We use psychophysics and neuroimaging (fMRI, M-EEG) in adults and children of different cultures and cognitive skills to study the relation between perception and symbolic cognition. Our research spans over two main areas: (1) semantic processing and spatial navigation, and (2) math skills and quantity perception. See a brief description of our work as well as some selected publications below:
(1) Semantic processing and spatial navigation
Description: we study how the meaning of concrete words/concepts is constructed, stored and retrieved. We use imaging and behavioral methods to test the hypothesis that word meaning is an emergent property of the simultaneous re-activation of both single and multiple conjoint features of the objects referred to by the words.
The single sensory features that define the meaning of concrete words (e.g. individual dimensions of the semantic space - the prototypical size, shape, sund of objects) are represented independently sensory-specific cortical regions. During word reading these representations emerge very early in time (by 200 ms) and in parallel.
A second type of representation that characterize semantic is one that integrates different sensory-motor features in a single conjunctive multidimensional space. Those representations emerge in the temporal, frontal, and parietal lobe, and are encoded through a variety of neuronal codes that also support spatial navigation: grid-like, distance-dependent, and direction-specific.
People: M. Piazza
Collaborators: S. Viganò, M.Buiatti, V.Rubino, R.Bottini
1. Grid-like and distance codes for representing word meaning in the human brain
S. Viganò, V. Rubino, A. Di Soccio, M. Buiatti, & M. Piazza (2021). NeuroImage, 232 (2021), 117876
Figure 1: Stimulus space and experimental design
Figure 2: Grid-Like code, model, analyses (model-based RSA), and results
Figure 3: Distance code, model, analyses (fMRI adaptation), results
2. “Word meaning in the ventral visual path: a perceptual to conceptual gradient of semantic coding”
V. Borghesani, F. Pedregosa, A. Amadon, E. Eger, M. Buiatti, & M. Piazza. (2016). NeuroImage. 143, 128-140.
(2) Math skills and quantity perception
Description: Humans share with other animals the ability to extract and mentally represent discrete (number) and continuous (area, density) quantities from their physical environment. We study those skills, their neuronal correlates, their development, and their role in grounding higher level cognitive skills, such as formal symbolic maths. We also study dyscalculia with the aim of understanding whether and how impaired perceptual quantity-related skills may hinder the ability to properly acquire knowledge and skills in symbolic number processing.
People: M. Piazza, A. Karami, E. Eccher, M. Amalric
Collaborations: S. Dehaene, E. Eger, V. Izard, D. Hyde, G.Decarli
1. "Learning to focus on number”
M. Piazza, V. De Feo, S. Panzeri, and S. Dehaene. (2018). Cognition, 181, 35-45.
With age and education, children become increasingly accurate in processing numerosity. This developmental trend is often interpreted as a progressive refinement of the mental representation of number. Here we provide empirical and theoretical support for an alternative possibility, the filtering hypothesis, which proposes that development primarily affects the ability to focus on the relevant dimension of number and to avoid interference from irrelevant but often co-varying quantitative dimensions. Data from the same numerical comparison task in adults and children of various levels of numeracy, including Mundurucú Indians and western dyscalculics, show that, as predicted by the filtering hypothesis, age and education primarily increase the ability to focus on number and filter out potentially interfering information on the non-numerical dimensions. These findings can be captured by a minimal computational model where learning consists in the training of a multivariate classifier whose discrimination boundaries get progressively aligned to the task-relevant dimension of number. This view of development has important consequences for education.
Figure 1. The filtering and sharpening hypotheses