Detection of change in threat-related and innocuous scenes among snake-fearful and snake-tolerant participants: data from the flicker task.

Visual change detection mirrors conscious attention. In the flicker task, pairs of scenes are presented rapidly; the second scene differs from the first, and the participant identifies the change. Change occurs in either a central-interest region or marginal-interest region of the scene. Detecting change in a marginal-interest region requires that attention be disengaged from the central-interest region. In two flicker experiments the dependent variable was the number of scene-pair repetitions before the change was identified. The independent variables were snake-fearful versus snake-tolerant participants, presence versus absence of a snake in the scene, and a change within a central-interest versus marginal-interest region. Snake-fearful participants took longer than snake-tolerant participants to identify changes in scenes without a snake. The explanation is offered that snake-fearful participants took longer than snake-tolerant participants to disengage attention from scenes in which a snake was present; delayed disengagement from scenes that included a snake impeded the detection of change in scenes that did not.