0125 Sleep Deprivation Impairs the Ability to Overcome Pre-Existing Framing Bias

Introduction When presented with a choice between sure gains or losses versus gambles, people tend to select sure gains over gambles, but gambles over sure losses. This pre-existing framing bias is embedded in the Framed Gambling Task (FGT), in which subjects choose between a sure option (gain or loss) and a gamble (card from one of two decks). For optimal performance, subjects need to recognize that one deck (‘good deck’) results in better average outcomes than the other deck (‘bad deck’) and select the gamble or sure option depending on the deck (good/bad) rather than the frame (sure loss/gain). A speeded version of the FGT, with 2s response deadlines to induce time pressure, was used in a laboratory total sleep deprivation (TSD) study to determine the impact of sleep loss on the ability to overcome pre-existing framing bias. Methods Eight-six subjects (ages 21–38; 47 females) were randomized (2:1 ratio) to a TSD condition (n=56) or control condition (n=30). They completed the speeded FGT at 11:00 on the baseline day (session 1), and again the following day (session 2) after 27h of wakefulness (TSD group) or 3h of wakefulness (control group). Performance accuracy was defined in terms of optimal task performance, i.e., gambling when the good deck was presented and not gambling when the bad deck was presented. Each test bout had 72 trials across three trial blocks. Results Accuracy improved across trial blocks (F1,84=20.44, p<0.001). In session 2, the TSD group showed lower accuracy (condition by session interaction: F2,84=4.15, p=0.045) and less improvement across trial blocks (condition by session by trial block interaction: F2,168=3.97, p=0.021) than the control group. Even under TSD, the frequency of response timeouts (RT>2s) was low (<3.5% of trials). Conclusion Sleep deprivation degraded FGT performance under time pressure, indicating reduced ability to overcome pre-existing framing bias. Support PRMRP award W81XWH-16-1-0319

The Role of Passing Time in Decision-Making

Theories of perceptual decision-making have been dominated by the idea that evidence accumulates in favor of different alternatives until some fixed threshold amount is reached, which triggers a decision. Recent theories have suggested that these thresholds may not be fixed during each decision, but change as time passes. These collapsing thresholds can improve performance in particular decision environments, but reviews of data from typical decision-making paradigms have failed to support collapsing thresholds. We designed three experiments to test collapsing threshold assumptions in decision environments specifically tailored to make them optimal. An emphasis on decision speed encouraged the adoption of collapsing thresholds – most strongly through the use of response deadlines, but also through instruction to a lesser extent – but setting an explicit goal of reward rate optimality through both instructions and task design did not. Our results provide a new explanation for previous findings regarding decision-making differences between humans and non-human primates.