Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Psychology

Supervisor

Stevenson, Ryan A.

Abstract

Older adults experience a greater benefit from multisensory integration than their younger counterparts, but it is unclear why. One hypothesis is that age-related sensory decline weakens unisensory stimulus effectiveness, producing a boost in multisensory gain through inverse effectiveness. Many previous studies present stimuli at the same intensity for both younger and older adults (i.e., stimulus-matched), as opposed to accounting for each participant’s unique perceptual ability (i.e., perception-matched). This makes it difficult to discern the source of age-related differences in multisensory gain. Through a combination of stimulus-matched and perception-matched tasks, I found that older adults exhibit enhanced multisensory gain at low levels of detection and speech-perception, and higher levels of processing like semantic processing. Critically, when accounting for individual differences in perception, I found no age-related enhancements. Together, these findings suggest that sensory decline paired with existing mechanisms such as inverse effectiveness function together to enhance multisensory gain among older individuals.

Summary for Lay Audience

Older adults have been found to benefit more from complimentary auditory and visual information from their environment relative to younger adults. Behaviourally, this benefit manifests as faster response times, and greater accuracy in situations where they have multiple redundant cues, as opposed to a singular cue. One possible explanation for this increased benefit among older individuals is age-related sensory loss. Older adults often experience some degree of sensory decline (e.g., hearing or vision loss) as a natural part of aging. That is, it becomes more beneficial for older adults to have access to redundant auditory and visual cues from the environment, as it is more reliable and informative than a single auditory, or single visual cue. As such, two main research questions were explored: (1) do older adults exhibit enhanced benefit across levels of processing; and (2) when accounting for age-related differences in perception, do older adults continue to experience an enhanced multisensory benefit? I explored these questions through two studies. In the first study, I found evidence to support that older adults do experience a greater benefit from multiple sensory cues relative to younger adults. Importantly, in the second study I found that if we account for individual differences in perception between younger and older adults, older adults no longer experience an enhanced benefit. Together, my findings suggest that older adults do indeed experience greater benefit from redundant sensory cues because of age-related sensory decline.

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