16 research outputs found
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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 observers’ 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
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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 – the so-called ‘Other-Ethnicity Effect’. The present study sought to determine whether the perceptual difficulties seen in developmental prosopagnosia – diagnosed using same-ethnicity faces – 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 participants’ 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
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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 individuals’ 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
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Poor face recognition predicts social anxiety in autism: a short report
In the present study, we sought to examine whether face recognition problems impact the social anxiety experienced by autistic people. Many autistic people – perhaps between 15% and 30% – exhibit severe face recognition problems that closely resemble developmental prosopagnosia. At present, however, little is known about the psychosocial consequences of these difficulties. Autistic participants (N = 60) with varying degrees of face recognition ability completed two measures of face recognition (the original and Australian variants of the Cambridge Face Memory test), a measure of social anxiety (the Social Interaction Anxiety Scale), and a bespoke survey that enquired about individuals’ experiences of face recognition and social interaction. Relative to autistic individuals with average or above-average face recognition, autistic individuals with poor face recognition described significantly higher levels of social anxiety. Moreover, more than half our participants felt that poor face recognition hampered their social interaction, while over a third thought that poor face recognition had undermined their efforts to make friends. These initial results suggest that poor face recognition may be an important determinant of social anxiety in autism
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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
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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 participants’ 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
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Perceptual sensitivity to changes in interpersonal distance when observing social interactions: the effects of dyad arrangement and orientation
In recent years, there has been growing interest in how we perceive dyadic interactions between people. It has been proposed that pairs of individuals shown upright and face-to-face recruit a form of configural processing, similar to that engaged by upright faces. This processing is thought to aid the detection and interpretation of social interactions. Dyadic arrangements shown back-to-back or upside-down are not thought to engage configural dyad processing. One of the key advantages conveyed by configural face processing is greater sensitivity to the spatial relationships between facial features when faces are viewed upright, than when viewed upside-down. If upright dyads arranged face-to-face engage similar configural processing that is not engaged by non-facing or inverted dyads, participants should therefore exhibit disproportionate sensitivity to the spatial relations between the constituent actors under these conditions. In four well-powered experiments, we find no evidence for this prediction: participants exhibited similar levels of sensitivity to changes in interpersonal distance regardless of whether dyads were shown upright or inverted, face-to-face or back-to-back. In contrast, we observe clear evidence that upright presentation affords greater sensitivity to inter-feature spatial relationships (interocular distance) when viewing faces. These results suggest that any configural processing engaged by upright facing dyads likely differs qualitatively from that engaged by upright faces
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Autistic adults have insight into their relative face recognition ability
The PI20 is a self-report questionnaire that assesses the presence of lifelong face recognition difficulties. The items on this scale ask respondents to assess their face recognition ability relative to the rest of the population, either explicitly or implicitly. Recent reports suggest that the PI20 scores of autistic participants exhibit little or no correlation with their performance on the Cambridge Face Memory Test – a key measure of face recognition ability. These reports are suggestive of a meta-cognitive deficit whereby autistic individuals are unable to infer whether their face recognition is impaired relative to the wider population. In the present study, however, we observed significant correlations between the PI20 scores of 77 autistic adults and their performance on two variants of the Cambridge Face Memory Test. These findings indicate that autistic individuals can infer whether their face recognition ability is impaired. Consistent with previous research, we observed a wide spread of face recognition abilities within our autistic sample. While some individuals approached ceiling levels of performance, others met the prevailing diagnostic criteria for developmental prosopagnosia. This variability showed little or no association with non-verbal intelligence, autism severity, or the presence of co-occurring alexithymia or ADHD