Jennifer A. Walsh

Norm-based coding of facial identity in adults with autism spectrum disorder

It is unclear whether reported deficits in face processing in individuals with autism spectrum disorders (ASD) can be explained by deficits in perceptual face coding mechanisms. In the current study, we examined whether adults with ASD showed evidence of norm-based opponent coding of facial identity, a perceptual process underlying the recognition of facial identity in typical adults. We began with an original face and an averaged face and then created an anti-face that differed from the averaged face in the opposite direction from the original face by a small amount (near adaptor) or a large amount (far adaptor). To test for norm-based coding, we adapted participants on different trials to the near versus far adaptor, then asked them to judge the identity of the averaged face. We varied the size of the test and adapting faces in order to reduce any contribution of low-level adaptation. Consistent with the predictions of norm-based coding, high functioning adults with ASD (n = 27) and matched typical participants (n = 28) showed identity aftereffects that were larger for the far than near adaptor. Unlike results with children with ASD, the strength of the aftereffects were similar in the two groups. This is the first study to demonstrate norm-based coding of facial identity in adults with ASD.

The influences of face inversion and facial expression on sensitivity to eye contact in high-functioning adults with autism spectrum disorders.

We examined the influences of face inversion and facial expression on sensitivity to eye contact in high-functioning adults with and without an autism spectrum disorder (ASD). Participants judged the direction of gaze of angry, fearful, and neutral faces. In the typical group only, the range of directions of gaze leading to the perception of eye contact (the cone of gaze) was narrower for upright than inverted faces. In both groups, the cone of gaze was wider for angry faces than for fearful or neutral faces. These results suggest that in high-functioning adults with ASD, the perception of eye contact is not tuned to be finer for upright than inverted faces, but that information is nevertheless integrated across expression and gaze direction.

Emotion Perception or Social Cognitive Complexity: What Drives Face Processing Deficits in Autism Spectrum Disorder?

Some, but not all, relevant studies have revealed face processing deficits among those with autism spectrum disorder (ASD). In particular, deficits are revealed in face processing tasks that involve emotion perception. The current study examined whether either deficits in processing emotional expression or deficits in processing social cognitive complexity drive face processing deficits in ASD. We tested adults with and without ASD on a battery of face processing tasks that varied with respect to emotional expression processing and social cognitive complexity. Results revealed significant group differences on tasks involving emotional expression processing, but typical performance on a non-emotional but socially complex task. These results support an emotion processing rather than a social complexity explanation for face processing deficits in ASD.

Adults with autism spectrum disorder show evidence of figural aftereffects with male and female faces

The norm-based coding model of face perception posits that face perception involves an implicit comparison of observed faces to a representation of an average face (prototype) that is shaped by experience. Using some methods, observers with autism spectrum disorder (ASD) have shown atypical face perception, but other methods suggest preserved face perception. Here, we used a figural aftereffects paradigm to test whether adults with ASD showed evidence of norm-based coding of faces, and whether they encode separate prototypes for male and female faces, as typical observers do. Following prolonged exposure to distorted faces that differ from their stored prototype, neurotypical adults show aftereffects: their prototype shifts in the direction of the adapting face. We measured aftereffects following adaptation to one distorted gender. There were no significant group differences in the size or direction of the aftereffects; both groups showed sex-selective aftereffects after adapting to expanded female faces but showed aftereffects for both sexes after adapting to contracted face of either sex, demonstrating that adults with and without ASD show evidence of partially dissociable male and female face prototypes. This is the first study to examine sex-selective prototypes using figural aftereffects in adults with ASD and replicates the findings of previous studies examining aftereffects in adults with ASD. The results contrast with studies reporting diminished adaptation in children with ASD.

Afterimage induced neural activity during emotional face perception.

The N170 response differs when positive versus negative facial expressions are viewed. This neural response could be associated with the perception of emotions, or some feature of the stimulus. We used an aftereffect paradigm to clarify. Consistent with previous reports of emotional aftereffects, a neutral face was more likely to be described as happy following a sad face adaptation, and more likely to be described as sad following a happy face adaptation. In addition, similar to previous observations with actual emotional faces, we found differences in the latency of the N170 elicited by the neutral face following sad versus happy face adaptation, demonstrating that the emotion-specific effect on the N170 emerges even when emotion expressions are perceptually different but physically identical. The re-entry of emotional information from other brain regions may be driving the emotional aftereffects and the N170 latency differences.

Disambiguating auditory information causes priming, but not aftereffects, in the perception of ambiguous faces

In five experiments, we used a visual aftereffects paradigm to probe whether emotion- and gender-relevant information presented in the auditory domain would affect the formation of visual aftereffects or would instead create a priming effect. In experiment 1, participants fixated on surprise facial expressions while listening to a story that described the surprise as either happy or sad, and then were asked to classify the expression of a briefly presented neutral face. Subsequently, the identity of the model (experiment 2) and the timing of the auditory presentation (experiment 3) were manipulated. In experiment 4, this approach was extended to judgments of gender. Experiment 5 serves as a control experiment in which the story, but no visual stimuli, was presented during the adaptation phase. In each case results revealed evidence of priming, but no evidence that information in the auditory domain affected the formation of aftereffects.

Emotion perception or social cognitive complexity: What drives face processing deficits in autism spectrum disorder?

Faces convey information about sex, identity, age, ethnic group, and internal emotional state, and typical individuals are expert at encoding and interpreting facial information. Individuals with ASD have difficulties with social perception and cognition, and there has been a great deal of scientific focus on the ability of those individuals with ASDs to processing facial information. Still, there is not a clear consensus as to what the core deficits in face processing are characteristic of ASD. The current study examined whether the anomalies in face processing seen in adults with ASD are better explained as a deficit in processing emotions, or a deficit in processing the complexity of social stimuli. Participants completed a battery of four face processing tasks: identity discrimination, basic expression perception, complex emotion expression, and trustworthiness perception. The tasks either did or did not involve processing facial expressions, and also varied in the level of social cognitive complexity. If the deficits in face processing in ASD are driven by a core deficit in processing emotional expression information, participants with ASD would perform worse on the basic and complex expression perception tasks. In contrast, if their deficit is related to processing socially complex facial information, they would show poorer performance on the complex expression and trustworthiness perception tasks. Results revealed that ASD participants showed worse performance on basic expression recognition task (t(44) = 3.06, p = .004) and the complex expression recognition task t(44) = 4.26, p < .001 compared to typical participants. In contrast, there were no significant group differences in performance on the identification task (t(44) = 1.33, p = .19) or the trustworthy perception task t(44) = .93, p = .36. These results support an emotion processing rather than a social complexity explanation for face processing deficits in ASD. Meeting abstract presented at VSS 2015.