Chiara Tortelli, Irene Senna, Paola Binda, Marc O. Ernst
Investigating the trajectory of the development of local/global preference in vision and haptics
BraYn Conference 2021
Several studies have investigated local/global perception in vision, but less attention has been given to touch. Here we explore its developmental path and compare performance for tactile and visual stimuli. Forty-four typically developing individuals between 6 to 26 years completed a similarity judgment task on 3D printed stimuli made of local elements (squares or triangles) arranged to form a global shape (square or triangle). Stimuli were presented in groups of three: a target and two probes. One of the probes had the same global shape as the target stimulus, the other had the same local shape, and participants reported which one was more similar to the target. Responses were categorized as “global” when the chosen stimulus had the same global configuration as the target and “local” otherwise. Across trials, we varied the size and density of the local stimuli and the modality with which they were presented: tactile (presented to blindfolded participants) or visual (participants could not touch the stimuli). The results suggest a three-way interaction between age, size and modality. For stimuli made of small local elements, the proportion of global responses increased with age, in both vision and touch. The same happened for stimuli made of large local elements presented visually; however, when these were presented haptically, there was no global preference, irrespectively of age. As a consequence, local-global preferences in vision and touch became systematically more different in adults than in children. At the same time, children were far more likely than adults to display idiosyncratic differences between vision and touch (variable in sign and amplitude across individuals and conditions, yet reliable across repetitions). These results confirm that local/global preferences develop with age and so does the coordination between vision and touch, although the development of the two modalities may follow partially distinct trajectories.