Spotlight failure effect in exogenous orienting.

Many experimental results about spatial attention have been explained by assuming the existence of an attentional "spotlight" which can move from one location in visual space to another. Such an account has been recently challenged by findings which show the influence of nonspatial factors in spatial attention. In particular, the so-called "spotlight failure" effect refers to the influence of the probability of occurrence of different stimuli. However, such an effect has only been reported in the case of endogenous (or central) orientation, rather than on exogenous (or peripheral) orienting. We present evidence showing that the spotlight failure effect can be obtained with exogenous orienting, even at a short SOA (100 ms). Besides, experimental instructions can modulate the effect, which agrees with theoretical accounts proposing that top-down factors can influence attentional capture.