Developmental Changes in the Visual Processing of Trustworthy and Untrustworthy Faces Open Access

Steele, Jacqueline (Spring 2018)

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Reading others’ facial cues (i.e. trustworthiness) in social interactions is crucial to understanding their intentions and emotions, and is impaired in individuals with Autism Spectrum Disorder (ASD). Characterizing the emergence and development of this skill and supporting brain regions may further broaden our understanding of impaired socioemotional development observed in children with ASD. Rhesus macaques, a highly translational nonhuman primate model of early socioemotional development, allow for densely sampled longitudinal neuroimaging studies not feasible in human infants. Therefore, this study aims to characterize early development of social and facial feature perception and the underlying brain regions in rhesus infants. We conducted analyses of eye-tracking and MRI data collected longitudinally in 31 infant male macaques (1week – 24 weeks) living with their mothers in complex social groups. Each eye-tracking session included trials of 2 human and 2 monkey faces representing extreme levels of trustworthiness. Looking behavior, including fixation to eye and mouth regions was characterized for trustworthy and untrustworthy faces. Structural MRI scans sequences acquired using a 3T scanner were used to characterize volumetric changes of the prefrontal cortex (PFC), the temporo-parieto-occipital junction (TPO) of the superior temporal sulcus (STS), inferotemporal area (TE), insula, and amygdala (AMY)- all areas involved in visual processing of “trust” in faces. Our sMRI results show region specific developmental growth trajectories. Our eye-tracking results show that when viewing faces, the subjects preferentially looked at untrustworthy eyes in comparison to trustworthy eyes regardless of the stimuli species. Also, the subjects show a significant decline in the amount of time spent looking at human faces at 9 weeks of age in comparison to 5 and 21 weeks of age. This age range corresponds to an age range (8-16 weeks of age) where the AMY, TE, PFC, and insula show slowing in their growth. Our results parallel the developmental trajectories of social visual engagement in human infants (Jones & Klin, 2013), and further validate rhesus monkeys as a translational model of early socioemotional development.    

Table of Contents

Table of Contents

Introduction 1

Methods 12

Subjects 12

Structural MRI 12

Image Acquisition 12

Image Processing and Analysis 13

Eye-Tracking Technique 16

Eye-Tracking Data Acquisition 16

Stimuli Selection 18

Statistical Analysis 18

sMRI Data 18

Eye-Tracking Data 19

Results 20

Structural MRI Data 20

Absolute Volume 20

ICV-Corrected Brain Region Volumes 23

Eye-Tracking Data 25

Human Stimuli 25

Monkey Stimuli 28

Discussion 31

Tables 49

Figures 51

References 77



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