Show Reference: "Crossmodal binding: Evaluating the “unity assumption” using audiovisual speech stimuli"

Crossmodal binding: Evaluating the “unity assumption” using audiovisual speech stimuli In Perception & Psychophysics, Vol. 69, No. 5. (2007), pp. 744-756, doi:10.3758/bf03193776 by Argiro Vatakis, Charles Spence
    abstract = {We investigated whether the  ” unity assumption,” according to which an observer assumes that two different sensory signals refer to the same underlying multisensory event, influences the multisensory integration of audiovisual speech stimuli. Syllables (Experiments 1, 3, and 4) or words (Experiment 2) were presented to participants at a range of different stimulus onset asynchronies using the method of constant stimuli. Participants made unspeeded temporal order judgments regarding which stream (either auditory or visual) had been presented first. The auditory and visual speech stimuli in Experiments 1–3 were either gender matched (i.e., a female face presented together with a female voice) or else gender mismatched (i.e., a female face presented together with a male voice). In Experiment 4, different utterances from the same female speaker were used to generate the matched and mismatched speech video clips. Measuring in terms of the just noticeable difference the participants in all four experiments found it easier to judge which sensory modality had been presented first when evaluating mismatched stimuli than when evaluating the matched-speech stimuli. These results therefore provide the first empirical support for the  ” unity assumption” in the domain of the multisensory temporal integration of audiovisual speech stimuli.},
    author = {Vatakis, Argiro and Spence, Charles},
    booktitle = {Perception \& Psychophysics},
    doi = {10.3758/bf03193776},
    keywords = {auditory, semantic, speech, unity-assumption, visual},
    number = {5},
    pages = {744--756},
    posted-at = {2014-05-07 17:11:57},
    priority = {2},
    publisher = {Springer-Verlag},
    title = {Crossmodal binding: Evaluating the ``unity assumption'' using audiovisual speech stimuli},
    url = {},
    volume = {69},
    year = {2007}

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Vatakis and Spence found support for the concept of a `unity assumption' in an experiment in which participants were to judge whether a visual lip stream or an auditory utterance was presented first: Participants found this task easier if the visual and auditory stream did not match in terms of gender of voice or content, suggesting that their unity hypothesis was weak in these cases, causing them not to integrate them.