Discussion
In the present study, the behavioral and cortical properties of the McGurk effect and its sensitivity to different SOAs were investigated. A strong McGurk effect was found on behavioral data. The McGurk effect in our research sample was skewed to the right visual lead, auditory lag side in both he ID- and SJ-task. This is in line with the typical visual lead McGurk bias which was found by Wassenhove et al. (2007) and Munhall et al. (1996). It suggests that our brains are used to reduce differences in time onset between auditory and visual stimuli. As mentioned before, light travels faster than sound, but both arise mainly from the same source as the auditory stimulus. Our brains adapt to this and form a perception which unites these stimuli. (Fuijisaki, Shimojo, Kashino & Nishida, 2004).
However, a certain degree of flexibility in multisensory processing was found by Powers, Hillock and Wallace (2009). They stated that psychopathology is sometimes accompanied by this altered multisensory processing. We found an increased auditory lead bias among participants scoring higher on autistic characteristics. Skewing to the left side of the curve for the ID-task was found, indicating an altered McGurk perception within this population. A similar result of this auditory lead bias was found by Donohue, Darling and Mitroff (2012) on a simultaneous judgment task. It was stated that a greater sensitivity for auditory stimuli would lead to a higher priority and more processing time, resulting in a simultaneous percept when an auditory stimulus is leading the visual stimulus. The sensitivity for auditory stimuli is illustrated by Greenspan and Weider (1997), who found that their entire sample consisting of autistic participants repor...
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...e dominant than the effect of audiovisual (i.e. phonetic) change. This could be justified by the results revealing mainly an visual MMN result on audiovisual data. Furthermore, in addition to the preceding statement, only the SOAs in which the visual stimulus preceded the auditory stimulus were tested in the EEG-experiment. This visual change effect could have overruled the lagging audiovisual effect. In prior research, neither a visual MMN nor an auditory MMN was elicited when the audiovisual MMN was found (Colin, Radeau, & Deltenre, 2001; Colin et al., 2002; Saint-amour et al., 2007).
To conclude, it remains important to do further research in this area in order to get a better understanding of the phonetic pathway and audiovisual processing. Further research in the behavioural and cortical McGurk mechanisms in the healthy- and clinical population is necessary.
...ut a 7 years old girl which loss her ability to understand speech. She had a normal hearing and understood various environmental sounds. Her brain was computerized using axial tomography but the result was normal. But electroencephalogram showed wave activity from her left side of the temporal leads. She was diagnose as having verbal auditory agnosia. The treatment consisted of diazepam therapy. Diazepam therapy orally began with taking 2 mg diazepam every day. Diazepam is commonly used to treat anxiety,panic attacks,insomnia and some other medical issues. One year later, her impaired auditory was dramatically improved. The dichotic listening test revealed a left ear advantage for both environmental sounds and spoken words. The results seemed to suggest that in this patient the right hemisphere might be functioning as a speech center instead of the left one.
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Brain Stem Reflexes refer to a process where an emotion is induced by sound or music because the fundamental acoustical characteristics of the sound or music are received by the brain stem which signals a potentially urgent and important event. Sounds that are sudden, dissonant, loud, or have fast temporal patterns induce arousal or feelings of unpleasantness in the listener (Berlyne 1971; Burt et al. 1995; Foss et al. 1989; Halpern et al. 1986). These responses show the impact of auditory sensations (music as sound in the most basic sense). Our perceptual system is continually scanning the immediate surro...
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...and colleagues create a self administered measure that allows an individual with a normal level of intelligence to see if they have traits associated to ASD. The Autism Quotient Questionnaire (AQ) was designed to measure five different areas in 50 different questions (Appendix 1). These different areas include: attention switching, attention to detail, imagination, social skill, and communication (Baron-Cohen, Wheelwright, Skinner, Martin, & Clubley, 2001). The AQ is not meant to serve as a diagnostic tool. However, research has shown the AQ to have reasonable construct validity in the questions pertaining to each of the five areas of measure and reasonable face validity due to the fact that it is measuring autistic traits. In addition, the AQ has shown to have exceptional test-retest reliability (Baron-Cohen, Wheelwright, Skinner, Martin, & Clubley, 2001).
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