Visual spatiotemporal processing in the elderly

We used backward masking paradigm to investigate the effects of aging on visual spatiotemporal processing. First, thirty-three older (M=65.3 years) and ten younger adults (M=24.3 years) had to indicate the offset direction of a vernier that was masked by a 5- or 25-element grating. We replicated results from our previous study (Roinishvili et al, 2011 Vision Research51(4) 417–23) and found stronger masking effects in older compared to younger adults. Interestingly, stimulus onset asynchronies between target and mask were significantly longer in older adults whose individually determined vernier durations were above 30msec compared to older adults with vernier durations below or equal to 30msec. Second, we investigated effects of aging on visual spatiotemporal processing using two different masks with either a spatial or a temporal inhomogeneity. Older adults with vernier durations that were similar to young controls were sensitive to temporal and spatial inhomogeneities in the mask indicating fast and spatially intact processing. However, older adults whose individually determined vernier durations were significantly longer than those of younger adults were not as sensitive to temporal and spatial inhomogeneities in the mask, indicating that small spatio-temporal details are filtered out, which is highly likely due to blurred vision.