13 research outputs found
Recommended from our members
Visual search for facing and non-facing people: the effect of actor inversion
In recent years, there has been growing interest in how human observers perceive, attend to, and recall, social interactions viewed from third-person perspectives. One of the interesting findings to emerge from this new literature is the search advantage for facing dyads. When hidden amongst pairs of individuals facing in the same direction, pairs of individuals arranged front-to-front are found faster in visual search tasks than pairs of individuals arranged back-to-back. Interestingly, the search advantage for facing dyads appears to be sensitive to the orientation of the people depicted. While front-to-front target pairs are found faster than back-to-back targets when target and distractor pairings are shown upright, front-to-front and back-to-back targets are found equally quickly when pairings are shown upside-down. In the present study, we sought to better understand why the search advantage for facing dyads is sensitive to the orientation of the people depicted. To begin, we show that the orientation sensitivity of the search advantage is seen with dyads constructed from faces only, and from bodies with the head and face occluded. We replicate these effects using two different visual search paradigms. We go on to show that individual faces and bodies, viewed in profile, produce strong attentional cueing effects when shown upright, but not when presented upside-down. Together with recent evidence that arrows arranged front-to-front also produce the search advantage for facing dyads, these findings support the view that the search advantage is a by-product of the ability of constituent elements to direct observersâ visuo-spatial attention
Nonlinear transduction of emotional facial expression
To create neural representations of external stimuli, the brain performs a number of processing steps that transform its inputs. For fundamental attributes, such as stimulus contrast, this involves one or more nonlinearities that are believed to optimise the neural code to represent features of the natural environment. Here we ask if the same is also true of more complex stimulus dimensions, such as emotional facial expression. We report the results of three experiments combining morphed facial stimuli with electrophysiological and psychophysical methods to measure the function mapping emotional expression intensity to internal response. The results converge on a nonlinearity that accelerates over weak expressions, and then becomes compressive for stronger expressions, similar to the situation for lower level stimulus properties. We further demonstrate that the nonlinearity is not attributable to the morphing procedure used in stimulus generation
Recommended from our members
Does developmental prosopagnosia impair identification of other-ethnicity faces?
Current approaches to the diagnosis of developmental prosopagnosia emphasise the perception and identification of same-ethnicity faces. This convention ensures that perceptual impairment arising from developmental prosopagnosia can be distinguished from problems arising from a lack of visual experience with particular facial ethnicities â the so-called âOther-Ethnicity Effectâ. The present study sought to determine whether the perceptual difficulties seen in developmental prosopagnosia â diagnosed using same-ethnicity faces â extend to other-ethnicity faces. First, we sought to determine whether a group of Caucasian developmental prosopagnosics (N = 15) and typical Caucasian controls (N = 30) had similar experience with same- and other-ethnicity faces during development. All participants therefore completed a contact questionnaire that enquired about their experience of Caucasian, Black, and East Asian faces, at different developmental stages. Importantly, the two groups described very similar levels of visual experience with other-ethnicity faces. Second, we administered a sequential matching task to measure participantsâ ability to discriminate same- (Caucasian) and other-ethnicity (Black, East Asian) faces. Relative to the experience-matched controls, the prosopagnosics were less accurate at discriminating both same- and other-ethnicity faces, and we found no evidence of disproportionate impairment for same-ethnicity faces. Given that the prosopagnosics and controls had similar opportunity to develop visual expertise for other-ethnicity faces, these results indicate that developmental prosopagnosia impairs recognition of both same- and other-ethnicity faces. The fact that developmental prosopagnosia affects the perception of both same- and other-ethnicity faces suggests that different facial ethnicities engage similar visual processing mechanisms. Our findings support the view that susceptibility to developmental prosopagnosia, and a lack of contact with other-ethnicity faces, contribute independently to the poor recognition of other-ethnicity faces
Recommended from our members
Is developmental prosopagnosia best characterised as an apperceptive or mnemonic condition?
Traditionally, developmental prosopagnosia (DP) has been thought of as an apperceptive
condition that hinders individualsâ ability to encode face structure. However, several authors
have recently raised the possibility that many DPs may be able to form accurate percepts,
but be unable to maintain those percepts over time. The present study sought to distinguish
these possibilities. In our first experiment 16 DPs and 22 typical controls completed a
delayed match-to-sample task with face and car stimuli, with a retention interval of 1-second
(low demand) or 6-seconds (high demand). As expected, the participants with DP were
worse than the controls at face matching, and were disproportionately impaired at matching
faces relative to cars. However, the relative degree of impairment seen in the DPs did not
interact with retention interval; they exhibited similar levels of impairment when matching
faces with 1- and 6-second delays. Next, we compared the performance of 72 DPs and 54
typical controls on the Cambridge Face Perception Test (CFPT), a task that measures face
perception ability in a way that minimises the memory demands. As expected, we found
that the DPs were impaired at the group level. This difference was not attributable to a few
individuals with an apperceptive profile; rather we found evidence that the distribution of
CFPT scores seen in the DP sample was shifted relative to that of typical controls. Some
heterogeneity is likely in any neurodevelopmental population, and DP is no different.
