Heads First: Visual Aftereffects Reveal Hierarchical Integration of Cues to Social Attention.

Sarah Cooney,Nuala Brady,Holly Dignam,Nicholas Seow Chiang Price

doi:10.1371/journal.pone.0135742

Abstract

Determining where another person is attending is an important skill for social interaction that relies on various visual cues, including the turning direction of the head and body. This study reports a novel high-level visual aftereffect that addresses the important question of how these sources of information are combined in gauging social attention. We show that adapting to images of heads turned 25° to the right or left produces a perceptual bias in judging the turning direction of subsequently presented bodies. In contrast, little to no change in the judgment of head orientation occurs after adapting to extremely oriented bodies. The unidirectional nature of the aftereffect suggests that cues from the human body signaling social attention are combined in a hierarchical fashion and is consistent with evidence from single-cell recording studies in nonhuman primates showing that information about head orientation can override information about body posture when both are visible.

Highlights

Facilitated by a number of visual cues, such as eye-gaze, pointing gestures, head orientation and body posture, the ability to discriminate the direction of another person’s attention is an important skill in social interaction
Studies employing visual adaptation almost invariably examine these cues in isolation, while studies investigating the important question of how these cues are integrated typically employ the cueing and interference paradigms
Same-category adaptation was strong whereas there was no evidence of cross-category adaptation. (See S1 Fig). This lack of cross-category adaptation may reflect the proposed hierarchy whereby cues to social attention from the head may override those of the body

Summary

Introduction

Facilitated by a number of visual cues, such as eye-gaze, pointing gestures, head orientation and body posture, the ability to discriminate the direction of another person’s attention is an important skill in social interaction. Lawson and colleagues [8] report a viewpoint aftereffect in the perception of body orientation such that after adapting to bodies that are oriented either to the right or left participants perceive forward facing test bodies as turned in the opposite direction. A very similar viewpoint aftereffect is reported in the perception of human heads [9] In both studies the pattern of aftereffects is consistent with a multichannel model in which separate mechanisms code the direction of left, right and forward facing bodies or heads. Assuming different cues to social attention are commonly coded at some level of visual processing [10] we expected that adapting to extremely oriented heads would influence the perception of body orientation. Assuming a hierarchical coding of cues to social attention such that cues from head orientation override those from body orientation processing [10], the effects of cross-category adaptation were expected to be weaker or absent

Methods

Participants

Procedure

Results

Discussion