Hearing is Seeing: The Implicit McGurk Illusion - a Perceptual or Cognitive Phenomenon?

Volkmann, Konstantin (2014) Hearing is Seeing: The Implicit McGurk Illusion - a Perceptual or Cognitive Phenomenon? Oxford Brookes University. (Unpublished)

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Abstract

This study addresses the question of whether audiovisual speech integration is an automatic and unconscious process or subject to attentional demands. The experimental approach utilised a variant of Garner’s (1974) speeded classification task, with audiovisual stimuli comprising of disyllabic non-words. Observers had to classify the first syllable while the second syllable was experimentally manipulated. The rationale under consideration was that in a series of trials, task-irrelevant variations of the second syllable will slow down response latencies, henceforth called syllabic interference effect. This effect was produced in Experiment 1. Experiment 2 demonstrated that this effect can also be induced by virtue of a McGurk percept while Experiment 3 illustrated the elimination of such effects on the basis of a McGurk percept. Further, participants repeatedly attended the experiments over five consecutive days. Findings reinforce the claim that audiovisual integration occurs before selective attention can be allocated and support the assumption of it being an automatic process. The observed stability of the effects over time suggests that audiovisual integration is immune to top-down control often achieved through practice and thus represents a purely perceptual phenomenon. Results are discussed with regards to the question of cognitive impenetrability of audiovisual speech integration.