Generally, however, these findings suggest that selective STFM impairment may be
relatively uncommon in this population. Instead, deficits of perceptual encoding may play
a larger role in DP than currently acknowledged
Recommended from our members
The influence of anxiety on the initial selection of emotional faces presented in binocular rivalry
Neurocognitive theories of anxiety predict that threat-related information can be evaluated before attentional selection, and can influence behaviour differentially in high anxious compared to low anxious individuals. We investigate this further by presenting emotional and neutral faces in an adapted binocular rivalry paradigm. We show that the initial selection of emotional faces presented in binocular rivalry is highly influenced by self-reported state and trait anxiety-level. Heightened anxiety was correlated with increased perception of angry and fearful faces, and decreased perception of happy expressions. These results are consistent with recent evidence of involuntary selection of threat in anxiety
Recommended from our members
Impaired grouping of ambient facial images in autism
Ambient facial images depict individuals from a variety of viewing angles, with a range of poses and expressions, under different lighting conditions. Exposure to ambient images is thought to help observers form robust representations of the individuals depicted. Previous results suggest that autistic people may derive less benefit from exposure to this exemplar variation than non-autistic people. To date, however, it remains unclear why. One possibility is that autistic individuals possess atypical perceptual learning mechanisms. Alternatively, however, the learning mechanisms may be intact, but receive low-quality perceptual input from face encoding processes. To examine this second possibility, we investigated whether autistic people are less able to group ambient images of unfamiliar individuals based on their identity. Participants were asked to identify which of four ambient images depicted an oddball identity. Each trial assessed the grouping of different facial identities, thereby preventing face learning across trials. As such, the task assessed participantsâ ability to group ambient images of unfamiliar people. In two experiments we found that matched non-autistic controls correctly identified the oddball identities more often than our autistic participants. These results imply that poor face learning from variation by autistic individuals may well be attributable to low-quality perceptual input, not aberrant learning mechanisms per se
Recommended from our members
On the âspecialâ status of emotional faces... Comment on Yang, Hong, and Blake (2010)
A wealth of literature suggests that emotional faces are given special status as visual objects: Cognitive models suggest that emotional stimuli, particularly threat-relevant facial expressions such as fear and anger, are prioritized in visual processing and may be identified by a subcortical âquick and dirtyâ pathway in the absence of awareness (Tamietto & de Gelder, 2010). Both neuroimaging studies (Williams, Morris, McGlone, Abbott, & Mattingley, 2004) and backward masking studies (Whalen, Rauch, Etcoff, McInerney, & Lee, 1998) have supported the notion of emotion processing without awareness. Recently, our own group (Adams, Gray, Garner, & Graf, 2010) showed adaptation to emotional faces that were rendered invisible using a variant of binocular rivalry: continual flash suppression (CFS, Tsuchiya & Koch, 2005). Here we (i) respond to Yang, Hong, and Blake's (2010) criticisms of our adaptation paper and (ii) provide a unified account of adaptation to facial expression, identity, and gender, under conditions of unawareness
Recommended from our members
Faces and awareness: low-level, not emotional factors determine perceptual dominance
Threat-relevant stimuli such as fear faces are prioritized by the human visual system. Recent research suggests that this prioritization begins during unconscious processing: a specialized (possibly subcortical) pathway evaluates the threat relevance of visual input, resulting in preferential access to awareness for threat stimuli. Our data challenge this claim. We used a continuous flash suppression (CFS) paradigm to present emotional face stimuli outside of awareness. It has been shown using CFS that salient (e.g., high contrast) and recognizable stimuli (faces, words) become visible more quickly than less salient or less recognizable stimuli. We found that although fearful faces emerge from suppression faster than other faces, this was wholly explained by their low-level visual properties, rather than their emotional content. We conclude that, in the competition for visual awareness, the visual system prefers and promotes unconscious stimuli that are more âface-like,â but the emotional content of a face has no effect on stimulus salienc
Recommended from our members
Autistic adults exhibit typical sensitivity to changes in interpersonal distance
The visual processing differences seen in autism often impede individualsâ visual perception of the social world. It has recently been suggested that pairs of individuals shown facing each other â so-called âfacing dyadsâ â engage a form a visual processing similar to that recruited by faces. Given that many autistic people experience difficulties when asked to identify faces, we reasoned that autistic individuals may also make less accurate judgements about facing dyads. We examined whether groups of autistic and non-autistic participants differed in their ability to judge interpersonal distance â a key visual feature of facing dyads. Contrary to our hypothesis, the autistic and non-autistic participants displayed similar ability to detect changes in interpersonal distance. As expected, however, our autistic participants showed worse face recognition than our non-autistic participants. These findings suggest that the visual processing of faces may be selectively impaired in autism without affecting the perception of facing dyads