For individuals in the early stages of Alzheimer's, memory problems may be linked to an inability to recognise minor differences between similar objects.
The research contributes to growing evidence that part of the brain once believed to support memory alone, also plays a role in perceiving objects.
"Not only does memory seem to be very closely linked to perception, but it's also likely that one affects the other," said Morgan Barense of the University of Toronto's Department of Psychology.
"Alzheimer's patients may have trouble recognizing a loved one's face not just because they can't remember it but also because they aren't able to correctly perceive its distinct combination of features to begin with."
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Researchers tested patients with mild cognitive impairment (MCI) – a disorder commonly thought to be a precursor to Alzheimer's disease – on their ability to determine whether two rotated side-by-side pictures were different or identical.
The findings suggest that reducing "visual clutter" could help MCI patients with everyday tasks. For example, buttons on a telephone tend to be the same size and color, with only numbers changing. Using a phone with buttons of varying size and colour could greatly help someone who struggles with object perception.
In one set of trials, many pairs of photos of blob-like objects were shown. When the objects weren't a perfect match they varied only slightly, by shape or pattern. In these instances, as expected, MCI patients struggled to identify identical pairings.
In another set of trials, the blob-like objects were shown alongside photographs that were more extreme in their variations. For example, a picture of a butterfly was shown next to a photo of a microwave. Combining the very similar objects with contrasting photos greatly reduced the amount of interference.
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The study is published in the October issue of "Hippocampus".