HEAD-INJURED PATIENTS AND CONTROL-GROUP - IMPLICIT VERSUS EXPLICIT MEASURES OF FREQUENCY OF OCCURRENCE

This study was conducted in order to investigate the possibility that effortful processes are involved in the retrieval stage of the putativ e automatic task - frequency judgment. Head-injured (HI) and control g roups were tested on a frequency of occurrence task under explicit - i ntentional retrieval (i.e., frequency estimation) and implicit - unint entional retrieval (i.e., word-stem priming) conditions. Subjects were presented with a list of nouns that appeared once, three times, and s ix times. Following presentation, subjects were first given a priming task, then a recall task, and finally a frequency judgment task. Altho ugh the control group performed better than the HI group on recall and frequency judgment tasks, the groups did not differ on the priming ta sk. The results are discussed in terms of the relationship between eff ortful and automatic memory processes.