Dyadic interaction processing in the posterior temporal cortex

Abstract

Recent behavioural evidence shows that visual displays of two individuals interacting are not simply encoded as separate individuals, but as an interactive unit that is 'more than the sum of its parts'. Recent functional magnetic resonance imaging (fMRI) evidence shows the importance of the posterior superior temporal sulcus (pSTS) in processing human social interactions, and suggests that it may represent human-object interactions as qualitatively 'greater' than the average of their constituent parts. The current study aimed to investigate whether the pSTS or other posterior temporal lobe region(s): 1) Demonstrated evidence of a dyadic information effect - that is, qualitatively different responses to an interacting dyad than to averaged responses of the same two interactors, presented in isolation, and; 2) Significantly differentiated between different types of social interactions. Multivoxel pattern analysis was performed in which a classifier was trained to differentiate between qualitatively different types of dyadic interactions. Above-chance classification of interactions was observed in 'interaction selective' pSTS-I and extrastriate body area (EBA), but not in other regions of interest (i.e. face-selective STS and mentalizing-selective temporo-parietal junction). A dyadic information effect was not observed in the pSTS-I, but instead was shown in the EBA; that is, classification of dyadic interactions did not fully generalise to averaged responses to the isolated interactors, indicating that dyadic representations in the EBA contain unique information that cannot be recovered from the interactors presented in isolation. These findings complement previous observations for congruent grouping of human bodies and objects in the broader lateral occipital temporal cortex area.

Developmental Changes in Visual Responses to Social Interactions

“…Both adults and children showed significantly greater interaction selectivity in the right pSTS than all other ROIs, and this was supported by the whole-brain findings that show this was the most active region. These findings are consistent with previous accounts that the pSTS -especially in the right hemisphere -is strongly responsive to dyadic social interactions (Georgescu et al, 2014;Isik et al, 2017;Kujala, Carlson, & Hari, 2012a;Lahnakoski et al, 2012;Walbrin et al, 2018;Walbrin & Koldewyn, 2019).…”

“…These results emphasize the important role that this region plays in perceiving and understanding social interactions, but it is also clear that activity in this region does not tell the whole story. Indeed, another line of recent research implicates the complementary functioning of neighbouring extrastriate body area (EBA) in the configural processing of both dynamic (Walbrin & Koldewyn, 2019) and static interacting human dyads . Additionally, responses across posterior-temporal regions, including EBA and pSTS, are sensitive to the apparent congruency of an interacting dyad (Quadflieg et al, 2015).…”

Moving toward versus away from another: how body motion direction changes the representation of bodies and actions in the visual cortex

“…The recruitment of regions associated with processing of social stimuli, and social tasks in general (temporoparietal junction, dorsolateral prefrontal cortex, inferior frontal gyrus, precentral gyrus, and insula), suggests that face-to-face bodies, more than non-facing bodies, might spontaneously trigger some sort of social inference, even in the absence of a semantically specified interaction content. Future research shall address the overlap between the network described here for facing (vs. non-facing) dyads and the network activated by the processing of social interaction contents described elsewhere (Centelles et al 2011;Baldassano et al 2016;Isik et al 2017;Walbrin et al 2018;Walbrin and Koldewyn 2019). Moreover, extending the effective connectivity analysis to other areas responsive to facing (vs. non-facing) dyads will help characterize the relationship (and integration) between the processing of relational cues of interaction (i.e., facingness) in the visual EBA and bm-pSTS, and the processing of social interaction in other, non-visual aspects of the network.…”

FFA and OFA encode distinct types of face identity information

“…It is likely that the pSTS as defined in the present study contains overlapping and interspersed groups of voxels that respond to faces only, voices only, or both faces and voices (Beauchamp et al, 2004) that make the overlapping representational geometry difficult to explain. On the other hand, it is possible that the pSTS represents information about people that we did not consider here, such as idiosyncratic facial movements (Yovel & O'Toole, 2016), emotional and mental states (Thornton et al, 2019), social distance or network position (Parkinson et al, 2014;, or type of social interactions (Walbrin & Koldewyn, 2019). Future studies may need to explore an even richer set of social, perceptual, and stimulus-based models to better characterise responses in the pSTS.…”