Abstract
The Iowa Gambling Task (IGT) has contributed greatly to the study of affective decision making. However, researchers have observed high inter-study and inter-individual variability in IGT performance in healthy participants, and many are classified as impaired using standard criteria. Additionally, while decision-making deficits are often attributed to atypical sensitivity to reward and/or punishment, the IGT lacks an integrated sensitivity measure. Adopting an operant perspective, two experiments were conducted to explore these issues. In Experiment 1, 50 healthy participants completed a 200-trial version of the IGT which otherwise closely emulated Bechara et al.'s (1999) original computer task. Group data for Trials 1–100 closely replicated Bechara et al.'s original findings of high net scores and preferences for advantageous decks, suggesting that implementations that depart significantly from Bechara's standard IGT contribute to inter-study variability. During Trials 101–200, mean net scores improved significantly and the percentage of participants meeting the “impaired” criterion was halved. An operant-style stability criterion applied to individual data revealed this was likely related to individual differences in learning rate. Experiment 2 used a novel operant card task—the Auckland Card Task (ACT)—to derive quantitative estimates of sensitivity using the generalized matching law. Relative to individuals who mastered the IGT, persistent poor performers on the IGT exhibited significantly lower sensitivity to magnitudes (but not frequencies) of rewards and punishers on the ACT. Overall, our findings demonstrate the utility of operant-style analysis of IGT data and the potential of applying operant concurrent-schedule procedures to the study of human decision making.
Highlights
Our close replication of Bechara et al.’s (1999) computerized experimental task and instructions resulted in mean net scores in Trials 1–100 that were comparable to Bechara et al (1998, 1999), in contrast to the relatively low scores reported in the majority of Iowa Gambling Task (IGT) studies reviewed by Steingroever et al (2013)
Like Bechara et al (1994), but in contrast to many of the IGT studies reviewed by Steingroever et al (2013), our group data for the first 100 trials showed no evidence of the tendency to avoid frequent punishers (i.e., the frequency-of-losses effect; Dunn et al, TABLE 3 | Mean net scores and variability statistics in participants who developed stable preferences for the good decks (C and/or D) in the present study
While poor decision makers had little difficulty determining whether rewards or penalties occurred more often on one deck than the other in the Auckland Card Task (ACT), they were poor at discriminating the average dollar amounts of rewards and penalties on each deck
Summary
In situations involving complexity (where choice alternatives have multiple reward and punishment dimensions which may conflict) or uncertainty The IGT: an operant approach rewards and punishers occur unpredictably), is associated with brain injury to ventromedial prefrontal cortex (VMPFC). The Iowa Gambling Task (IGT; Bechara et al, 1994) was designed to assess decision-making abilities in VMPFC patients under such conditions of complexity and uncertainty. Participants are instructed to maximize winnings while choosing repeatedly from four decks of playing cards that unpredictably yield wins and losses. The contingencies of reward and punishment are counter-intuitively arranged so that the decks with higher wins ($100) result in a long-term net loss, while the decks with smaller wins ($50) yield a net gain. The IGT has contributed to understanding decisionmaking deficits in patients with VMPFC damage, but has been successfully applied to a variety of disorders arising from poor impulse control (e.g., pathological gambling; Brand et al, 2005)
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