The physiological effects of visual distracters on audiovisual matching of letters and novel symbols
Poster Presentation

Ayla Barutchu
La Trobe University

Sophie Cullum Jenkins
La Trobe University

Amy Griffiths
La Trobe University

Melissa Hatty
La Trobe University

Felicity Wilkinson
La Trobe University

David Crewther
Swinburne University of Technology

Sheila Crewther
La Trobe University

     Abstract ID Number: 98
     Full text: Not available
     Last modified: March 26, 2007
     Presentation date: 07/06/2007 10:00 AM in Quad Maclauren Hall
     (View Schedule)

Abstract
Introduction: Little is known about how we recognise and form associations across the senses in noisy environments. Thus the aim of this study was to investigate the effect of distracters on the audiovisual integration of letters and novel symbols.
Method: Seventeen females (20-35years) were presented with letters (graphemes and phonemes) or novel symbols and sounds as unisensory or multisensory stimuli. The visual component of stimuli consisted of graphemes and symbols being presented individually or in sets of three. Participants were asked to manually indicate when a match between audition and vision was detected. Event Related Potentials, motor reaction times and response accuracy were recorded.
Results: Visual distracters slowed reaction times and induced a higher error rate for both letters and symbols. Motor reaction times were faster for symbols than for letters. Electrophysiological measures showed early multisensory integration at occipitoparietal electrode sites. Visual distracters also modulated P1 and N1 amplitude at occipitoparietal electrodes. Right hemisphere parietal electrodes showed an increase in N1 amplitude for symbols, with minimal differences between letters and symbols at left parietal electrodes.
Conclusion: Extracting and matching audiovisual information amongst distracters leads to an increase in neural activity, with the right hemisphere being more engaged in processing novel information.