Dissociating intuitive physics from intuitive psychology: Evidence from Williams syndrome

Abstract

Prior work suggests that our understanding of how things work ("intuitive physics") and how people work ("intuitive psychology") are distinct domains of human cognition. Here we directly test the dissociability of these two domains by investigating knowledge of intuitive physics and intuitive psychology in adults with Williams syndrome (WS) - a genetic developmental disorder characterized by severely impaired spatial cognition, but relatively spared social cognition. WS adults and mental-age matched (MA) controls completed an intuitive physics task and an intuitive psychology task. If intuitive physics is a distinct domain (from intuitive psychology), then we should observe differential impairment on the physics task for individuals with WS compared to MA controls. Indeed, adults with WS performed significantly worse on the intuitive physics than the intuitive psychology task, relative to controls. These results support the hypothesis that knowledge of the physical world can be disrupted independently from knowledge of the social world.

Keywords: Naïve physics; Naïve psychology; Physical reasoning; Social perception; Williams-Beuren syndrome (WS).

Figure 1

(A) Intuitive Physics Task. Participants watched 6s videos of unstable towers of blocks and had to judge whether the tower would fall on the red side (e.g., left image) or the green side (e.g., right image). (B) Intuitive Psychology Task. Participants watched 6s videos of children playing with toys and had to judge whether the child was playing alone (e.g., left image) or with an off-screen friend who could not be seen (e.g., right image).

Figure 2

Average performance of WS Adults, MA Controls (average age = 8) (Experiment 1), and 4 year olds (Experiment 2) on the Intuitive Physics and Intuitive Psychology tasks. Error bars indicate 95% confidence intervals.

Figure 3

Average performance of WS Adults, MA Controls (average age = 8), and 4 year olds on each difficulty level (easy, medium, hard) of the Intuitive Physics task. Error bars indicate 95% confidence intervals.