How do we process multiple-person scenario?
(Project THEMPO – ERC StG)
Trani, Puglia. Photo by Giovanni Albore
The abilities to quickly recognize our conspecifics and to quickly understand what they are doing is a fundamental task for our social life. In the past decades, cognitive neuroscientists have gained important knowledge on these abilities, by studying how the humans recognizes faces and bodies, and infers goals and intentions behind a given facial expression or body movement. Faces and bodies are the physical actors of social life; but social life is only realized through the relations between those entities. In sum, faces and bodies are socially relevant in that they carry the potential to realize social relations.
Our recent work that demonstrates human vision is sensitive to socially relevant spatial relations as much as to social entities. A set of behavioral phenomena has revealed the existence of highly efficient visual mechanisms for detection and recognition of multiple bodies in spatial relations that cue social interaction (e.g., face-to-face). Another set of results based on neuroimaging data (fMRI and EEG) has shown that spatial relations among bodies matter in visual perception, so much that a body is represented in profoundly different ways depending on whether or not it faces toward another, and is reciprocated. This research is revealing uncharted functions of vision and the building blocks of social cognition.
Over the past decades, cognitive neuroscientists have gathered evidence showing that a human face or a human body is special to our mind/brain, that is, it is processed with the highest priority and more efficiently than other objects in the environment. But how does the system behave when, instead on one person, we see two (or more) people?
We have set up a behavioral paradigm, based on backward masking, to measure the potency of stimuli in gaining access to awareness. In this paradigm, stimuli are presented at perceptual threshold so that sometimes the visual system fails to process them. The rationale is that, under conditions of low-visibility, stimuli that are privileged by the human visual system are more likely to pass the threshold to be recognized correctly, than other stimuli. In this way, we have shown that two bodies facing one another were more likely to be recognized than the same two bodies facing away away from each other (Papeo et al., 2017). Moreover, we have measured the inversion effect (IE), the cost on recognition, of seeing bodies upside-down as opposed to upright, as an index of visual sensitivity: the greater the visual sensitivity, the greater the IE. IE was increased for facing (vs. nonfacing) dyads, whether the head/face direction was visible or not, which implies that visual sensitivity concerns two bodies, not just two faces/heads. Moreover, the difference in IE for facing vs. nonfacing dyads disappeared when one body was replaced by another object. This implies selective sensitivity to a body facing another body, as opposed to a body facing anything. Finally, the IE was reduced when reciprocity was eliminated (one body faced another but the latter faced away) (Papeo & Abassi, 2019). Thus, the visual system is sensitive selectively to dyadic configurations that approximate a prototypical social exchange with two bodies spatially close and mutually accessible to one another.
This research adds to a body of results, showing that the human perceptual system is tuned to entities with social value, and go beyond this showing that visual perception is sensitive not only to socially-relavant entities but also to socially-relevant relations between those entities.
Papeo L., Stein T., Soto-Faraco S. (2017). The two-body inversion effect. Psychological Science, 28(3), 369-379 » PDF
Papeo L., Abassi E. (2019). Seeing social events: The visual specialization for dyadic human-human interactions. the Journal of Experimental Psychology: Human Perception and Performance, XX(X), XX-XX » PDF
A new asymmetry in the visual search for people among people
Visual search study
Papeo L., Goupil N. & Soto-Faraco S. (2019). Visual search for people among people. Psychological science 30(10), 1483-1496 »Preprint on Psyarxiv
Two-body representation in visual cortex
fMRI results coming soon 🙂
Abassi E. & Papeo L. (in prep). Neural sensitivity to a two-body shape Submitted for publication, XX(X), XXX » PDF