Reward Components Research Articles

Personality and the effort-reward imbalance model of stress: Individual differences in reward sensitivity

The Effort-Reward Imbalance (ERI) model comprises both situational components (i.e. effort and reward) and a person-specific component (overcommitment). The aims of this study were to investigate the role of theoretically and historically linked personality variables (i.e. overcommitment and Type A personality) within the ERI model and to expand and extend the ERI model by investigating the contribution of individual reward components to both psychological (i.e. psychological distress) and attitudinal (i.e. affective commitment) employee strain indicators. A total of 897 police officers from a large Australian police agency participated in the study. The results provided no evidence of an interaction effect of effort or reward with overcommitment. The Type A variables did, however, make significant contributions and were involved in a number of interactions, suggesting that the person-specific component of the ERI model could be extended with the Type A personality profile. The findings also suggest that the esteem component of reward has the greatest relevance to employee outcomes, although tangible aspects of reward are more likely to act as a buffer of perceived work demand.

From prediction error to incentive salience: mesolimbic computation of reward motivation

Reward contains separable psychological components of learning, incentive motivation and pleasure. Most computational models have focused only on the learning component of reward, but the motivational component is equally important in reward circuitry, and even more directly controls behavior. Modeling the motivational component requires recognition of additional control factors besides learning. Here I discuss how mesocorticolimbic mechanisms generate the motivation component of incentive salience. Incentive salience takes Pavlovian learning and memory as one input and as an equally important input takes neurobiological state factors (e.g. drug states, appetite states, satiety states) that can vary independently of learning. Neurobiological state changes can produce unlearned fluctuations or even reversals in the ability of a previously learned reward cue to trigger motivation. Such fluctuations in cue-triggered motivation can dramatically depart from all previously learned values about the associated reward outcome. Thus, one consequence of the difference between incentive salience and learning can be to decouple cue-triggered motivation of the moment from previously learned values of how good the associated reward has been in the past. Another consequence can be to produce irrationally strong motivation urges that are not justified by any memories of previous reward values (and without distorting associative predictions of future reward value). Such irrationally strong motivation may be especially problematic in addiction. To understand these phenomena, future models of mesocorticolimbic reward function should address the neurobiological state factors that participate to control generation of incentive salience.

The Joint Sales Impact of Frequency Reward and Customer Tier Components of Loyalty Programs

We estimate the joint impact of the frequency reward and customer tier components of a loyalty program on customer behavior and resultant sales. We provide an integrated analysis of a loyalty program incorporating customers' purchase and cash-in decisions, points pressure and rewarded behavior effects, heterogeneity, and forward-looking behavior. We focus on four key research questions: (1) How important is it to combine both components in one model? (2) Does points pressure exist in the context of a two-component loyalty program? (3) How is the market segmented in its response to the combined program? (4) Do the programs complement each other in terms of the incremental sales they produce? Our most basic message is that the frequency reward and customer tier components of loyalty programs should be modeled jointly rather than in separate models. We find strong evidence for points pressure for both the customer tier and frequency reward components using both model-based and model-free evidence. We find a two-segment solution revealing a “service-oriented” segment that highly values cash-ins for room upgrades and staying in “luxury” hotels, and a “price-oriented” segment that is more price sensitive and highly values the frequency reward aspects of the loyalty program. Furthermore, we find that both components generate incremental sales. Also, there was slight synergy between the programs but not a huge amount. Overall, each component contributes to increased revenues and does not interfere with the other.

Hedonics of Food Consumption: Are Food ‘Liking’ and ‘Wanting’ Viable Targets for Appetite Control in the Obese?

In an environment where energy-dense and highly palatable foods are ubiquitous, it seems plausible that the hedonic system of appetite control will play a primary role in eating behavior—undermining homeostatic processes and driving consumption beyond energy requirements. A relevant issue in the hedonics of food consumption is the distinction between “liking” and “wanting” components of food reward. Separate neural pathways exist to mediate these processes, and experimental behavioral methods have been developed to distinguish and to measure them separately in humans. We examine the evidence that “liking” and “wanting” are involved in weight gain, obesity, and certain forms of disordered eating. Then it is questioned whether “liking” and “wanting” are involved in “food addiction.” We conclude that elevated “liking” and “wanting” are psychological markers of a susceptible phenotype for overconsumption. These processes contribute to what can be termed “hedonically driven eating” and represent viable targets for appetite control.

