An acquired deficit of intermodal temporal processing for audiovisual speech: A case study

Abstract

Integrating sensory information across modalities is necessary for a cohesive experience of the world; disrupting the ability to bind the multisensory stimuli arising from an event leads to a disjointed and confusing percept. We previously reported (Hamilton et al., 2006) a patient, AWF, who suffered an acute neural incident after which he displayed a distinct inability to integrate auditory and visual speech information. While our prior experiments involving AWF suggested that he had a deficit of audiovisual speech processing, they did not explore the hypothesis that his deficits in audiovisual integration are restricted to speech. In order to test this notion, we conducted a series of experiments aimed at testing AWF’s ability to integrate cross-modal information from both speech and non-speech events. AWF was tasked with making temporal order judgments (TOJs) for videos of object noises (such as hands clapping) or speech, wherein the onsets of auditory and visual information were manipulated. Results from the experiments show that while AWF performed worse than controls in his ability to accurately judge even the most salient onset differences for speech videos, he did not differ significantly from controls in his ability to make TOJs for the object videos. These results illustrate the possibility of disruption of intermodal binding for audiovisual speech events with spared binding for real-world, non-speech events.