Subitizing object parts reveals a second stage of individuation

Open Practices Statement The experimental programs, data and code for data analysis for all studies are made available publicly available on OSF at https://osf.io/wv9hq/. None of the experiments were preregistered.Peer reviewedPublisher PD

Estimating neural activity from visual areas using functionally defined EEG templates

This work was supported by BBSRC grant BB/N018516/1 and Wellcome Trust ISSF 204821/Z/16/Z.Electroencephalography (EEG) is a common and inexpensive method to record neural activity in humans. However, it lacks spatial resolution making it difficult to determine which areas of the brain are responsible for the observed EEG response. Here we present a new easy-to-use method that relies on EEG topographical templates. Using MRI and fMRI scans of 50 participants, we simulated how the activity in each visual area appears on the scalp and averaged this signal to produce functionally defined EEG templates. Once created, these templates can be used to estimate how much each visual area contributes to the observed EEG activity. We tested this method on extensive simulations and on real data. The proposed procedure is as good as bespoke individual source localization methods, robust to a wide range of factors, and has several strengths. First, because it does not rely on individual brain scans, it is inexpensive and can be used on any EEG data set, past or present. Second, the results are readily interpretable in terms of functional brain regions and can be compared across neuroimaging techniques. Finally, this method is easy to understand, simple to use and expandable to other brain sources.Publisher PDFPeer reviewe

Neural responses to apparent motion can be predicted by responses to non-moving stimuli

Funding: UK BBSRC grant BB/N018516/1 (JMA).When two objects are presented in alternation at two locations, they are seen as a single object moving from one location to the other. This apparent motion (AM) percept is experienced for objects located at short and also at long distances. However, current models cannot explain how the brain integrates information over large distances to create such long-range AM. This study investigates the neural markers of AM by parcelling out the contribution of spatial and temporal interactions not specific to motion. In two experiments, participants’ EEG was recorded while they viewed two stimuli inducing AM. Different combinations of these stimuli were also shown in a static context to predict an AM neural response where no motion is perceived. We compared the goodness of fit between these different predictions and found consistent results in both experiments. At short-range, the addition of the inhibitory spatial and temporal interactions not specific to motion improved the AM prediction. However, there was no indication that spatial or temporal non-linear interactions were present at long-range. This suggests that short- and long-range AM rely on different neural mechanisms. Importantly, our results also show that at both short- and long-range, responses generated by a moving stimulus could be well predicted from conditions in which no motion is perceived. That is, the EEG response to a moving stimulus is simply a combination of individual responses to non-moving stimuli. This demonstrates a dissociation between the brain response and the subjective percept of motion.Publisher PDFPeer reviewe

A simple rule to describe interactions between visual categories

Acknowledgements: We thank Prof Thomas Palmeri for helpful comments on a previous version of the manuscript. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Peer Review The peer review history for this article is available at https://publons.com/publon/10.1111/ejn.14890. DATA AVAILABILITY STATEMENT The programmes used to run the two experiments and the collected data are available on the OSF website (OSF.IO/ASB4E). A substantial proportion of the stimuli were sourced from the copyright protected Corel database and thus cannot be shared on OSF.Peer reviewedPublisher PD

Competition between emotional faces in visuospatial working memory.

Visuospatial working memory (VSWM) helps track the identity and location of people during social interactions. Previous work showed better VSWM when all faces at encoding displayed a happy compared to an angry expression, reflecting a prosocial preference for monitoring who was where. However, social environments are not typically uniform, and certain expressions may more strongly compete for and bias face monitoring according to valence and/or arousal properties. Here, we used heterogeneous encoding displays in which two faces shared one emotion and two shared another, and asked participants to relocate a central neutral probe face after a blank delay. When considering the emotion of the probed face independently of the co-occurring emotion at encoding, an overall happy benefit was replicated. However, accuracy was modulated by the nonprobed emotion, with a relocation benefit for angry over sad, happy over fearful, and sad over happy faces. These effects did not depend on encoding fixation time, stimulus arousal, perceptual similarity, or response bias. Thus, emotional competition for faces in VSWM is complex and appears to rely on more than simple arousal- or valence-biased mechanisms. We propose a “social value (SV)” account to better explain when and why certain emotions may be prioritized in VSWM

