This study is the first to demonstrate training-related benefits to gross motor performance stemming from cognitive dual-task training. The results support the view that motor control in aging is influenced by executive control and have implications for theories of cognitive training and transfer.

While aging can lead to significant declines in perceptual and cognitive function, the effects of age on multisensory integration, the process in which the brain combines information across the senses, are less clear. Recent reports suggest that older adults are susceptible to the sound-induced flash illusion (Shams et al., 2000) across a much wider range of temporal asynchronies than younger adults (Setti et al., 2011). To assess whether this cost for multisensory integration is a general phenomenon of combining asynchronous audiovisual input, we compared the time courses of two variants of the sound-induced flash illusion in young and older adults: the fission illusion, where one flash accompanied by two beeps appears as two flashes, and the fusion illusion, where two flashes accompanied by one beep appear as one flash. Twenty-five younger (18–30 years) and older (65+ years) adults were required to report whether they perceived one or two flashes, whilst ignoring irrelevant auditory beeps, in bimodal trials where auditory and visual stimuli were separated by one of six stimulus onset asynchronies (SOAs). There was a marked difference in the pattern of results for the two variants of the illusion. In conditions known to produce the fission illusion, older adults were significantly more susceptible to the illusion at longer SOAs compared to younger participants. In contrast, the performance of the younger and older groups was almost identical in conditions known to produce the fusion illusion. This surprising difference between sound-induced fission and fusion in older adults suggests dissociable age-related effects in multisensory integration, consistent with the idea that these illusions are mediated by distinct neural mechanisms.

Perception of global patterns requires the integration of local orientation information across space. The present study examined whether this integration ability declines in older age. We measured contrast thresholds for discriminating the global orientation of a "C" shaped contour against a blank background in younger and older subjects. Performance of younger subjects improved when the elements composing the "C" were aligned along the contour path, as opposed to being orthogonal to it or of mixed orientations. However, older subjects' performance was not affected by the orientation of the local elements. This indicates an age-related decline in contour integration.

To accurately represent the environment, our brains must integrate sensory signals from a common source while segregating those from independent sources. A reasonable strategy for performing this task is to restrict integration to cues that coincide in space and time. However, because multisensory signals are subject to differential transmission and processing delays, the brain must retain a degree of tolerance for temporal discrepancies. Recent research suggests that the width of this ‘temporal binding window’ can be reduced through perceptual learning, however, little is known about the mechanisms underlying these experience-dependent effects. Here, in separate experiments, we measure the temporal and spatial binding windows of human participants before and after training on an audiovisual temporal discrimination task. We show that training leads to two distinct effects on multisensory integration in the form of (i) a specific narrowing of the temporal binding window that does not transfer to spatial binding and (ii) a general reduction in the magnitude of crossmodal interactions across all spatiotemporal disparities. These effects arise naturally from a Bayesian model of causal inference in which learning improves the precision of audiovisual timing estimation, whilst concomitantly decreasing the prior expectation that stimuli emanate from a common source.

We used a random-dot two-frame apparent motion paradigm to investigate whether age-related declines in motion perception are caused by deficits in integrating spatial information, temporal information, or both. Two random-dot patterns were presented sequentially on a black screen, separated by a blank inter-stimulus interval ranging from 0.01 s to 0.240 s. From the first to the second pattern, all the dots were shifted to the left or right by an equal displacement ranging from 0.03 deg to 1.64 deg. The spatiotemporal range yielding good direction discrimination performance was greatly reduced with age. For ISIs longer than 0.04 s, older subjects performed less accurately than younger subjects across a wide range of spatial displacements. Older subjects also showed poorer performance for large spatial displacements across a wide range of ISIs. Age-related differences in performance were also found with small displacements; however, these were largely accounted for by age-related declines in visual acuity. Overall, the results show that the maximum temporal interval and maximum spatial displacement over which two frames can be integrated are reduced in older age.

The present study examined the effect of aging on the detection and discrimination of contours embedded in a dense field of distractors. The minimum stimulus duration required to correctly discriminate (Experiment 1) and detect (Experiment 2) three types of "C" shaped contours was measured. Overall, older subjects required longer stimulus durations than younger subjects in all conditions. Comparing performance for contours comprising elements oriented tangentially to the contour path (aligned) and those oriented orthogonally to the contour (radial) revealed that the effect of local orientation on contour discrimination is slightly greater in older than younger subjects. Control experiments showed that these age differences were not due to differences in retinal illuminance, or the detectability or discriminability of the elements comprising the contours. These findings suggest that ability to extract global contours embedded in clutter declines in older age.

No abstract

Recent evidence suggests that familiarity with an environment may protect against spatial memory decline for familiar objects in older adults. We investigated whether a familiar context also reduces age-related decline in spatial memory for novel objects. Twenty-four younger and 23 older participants viewed a virtual rendering of a local environment along two different routes, each through a well-known (West) or lesser-known (East) area within the environment. Older and younger participants reported being more familiar with one (i.e. West) area than the other. In each trial, participants were presented with one route and were instructed to learn ten novel objects and their locations along the route. Following learning, participants immediately completed five test blocks: an object recognition task, an egocentric spatial processing (direction judgement) task, an allocentric spatial processing (proximity judgement) task and two pen-and-paper tests to measure cognitive mapping abilities. First we found an age effect with worse performance by older than younger adults in all spatial tasks, particularly in allocentric spatial processing. However, our results suggested better memory for objects and directions, but not proximity judgements, when the task was associated with more familiar than unfamiliar contexts, in both age groups. There was no benefit of context when a separate young adult group (N = 24) was tested, who reported being equally familiar with both areas. These results suggest an important facilitatory role of context familiarity on object recognition, and in particular egocentric spatial memory, and have implications for enhancing spatial memory in older adults.