Temporal Window of Integration XOR Temporal Window of Synchrony

One of the most extensively studied constructs in multisensory research is the temporal window of integration. Its extent has been variously estimated by measuring the temporal boundaries within which stimuli in different sensory modalities are perceived as simultaneous or elicit multisensory integration effects. However, there is ample evidence that these two approaches produce distinct psychometric outcomes, as the widths of the windows they yield differ even when estimated with equivalent designs and stimuli. In fact, these two estimates can sometimes even be negatively correlated. What is more, the perception of synchrony has been found to be neither necessary nor sufficient for the occurrence of multisensory illusions. This suggests that subjective simultaneity and integration phenomena are dissociable, undermining the conclusions of studies that use them interchangeably. Failing to disentangle the temporal windows in which they occur has led to contradictory findings and considerable confusion in basic research that has started extending to other domains. In clinical studies, for example, this confusion has affected work ranging from neuropsychological conditions (such as schizophrenia, mild cognitive impairment, dyslexia, and autism) to more general health factors (such as obesity and inflammation); in applied research, it is seen in studies using virtual reality, human-computer interfaces, and warning systems in vehicles. In this brief review, we discuss the importance of distinguishing these two constructs. We propose that, while the temporal boundaries of integration phenomena are aptly described as the temporal window of integration (TWI), the temporal boundaries of simultaneity judgements should be referred to as the temporal window of synchrony (TWS).