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Jutta Billino, Knut Drewing; Age-related differences in visuo-haptic integration. Journal of Vision 2014;14(10):233. doi: 10.1167/14.10.233.
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Over the last years demographic changes have fostered research on functional aging. Age-related decline within individual sensory systems is well documented, but there is still a lack of understanding how multisensory processing is altered across life span. We studied age effects on visuo-haptic length judgments and evaluated optimality of multisensory integration. In a two-interval forced choice task 24 young adults (20-25 years) and 25 senior adults (69-77 years) compared the length of standard stimuli to a set of comparison stimuli. Standard stimuli were presented to vision, haptics, or to both senses. In the visuo-haptic condition intersensory conflicts were introduced by magnifying and reducing optical lenses. Comparison stimuli were always explored in the haptic modality alone. We determined psychometric functions for each modality condition. Age groups did not differ in their points of subjective equality (PSE) in any condition. Visuo-haptic PSEs lay in-between the results for the unisensory conditions indicating multisensory combination in both age groups. Discrimination thresholds, i.e. just noticeable differences (JND), showed significant sensitivity differences only in the visual modality. Based on measured PSEs and JNDS we calculated the weights given to each modality and estimated optimal weights suggested by the Maximum-Likelihood-Model. We found that young and senior adults integrated visuo-haptic signals quite similarly with visual information contributing about 30% to length judgments. Comparison between measured and estimated weights, however, revealed greater deviation from optimal integration in young adults than in senior adults (-28% vs. +3%, respectively). Our results provide evidence that although both age groups integrate visual and haptic signals, senior adults exploit available sensory information far more efficiently than younger adults. We suggest that optimal weighting of multisensory signals might support successful compensation for sensory decline during aging.
Meeting abstract presented at VSS 2014
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