Investigated the effects of arousal on the range of stimulus responsiveness in terms of sensitivity and response criterion changes, the amount of attention initially focused on the stimulus, and the locus of effect of arousal. 20 undergraduates simultaneously performed a pursuit-rotor tracking task and an auditory signal detection task under different levels of arousal, temporal locus of effect conditions, and degrees of attention being focused on the auditory cue. Results indicate that arousal narrows the range of cues processed by systematically reducing responsiveness to those aspects of the situation which initially attract a lesser degree of attentional focus. This stimulus loss under arousal represents, independently of any response criterion changes, an actual diminution in the Ss' sensitivity. It also seems that arousal mediates its effect not so much by impeding the initial sensory impression as by affecting the capacity limitations and attentional control processes operating within short-term memory. (PsycINFO Database Record (c) 2006 APA, all rights reserved)