A Combined Effect of Self and Reward: Relationship of Self- and Reward-Bias on Associative Learning

Previous studies have demonstrated that individuals process information related to themselves or a high reward quickly and have referred to this as self-bias or reward-bias. However, no previous study has presented self- and reward-bias simultaneously. The present study investigated perceptual processing using the associated learning paradigm when both self and reward were prioritized (condition of double salience) as well as when only self or reward was prioritized (condition of single salience). The present study established these two conditions by manipulating self-relevance (self vs. stranger in Experiment 1; self vs. friend in Experiment 2). The results showed that (1) when the self was pitted against a stranger and received a high or low reward, perceptual processing of the participants mainly involved self-bias (Experiment 1); (2) when the self was pitted against a friend, perceptual processing involved both self-bias and reward-bias (Experiment 2). The study revealed a complex relationship between self- and reward-bias, which depends on the degree of affinity between oneself and others.

Attention bias to reward predicts behavioral problems and moderates early risk to externalizing and attention problems

The current study had three goals. First, we replicated recent evidence that suggests a concurrent relation between attention bias to reward and externalizing and attention problems at age 7. Second, we extended these findings by examining the relations between attention and behavioral measures of early exuberance (3 years), early effortful control (4 years), and concurrent effortful control (7 years), as well as later behavioral problems (9 years). Third, we evaluated the role of attention to reward in the longitudinal pathways between early exuberance and early effortful control to predict externalizing and attention problems. Results revealed that attention bias to reward was associated concurrently and longitudinally with behavioral problems. Moreover, greater reward bias was concurrently associated with lower levels of parent-reported effortful control. Finally, attention bias to reward moderated the longitudinal relations between early risk factors for behavioral problems (gender, exuberance, and effortful control) and later externalizing and attention problems, such that these early risk factors were most predictive of behavioral problems for males with a large attention bias to reward. These findings suggest that attention bias to reward may act as a moderator of early risk, aiding the identification of children at the highest risk for later behavioral problems.

Outcomes of temperamental inhibition in young children are moderated by attentional biases

The current longitudinal study examined the association of temperamental inhibition (assessed by behavioral observation and parental reports) at three years old with reward and punishment bias (measured by a spatial cueing task) and mothers’ and teachers’ reports of internalizing behaviors and social competence at five years old in 153 Chinese children. As predicted, behavioral inhibition positively predicted later mother-rated internalizing behaviors. In addition, punishment bias moderated this relation such that children with higher punishment bias showed a positive inhibition–internalizing link. Furthermore, inhibition negatively predicted both mother-rated and teacher-rated social competence. However, novel findings were that reward bias moderated the relation between inhibition and teacher-rated social competence, such that inhibited children showed an increased risk of low competence when they had lower reward bias.

Distinct dynamics of ramping activity in the frontal cortex and caudate nucleus in monkeys

The prefronto-striatal network is involved in many cognitive functions, including perceptual decision making and reward-modulated behaviors. For well-trained subjects, neural responses frequently show similar patterns in the prefrontal cortex and striatum, making it difficult to tease apart distinct regional contributions. Here I show that, despite similar mean firing rate patterns, prefrontal and striatal responses differ in other temporal dynamics for both perceptual and reward-based tasks. Compared with simulation results, the temporal dynamics of prefrontal activity are consistent with an accumulation of sensory evidence used to solve a perceptual task but not with an accumulation of reward context-related information used for the development of a reward bias. In contrast, the dynamics of striatal activity is consistent with an accumulation of reward context-related information and with an accumulation of sensory evidence during early stimulus viewing. These results suggest that prefrontal and striatal neurons may have specialized functions for different tasks even with similar average activity.

The Decimal Effect: Behavioral and Neural Bases for a Novel Influence on Intertemporal Choice in Healthy Individuals and in ADHD

We identify a novel contextual variable that alters the evaluation of delayed rewards in healthy participants and those diagnosed with attention deficit/hyperactivity disorder (ADHD). When intertemporal choices are constructed of monetary outcomes with rounded values (e.g., $25.00), discount rates are greater than when the rewards have nonzero decimal values (e.g., $25.12). This finding is well explained within a dual system framework for temporal discounting in which preferences are constructed from separate affective and deliberative processes. Specifically, we find that round dollar values produce greater positive affect than do nonzero decimal values. This suggests that relative involvement of affective processes may underlie our observed difference in intertemporal preferences. Furthermore, we demonstrate that intertemporal choices with rounded values recruit greater brain responses in the nucleus accumbens to a degree that correlates with the size of the behavioral effect across participants. Our demonstration that a simple contextual manipulation can alter self-control in ADHD has implications for treatment of individuals with disorders of impulsivity. Overall, the decimal effect highlights mechanisms by which the properties of a reward bias perceived value and consequent preferences.

Effects of Acute Dopamine Precusor Depletion on Immediate Reward Selection Bias and Working Memory Depend on Catechol-O-methyltransferase Genotype

Little agreement exists as to acute dopamine (DA) manipulation effects on intertemporal choice in humans. We previously found that catechol-O-methyltransferase (COMT) Val158Met genotype predicts individual differences in immediate reward selection bias among adults. Moreover, we and others have shown that the relationship between COMT genotype and immediate reward bias is inverted in adolescents. No previous pharmacology studies testing DA manipulation effects on intertemporal choice have accounted for COMT genotype, and many have included participants in the adolescent age range (18–21 years) as adults. Moreover, many studies have included female participants without strict cycle phase control, although recent evidence demonstrates that cyclic estradiol elevations interact with COMT genotype to affect DA-dependent cognition. These factors may have interacted with DA manipulations in past studies, potentially occluding detection of effects. Therefore, we predicted that, among healthy male adults (ages 22–40 years), frontal DA tone, as indexed by COMT genotype, would interact with acute changes in DA signaling to affect intertemporal choice. In a double-blind, placebo-controlled design, we decreased central DA via administration of an amino acid beverage deficient in the DA precursors, phenylalanine and tyrosine, and tested effects on immediate reward bias in a delay-discounting (DD) task and working memory (WM) in an n-back task. We found no main effect of beverage on DD or WM performance but did find significant beverage*genotype effects. These results suggest that the effect of DA manipulations on DD depends on individual differences in frontal DA tone, which may have impeded some past efforts to characterize DA's role in immediate reward bias in humans.