Chapter III: Face Preference Decision-Making And Visual Behavior
3.1 Overview
Now that the methodological structure for analysis of the eyetracking data in Chapter II has been discussed, the attention should be turned to the empirical studies in this thesis. Chapter III is composed of two studies that examine face preference and visual behavior. In these studies, we tested people with autism spectrum disorder (ASD) and amygdala lesion patients to address two important questions regarding social processing: 1) do known deficits in objectively evaluating faces also interfere with making subjective decisions about faces? And 2) are the visual behaviors that accompany face preference decisions in controls the same in people with social processing deficits?
There is considerable evidence for abnormal social processing in people with ASD, specifically in the context of objective decision-making, such as identification of familiar faces and recognition of emotional expressions. It remains unknown, however, whether reported deficits in social processing also extend to making preference-based decisions amongst social stimuli, such as those regarding face preference or attractiveness. The aim of the studies in this chapter was to explore the extent to which these known aberrations in social processing interfere with preference decision-making.
We present two studies in ASD and amygdala lesion patients that investigate whether preference decisions for faces are altered in these conditions. Both studies utilized a 2- alternative forced-choice task in which subjects inspected pairs of face stimuli or pairs of non- face stimuli and made a decision about which stimulus they prefer.
In the first study in this chapter, the “Gaze Cascade” study, we examined the link between gaze and preference formation in people with ASD and amygdala lesions. Specifically, we were interested in investigating whether reported deficits in social processing influence the temporal
evolution of preference-based decisions among social stimuli, as well as the eventual outcome of those preference-based decisions. Furthermore, we sought to examine whether the eye movements of people with ASD and amygdala lesions would indicate a fundamentally altered evaluation process when deciding among social stimuli.
In the second study, the “Familiarity versus Novelty” study, we examined the evolution of category-specific preference biases by investigating in high-functioning autism a principle reported in the literature for neurotypicals: the preference for familiar faces over novel faces.
We have seen that repeated visual exposure to a face increases preference for that face, and that the effect is likely linked to how we acquire and develop face expertise. But what happens in a population, such as people with autism, who demonstrate impairments in developing face expertise? In this study, we explored established preference principles for social and non-social stimulus categories that have been observed in controls.
We found that people with ASD and amygdala lesion patients made similar preference decisions as controls in judging face attractiveness in the “Gaze Cascade” study, and that people with ASD demonstrated similar preference biases and visual orienting as controls in the
“Familiarity versus Novelty” tasks. In addition, both ASD and amygdala lesion patients demonstrated a similar visual sampling process, linking preference and attentional orienting.
However, people with ASD displayed two key differences compared to neurotypicals: the ASD group was significantly faster in making preference decisions, and reaction times in the ASD group were insensitive to decision difficulty, particularly for social preference decisions.
We suggest that the known perceptual advantage in ASD, coupled with the absence of higher- order social attributions and diminished interest in social stimuli in ASD, could confer a response time advantage to the ASD group in the face preference tasks. Evidence in the literature is consistent with this possibility and we discuss these points in the Discussion.
Furthermore, it could also be the case that face preference formation is not significantly impaired by the alterations in observed face processing or perhaps even social processing, given that subjective attractiveness judgments do not require the retrieval of social knowledge or high-order mentalizing.
That the ability to form social preferences remains intact in a clinically diagnosed population with putative deficits in social processing suggests that social preference formation is an aspect of social processing that operates by way of a different or perhaps similar but less complex underlying cognitive mechanism than other aspects of social processing. The results contribute to the growing literature, showing that many basic elements of social processing are spared or compensated for, and that social processing impairments in high-functioning autism become more prominent during higher-order complex judgments that require linking perceptual information with relevant social knowledge. In other words, impairments in social cognition that occur earlier in the processing stream could be compensated for, or simply not relevant to, some aspects of social functioning. Indeed, the results from the gaze cascade study and familiarity/novelty studies in this chapter indicate that the mechanism linking gaze to preference formation for faces, and the ability to form preferences about faces as well as maintain those preferences, appears intact in ASD. However, we also discuss evidence that there are underlying differences in the behavioral strategy used by individuals with autism.
The gaze cascade study in ASD has been published as (Gharib, Mier, Adolphs, & Shimojo, 2015). Daniela Mier also assisted with data collection in the Familiarity versus Novelty study.
3.2 Gaze Cascade Study in Autism