Rewarding performance feedback alters reported time of action

Past studies have shown that the perceived time of actions is retrospectively influenced by post-action events. The current study examined whether rewarding performance feedback (even when false) altered the reported time of action. In Experiment 1, participants performed a speeded button press task and received monetary reward for a presumed "fast," or a monetary punishment for a presumed "slow" response. Rewarded trials resulted in the false perception that the response action occurred earlier than punished trials. In Experiments 2 and 3, the need for a speeded response and reward were independently manipulated in order to decouple the cognitive and reward components in the feedback signal. When tested independently, neither variable affected the judged time of action. We conclude that meaningful feedback (fast or slow) is only used when made salient by reward, to modulate the judged time of an action.

Experience-dependent reactivations of ventral tegmental area neurons in the rat

The hippocampus stores information during the acquisition of new memory episodes. These memories are replayed during sleep as part of a memory consolidation process. The neural mechanisms underlying these reactivations are currently under investigation. One hypothesis is that reactivation occurs as a result of local attractor dynamics within the structure in which they occur. Another possibility is that reactivation in these various areas is at least in part inherited from one or several other structures that project to them. Theoretical and experimental work on reinforcement learning have proposed many ways in which learning can be modulated by the value associated with a stimulus. Beyond initial memory acquisition, however, it is still unclear why specific memory items are consolidated and others are not [1,2]. One possibility is that, as with memory acquisition, the consolidation process is modulated by the value associated with a specific memory item. Research has shown that this value may be at least in part encoded by subcortical structures such as the ventral tegmental area (VTA) [3,4]. We provide new evidence in the rodent that 45% VTA neurons are sensitive to and selective for different types of stimuli. In three different tasks involving various amounts spatial and reward components, we show that putative dopaminergic VTA neurons strongly reactivate during a rest period following the tasks. This reactivation takes the form of population-wide activity patterns lasting from a few 100 ms up to a few seconds. In the non-spatial task, a statistical analysis of this reactivation using the explained variance measure showed that most of the reactivation relies on the activity of stimulus-sensitive neurons. Stimulus insensitive neurons exhibited significant reactivation if the task used involved motor and spatial components. VTA has widespread connections to the rest of the brain, including hippocampus and neocortex. Almost all experiments that have shown memory trace reactivation were based on tasks that involved rewards. The selective reactivation of non-GABAergic cells in the VTA suggests that reactivations in hippocampus and cortex could be modulated by the VTA. The finding that reward-sensitive neurons primarily reactivated when rewards were present during the task suggests a mechanism by which hippocampal and neocortical reactivations can be modulated by the value of the memory items they encode. In turn, cortex and hippocampus could modulate VTA activity as part of a loop in which memory content and memory value are dynamically and selectively established. Future conceptual and computational models of reinforcement learning and memory consolidation could account for the type of selectivity and dynamics of VTA neural firing we described here.

Disentangling pleasure from incentive salience and learning signals in brain reward circuitry.

Multiple signals for reward-hedonic impact, motivation, and learned associative prediction-are funneled through brain mesocorticolimbic circuits involving the nucleus accumbens and ventral pallidum. Here, we show how the hedonic "liking" and motivation "wanting" signals for a sweet reward are distinctly modulated and tracked in this circuit separately from signals for Pavlovian predictions (learning). Animals first learned to associate a fixed sequence of Pavlovian cues with sucrose reward. Subsequent intraaccumbens microinjections of an opioid-stimulating drug increased the hedonic liking impact of sucrose in behavior and firing signals of ventral pallidum neurons, and likewise, they increased incentive salience signals in firing to the reward-proximal incentive cue (but did not alter firing signals to the learned prediction value of a reward-distal cue). Microinjection of a dopamine-stimulating drug instead enhanced only the motivation component but did not alter hedonic impact or learned prediction signals. Different dedicated neuronal subpopulations in the ventral pallidum tracked signal enhancements for hedonic impact vs. incentive salience, and a faster firing pattern also distinguished incentive signals from slower hedonic signals, even for a third overlapping population. These results reveal separate neural representations of wanting, liking, and prediction components of the same reward within the nucleus accumbens to ventral pallidum segment of mesocorticolimbic circuitry.

