Date of Award

2009

Degree Type

Thesis

Degree Name

Bachelor of Arts Honours

School

School of Psychology and Social Sciences

Faculty

Faculty of Computing, Health and Science

First Advisor

Dr Ken Robinson

Abstract

The threat superiority effect refers to faster and more accurate detection of fearful stimuli. This has been explained as evidence for evolution, as ancient fearful stimuli are detected more quickly than modern fearful stimuli. The aim of this study was to investigate which of two alternate evolutionary explanations best explains the findings. Whereas Ohman and Mineka (2001) dealt only with avoidant responses, Lang suggested that stimuli may evoke either an avoidant (fearful) or approach response, associated with negative or positive valence, respectively. The experiment employed a same-different task where Age (ancient, modern), and Valence (approach, avoidant, neutral) were manipulated and presented to 37 (19 females and 18 males) participants. Participants were presented with slides of 9 images, and asked to determine whether all images come from the same category (for example they are all flowers) or a different category (there is a snake among the flowers) as quickly and as accurately as possible. Ancient approach (horses) and avoidant (snakes) stimuli were detected faster than the neutral stimuli (mushrooms), but both modern approach (pizzas) and modern neutral (clocks) stimuli were detected faster than avoidant (guns) stimuli. These findings are most consistent with the evolutionary explanation of Lang (1995). It is suggested that the disparate results in the literature may be due to confounds associated with stimulus similarity.

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