Psychology ETDs

Per A. Lysne

Publication Date

2-9-2010

Abstract

Darwin proposed that communication of information concerning psychological state was an evolved mechanism. Much emotional signaling in humans occurs via facial expression. Neuroimaging techniques have identified regions involved in facial emotion perception and, although successively more sophisticated models have sought to explain this processing, results suggest that further development is needed. Neuroimaging research in facial emotion perception is currently focused on characterizing major sources of activation in development of these models. Although facial processing is a visual task, decoding of expression has been theorized to take place not in the primary visual regions of the occipital cortex but later within specialized portions of temporal cortex. Portions of the fusiform gyrus respond preferentially to facial stimuli and, although current models hypothesize that processing of facial expression takes place elsewhere, some evidence suggests that facial expression modulates the fusiform response. Lewis et al. (2003) found differential activation of an equivalent current magnetic dipole in the right fusiform when viewing happy versus disgusted versus neutral faces. The current work sought to replicate and extend these findings by, 1) expanding the stimulus set to all six basic emotions and a non-face control condition, 2) investigating the primary visual response of the calcarine fissure for an emotion-dependent component, and 3) investigating effects of gender and age. Contrary to expectations, findings here included emotion-related differences in peak amplitude and latency in responses of both the calcarine and fusiform. In the calcarine happy faces were seen to elicit greater amplitude than neutral, swirled, and sad faces, while in the fusiform fearful and surprised faces resulted in greater amplitude than disgusted faces and non-face objects. In the fusiform swirled faces elicited longer response latencies than recognizable faces regardless of emotion with fewer significant comparisons making a similar suggestion in the calcarine. Surprised faces required greater latencies in the right fusiform than happy and neutral faces. Partial support for the findings of Lewis and colleagues is suggested. A main effect was found for gender, with women displaying greater amplitude, shorter-latency responses. The amplitude response of the fusiform was greater than the calcarine and this differential increased with age.

Degree Name

Psychology

Level of Degree

Masters

Department Name

Psychology

First Committee Member (Chair)

Thoma, Robert

Second Committee Member

Clark, Vincent

Third Committee Member

Lewis, Stephen

Sponsors

The MIND Research Network

Language

English

Keywords

Face perception--Physiological aspects, Facial expression--Physiological aspects, Temporal lobes, Magnetoencephalography, Neuropsychology.

Document Type

Thesis

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