The Effects of Implicit and Explicit Memory on Iowa Gambling Task Performance

Abstract

The Iowa Gambling Task (IGT) has repeatedly been used to show that damage to the prefrontal cortex causes deficits in decision making ability (Bechara, Damasio, Damasio & Anderson, 1994). There is currently a lack of research exploring the effects of implicit and explicit memory ability on performance on the IGT. Based on the somatic marker hypothesis (Damasio, 1996) it was hypothesised that performance on the earlier stages of the IGT would be influenced by implicit memory ability affecting the strength of covert, biophysical biases. The performance on the latter stages of the IGT was also hypothesised to be influenced by explicit memory ability as the participant begins to cement his/her concept of the nature of the task. 38 undergraduate participants (mean age = 21.63) completed a serial reaction time task (SRTT) to measure implicit memory and the Rey Auditory Verbal Learning Task (RAVLT) to measure explicit memory. Significant correlations were found between block 4 of the IGT and the delay and post-interference trials of the RAVLT. Due to the long temporal delay between stimulus presentation and recall it was suggested that long term memory (LTM) plays a major part in the latter stages of the IGT. This was attributed to a stronger LTM having greater ability at encoding and retrieving the results of earlier deck selections therefore forming a more accurate representation of the nature of each deck. Proposals for future research included alternative methodologies to test the influence of LTM on the IGT and recording all participant vocalisations during the IGT.