed by distinct representational organizations in specific brain regions. They also stress the variability of motivation-control interactions, which appear to be highly dependent on task attributes, such as complexity or novelty.SIGNIFICANCE STATEMENT In comparison with other primates, humans display a remarkable success in novel task contexts thanks to our ability to transform instructions into effective actions. This skill is associated with proactive task-set reconfigurations in frontoparietal cortices. It remains yet unknown, however, how the brain encodes in anticipation the flexible, rich repertoire of novel tasks that we can achieve. Here we explored cognitive control and motivation-related variables that might orchestrate the representational space for novel instructions. Our results showed that different dimensions become relevant for task prospective encoding, depending on the brain region, and that the lateral PFC simultaneously organized task representations following different control-related variables. Motivation exerted a general modulation upon this process, diminishing rather than increasing distances among instruction representations.

2018

1. González-García, C., Flounders, M., Chang, R., Baria, A. & He, B. (2018). Content-specific activity in frontoparietal and default-mode networks during prior-guided visual perception. eLife, 7, e36068. https://doi.org/10.7554/eLife.36068

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   How prior knowledge shapes perceptual processing across the human brain, particularly in the frontoparietal (FPN) and default-mode (DMN) networks, remains unknown. Using ultra-high-field (7T) functional magnetic resonance imaging (fMRI), we elucidated the effects that the acquisition of prior knowledge has on perceptual processing across the brain. We observed that prior knowledge significantly impacted neural representations in the FPN and DMN, rendering responses to individual visual images more distinct from each other, and more similar to the image-specific prior. In addition, neural representations were structured in a hierarchy that remained stable across perceptual conditions, with early visual areas and DMN anchored at the two extremes. Two large-scale cortical gradients occur along this hierarchy: first, dimensionality of the neural representational space increased along the hierarchy; second, prior’s impact on neural representations was greater in higher-order areas. These results reveal extensive and graded influences of prior knowledge on perceptual processing across the brain.

2. Arco, J., González-García, C., Díaz-Gutiérrez, P., Ramírez, J. & Ruz, M. (2018). Influence of activation pattern estimates and statistical significance tests in fMRI decoding analysis. Journal of Neuroscience Methods, 308, 248-260. https://doi.org/10.1016/j.jneumeth.2018.06.017

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   The use of Multi-Voxel Pattern Analysis (MVPA) has increased considerably in recent functional magnetic resonance imaging (fMRI) studies. A crucial step consists in the choice of a method for the estimation of responses. However, a systematic comparison of the different estimation alternatives and their adequacy to predominant experimental design is missing. In the current study we compared three pattern estimation methods: Least-Squares Unitary (LSU), based on run-wise estimation, Least-Squares All (LSA) and Least-Squares Separate (LSS), which rely on trial-wise estimation. We compared the efficiency of these methods in an experiment where sustained activity needed to be isolated from zero-duration events as well as in a block-design approach and in a event-related design. We evaluated the sensitivity of the t-test in comparison with two non-parametric methods based on permutation testing: one proposed in Stelzer et al. (2013), equivalent to performing a permutation in each voxel separately and the Threshold-Free Cluster Enhancement. LSS resulted the most accurate approach to address the large overlap of signal among close events in the event-related designs. We found a larger sensitivity of Stelzer’s method in all settings, especially in the event-related designs, where voxels close to surpass the statistical threshold with the other approaches were now marked as informative regions. Our results provide evidence that LSS is the most accurate approach for unmixing events with different duration and large overlap of signal. This is consistent with previous studies showing that LSS handles large collinearity better than other methods. Moreover, Stelzer’s potentiates this better estimation with its large sensitivity.

2017

1. González-García, C., Arco, J., Palenciano, A., Ramírez, J. & Ruz, M. (2017). Encoding, preparation and implementation of novel complex verbal instructions. NeuroImage, 148, 264-273. https://doi.org/10.1016/j.neuroimage.2017.01.037

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   Verbal instructions allow humans to acquire and implement complex novel rules in few seconds. A major question that remains elusive is how the brain represents this information prior to successful task execution. In this experiment, we studied the brain regions involved in representing categorical stimulus information during the encoding of novel instructions, their preparation and also their implementation, as well as the relation of the fidelity of these representations to observable behavior. To do so, we devised a novel instructions paradigm to delimitate these three stages. Using univariate and multivariate analyses of functional magnetic resonance data, our study revealed that the semantic content (faces or letters) of complex novel instructions can be decoded several seconds before the onset of a target, as soon as instructions are encoded. Crucially, the quality of the information represented in domain-general and category-selective regions correlated with subsequent behavioral performance. This suggests that the rapid transformation of novel instructions into coherent behavior is supported by control mechanisms that use available, relevant information about the current rule prior to its execution. In addition, our results highlight the relation between these control processes and others such as prospective memory and maintenance of future intentions.

