Implicit Reward Research Articles

The association between obesity severity and food reward in adolescents with obesity: a one-stage individual participant data meta-analysis.

Food reward and cue reactivity have been linked prospectively to problematic eating behaviours and excess weight gain in adults and children. However, evidence to date in support of an association between degree of adiposity and food reward is tenuous. A non-linear relationship between reward sensitivity and obesity degree has been previously proposed, suggesting a peak is reached in mild obesity and decreases in more severe obesity in a quadratic fashion. To investigate and characterise in detail the relationship between obesity severity, body composition, and explicit and implicit food reward in adolescents with obesity. Data from seven clinical trials in adolescents with obesity were aggregated and analysed in an independent participant data meta-analysis. Linear and curvilinear relationships between the degree of obesity and explicit and implicit reward for sweet and high fat foods were tested in fasted and fed states with BMI-zscore as a continuous and discrete predictor using clinically recognised partitions. Although positive associations between obesity severity and preference for high-fat (i.e. energy dense) foods were observed when fasted, none reached significance in either analysis. Conversely, adiposity was reliably associated with lower reward for sweet, particularly when measured as implicit wanting (p = 0.012, ηp2 = 0.06), independent of metabolic state. However, this significant association was only observed in the linear model. Fat distribution was consistently associated with explicit and implicit preference for high-fat foods. A limited relationship was demonstrated between obesity severity and food reward in adolescents, although a lower preference for sweet could be a signal of severe obesity in a linear trend. Obesity is likely a heterogenous condition associated with multiple potential phenotypes, which metrics of body composition may help define. NCT02925572: https://classic. gov/ct2/show/NCT02925572 . NCT03807609: https://classic. gov/ct2/show/NCT03807609 . NCT03742622: https://classic. gov/ct2/show/NCT03742622 . NCT03967782: https://classic. gov/ct2/show/NCT03967782 . NCT03968458: https://classic. gov/ct2/show/NCT03968458 . NCT04739189: https://classic. gov/ct2/show/NCT04739189 . NCT05365685: https://www. gov/study/NCT05365685?tab=history .

Intelligence Predicts Sensory Discrimination Ability but Not Implicit Reward Learning

Abstract: Previous research has made use of sensory discrimination tasks that incorporate differential reinforcement schedules as a method for measuring individual differences in implicit reward learning. One such task was popularized by Pizzagalli and colleagues (2005) with the intent of behaviorally assessing anhedonia and reward sensitivity. Various studies have examined implicit reward learning in relation to clinical symptoms and personality traits, including anhedonia, depression, and Extraversion. Despite extensive use of these tasks, they have not been extensively examined in relation to intelligence, which affects performance on many cognitive tasks. Other research suggests positive associations of intelligence with sensory discrimination ability. The present study utilized a probabilistic reward task in a large community sample to determine the relations among IQ, sensory discrimination ability, and implicit reward learning. Participants ( N = 298) completed a sensory discrimination task, as well as an IQ test. IQ was not associated with participants’ levels of implicit reward learning but was positively associated with sensory discrimination ability. These findings provide a further understanding of the complex relations among implicit learning, sensory discrimination ability, and intelligence.

The use of lectures: effective pedagogy or seeds scattered on the wind?

This case study of large-class teaching at a UK university focuses on the place of large-scale lectures in academics’ approaches to teaching, their use by students in their studies, and their relationship to institutional quality assurance policies. The case is a second-year module comprised of 180 students, and it includes two-hour lectures as the primary mode of teaching. The data is drawn from a range of sources including observations, interviews, focus groups, institutional documentation, and a student survey. Observations revealed largely transmissive lectures with little student interaction. The analytic framework of constructive alignment and outcome-based education is used to examine the promoted educational values and the practice experienced by students. The results are further explored in relation to two texts celebrating 50 years since publication: Donald Bligh’s What’s the Use of Lectures and Benson Snyder’s The Hidden Curriculum, Both highlight the dissonance of espoused approaches to teaching, and the realities of large-class environments. While the institutional literature foregrounds student-centred, ‘active learning’ approaches, the teacher-centred practice observed would have been very familiar to Bligh and Snyder; the principles of constructive alignment were visible only at the policy level. The implicit reward mechanisms of the hidden curriculum ensure that the majority of students succeed and are satisfied with the educational offering. The students who attended the lectures appeared to enjoy them and indicated that the primary benefits are the structure offered by live lectures and the support of the peer networks which develop as a result of attendance.

