Perceived face size in healthy adults

Abstract

Perceptual body size distortions have traditionally been studied using subjective, qualitative measures that assess only one type of body representation–the conscious body image. Previous research on perceived body size has typically focused on measuring distortions of the entire body and has tended to overlook the face. Here, we present a novel psychophysical method for determining perceived body size that taps into implicit body representation. Using a two-alternative forced choice (2AFC), participants were sequentially shown two life-size images of their own face, viewed upright, upside down, or tilted 90°. In one interval, the width or length dimension was varied, while the other interval contained an undistorted image. Participants reported which image most closely matched their own face. An adaptive staircase adjusted the distorted image to hone in on the image that was equally likely to be judged as matching their perceived face as the accurate image. When viewed upright or upside down, face width was overestimated and length underestimated, whereas perception was accurate for the on-side views. These results provide the first psychophysically robust measurements of how accurately healthy participants perceive the size of their face, revealing distortions of the implicit body representation independent of the conscious body image.

My true face: Unmasking one's own face representation

“…We also found that all face features were perceived to be much wider than their true size, confirming the tendency to perceive the face as wider (D'Amour & Harris, 2017;Fuentes et al, 2013). Width overestimation may be associated with representation in the somatosensory cortex.…”

“…In contrast, face research has been predominantly focused on face recognition across sensory modalities (Casey & Newell, 2005), whilst few attempts have been made to study the underlying body model as per other body parts. In previous studies, there is a predominant use of depictive tasks that rely on visual information, for example, pointing to different locations for size estimation on a computer screen (Fuentes, Runa, Blanco, Orvalho, & Haggard, 2013), drawing the head's outline (Bianchi, Savardi, & Bertamini, 2008) or using visual estimation tasks (D'Amour & Harris, 2017;Felisberti & Musholt, 2014;Linkenauger et al, 2015). In general, the representation of the face is distorted, showing a tendency to overestimate width and underestimate length (D'Amour & Harris, 2017;Fuentes et al, 2013;Linkenauger et al, 2015).…”

Body Size Judgments at 17 ms: Evidence From Perceptual and Attitudinal Body Image Indexes

“…The emphasis on explicit aspects of body image may be highlighted by a specific methodological choice directed to assess conscious body stimuli on visual research (e.g., Barra et al, 2017;Leehr et al, 2018). This literature is more commonly associated with the presentation of face stimuli in the field of face perception aiming at the discrimination of emotions (Thompson and Wilson, 2012;D'Amour and Harris, 2017). Examples of research comprise Stoddard et al (2017) research on the recognition of emotions and early signs of psychopathology, and Bedford et al (2017) study on the typical development of emotion recognition in infants.…”

The perceived size of the implicit representation of the dorsum and palm of the hand

“…All these sensory processes and tasks require knowledge about how the brain represents the hand and therefore can be impacted by any size or shape distortions that may occur. We recently developed a novel psychophysical method for determining perceived body size that provides an objective, unbiased, implicit measure of the body representation in the brain [15,16]. Here, we examine the perceived size of the dorsum and palm of the hand to a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 determine and compare baseline size accuracy when the hand is viewed in various orientations and to compare the representation of the two sides of the hand.…”

“…The hand is more likely to be identified as belonging to the self when viewed in a familiar orientation [31,32]. Our previous rationale for varying the orientation of the face while assessing its perceived size [15] had to do with unique properties that the face lacks compared to much of the rest of the body especially the hands, properties such as interaction, movement, and visual perspective. We used the opposite line of thought in the current study.…”