Chapter IV: Task-dependent Modulation Of Face Gaze
4.1 Overview
The third and final study in this dissertation is the “Don’t Look” study. The purpose of this experiment was to investigate the flexibility of face scanning strategies used by individuals with high-functioning autism and amygdala lesion patients. Participants were instructed to view faces while avoiding specific facial features, so we could investigate strategies for face exploration and the ability to update those strategies under changing viewing contexts.
In exploring why some aspects of gaze and preference behavior in ASD appeared no different from healthy controls in the prior studies, I became familiar with a growing discussion in the literature regarding inconsistent findings of social impairments in autism, particularly as they relate to deficits in face processing. As discussed in the Introduction of this dissertation, there are a variety factors that contribute to seemingly divergent findings for face processing in autism, including task demands and the characteristics of stimuli that are used. For example, differences in stimuli can affect the severity of social impairments in ASD, possibly due to the greater cognitive effort required to process more complex social stimuli. Similarly, some studies have reported differences in eye gaze become more prominent in cognitively demanding tasks.
Another (not mutually-excusive) factor that can mitigate the effect of social deficits is the use of compensatory strategies during social processing in ASD. There is evidence to suggest that people with autism, particularly those who are high-functioning, compensate for social deficits by using atypical cognitive and visual strategies which give the appearance of behavior that differs very little from the behavior demonstrated by neurotypicals. Though these strategies are usually not as flexible or adaptive in situations that are unusual or require high cognitive effort, they are often sufficient for many other day-to-day situations.
Given that in the Gaze Cascade study, people with ASD demonstrated rather normal face gaze and faster reaction times relative to neurotypicals when making face preference decisions, we suggested that people with ASD may have approached the task as a perceptual task rather than a social one, i.e., the decision-making aspect of the task had mitigated or circumvented the effect of social impairments on gaze and attention. This is why, in the Don’t Look study, our aim was to examine face gaze separate from an explicit decision-making task in order to understand how people with autism spontaneously look at faces.
To examine spontaneous face scanning strategies and the flexibility of those strategies, we designed a task in which we manipulated viewing strategies by giving instructions that were unrelated to our actual variables of interest: gaze to salient features of the face and propensity for face exploration. Subjects were instructed to avoid looking at the eyes while gaze to the remainder of the face was permitted, to avoid the mouth while gaze to the remainder of the face was permitted, or to look at the face without any restrictions.
The primary questions of our investigation were: 1) How do people with social processing impairments spontaneously explore the face (i.e., decoupled from social or explicit decision- making)? 2) How flexibly can face scanning strategies be adapted to changing social contexts?
And 3) if face gaze strategies can mitigate the appearance of atypical face scanning, could these strategies be engaged elsewhere to elicit differences in viewing behavior?
The amygdala group demonstrated similar gaze patterns to salient face regions as controls and appeared equally flexible in gaze strategies. There was, however, a tendency in the amygdala group to look away from the salient parts of the face less often than controls, and also to look off the head less than controls.
There were notable differences in the autism group relative to controls. We found that while the general pattern of gaze on the screen and to salient features of the face appeared normal in high-functioning autism, there were differences between groups in the details of the ASD group’s gaze pattern, and in the strategies they used in response to the viewing restrictions.
Similar to controls, the ASD group spent the majority of gaze time looking on the face (rather than off the face), and in the conditions in which gaze to the eyes was allowed, both groups
spent the most time looking at the general eye region regardless of stimulus type. However we found that people with ASD showed impairments in orienting to the parts of the eye region that communicate the most information, instead showing a bias for looking between the eyes and at the nose. Furthermore, people with ASD showed deficits in adapting their usual strategies for face scanning while simultaneously adhering to the task restriction to avoid specific features, indicating there was reduced flexibility of those strategies in people with high-functioning autism. In summary, while individuals with ASD, at least superficially, did not appear to differ in the general pattern of gaze to larger regions of the face, there was clear evidence to indicate atypical face gaze in the details of visual behavior and in the flexibility of gaze strategies. The results from these studies suggest that face scanning utilizes general perceptual process that might not be reliant upon amygdala functioning.
4.2 Don’t Look Study in Autism