Abstract
Previous evidence demonstrates that the posterior superior temporal sulcus (pSTS) plays a central role in the perception of social interactions (Georgescu et al., 2014). However, it is unknown whether this region discriminates between different types of interactions. Additionally, pSTS activation is also modulated by other social processes, such as theory of mind (ToM) attribution (Schurz et al., 2014) and body perception (Deen et al., 2015), and it is unclear whether these processes are necessary to perceive interactive behaviour. Using interactive shape stimuli (i.e. 2 animated circles that convey intentional behaviour) along with an orthogonal response task to limit explicit mentalizing, two hypotheses were posed: 1) pSTS activity will differentiate interactions from non-interactions; 2) pSTS activity will differentiate cooperative from competitive interactions. Multivariate support vector machine analysis was implemented for whole-brain searchlight analysis and within 3 regions of interest (ROI): The pSTS and temporo-parietal junction (TPJ) were defined with independent localizer tasks (i.e. human interaction and false belief tasks, respectively) to determine whether these regions differed in response to interactive shape stimuli; following searchlight analysis, an additional post-hoc ROI – the posterior superior temporal gyrus (pSTG) – was independently defined. For the cooperation vs. competition contrast, searchlight analysis revealed a single cluster in the right pSTG, along with above-chance classification in the pSTG and pSTS (>55%; ps < .05), but not TPJ. For the interaction vs. non-interaction contrast, searchlight analysis revealed a bilateral network along with right pSTS activity, and above-chance classification (>59%; ps < .05) in all 3 ROIs. These findings cannot easily be attributed to human body information or explicit mentalizing (i.e. interaction sensitivity was relatively weaker in TPJ, and the orthogonal task limited explicit ToM inferences); therefore, these results implicate the posterior superior temporal cortex as a central region in the visual perception of interactive behavior.
Meeting abstract presented at VSS 2017