Visuospatial attention modulates audiovisual temporal perception: Context-dependent associations between prestimulus...

Audiovisual temporal perception depends on the timing of sensory events and on preparatory attention. We examined how visuospatial cueing affects explicit synchrony judgments and sound-induced flash illusions, and how prestimulus EEG relates to these perceptual reports. In Experiment 1 (N = 39), participants judged beep-flash synchrony across auditory- and visual-leading stimulus onset asynchronies (SOAs). In Experiment 2 (N = 36), they reported flashes in fusion and fission conditions across SOAs and corresponding references. Experiment 1 showed a Cue validity × SOA interaction, with more synchrony reports on valid trials at -100 and +50 ms. Cueing shifted the point of subjective simultaneity among 21 participants with reliable fits. Trial-level posterior alpha lateralization was associated with synchrony reports as a function of Cue validity. In Experiment 2, valid cues reduced raw fusion reports at -100, -50, and +100 ms. A Cue validity × SOA interaction persisted for reference-adjusted fusion scores, whereas neither raw nor adjusted fission showed a corresponding interaction. The association between reference-adjusted alpha lateralization and fusion reports varied with Cue validity and SOA, although a direct comparison with the visual reference did not establish an illusion-specific association. These EEG-behavior associations were stable after accounting for temporal progression, preceding trials, cue side, and an ocular-sensitive EEG proxy. Together, the findings indicate timing- and context-dependent effects of visuospatial attention on audiovisual temporal perception and identify preparatory posterior alpha lateralization as a correlate of subsequent reports.