Three studies examined the impact of social stimuli on visual attention. Chapter two confirmed that, hands, feet, and bodies exhibited equivalent attentional pull in a dot probe detection, two-alternative forced choice paradigm. Chapter three utilized a Posner style covert attentional cueing paradigm to examine the impact of directed human action (throwing a ball) on spatial attention. We manipulated the effect of context by including social (humans) or non-social (trees) flanking images and probed the uniquely social nature of the processing in this task by including individuals with autism spectrum disorder (ASD), a group with known social deficits, as a comparison group. We also manipulated predictability using predictive and non-predictive cue blocks between subjects. Participants with and without ASD demonstrated similar cueing effects when cues were predictive. ASD participants showed no cueing advantage when cues were non-predictive while neurotypical participants experienced cueing only in social contexts when cues were non-predictive – consistent with automatic social processing. Intelligence as measured by the FSIQ from the WAIS 4 was also analyzed. Unexpectedly, higher IQ resulted in slower RTs with the ASD group. We examined this relationship further by examining severity of diagnosis measured by ADOS-G and FSIQ in participants with ASD. In a final study we looked at the relationship between RT and eye movements in visual search for social stimuli like faces and bodies. Consistent with previous results, faces resulted in faster RTs when they were the targets. They also elicited more first fixations and shorter fixation durations. Faces were not, however, more distracting when they appeared in irrelevant singleton frames. Unexpectedly, the bodies images used in this experiment did not result in attentional capture. Possible reasons for this are discussed. / Dissertation / Doctor of Psychology (PsyD) / As humans, other humans are among the most important things we visually perceive. They are sources of threat, alliance, uncertainty, and love. Because we cannot attend to all of the things we see at once, evolution has prepared us with mental traits that favour rapid processing of complex social scenes. Across three studies, we examine how other humans affect our attention. In the first study we confirm that human bodies and their parts (like feet or hands) are equally capable of drawing our attention. Our second study examines the ability of dynamic human poses to direct our attention in the direction of the depicted action. We note that an implied social interaction leads to better performance among typically developing individuals, but leads to deficits in individuals with autism spectrum disorder, a condition characterized by social delays and impairments. Finally, we look at how important social images, like human faces or bodies, unconsciously attract and influence our eyes movements when searching among distracting images.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/18223 |
| Date | 11 1900 |
| Creators | Morrisey, Marcus Neil |
| Contributors | Rutherford, M.D., Psychology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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