The implicit reward value of the owner's face for dogs

SummaryIt is increasingly assumed that domestication has equipped dogs with unique socio-cognitive skills, which raises the possibility of intriguing parallels between the social motivational systems of the two species. However, the positive incentive value of human facial stimuli is a largely unexplored area. Here, we investigated whether the owner's face serves as a social reinforcer. In a two-way choice task N = 39 dogs were presented with a short video about their owners' head showing the face (facing owner [FO]) vs. the back of the head (non-facing owner). Despite both locations containing equal food reward, dogs approached the container associated with FO more frequently (p < .001), and this was not affected by side, trial order, and choice latency. However, the considerable inter-individual differences in dogs' task performance suggest that the added social component required special social skills which need to be further explored.

Avoiding pitfalls: Bayes factors can be a reliable tool for post hoc data selection in implicit learning.

Research on implicit processes has revealed problems with awareness categorizations based on nonsignificant results. Moreover, post hoc categorizations result in regression to the mean (RTM), by which aware participants are wrongly categorized as unaware. Using Bayes factors to obtain sensitive evidence for participants' lack of knowledge may deal with nonsignificance being nonevidential, but also may prevent regression-to-the-mean effects. Here, we examine the reliability of a novel Bayesian awareness categorization procedure. Participants completed a reward learning task followed by a flanker task measuring attention towards conditioned stimuli. They were categorized as B_Aware and B_Unaware of stimulus-outcome contingencies, and those with insensitive Bayes factors were deemed B_Insensitive. We found that performance for B_Unaware participants was below chance level using unbiased tests. This was further confirmed using a resampling procedure with multiple iterations, contrary to the prediction of RTM effects. Conversely, when categorizing participants using t tests, t_Unaware participants showed RTM effects. We also propose a group boundary optimization procedure to determine the threshold at which regression to the mean is observed. Using Bayes factors instead of t tests as a post hoc categorization tool allows evaluating evidence of unawareness, which in turn helps avoid RTM. The reliability of the Bayesian awareness categorization procedure strengthens previous evidence for implicit reward conditioning. The toolbox used for the categorization procedure is detailed and made available. Post hoc group selection can provide evidence for implicit processes; the relevance of RTM needs to be considered for each study and cannot simply be assumed to be a problem.

Packet Flow Based Reinforcement Learning MAC Protocol for Underwater Acoustic Sensor Networks.

Medium access control (MAC) is one of the key requirements in underwater acoustic sensor networks (UASNs). For a MAC protocol to provide its basic function of efficient sharing of channel access, the highly dynamic underwater environment demands MAC protocols to be adaptive as well. Q-learning is one of the promising techniques employed in intelligent MAC protocol solutions, however, due to the long propagation delay, the performance of this approach is severely limited by reliance on an explicit reward signal to function. In this paper, we propose a restructured and a modified two stage Q-learning process to extract an implicit reward signal for a novel MAC protocol: Packet flow ALOHA with Q-learning (ALOHA-QUPAF). Based on a simulated pipeline monitoring chain network, results show that the protocol outperforms both ALOHA-Q and framed ALOHA by at least 13% and 148% in all simulated scenarios, respectively.

Reward learning in unmedicated women with bulimia nervosa: A pilot investigation

Bulimia nervosa (BN) is characterized by recurrent engagement in eating disorder behaviors despite negative consequences, potentially reflecting aberrant stimulus-response or reward-learning processes. Indeed, frontostriatal circuitry involved in reward learning is altered in persons with BN and preliminary research suggests reward learning is impaired in persons with BN. Additional research on reward learning in BN and its association with eating disorder symptom expression is warranted to further the field's understanding of potential pathophysiological mechanisms of BN. To this end, the probabilistic reward learning task (PRLT) was administered to unmedicated women with BN (n = 15) and demographically matched psychiatrically healthy women (n = 18). Contrary to our hypotheses, results demonstrated that women with BN showed greater reward learning during the PRLT relative to healthy comparison women when covarying for symptoms of depression, social anxiety, and mania. Exploratory analyses showed that binge-eating frequency was inversely associated with reward learning in women with BN; however, results should be interpreted with caution due to the small sample size. Together, results suggest that women with BN do not have deficits in implicit reward learning. Given the preliminary nature of this investigation, larger-scale studies are needed to further examine reward learning in current BN and could compare reward learning using general (e.g., monetary) and disorder-specific (e.g., food) reinforcers. Further work is needed to confirm the inverse association between reward learning and binge eating.

