Performance on the Iowa Gambling Task: From 5 to 89 years of age

Abstract

The present study focuses on the role of frequency bias and expected value on the learning processes driving performance on the Iowa Gambling Task (IGT) in individuals between 5 and 89 years of age. As in previous studies, children performed poorly on the IGT, were increasingly influenced by frequency of losses during learning, and constantly changed their decisions. Decision-making strategies changed after childhood from erratic behavior to more consistent strategies that promoted expected value of deck choices. Performance deficits as well as a loss frequency bias were found in older adults. However, age-related deficits were distinct between children and older adults. Cognitive modeling analysis indicated that older adults were more likely to forget about recent outcomes and were more consistent than children when selecting decks. Cognitive ability was associated with a modeling parameter for memory as well as IGT performance, suggesting the involvement of a cognitive component in young and middle-aged adult decision making. The interactions of modeling parameters suggested that cognitive changes were the cause of lowered performance in older adults. These analyses suggest critical developments in decision processes during the adolescent years and decline in a cognitive process leading to decision-making deficits after age 60.

Figure 1

Proportion of deck selection over 100 trials by decade. C and D trend lines are solid, A and B trend lines are dashed. Global maximum for D selections = 45.7 years.

Figure 2

Deck preferences and loss frequency preference by block for each age group. Low loss frequency decks are darker than high loss frequency. Freq = frequency.

Figure 3

Proportion of win-shift and loss-stay decisions by deck over 100 trials. Decks A and B are represented with dashed lines.

Figure 4

Model evaluation using Bayesian information criteria by age group. Decay = decay reinforcement rule; delta = delta learning rule; dep = trial-dependent choice rule; ind = trial-independent choice rule.