| Publications of year 2025 |
| Articles in journals |
| Abstract: | Number sense, the ability to rapidly estimate object quantities in a visual scene without precise counting, is a crucial cognitive capacity found in humans and many other animals. Recent studies have identified artificial neurons tuned to numbers of items in biologically inspired vision models, even before training, and proposed these artificial neural networks as candidate models for the emergence of number sense in the brain. But real-world numerosity perception requires abstraction from the properties of individual objects and their contexts, unlike the simplified dot patterns used in previous studies. Using novel synthetically generated photorealistic stimuli, we show that deep convolutional neural networks optimized for object recognition encode information on approximate numerosity across diverse objects and scene types, which could be linearly read out from distributed activity patterns of later convolutional layers of different network architectures tested. In contrast, untrained networks with random weights failed to represent numerosity with abstractness to other visual properties and instead captured mainly low-level visual features. Our findings emphasize the importance of using complex, naturalistic stimuli to investigate mechanisms of number sense in both biological and artificial systems, and they suggest that the capacity of untrained networks to account for early-life numerical abilities should be reassessed. They further point to a possible, so far underappreciated, contribution of the brain's ventral visual pathway to representing numerosity with abstractness to other high-level visual properties. |
| Abstract: | Mathematics is an underexplored domain of human cognition. While many studies have focused on subsets of math concepts such as numbers, fractions, or geometric shapes, few have ventured beyond these elementary domains. Here, we attempted to map out the full space of math concepts and to answer two specific questions: can distributed semantic models, such a GloVe, provide a satisfactory fit to human semantic judgements in mathematics? And how does this fit vary with education? We first analyzed all of the French and English Wikipedia pages with math contents, and used a semi-automatic procedure to extract the 1000 most frequent math terms in both languages. In a second step, we collected extensive behavioral judgements of familiarity and semantic similarity between them. About half of the variance in human similarity judgements was explained by vector embeddings that attempt to capture latent semantic structures based on cooccurence statistics. Participants' self-reported level of education modulated familiarity and similarity, allowing us to create a partial hierarchy among high-level math concepts. Our results converge onto the proposal of a map of math space, organized as a database of math terms with information about their frequency, familiarity, grade of acquisition, and entanglement with other concepts. |
| Abstract: | ABSTRACT At the physical level, the experience of pitch has a single determinant: the repetition rate of a waveform in the acoustic signal. Yet, psychologists describe pitch as composed of two perceptual dimensions, height and chroma. Chroma accounts for octave equivalence, whereby sounds with fundamental frequencies at a 1:2 ratio are perceived as sharing the same pitch. A current controversy debates whether chroma is a basic perceptual property dependent on biological constraints or a higher-order cognitive construct shaped by culture. Here, we used high-density electroencephalography (EEG) and time-resolved multivariate pattern analyses to characterize pitch processing in humans at 3 months of age. We found that, when exposed to repetitive sequences of orchestral tones, infants encode two separate pitch-related dimensions automatically and with divergent dynamics. Namely, our classifiers isolated height-specific information from the neural signal rapidly after the onset of the auditory sequences. Beyond approximately 600 ms, the performance of pitch height decoders fell to chance level and did not recover. In contrast, neural patterns displaying octave equivalence were retrieved later in the trial, over multiple time windows throughout the unfolding of the auditory sequence, and after sequence offset. Overall, this study reveals that very early in human development, the pitch of naturally rich tones is processed over two distinct encoding stages, capturing not only their absolute height but also their relative position in the octave. We speculate that separate encoding mechanisms reflect distinct functional roles carried by the two dimensions. |
