Dynamic expectations: Behavioral and electrophysiological evidence of sub-second updates in reward predictions

Expectations are often dynamic: sports fans know that expectations are rapidly updated as games unfold. Yet expectations have traditionally been studied as static. Here we present behavioral and electrophysiological evidence of sub-second changes in expectations using slot machines as a case study. In Study 1, we demonstrate that EEG signal before the slot machine stops varies based on proximity to winning. Study 2 introduces a behavioral paradigm to measure dynamic expectations via betting, and shows that expectation trajectories vary as a function of winning proximity. Notably, these expectation trajectories parallel Study 1's EEG activity. Studies 3 (EEG) and 4 (behavioral) replicate these findings in the loss domain. These four studies provide compelling evidence that dynamic sub-second updates in expectations can be behaviorally and electrophysiologically measured. Our research opens promising avenues for understanding the dynamic nature of reward expectations and their impact on cognitive processes.

Dynamic expectations: Behavioral and electrophysiological evidence of sub-second updates in reward predictions

Expectations are often dynamic: any sports fan knows that expectations are rapidly updated as games unfold. Yet expectations have traditionally been studied as static. Here, using slot machines as a case study, we provide parallel behavioral and electrophysiological evidence of sub-second moment-to-moment changes in expectations. In Study 1, we show that the dynamics of the EEG signal before the slot machine stopped differed depending on the nature of the outcome, including not only whether the participant won or lost, but also how close they came to winning. In line with our predictions, Near Win Before outcomes (the slot machine stops one item before a match) were similar to Wins, but different than Near Win After (the machine stops one item after a match) and Full Miss (the machine stops two or three items from a match). In Study 2, we designed a novel behavioral paradigm to measure moment-to-moment changes in expectations via dynamic betting. We found that different outcomes also elicited unique expectation trajectories in the deceleration phase. Notably, these behavioral expectation trajectories paralleled Study 1's EEG activity in the last second prior to the machine's stop. In Studies 3 (EEG) and 4 (behavior) we replicated these findings in the loss domain where a match entails a loss. Again, we found a significant correlation between behavioral and EEG results. These four studies provide the first evidence that dynamic sub-second updates in expectations can be behaviorally and electrophysiologically measured. Our findings open up new avenues for studying the ongoing dynamics of reward expectations and their role in healthy and unhealthy cognition.

Comparing rapid rule-learning strategies in humans and monkeys

Inter-species comparisons are key to deriving an understanding of the behavioral and neural correlates of human cognition from animal models. We perform a detailed comparison of macaque monkey and human strategies on an analogue of the Wisconsin Card Sort Test, a widely studied and applied multi-attribute measure of cognitive function, wherein performance requires the inference of a changing rule given ambiguous feedback. We found that well-trained monkeys rapidly infer rules but are three times slower than humans. Model fits to their choices revealed hidden states akin to feature-based attention in both species, and decision processes that resembled a Win-stay lose-shift strategy with key differences. Monkeys and humans test multiple rule hypotheses over a series of rule-search trials and perform inference-like computations to exclude candidates. An attention-set based learning stage categorization revealed that perseveration, random exploration and poor sensitivity to negative feedback explain the under-performance in monkeys.

Evaluation of a smoking cessation program for pregnant minority women

The purpose of this project was to develop and test culturally appropriate, low literacy, smoking cessation intervention materials designed to increase quit rates and prevent relapse postpartum for low-income African American and Hispanic women. A quasi-experimental, pretest-posttest design was used. Four Women, Infants, and Children (WIC) clinic sites in south and central Los Angeles were identified, pair-matched based on ethnic mix, and randomized to intervention (2 sites) or control status (2 sites). Participants were 18 years of age or older and either current or exsmokers (stopped smoking in the past year). The intervention group received the "Time for a Change: A Program for Healthy Moms and Babies" program including a 15-minute one-to-one counseling session and self-help guide, incorporating behavior-change strategies, booster postcard, and incentive contest. All materials were designed to match the cultural, language, and literacy needs of the target population. The smoking cessation intervention had a positive impact on both quit-smoking behavior during pregnancy and relapse prevention postpartum. Almost twice as many smokers in the intervention group (43%) reported quitting smoking at 9 months, compared to the control group (25%) (P < 0.01). At 6 weeks postpartum, 25% of the intervention baseline smokers were abstinent, compared to 12% of the control group (P < 0.01). Although no significant differences were observed for relapse during pregnancy among exsmokers at 6 weeks postpartum, a significantly higher proportion of intervention exsmokers were still abstinent (79%), compared to control exsmokers (62%) (P < 0.01). For the exsmokers, relapse prevention rates remained significant when adjusted for cotinine validated abstinence.(ABSTRACT TRUNCATED AT 250 WORDS)