Neural Signatures of Flexible Temporal Orienting under Spatial and Motor Uncertainty

The goal-dependent use of temporal expectations enhances visual performance, even without concurrent spatial or motor predictions, yet the underlying neural mechanisms remain unclear. To identify the stages of stimulus processing influenced by temporal orienting of attention, we recorded EEG while participants performed a visual identification task manipulating relevance and temporal predictability of targets. Colored targets appeared in one of two simultaneous visual streams. One color appeared unpredictably while two others appeared predictably early or late. Targets appeared in either stream and required a localization response using the corresponding hand. On each trial, one target was cued as task relevant. Behaviorally, participants used temporal expectations flexibly to optimize processing of goal-relevant targets. The target-defining cue elicited a contingent negative variation, modulated by the temporal predictability of anticipated early versus late targets. Target-related ERPs showed strong modulation by target relevance at multiple stages. Modulations impacted target selection (N2pc), motor preparation (lateralized readiness potential), and late decision-related factors (P300). Interestingly, only the P300 was additionally modulated by the temporal predictability of targets. The findings reveal how temporal attention can impact multiple stages of stimulus processing through the relevance and temporal predictability of targets even without spatial or motor certainty.