EFFECT OF BRAIN DAMAGE ON ADAPTABILITY

Abstract

An attempted study to investigate the effects of brain damage on the construct of expectancy and to relate expectancy to the descriptive concept of adaptability. Level of expectancy was defined with respect to reaction times (RTs) in a series of simple RT tests, a long RT indicating low expectancy, a short RT high expectancy. Three independent groups of 20 male Ss [subjects] were used: hospitalized brain-damaged (BD), hospitalized non-brain-damaged control (HC) and non-hospitalized non-braindamaged control (NC). Time taken for S to terminate a visual stimulus by pressing atelegraph key was the RT. No warning signal preceded stimulus onset. Part I of the study involved a series of 50 simple RT tests (trials). Time between stimulus presentations (intertrial interval) for the first 40 trials was 15 secs, for the last 10 trials three secs. Part II followed Part I after a brief (1 1/2 minute) rest and attempted to determine the short-term (sequence) effects of 2 intervals (three sec, short; nine sec, long). Order of interval presentation was fixed so that each S received 4 trials of each of 4 interval combinations (long-short, short-long, etc.). In general the results of this experiment support the following empirical statements: 1) RTs of BD Ss were significantly longer than those of the controls. 2) No practice effects were found; i. e., no significant changes in RTs occurred over trials within groups. 3) Transition from the 15- to the 3-sec interval in Part I produced longer RTs for all groups, but the relative effect (within groups) was comparable. 4) Sequence effects of short and long preceding intervals produced the predicted effects on both BD and NC Ss, but had a lesser effect on the RTs of the BD Ss. A differential in RT was taken as representative of a differential in expectancy which was in turn taken to be indicative of relative degree of adaptability. As the RTs were significantly longer for the BD Ss than those of the controls, it was inferred that their expectancy level was inferior to that of the control Ss. It was concluded therefore that these data tend to support that use of the descriptive concept of adaptability as a means for under -standing the psychological effects of intracranial organic pathology.