THE COGNITIVE aspects of problem solving behavior have frequently been analyzed by studying subjects' responses to selected stimuli (test items) rather than by investigating the processes that mediate between the stimulus and the response.
There is, for example, a large body of research relative to changes in intellectual functioning concomitant with the aging processes.1-11 Although there are some exceptions,12,13 in general there is agreement pointing to a gradual increment in performance with increasing age followed by a progressive decrement.
Similar results have been obtained when assessing changes in "quality of thinking" as indicated by tests of abstract and creative ability.14-16
In the area of problem solving and concept attainment, the results of Heglin17 indicate increasing susceptibility to set and a decreased ability to overcome set after fifty years of age. Clay18 has shown changes in problem