2023 年 93 巻 6 号 p. 506-515
The Iowa Gambling Task (IGT) is a widely used neuropsychological test to assess decision-making function in the frontal lobe. Previous studies have shown different results regarding the trajectory of Net Scores (the number of selected advantageous decks – the number of selected disadvantageous decks) across 5 Blocks for normal/healthy people. Some studies found that they increased from Block 1 to Block 5. Other studies, however, pointed out that they do not always increase from Block 1 to Block 5. This study examined the Net Scores of 89 Japanese college students using the growth mixture model and latent class growth analysis. The participants were classified into four groups: two groups where the Net Score increased (the early-increase group (17 %) and the late-increase group (4 %)) and two groups where the Net Score was relatively unchanged (the moderate-horizontal group (64 %) and the low-horizontal group (15 %)). These results were discussed in regard to the difference in the number of trials for each group before a stable, long-term advantageous choice could be made.