Eye Gaze And Perceptual Adaptation To Audiovisual Degraded Speech
Visual cues from a speaker’s face may improve perceptual adaptation to degraded speech over time, but current evidence is limited. We aimed to replicate results from previous studies and extend them to more demanding speech stimuli (sentences), to better represent real-life, challenging speech comprehension. In addition, we investigated whether particular eye gaze patterns towards the speaker’s mouth were related to adaptation, hypothesising that listeners who looked more at the speaker’s mouth would show greater adaptation. A group of listeners were presented with noise-vocoded sentences in audiovisual format while a control group were presented with the audio signal only, presented congruently with a still image of the speaker’s face. Results of previous adaptation studies were partially replicated: the audiovisual group had better recognition throughout and adapted slightly more rapidly, but both groups showed an equal amount of improvement overall (after exposure to 90 sentences). Longer fixations on the speaker’s mouth in the audiovisual group were related to better overall accuracy, although evidence for this relationship was relatively weak. An exploratory analysis further showed that the duration of fixations to the speaker’s mouth decreased over time. The results suggest that the benefits from visual cues to adaptation to unfamiliar speech vary more than previously thought. Longer fixations on a speaker’s mouth may play a role in successfully decoding these cues, but more evidence is needed to fully establish how patterns of eye gaze are related to audiovisual speech recognition.