The spatial precue effect for foveal detection/recognition tasks

Forty university students participated in a spatial precue task that employed foveally delivered stimuli and precues (75% validity). The influence of three factors (1) precue interval duration (200 ms, 1000 ms), (2) the level of stimulus processing required (detection, recognition), and (3) instructions (usual, augmented), upon the spatial precue effect (indexed as the RT difference between valid and invalid precue conditions) were examined. The results obtained indicated that factors (I) and (2), but not (3), exerted a significant influence upon the size of the spatial precue effect. Specifically, when the level of stimulus processing is one of 'recognition', a reliable spatial precue effect can be expected, regardless of precue interval duration. However, if one simply has to 'detect' the presence of the imperative input, a spatial precue effect will emerge if the precue interval is long (i.e. 1000 ms) but not when it is comparatively short (200 ms). These findings indicate that the 'willingness' of subjects to allocate attention to a position in foveal visual space can be controlled with individuals being less inclined to do so when the level of stimulus processing is low (detection) and when the time allowed to use advance information is short.