Examination of Disengagement of Snake Phobics' Attention from Images of Snakes
Type of Degreedissertation
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Changes occur in a number of psychological processes during fear. For example, increases in fear and arousal are sometimes followed by a narrowing of attention (Easterbrook, 1959; Baddeley, 1972) and increased selectivity of attention to the environment (Easterbrook, 1959; MacLeod & Mathews, 1991). Selective attention in specific phobia has traditionally been studied via the Stroop Task and the Dot Probe Task; however, use of these paradigms has been questioned due to a lack of evidence in support of the attentional biases which they purport to measure. The flicker task, developed by Rensink, O’Regan and Clark (1997), may offer a novel way to measure visual attention selectivity through change detection. In the flicker task brief blank-space intervals are interposed between repeated presentations of scene pairs to mimic the effects of eye movements. The second scene of each pair is changed at some point and the time or trials needed to detect that the scene has changed is recorded. McGlynn et al. (2008) used the flicker task to investigate the relation between selective attention and fear in two studies. In both studies, half of the participants were snake phobic, half were not. Half of the image pairs used included a snake, half did not. Half of the scene changes were made to central-interest aspects of the scene, half were made to marginal-interest areas. McGlynn et al. found that for both snake-phobics and controls, change detection required fewer repetitions for objects that were of central interest than for objects that were of marginal interest. Additionally, for snake-phobics, change detection required more repetitions in neutral stimuli than for controls. Results were explained with Fox’s (2001) delayed disengagement theory. According to the delayed disengagement theory, in the McGlynn et al. study, phobic participants may have been still processing previous feared stimuli during the presentation of the neutral stimuli, and were delayed in their ability to focus on the neutral stimuli and detect changes among these image-pairs. Like McGlynn et al. (2008), the current study examined the narrowing of attention among snake phobics via the flicker task. Thirteen snake phobics and fourteen snake-tolerant participants were exposed to 26 image-pairs, which depicted snakes in various contexts, via the flicker task. The second image of each pair contained one change made to the snake and one change made to an object other than the snake. The participants’ task was to find “a change” between the rapidly cycling image pairs. It was hypothesized that snake phobics, in contrast to snake-tolerant participants, would show evidence of preferential attention to the changes made to the snake than to changes made to other aspects of the scene. It was also predicted that snake-phobic participants would require more repetitions than snake-tolerant participants to detect the changes in the other aspects of the scene than in the snake changes. Neither of the hypotheses was confirmed. The explanation is offered that the fearsome scenes used in the flicker task (snakes), where inappropriate due to their evolutionary significance. Stimuli for which there is no evolved biological predisposition to associate them with threat (e.g., guns) should be employed in the future.