Climate Change and (a Culture of) Cooperation in the World's Most Agricultural Countries.

Overwhelming evidence suggests that a “culture of cooperation,” which is the implicit reward from cooperating in any economic activity, represents one of the most successful humanly devised social structures. Yet, our understanding of its determinants and impact is still limited. To clarify these issues, we propose a time inconsistency theory of state-building and we document that, in the world's most agricultural countries, adverse climate shocks push the nonelites to accumulate strong norms of cooperation. To illustrate, a strong culture signals the nonelites’ commitment to cooperate with the elites in joint investment activities despite the small expected payoff and encourages the elites to reciprocate by granting a more inclusive political process. These reforms, in turn, help convince the nonelites that a sufficient part of the investment returns will be shared via public good provision. Our estimates imply that the severity of droughts has two short run effects on agricultural output, a negative impact due to worse farming conditions and a positive effect due to stronger norms of trust and respect. Accordingly, policymakers should consider the direct and indirect impacts of climate change and favor endogenous cultural formation. Moreover, environmental policies should be designed through a more credible interdisciplinary approach.

Contextual Bandit Learning With Reward Oracles and Sampling Guidance in Multi-Agent Environments

Learning action policy for autonomous agents in a decentralized multi-agent environment has remained an interesting but difficult research problem. We propose to model this problem in a contextual bandit setting with delayed reward signals, in particular an individual short-term reward signal and a shared long-term reward signal. Our algorithm utilizes an approach with reward oracles to directly model these delayed reward signals and also relies on a learning scheme benefiting from the sampling guidance of an expert-designed policy. This algorithm is expected to apply to a wide range of problems, including those with constraints on accessing state transitions and those with implicit reward information. A demonstration, deployed by deep learning regressors, shows the effectiveness of the proposed algorithm in learning offensive action policy in the RoboCup Soccer 2D Simulation (RCSS) environment against a well-known adversary benchmark team compared to a baseline policy.

Diagnostic and dimensional evaluation of implicit reward learning in social anxiety disorder and major depression.

Increasing evidence supports the presence of an anhedonic endophenotype in major depressive disorder (MDD), characterized by impairments in various components of reward processing, particularly incentive motivation, effort-based decision making, and reward learning. In addition to its prominent role in MDD, reward processing dysregulation has been proposed as a transdiagnostic risk and/or maintenance factor for a range of other forms of psychopathology. Individuals with social anxiety disorder (SAD)-a condition that frequently co-occurs with MDD-demonstrate low trait positive affectivity and altered processing of rewards and positively valenced information. However, no studies to date have directly tested reward learning-the ability to modulate behavior in response to rewards-in this population. The current study evaluated reward learning in MDD, SAD, and healthy control subjects (N = 90) using a well-validated signal detection task. Given increasing data supporting transdiagnostic features of psychopathology, we also evaluated associations between anhedonia and task performance transdiagnostically in the patient sample. Contrary to expectations, results indicated no significant group differences in response bias in the full sample, suggesting no diagnostic differences in reward learning. However, dimensional analyses revealed that higher self-reported anhedonia (but not general distress or anxious arousal) was associated with worse reward learning in both the MDD and SAD groups explaining about 11% of the variance. Deficits in implicit reward learning are associated with anhedonia but not necessarily with major depressive disorder as a diagnosis, which supports the use of transdiagnostic approaches to understanding psychopathology.