2. Palenciano, A., Díaz-Gutiérrez, P., González-García, C. & Ruz, M. (2017). Neural mechanisms of cognitive control / Mecanismos neurales de control cognitivo. Studies in Psychology, 38(2), 311-337. https://doi.org/10.1080/02109395.2017.1305060

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   Understanding the neural basis of cognitive control is a central issue in cognitive neuroscience, given its core importance for the flexibility that characterizes human behaviour. This review integrates the main findings in the field, underscoring the role of fronto-parietal regions in both proactive (representing tasks in anticipation to prepare the system for action) and reactive (detecting and resolving conflicts in processing) control. In addition, we review the dynamics of interaction between these areas and other brain regions in the range of slow frequencies. Finally, we highlight central questions in the field that have yet to be answered.

2016

1. González-García, C., Mas-Herrero, E., Diego-Balaguer, R. & Ruz, M. (2016). Task-specific preparatory neural activations in low-interference contexts. Brain Structure and Function, 221(8), 3997 – 4006. https://doi.org/10.1007/s00429-015-1141-5

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   How the brain prepares for forthcoming events is a pivotal question in human neuroscience. In the last years, several studies have suggested that expectations of perceiving upcoming stimuli engage relevant perceptual areas. Similarly, some experiments manipulating the task to be performed with targets have also found pre-activations in task-related brain areas. However, the usual configuration of this type of paradigms entails high levels of interference and/or working memory load, together with a small set of target stimuli. We designed a cued task paradigm in which interference was reduced to a minimum, as evidenced by behavioral indices of performance, and that included a high number of targets to avoid their anticipation. This was achieved using a large set of univalent target stimuli preceded by fully valid cues in a functional magnetic resonance imaging experiment. We found category-specific patterns of activity in which semantic cues engaged the left inferior frontal gyrus whereas spatial cues preactivated the right superior parietal lobe. Together with functional connectivity analyses, the activation maps showed the specific involvement of semantic and spatial processes upon the presentation of the cues that are coherent with previous literature. Our results thus suggest that even in contexts of low interference that prevent the anticipation of specific targets, our brain takes advantage of current information to deal with upcoming demands. © 2015, Springer-Verlag Berlin Heidelberg.

2015

1. González-García, C., Tudela, P. & Ruz, M. (2015). Unconscious biases in task choices depend on conscious expectations. Consciousness and Cognition, 37, 44-56. https://doi.org/10.1016/j.concog.2015.08.001

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   Recent studies highlight the influence of non-conscious information on task-set selection. However, it has not yet been tested whether this influence depends on conscious settings, as some theoretical models propose. In a series of three experiments, we explored whether non-conscious abstract cues could bias choices between a semantic and a perceptual task. In Experiment 1, we observed a non-conscious influence on task-set selection even when perceptual priming and cue-target compound confounds did not apply. Experiments 2 and 3 showed that, under restrictive conditions of visibility, cues only biased task selection when the conscious task-setting mindset led participants to search for information during the time period of the cue. However, this conscious strategy did not modulate the effect found when a subjective measure of consciousness was used. Altogether, our results show that the configuration of the conscious mindset determines the potential bias of non-conscious information on task-set selection.

2014

1. González-García, C., Tudela, P. & Ruz, M. (2014). Functional magnetic resonance imaging: a critical analysis of its technical, statistical and theoretical implications in human neuroscience. Revista de neurologia, 58(7), 318—325.

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   The use of functional magnetic resonance imaging (fMRI) has represented an important step forward for the neurosciences. Nevertheless, it has also been subject to rather a lot of criticism. Aim: To study the most widespread criticism against fMRI, so that researchers who are starting to use it may know the different elements that must be taken into account to be able to take a suitable approach to this technique. The fact that fMRI allows brain activity to be observed makes it a very attractive and useful tool, and its use has grown exponentially since the last decade of the 20th century. At the same time, criticism against its use has become especially fierce. Most of this scepticism can be classified into aspects related with the technique and physiology, the analysis of data and their theoretical interpretation. In this study we will review the main arguments defended in each of these three areas, as well as looking at whether they are well-founded or not. Additionally, this work is also intended as a reference for novel researchers when it comes to identifying elements that must be taken into account as they approach fMRI. Despite the fact that fMRI is one of the most interesting options for observing the brain available today, its correct utilisation requires a great deal of control and knowledge. Even so, today most of the criticism it receives no longer has any solid foundation on which to stand.