Exogenous orienting of attention refers to rapid, involuntary shifts of attention that occur in response to salient events such as peripheral cues. Seminal work by Cheal and Lyon (1991) indicated that exogenous attention gradually accumulated at a cued location, peaked around 120ms after cue onset. Although widely cited, this temporal profile for exogenous attention is problematic because Cheal and Lyon used only Valid trials (i.e the target always appeared at the cued location), leaving open two alternative possibilities: (a) the effects were due to the gradual engagement of endogenous attention or (b) the effects were due to alerting. The current study addressed these issues by examining the profile of exogenous attention using nonpredictive cues, which do not engage endogenous attention and permit the comparison of performance at attended and unattended locations. As with Cheal and Lyon, we saw a gradual improvement in performance which peaked ~120ms after cue onset. However, this pattern manifested at attended and unattended locations, which is consistent with an arousal effect. Furthermore, a significant spatial cueing effect emerged at 30ms and was stable in magnitude up to ~150ms. Contrary to Cheal and Lyon, we conclude that the effects of exogenous attention do not accumulate over time. _________________ Dr Daniel T. Smith, CPsychol Dept. of Psychology Durham University Durham DH13LE @AttentionLab http://motorbiasproject.com/<http://motorbiasproject.com/workshop>