The influence of phasic alerting on multisensory temporal precision.

The relationship between attention and multisensory integration has attracted the attention of many researchers but remains a topic of debate. As a mechanism that regulates the intensity of attention, little is known regarding whether and how phasic alerting affects multisensory perception. Three experiments and warning cues were employed to investigate the influence of phasic alerting on multisensory temporal processing. Experiments 1 and 2 used a temporal order judgement task and a simultaneity judgement task with audiovisual target stimuli presented at varying stimulus onset asynchronies. Experiment 3 further adopted a dual task to generate a new estimate of participants' performance. Although these tasks differ in terms of the required cognitive mechanisms, decreased just noticeable difference scores in trials with warning cues consistently indicated that participants under phasic alerting had enhanced multisensory temporal precision. The point of subjective simultaneity values differed among the three tasks, suggesting that the influence of phasic alerting on perceptual deviation might be modulated by specific task demands. Experiment 4 adopted a strict method to verify that the mechanisms by which warning cues facilitate multisensory temporal precision are most likely transient general arousal rather than temporal expectancy. There is a close relationship between multisensory integration and some neurodevelopmental disorders. Considering that phasic alerting may heighten attentional capacity, future research could explore the potential medical interventions for the patients with relatively limited attention resources.