A comparison of implicit and explicit reward learning in low risk alcohol users versus people who binge drink and people with alcohol dependence

Chronic alcohol use leads to specific neurobiological alterations in the dopaminergic brain reward system, which probably are leading to a reward deficiency syndrome in alcohol dependence. The purpose of our study was to examine the effects of such hypothesized neurobiological alterations on the behavioral level, and more precisely on the implicit and explicit reward learning. Alcohol users were classified as dependent drinkers (using the DSM-IV criteria), binge drinkers (using criteria of the USA National Institute on Alcohol Abuse and Alcoholism) or low-risk drinkers (following recommendations of the Scientific board of trustees of the German Health Ministry). The final sample (n = 94) consisted of 36 low-risk alcohol users, 37 binge drinkers and 21 abstinent alcohol dependent patients. Participants were administered a probabilistic implicit reward learning task and an explicit reward- and punishment-based trial-and-error-learning task. Alcohol dependent patients showed a lower performance in implicit and explicit reward learning than low risk drinkers. Binge drinkers learned less than low-risk drinkers in the implicit learning task. The results support the assumption that binge drinking and alcohol dependence are related to a chronic reward deficit. Binge drinking accompanied by implicit reward learning deficits could increase the risk for the development of an alcohol dependence.

Implicit reward associations impact face processing: Time-resolved evidence from event-related brain potentials and pupil dilations

The present study aimed at investigating whether associated motivational salience causes preferential processing of inherently neutral faces similar to emotional expressions by means of event-related brain potentials (ERPs) and changes of the pupil size. To this aim, neutral faces were implicitly associated with monetary outcome, while participants (N = 44) performed a face-matching task with masked primes that ensured performance around chance level and thus an equal proportion of gain, loss, and zero outcomes. During learning, motivational context strongly impacted the processing of the fixation, prime and mask stimuli prior to the target face, indicated by enhanced amplitudes of subsequent ERP components and increased pupil size. In a separate test session, previously associated faces as well as novel faces with emotional expressions were presented within the same task but without motivational context and performance feedback. Most importantly, previously gain-associated faces amplified the LPC, although the individually contingent face-outcome assignments were not made explicit during the learning session. Emotional expressions impacted the N170 and EPN components. Modulations of the pupil size were absent in both motivationally-associated and emotional conditions. Our findings demonstrate that neural representations of neutral stimuli can acquire increased salience via implicit learning, with an advantage for gain over loss associations.

The impact of reward on attention in schizophrenia

Traditionally, attention was thought to be directed by either top-down goals or bottom-up salience. Recent studies have shown that the reward history of a stimulus feature also acts as a powerful attentional cue. This is particularly relevant in schizophrenia, which is characterized by motivational and attentional deficits. Here, we examine the impact of reward on selective attention.Forty-eight people with schizophrenia (PSZ) and 34 non-psychiatric control subject (NCS) discriminated the location of a target dot appearing inside a left circle or right circle. The circles were different colors, one of which was associated with reward via pre-training. In the first 2 blocks, targets were equally likely to appear in the left or right circle. In the last 4 blocks, the target was 75% likely on one side, thus allowing us to separately examine how attention was impacted by reward (color) and probability (location).PSZ had slower overall reaction times (RTs) than NCS. Both groups showed robust effects of spatial probability and reward history, with faster RTs for the rewarded color and for the more probable location. These effects were similar in PSZ and NCS. Negative symptom severity correlated with overall RT slowing, but there were no correlations between symptoms and reward-associated biasing of attention.PSZ demonstrated RT slowing but normal reward history and spatial probability-driven RT facilitation. These results are conceptually similar to prior findings showing intact implicit reward effects on response bias, and suggest that implicit processing of reward and probability is intact in PSZ.

T18. Characterizing Reward Responsiveness in Obsessive-Compulsive Disorder and Schizophrenia Through a Probabilistic Reward Task

Deficits in reward processing occur across the psychiatric spectrum. Identifying common and distinct impairments in the maintenance and integration of reward information may lead to a greater understanding of the mechanisms behind the affective disturbances across schizophrenia (SCZ) and obsessive-compulsive disorder (OCD). Here, we used the probabilistic reward task (PRT) to test the ability to learn implicit reward reinforcement across patients diagnosed with SCZ and OCD.

When perceptual learning occurs.

A study now finds that visual perceptual learning of complex features occurs due to enhancement of later, decision-related stages of visual processing, rather than earlier, visual encoding stages. It is suggested that strengthening of the readout of sensory information between stages may be reinforced by an implicit reward learning mechanism.

Increased reward value of non-social stimuli in children and adolescents with autism.

An econometric choice task was used to estimate the implicit reward value of social and non-social stimuli related to restricted interests in children and adolescents with (n = 12) and without (n = 22) autism spectrum disorder (ASD). Mixed effects logistic regression analyses revealed that groups differed in valuation of images related to restricted interests: control children were indifferent to cash payouts to view these images, but children with ASD were willing to receive less cash payout to view these images. Groups did not differ in valuation of social images or non-social images not related to restricted interests. Results highlight that motivational accounts of ASD should also consider the reward value of non-social stimuli related to restricted interests in ASD (Dichter and Adolphs, 2012).

