Dissertations, Theses, and Capstone Projects

Date of Degree

6-2024

Document Type

Dissertation

Degree Name

Ph.D.

Program

Psychology

Advisor

Jennifer B. Wagner

Committee Members

James Gordon

Antoinette Sabatino DiCriscio

Jennifer Drake

Subject Categories

Cognition and Perception | Cognitive Psychology | Cognitive Science

Keywords

Autism, autistic, pupillometry, hierarchical visual processing, global processing, local processing

Abstract

Autism spectrum disorder (ASD) and autistic traits in the general population are associated with differences in sensory processing, particularly within the visual domain. Previous studies examining global (i.e., overall gist) and local (i.e., detail) visual processing in relation to ASD have sometimes yielded contradictory findings yet converge on a common theme: slowed global processing and increased local bias associated with ASD. Despite this consensus, the mechanism underlying these differences remains unclear, whether it be differences in visual attention, higher or lower visual perception, and/or cognitive style. The use of traditional tasks and stimuli may further complicate the understanding of contributing factors, as these aspects of experimental design may conflate the potential underlying mechanisms. Furthermore, behavioral measures such as reaction time and accuracy may lack the sensitivity needed to capture subtle processing differences, which might be more effectively identified by using sensitive techniques such as eye-tracking and pupillometry.

With the aim of examining potential underlying mechanisms of global and local processing differences associated with autism and autistic traits, this dissertation investigates behavioral and pupillary responses in adults with varying levels of autistic traits during spontaneous (free viewing), directed global, and directed local visual processing tasks utilizing truly hierarchical stimuli. The primary objectives include replicating global bias findings under a theory of conscious vision, the Reverse Hierarchy Theory (RHT), exploring potential disruptions in hierarchical visual processing in high autistic traits individuals, and applying advanced analytic approaches to pupillary waveforms.

Chapter 1 provides a definition of global and local processing, discusses various tasks and paradigms for examining global precedence, reviews the extant literature on global and local processing in typical development and in relation to autism and autistic traits, discusses theoretical frameworks of global/local processing in autism, discusses issues with traditional hierarchical figures, considers new directions in the examination of global and local processing including pupillometry, and finally, outlines the aims and hypotheses of the current study. Chapter 2 describes the methodology of the current dissertation, including detailed descriptions of the participants, materials, assessments of autistic traits, stimuli, procedures, and paradigms. In Chapter 3, the results of the behavioral measures, including reaction time and accuracy, are reported. In Chapter 4, results of pupillary measures and associations between traditional time-domain measures of pupil responses (i.e., amplitude and latency) and frequency-domain (i.e., power) are reported. In Chapter 5, associations between behavioral and pupillary measures are explored. Chapter 6 is dedicated to presenting a comprehensive discussion of the findings and conclusions, exploring potential implications, addressing limitations, and providing suggestions for future research.

For behavioral responses, it was hypothesized that the full sample would favor reporting the global information over the local, replicating previous studies. Higher autistic traits were expected to be associated with increased reporting of local information, slower reaction times in the global task, and interference from the local level. Additionally, pupillary responses were anticipated to reveal a narrower attentional scope and local default in high traits individuals during spontaneous conditions. During the directed task, pupillary responses were expected to show task-dependent attentional narrowing for the full sample, characterized by greater constriction during the local task. High autistic traits were hypothesized to be associated with a dilated response trajectory during the global condition, and low autistic traits with a dilated response trajectory during the local condition. Moreover, analyses were conducted to examine power in the frequency domain in pupillary responses as an index of enhanced attentional recruitment, and associations between different pupillary measures and behavioral responses were explored.

Results from the spontaneous condition supported global bias in the full sample and faster reaction times for global reporting. Contrary to expectations, higher autistic traits did not correlate with more default reports of local information. However, pupillary responses revealed a constricted pattern in the high autistic traits group, suggesting a potentially more locally-focused strategy.

Analysis of the directed tasks revealed a global advantage in speed and accuracy for the full sample. However, when low and high traits groups were examined separately, results for the low traits group mirrored what was found for the full sample, but in the high traits group, the global advantage held only for reaction time, but not accuracy. When examining correlations between autistic traits and reaction time and accuracy for the global and local tasks, results showed higher autistic traits were associated with less global advantage in both reaction time and accuracy, stemming from slower global processing and less global accuracy. Pupillary responses indicated trends toward task-related differences in constriction during the early part of the response and dilation in the latter part of the response. While high frequency power correlated with this early pupil constriction, low frequency power correlated with dilation, suggesting distinct but overlapping underlying processes. Exploratory findings additionally highlighted associations between behavioral and pupillary measures, emphasizing the informative role of pupillary response latency in estimating processing efficiency.

The current study contributes novel insights into the nuanced relationship between autistic traits and visual processing, underscoring the importance of considering task difficulty and stimulus structure. Limitations, including task complexity, stimulus design, and the small autistic subgroup, are acknowledged. Future work is recommended to refine stimulus characteristics, explore task difficulty effects, and investigate baseline and resting state pupillary responses. Overall, the current study contributes to understanding neurodivergent visual processing, laying the groundwork for further research to elucidate underlying mechanisms.

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