The performance of young and old adults was compared in two different situations to investigate the reasons why the latter are especially poor at divided attention tasks. Although the two experimental tasks were quite different, one a single task and the other time-sharing, task difficulty was manipulated in a similar fashion in both situations. Specifically, in both tasks difficulty was varied by manipulation of number of items to be rehearsed and number of mental operations necessary for successful performance. The most salient difference in task demands, that is, divided versus nondivided attention, had little effect on results. Performance of both age groups declined as task difficulty increased, with the decline being greater and more rapid for the older subjects. Results are discussed in terms of competition for limited processing capacity in working memory.

Adult age differences on a variety of free recall measures were examined. Although primary memory capacity was found to be the same in young and old adults, there was a smaller recency effect in the older group. Recall of primacy items was also less for that group. However, the pattern of serial position effects was the same for the two age groups. Similarly, there was no age difference in the development of the strategy of recalling recency items early in the output sequence. Young adults showed the typical negative recency effect in final free recall, and old adults the absence of a positive recency effect. The results indicate that the lower level of recall of old, relative to young, adults cannot be attributed to a qualitative difference in the way the two age groups approach a free recall task.

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From the original Stanford-Binet scale, those items passed by between 10 and 90 per cent of a group of ten-year-old children were analyzed by the centroid method. Upon rotation, there appeared a common factor, for which two explanatory hypotheses are offered, the more tenable being that it is an effect of maturation. Primary factors tentatively identified are Number, Space, Imagery, Verbal Relations and Induction. A sixth factor apparently involves a reasoning ability and a seventh can not be interpreted.

Adult age differences were examined for relative frequency judgments on a task in which categories had either zero, one, three, or five instances in a study list. Judgments required selecting from pairs of category names which member had the greater representation of instances in the prior list. Contrary to the results obtained in earlier studies using a task in which discrete events vary in frequency of occurrence, an age difference favoring young adults over elderly adults in accuracy of frequency judgments was found for categories. Neither instructional variation (incidental learning vs. intentional learning) nor variation in priming (cuing vs. noncuing with the list of categories prior to the study trial) yielded either main effects or interaction effects with age. The results were interpreted in terms of an age deficit in either the storage or the retrieval of memory traces of category names established by the automatic elicitation of implicit associative responses to instances of taxonomic categories.