Taking Pleasure at Another's Misfortune: The Implicit Schadenfreude of Disaster Spectators

Implicit Schadenfreude of disaster spectators, with augmentation of implicit self-esteem and higher reward responsiveness as indicators, and the influence of insecurity and masculinity was explored in two studies. Both studies were conducted under conditions without any clearly legitimizing factors. Experimental (priming with disaster video) and control (priming with neutral video) groups were compared using the Implicit Association Test in Study 1, the results of which showed augmentation of implicit self-esteem in the experimental group. In Study 2, participants who read and believed a fabricated news report of fire disaster via a local area network website showed higher reward responsiveness in a reward-based signal-detection task. Other results showed that insecurity negatively predicted the augmentation of implicit self-esteem and reward responsiveness, while masculinity only negatively predicted the augmentation of implicit self-esteem.

Stimulus devaluation induced by stopping action.

Impulsive behavior in humans partly relates to inappropriate overvaluation of reward-associated stimuli. Hence, it is desirable to develop methods of behavioral modification that can reduce stimulus value. Here, we tested whether one kind of behavioral modification--the rapid stopping of actions in the face of reward-associated stimuli--could lead to subsequent devaluation of those stimuli. We developed a novel paradigm with three consecutive phases: implicit reward learning, a stop-signal task, and an auction procedure. In the learning phase, we associated abstract shapes with different levels of reward. In the stop-signal phase, we paired half those shapes with occasional stop-signals, requiring the rapid stopping of an initiated motor response, while the other half of shapes was not paired with stop signals. In the auction phase, we assessed the subjective value of each shape via willingness-to-pay. In 2 experiments, we found that participants bid less for shapes that were paired with stop-signals compared to shapes that were not. This suggests that the requirement to try to rapidly stop a response decrements stimulus value. Two follow-on control experiments suggested that the result was specifically due to stopping action rather than aversiveness, effort, conflict, or salience associated with stop signals. This study makes a theoretical link between research on inhibitory control and value. It also provides a novel behavioral paradigm with carefully operationalized learning, treatment, and valuation phases. This framework lends itself to both behavioral modification procedures in clinical disorders and research on the neural underpinnings of stimulus devaluation.

How Are Athletic Directors Rewarded in the NCAA Football Bowl Subdivision?

Intercollegiate athletics has been a source of ongoing controversy regarding the potential conflict in pursuing athletic success while maintaining academic standards. This study examines the implicit reward system for athletic directors (ADs) in the National Collegiate Athletic Association Football Bowl Subdivision. Using AD compensation for 2010-2011, the evidence shows that base salaries are largely determined by revenues generated within the athletic department. Earned bonuses are unrelated to revenues but are correlated positively with football success, the tenure of the AD, and the number of teams sponsored by the school.

The role of uncertainty and reward on eye movements in a virtual driving task

Eye movements during natural tasks are well coordinated with ongoing task demands and many variables could influence gaze strategies. Sprague and Ballard (2003) proposed a gaze-scheduling model that uses a utility-weighted uncertainty metric to prioritize fixations on task-relevant objects and predicted that human gaze should be influenced by both reward structure and task-relevant uncertainties. To test this conjecture, we tracked the eye movements of participants in a simulated driving task where uncertainty and implicit reward (via task priority) were varied. Participants were instructed to simultaneously perform a Follow Task where they followed a lead car at a specific distance and a Speed Task where they drove at an exact speed. We varied implicit reward by instructing the participants to emphasize one task over the other and varied uncertainty in the Speed Task with the presence or absence of uniform noise added to the car's velocity. Subjects' gaze data were classified for the image content near fixation and segmented into looks. Gaze measures, including look proportion, duration and interlook interval, showed that drivers more closely monitor the speedometer if it had a high level of uncertainty, but only if it was also associated with high task priority or implicit reward. The interaction observed appears to be an example of a simple mechanism whereby the reduction of visual uncertainty is gated by behavioral relevance. This lends qualitative support for the primary variables controlling gaze allocation proposed in the Sprague and Ballard model.