Fundamental units of numerosity estimation

We are grateful to two anonymous reviewers and Michele Fornaciai for suggesting alternative explanations (low-level features, attentional prioritisation effect) and ideas about mechanisms (divisive normalisation). Open Access via Elsevier agreementPeer reviewedPublisher PD

Theta-phase dependent neuronal coding during sequence learning in human single neurons

This work was supported by grants from the French Agence Nationale de la Recherche (ANR-12-JSH2-0004-01 and ANR AI-REPS–18-CE37-0007-01), the Fyssen foundation, and the Université Paul Sabatier, Toulouse, France (BQR, 2009 and Appel à Projets de Recherche Labellisés, 2013), to L.R., the European Research Council (ERC Consolidator Grant P-Cycles number 614244), the French Agence Nationale de la Recherche (ANR OSCI-DEEP ANR-19-NEUC-0004), and an ANITI (Artificial and Natural Intelligence Toulouse Institute) Research Chair (ANR-19-PI3A-0004) to R.V., the Studienstiftung des Deutschen Volkes (German Academic Scholarship Foundation) to B.Z., the European Union (ERC Grant Agreement n. 339490 “Cortic_al_gorithms” and grant agreements 720270 and 785907 “Human Brain Project SGA1 and SGA2’) and the Friends Foundation of the Netherlands Institute for Neuroscience to P.R.R.The ability to maintain a sequence of items in memory is a fundamental cognitive function. In the rodent hippocampus, the representation of sequentially organized spatial locations is reflected by the phase of action potentials relative to the theta oscillation (phase precession). We investigated whether the timing of neuronal activity relative to the theta brain oscillation also reflects sequence order in the medial temporal lobe of humans. We used a task in which human participants learned a fixed sequence of pictures and recorded single neuron and local field potential activity with implanted electrodes. We report that spikes for three consecutive items in the sequence (the preferred stimulus for each cell, as well as the stimuli immediately preceding and following it) were phase-locked at distinct phases of the theta oscillation. Consistent with phase precession, spikes were fired at progressively earlier phases as the sequence advanced. These findings generalize previous findings in the rodent hippocampus to the human temporal lobe and suggest that encoding stimulus information at distinct oscillatory phases may play a role in maintaining sequential order in memory.Publisher PDFPeer reviewe

Subitizing object parts reveals a second stage of individuation

Humans can efficiently individuate a small number of objects. This subitizing ability is thought to be a consequence of limited attentional resources. However, how and what is selected during the individuation process remain outstanding questions. We investigated these in four experiments by examining if parts of objects are enumerated as efficiently as distinct objects in the presence and absence of distractor objects. We found that distractor presence reduced subitizing efficiency. Crucially, parts connected to multiple objects were enumerated less efficiently than independent objects or parts connected to a single object. These results argue against direct individuation of parts and show that objecthood plays a fundamental role in individuation. Objects are selected first and their components are selected in subsequent steps. This reveals that individuation operates sequentially over multiple levels

Subitizing object parts reveals a second stage of individuation

Humans can efficiently individuate a small number of objects. This subitizing ability is thought to be a consequence of limited attentional resources. However, how and what is selected during the individuation process remain outstanding questions. We investigated these in three experiments by examining if parts of objects are enumerated as efficiently as distinct objects in the presence and absence of distractor objects. We found that distractor presence reduced subitizing efficiency. Crucially, parts connected to multiple objects were enumerated less efficiently than independent objects or parts connected to a single object. These results argue against direct individuation of parts and show that objecthood plays a fundamental role in individuation. Objects are selected first and their components are selected in subsequent steps. This reveals that individuation operates sequentially over multiple levels