Where You Look Matters for Body Perception: Preferred Gaze Location Contributes to the Body Inversion Effect

Abstract

The Body Inversion Effect (BIE; reduced visual discrimination performance for inverted compared to upright bodies) suggests that bodies are visually processed configurally; however, the specific importance of head posture information in the BIE has been indicated in reports of BIE reduction for whole bodies with fixed head position and for headless bodies. Through measurement of gaze patterns and investigation of the causal relation of fixation location to visual body discrimination performance, the present study reveals joint contributions of feature and configuration processing to visual body discrimination. Participants predominantly gazed at the (body-centric) upper body for upright bodies and the lower body for inverted bodies in the context of an experimental paradigm directly comparable to that of prior studies of the BIE. Subsequent manipulation of fixation location indicates that these preferential gaze locations causally contributed to the BIE for whole bodies largely due to the informative nature of gazing at or near the head. Also, a BIE was detected for both whole and headless bodies even when fixation location on the body was held constant, indicating a role of configural processing in body discrimination, though inclusion of the head posture information was still highly discriminative in the context of such processing. Interestingly, the impact of configuration (upright and inverted) to the BIE appears greater than that of differential preferred gaze locations.

The perception of (naked only) bodies and faceless heads relies on holistic processing: Evidence from the inversion effect

“…This interpretation has also been received support by functional MRI (fMRI) evidence showing that the BIE is mediated by face‐sensitive, and not body‐sensitive, brain regions (Brandman & Yovel, ). More recent behavioural evidence, in line with our results, has however showed a BIE (albeit of smaller magnitude) for headless bodies, thus positing for body‐specific holistic mechanisms (Arizpe, McKean, Tsao, & Chan, ; Robbins & Coltheart, ; Susilo et al ., ). Converging evidence comes from Susilo et al .…”

“…This interpretation has also been received support by functional MRI (fMRI) evidence showing that the BIE is mediated by face-sensitive, and not body-sensitive, brain regions (Brandman & Yovel, 2010). More recent behavioural evidence, in line with our results, has however showed a BIE (albeit of smaller magnitude) for headless bodies, thus positing for body-specific holistic mechanisms (Arizpe, McKean, Tsao, & Chan, 2017;Robbins & Coltheart, 2012;Susilo et al, 2013). Converging evidence comes from Susilo et al (2013) that have demonstrated in patients with acquired prosopagnosia (i.e., the impairment in recognizing people by their faces) the existence of body inversion effects (with and without heads), but not the face-inversion effect.…”

“…A new finding from our study is that minimally clothed bodies (with and without a head) only lead to a BIE. Previous research, on the other hand, did show inversion effects for clothed bodies (Arizpe et al ., ; Barra, Senot, & Auclair, ; Robbins & Coltheart, ). Despite speculative in nature, it is likely that divergences between the current and previous studies might be (at least partially) driven by methodological differences.…”

Measuring objectification through the Body Inversion Paradigm: Methodological issues

“…The inversion effect observed in the IBRT is probably highly dependent on the specific set of stimuli and on other, so-far unknown, aspects of the administration conditions. Taken together, in line with perceptual research on BIE [33][34][35], these results call for more research to understand which are the aspects of human stimuli that most strongly impact inversion, and they suggest that high methodological attention should be paid in designing research using the IBRT (for instance, one should always use at least two different stimulus sets to ensure that the results are not due to idiosyncratic characteristics of materials).…”

“…Others insist that "the extensive understanding that we have about mechanisms that may underlie the face inversion effect may not be necessarily applicable to account for the BIE, until further research is completed with human bodies" ([34] p. 766]. Some others contend that the head posture plays a central role in explaining the BIE (e.g., [35]).…”