An investigation of age differences in backward monoptic visual noise masking was carried out with young and old adult subjects. It was found that the older subjects were susceptible to the backward masking effect over significantly longer delays between the target and masking stimulus. The masking effect seems to be, at least in part, attributable to age changes in the central mechanisms concerned with perceptual processing which limit the rate at which stimuli can be "cleared" through the nervous system. Backward masking studies of different types seem to hold considerable promise for assessment of the peripheral and central components of age change in visual perceptual processing.

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Forty industrial workers between 20 and 60 years of age took part in the experiment. Each sat facing a display in an enclosure. His task was to locate targets with a pointer, under two conditons: when he was able to make whatever use he chose of direct vision, and wearing a pair of red goggles through which only the diplay could be seen. On the average, those over 40 years of age took more time than younger subjects over those portions of the task which were concerned with the initiation of a fresh action. When unable to make use of vision the older had far greater difficulty in locating the targets and attempted to supplement tactile and kinesthetic cues by making postural adjustments, turning their heads and often their bodies in the direction of the target at which they were aiming. These findings are discussed in relation to an earlier observation of the greater tendency for older people to look at what they are doing.

Subjects were required to throw at a target under three conditions of varying difficulty. Six groups of 14 subjects were used, each group receiving one of the six possible orders of presentation of the three conditions. Results in terms of mean distance from the "bull " indicated that the three conditions were producing different transfer effects. These could not be adequately explained in terms of stimulus-or response-similarity, and accordingly a tentative hypothesis is put forward in terms of the relative difficulty of the condition presented first, to those presented subsequently. It is suggested that transfer tends to be positive from a relatively difficult initial task to a subsequent -task which is easier, while transfer will tend to be negative from a relatively easy initial task to one which is more difficult.The first of the three conditions presented exerted considerably more powerful transfer effects than the second. Three possibilities as to why this should be so, are outlined.

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