The effect of within-meal protein content and taste on subsequent food choice and satiety

It is posed that protein intake is tightly regulated by the human body. The role of sensory qualities in the satiating effects of protein, however, requires further clarification. Our objective was to determine the effect of within-meal protein content and taste on subsequent food choice and satiety. We used a cross-over design whereby sixty healthy, unrestrained subjects (twenty-three males and thirty-seven females) with a mean age of 20·8 (SD 2·1) years and a mean BMI of 21·5 (SD 1·6) kg/m2 were offered one of four isoenergetic preloads (rice meal) for lunch: two low in protein (about 7 % energy derived from protein) and two high in protein (about 25 % energy from protein). Both had a sweet and savoury version. At 30 min after preload consumption, subjects were offered an ad libitum buffet, consisting of food products differing in protein content (low/high) and taste (sweet/savoury). In addition, the computerised Leeds Food Preference Questionnaire (LFPQ) was run to assess several components of food reward. The results showed no effect of protein content of the preloads on subsequent food choice. There was an effect of taste; after eating the savoury preloads, choice and intake of sweet products were higher than of savoury products. No such preference was seen after the sweet preloads. No differences in satiety were observed. To conclude, within one eating episode, within-meal protein content in these quantities seems not to have an effect on subsequent food choice. This appears to be mostly determined by taste, whereby savoury taste exerts the strongest modulating effect. The results of the LFPQ provided insight into underlying processes.

S16-03 - Relationships between negative symptoms and abnormalities in the anticipatory component of reward

A dysfunction of the dopaminergic reward system has been postulated in the pathophysiology of schizophrenia. A subcortical hyperdopaminergic state in unmedicated schizophrenia patients has been associated with the pathogenesis of positive symptoms and a prefrontal hypodopaminergic state with cognitive and negative symptoms. But negative symptoms like anhedonia have also been hypothesized to be associated with a dysfunction of the mesolimbic dopaminergic system. However, preclinical studies indicate that the mesolimbic dopaminergic system mediates motivation and incentive salience of reward-indicating stimuli rather than the ability to experience pleasure.Recent neuroimaging findings in schizophrenia patients confirmed dysfunctional activation during reinforcement learning. We used functional magnetic resonance imaging (fMRI) to assess the BOLD response in the ventral striatum of unmedicated schizophrenia patients during presentation of reward-indicating stimuli and during reversal learning. Compared with healthy controls, unmedicated schizophrenics showed reduced ventral striatal activation during presentation of reward-indicating cues, which was negatively correlated with the severity of negative symptoms. During reversal learning unmedicated schizophrenia patients displayed behavioral impairments and reduced activation in the ventral striatum and the ventrolateral PFC. In unmedicated schizophrenic patients, a high striatal dopamine turnover may interfere with neuronal processing of reward-indicating stimuli by phasic dopamine release, thus contributing to negative symptoms as such as loss of drive and motivation.

Role of internal marketing, organizational commitment, and job stress in discerning the turnover intention of Korean nurses

The purpose of this study was to examine the discriminating factors of Korean nurses' turnover intention (TI) among internal marketing (IM), organizational commitment (OC), and job stress (JS). Nurses (n = 185) who had worked for 1-10 years were surveyed from six general hospitals in South Korea. The data were collected by using questionnaires and were analyzed with descriptive statistics and discriminant analysis. The participants were grouped into three groups, depending on the level of their TI: "low TI group" (n = 58), "moderate TI group" (n = 96), and "high TI group" (n = 31). One function significantly discriminated between the high TI and low TI groups. The function correctly classified 84.3% of the participants into the two groups and 75.3% were correctly classified in the cross-validation. Organizational commitment was the most important factor. Job stress and the IM components of staffing-promotion, reward, management philosophy, working environment, and segmentation were significant discriminant factors of TI. Based on the findings of this study, we could conclude that OC, JS, and IM play important roles in the TI of nurses. Implying a career development system as an OC management strategy, an innovative promotion policy to change conservative organizational climates and a balance of effort-reward can be considered as managerial interventions to reduce nurses' TI.