| Abstract: | Visual numerosity, traditionally linked to the parietal cortex, is now thought to be represented across a broader cortical network, including early visual and associative areas in both streams. However, how numerosity is encoded relative to other visual features remains unclear. We conducted a whole-brain functional magnetic resonance imaging (fMRI) study with thirty-one adults performing a numerosity estimation task on visual sets varying in number, item size, total item area, field area, and density, ensuring tight stimulus control. Using model-based representational similarity analyses, we found numerosity represented independently of other visual properties in early visual areas and amplified in retinotopic and non-retinotopic associative regions across both streams. Dimensionality reduction of BOLD patterns revealed distinct geometries: a one-dimensional representation of numerical rank in early visual and ventral retinotopic areas, and a curved structure encoding rank and distance-to-endpoints in associative dorsal and ventral regions. These results demonstrate distinct neural coding schemes for numerosity across cortical regions. |
| Abstract: | Around the world, teenage boys outperform girls on mathematics tests, and men are more likely to pursue related careers -- despite baby boys showing no superior sense of numbers or grasp of logic. Now, a gigantic study of schoolchildren in France pinpoints that this 'mathematical gender gap' appears during the first year of school. The finding could help to focus efforts to stop girls from falling behind. Boys and girls receive similar maths scores at the start of school, but boys pull ahead of girls after just four months (see 'Watch the mathematics gender gap emerge'). A more dramatic gap in mathematical performance emerges after 12 months of school, according to the analysis, published on 11 June in Nature1. "This paper suggests that the gender inequalities in children's maths performance aren't innate or inevitable," says psychologist Jillian Lauer at the University of Cambridge, UK. "If we want to stop girls from falling behind, we need to focus on their early experiences at school." |
| Abstract: | Abstract Postdiction is a perceptual phenomenon where the perception of an earlier stimulus is influenced by a later one. This effect is commonly studied using the 'rabbit illusion', in which temporally regular, but spatially irregular, stimuli are perceived as equidistant. While previous research has focused on short inter-stimulus intervals (100-200 ms), the role of longer intervals, which may engage late attentional processes, remains unexplored. This study investigates whether postdiction is purely perceptual or also involves attentional mechanisms by using visual stimuli separated by extended intervals. 33 participants (17 females) were assigned to two experimental groups with two different temporal inter-flash intervals (IFI) between stimuli (250 ms: 250-IFI group; 500 ms: 500-IFI). Two stimulation protocols of active transcranial electrical stimulation (tES) and one control condition were tested on the left precuneus/inferior parietal gyrus: (i) transcranial alternating current stimulation (tACS) at the individual alpha frequency (IAF) (IAF-tACS); (ii) transcranial random noise stimulation across the whole alpha band (i.e., 8-12 Hz, Alpha-tRNS) and (iii) a placebo (Sham) stimulation. The postdiction phenomenon was observable in both experimental groups. The participants in the 500-IFI group demonstrated enhanced performance in detecting the illusion during the rabbit illusion task when IAF-tACS was applied. The behavioral results suggest that attentional functions, beyond perceptual ones, play a key role in the postdiction phenomenon. |
| Abstract: | Abstract Temporal landmarks are salient events that structure the way humans think about time. They may be personal events, such as one's birthday, or shared cultural events, such as the COVID-19 pandemic. Due to societal habits, the cyclical weekly structure - for example, working on weekdays, resting on the weekends - helps individuals orient themselves in time. In the "day-of-the-week effect," individuals are faster at reporting which day of the week it is on weekends than they are on weekdays. Herein, we hypothesized that the disruption of social habits during the COVID-19 pandemic lockdowns may have weakened this effect, thereby accounting for the "Blursday" phenomenon. In the current study, speeded responses to the question "What day of the week is it?" were collected online from 1,742 French participants, during and after the lockdown periods. We found that reaction times for days of the weekends remained faster than for weekdays during the lockdown, although the overall reaction times were significantly slower during lockdown. We also found that responses were slower as governmental stringency rules and restrictions in mobility increased. Our results suggest that the weekend landmark remains a stable temporal anchor in French culture despite the experienced temporal distortions induced by the disruption of social habits during the pandemic. We conclude that cultural temporal landmarks shape socially shared temporal cognitive maps. |
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Note that this is not the exhaustive list of publications, but only a selection. Contact the individual authors for complete lists of references.
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