The role of temporal predictability in the anticipatory biasing of sensory cortex during visuospatial shifts of attention.

The presentation of an attention-directing cue elicits a lateralized ERP deflection called the late directing attention positivity (LDAP) and lateralized changes in alpha-band elelctroencephalogram oscillations. Both of these electrophysiological responses have been independently linked to biasing of visual cortex in anticipation of an impending target. However, the LDAP is not always observed, and the link between the ERP and alpha-band modulations remains unclear. Here, we examined the effect of advance knowledge of the time of target onset on the ERP and alpha-band responses to cues. The LDAP was present only when the attention-directing cues accurately indicated the time of target appearance, whereas two sequential attention-related alpha-band modulations were observed regardless of the temporal information provided by the cues. Thus, alpha-band activity may be a more reliable index of pretarget biasing of visual cortical activity than lateralized ERP effects.