Multisensory Texture Perception in Individuals with Williams Syndrome.

The sensory profile of people with Williams syndrome (WS) is characterised by atypical visual and auditory perceptions that affect their daily lives and learning. However, no research has been carried out on the haptic perception, in particular in multisensory (visual and haptic) situations. The aim of this study was to evaluate the communication of texture information from one modality to the other in people with WS. Children and adults with WS were included, as well as typically developing (TD) participants matched on chronological age (TD-CA), and TD children matched on mental age (TD-MA). All participants (N = 69) completed three matching tasks in which they had to compare two fabrics (same or different): visual, haptic and visuo-haptic. When the textures were different, the haptic and visual performances of people with WS were similar to those of TD-MA participants. Moreover, their visuo-haptic performances were lower than those of the two TD groups. These results suggest a delay in the acquisition of multisensory transfer abilities in individuals with WS. A positive link between MA and visual and visuo-haptic abilities only in people with WS suggests that they could benefit from an early intervention to develop their abilities to process and transfer multisensory information.

Adults and 5-year-old children draw rectangles and triangles around a prototype but not in the golden ratio.

This study uses a production task to probe the representations of two geometrical shape categories (rectangles and triangles) in adults and children before the onset of geometry instruction. We specifically assessed whether drawings of these shapes would average around a prototype and whether the prototypical side-length ratio of the shapes would be situated in the range of the 'golden ratio', as it has been reported in the perception domain. We asked 78 adults and 68 five-year-old children to draw one rectangle and one triangle. In both populations, the prototypical rectangle was horizontally oriented with a ratio between sides superior to the 'golden' value of 1.62. For the triangle, both children and adults tended to produce horizontal acute isosceles triangles with a ratio inferior to the golden value. These findings suggest that adults' and children's shape categories of triangles and rectangles are organized around a prototypical shape, but the characteristics of this prototype may differ to a certain extent with the ones observed in previous perceptual tasks. Implications of this perception/production dissociation for length concept development, as well as the potential origins of these prototypes are discussed.