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Visual Behavior and Preference Decision-Making in Response to Faces in High-Functioning Autism


Gharib, Alma Mariam (2015) Visual Behavior and Preference Decision-Making in Response to Faces in High-Functioning Autism. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9DN4307.


How do we come to the decision that we like a face? This thesis investigates this important aspect of social processing and communication by examining preference decisions for faces and the role that visual behavior plays in the process. I present a series of studies designed to investigate face preference formation and gaze patterns using eye-tracking and self-reported preference ratings. I tested healthy control subjects and two clinical populations known to have deficits in social processing: people with autism and patients with amygdala lesions. In studies one and two, I explore whether known social cognition deficits in people with autism and amygdala lesions also impair subjective decision-making regarding the attractiveness of faces. In study three, I investigate the flexibility of rule-based visual strategies used by these populations during face perception. Additionally, I present a custom algorithm developed to process raw eyetracking data, which was used to analyze all eyetracking data in this thesis.

People with autism and patients with amygdala lesions are known to have general deficits in social processing, including difficulty orienting toward and evaluating faces. Nevertheless, I find that their behavior is markedly similar in many areas where we would expect them to have abnormalities or deficiencies. Their preference decisions when judging facial attractiveness were highly correlated with those made by controls, and both groups showed the same biases for familiar faces over novel faces. In addition, people with autism exhibit the same visual sampling behavior linking preference and attentional orienting, but reach their decisions faster than controls and also appear insensitive to the difficulty of the choice. Finally, gaze to the eye region appears normal in the absence of an explicit decision-making task, but only when analyzed in a similar manner as previous studies. However, when face sub-regions were analyzed in greater detail, people with autism demonstrate abnormalities in face gaze patterns, failing to emphasize the most information-rich regions of the face. Furthermore, people with autism demonstrate impairments in their ability to update those gaze patterns to accommodate different viewing restrictions. Taken together, these findings support the idea that the normal formation of face preferences can be preserved in the presence of general social processing impairments. Patterns in the eyetracking and behavioral data indicate that this is made possible, in part, by compensatory atypical processing and visual strategies.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Social neuroscience; autism; decision-making; amygdala; face perception; preference formation
Degree Grantor:California Institute of Technology
Division:Biology and Biological Engineering
Major Option:Neurobiology
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Shimojo, Shinsuke (advisor)
  • Adolphs, Ralph (co-advisor)
Thesis Committee:
  • Adolphs, Ralph (chair)
  • Shimojo, Shinsuke
  • Allman, John Morgan
  • Perona, Pietro
Defense Date:27 May 2015
Non-Caltech Author Email:alma.gharib (AT)
Record Number:CaltechTHESIS:06052015-203007731
Persistent URL:
Gharib, Alma Mariam0000-0002-7588-407X
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9006
Deposited By: Alma Gharib
Deposited On:07 Mar 2017 18:29
Last Modified:04 Oct 2019 00:08

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