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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.

The article evaluates the relative credibility of desensitization and pseudotherapy. Since that procedure clearly violated standard analogue research practice, which exposes S to one treatment or the other, Ss in this experiment heard only desensitization or pseudotherapy. Twenty moderately avoidant and 20 mildly avoidant Ss were chosen as though they were to participate in a snake!avoidance desensitization experiment. The implication of this finding is that a great many experimental studies of systematic desensitization have failed to control satisfactorily for the operation of expectancy effects and nonspecific forms of behavioral influence.

The article presents a study conducted to measure heart-rate reaction of college students. The goal of most investigators is to develop experimentally supported substantive generalizations of relevance to the practices of clinical behavior therapy. The present experiment addressed this issue by selecting snake fearful Ss with widely used procedures, confronting them with a live snake, and measuring their heart-rate reactions. In coLntrolled studies of behavior therapy measurements of physiological responses to snakes among snake-phobic Ss sometimes are recorded. The study assessed the extent to which heart-rate responsivity in the presence of a snake is correlated with behavioral avoidance of a snake. Those who were behaviorally avoidant showed less heart-rate responsivity to the neutral stimulus than the snake.