The elderly and the control of simple behaviour by probabilistic information.

The probabilities of events in the environment are important as controllers of how we cope with that environment. Attention is deployed to parts of the visual field where important events are most likely to happen; in predicting what will happen next in a situation, probable things tend to be predicted. This paper assess adult age differences in the use of probabilistic information, using the laboratory task-settings of choice reaction time, simple prediction, and selective attending. In almost all situations the elderly are less influenced by event probabilities than their juniors, although they are just as capable of registering the probabilities involved. This consistent age effect contradicts the predictions of Griew's theory which assumes that behavioural experience operates by increasing the use of probabilistic information. A second finding was that value and reward manipulations which alter the response patterns of the young do not influence the elderly to the same extent. It is tentatively concluded that attenuated use of probability information characterises the elderly, as does a reduced response to simple payoffs. Some avenues of theoretical exploration are discussed, together with some caveats concerning the applicability of the findings.