Infantile experience and play motivation

Fully-fledged affective systems in mature animals are in part the result of the impact of infantile experience on brain development. The present experimental series examines whether tactile stimulation in infancy (early handling) influences rough-and-tumble play (R&T) throughout the juvenile period, using a testing regime of 17 days divided into five parts where handled (H) and nonhandled (NH) Wistar rats are assessed daily. In Parts 1 and 2 (age range at the start: 30–33 days) the objective is to study the amount of R&T that the rats are capable of exhibiting under varying lengths of social deprivation. In Part 3 (37–40 days) the objective is to determine whether familiarity with the experimental situation has independent or interactive effects with early handling. In Part 4 (40–43 days) the objective is to obtain evidence of the suppressing effects of an unexpected contextual change. In Part 5 (56–59 days) the objective is to study whether the effects of early handling can still be present at an age when R&T has practically vanished in NH rats. Results show that early handling invigorates R&T affecting pins (i.e., the most rewarding component) at the expense of dorsal contacts by enhancing play motivation in a specific manner, and that it is able to dilate the inverted-U developmental curve of this behavior, thereby providing strong evidence for a direct effect on the neuropsychological systems for play motivation.

The Role of Effort–Reward Imbalance for Reservists on a Military Deployment

The present study extended the effort–reward imbalance (ERI) model (Siegrist, 1996b), first by differentiating between separate reward components, second by including intrinsic reward, and third by additionally predicting a non-health outcome (i.e., turnover intention) in a military context. Regression analyses of 789 reservists found financial and esteem reward to moderate the impact of extrinsic effort on depressive symptoms, whereas only financial reward moderated the effort turnover intentions relationship. Results supported the usefulness of the extended ERI model in the military context. Relevant areas for future research on the military effort–reward perspective are discussed.

Adolescent social defeat alters neural, endocrine and behavioral responses to amphetamine in adult male rats

The mesocorticolimbic dopamine system, which governs components of reward and goal-directed behaviors, undergoes final maturation during adolescence. Adolescent social stress contributes to adult behavioral dysfunction and is linked to adult psychiatric and addiction disorders. Here, behavioral, corticosterone and limbic dopamine responses to amphetamine were examined in adult male rats previously exposed to repeated social defeat stress during mid-adolescence. Amphetamine (2.5 mg/kg, ip) was administered after a novel environment test, with behavior observed in the same context for 90 min thereafter. Adult rats that had been defeated in adolescence showed increased locomotion in the novel environment but reduced amphetamine-induced locomotion relative to non-defeated age matched controls. Monoamine and corticosterone responses to amphetamine were examined following a second amphetamine injection 3 days later. In previously defeated rats, corticosterone and medial prefrontal cortex dopamine responses to amphetamine were blunted while dopamine responses in the nucleus accumbens core were elevated. Our results suggest that experience of social defeat stress during adolescent development can contribute to altered behavioral and endocrine responses to amphetamine in adulthood. Furthermore, these effects are paralleled by changes in amphetamine-induced dopamine responses in corticolimbic systems implicated in addiction disorders.

Heterogeneity of Reward Mechanisms

The finding that many drugs that have abuse potential and other natural stimuli such as food or sexual activity cause similar chemical changes in the brain, an increase in extracellular dopamine (DA) in the shell of the nucleus accumbens (NAccS), indicated some time ago that the reward mechanism is at least very similar for all stimuli and that the mechanism is relatively simple. The presently available information shows that the mechanisms involved are more complex and have multiple elements. Multiple brain regions, multiple receptors, multiple distinct neurons, multiple transmitters, multiple transporters, circuits, peptides, proteins, metabolism of transmitters, and phosphorylation, all participate in reward mechanisms. The system is variable, is changed during development, is sex-dependent, and is influenced by genetic differences. Not all of the elements participate in the reward of all stimuli. Different set of mechanisms are involved in the reward of different drugs of abuse, yet different mechanisms in the reward of natural stimuli such as food or sexual activity; thus there are different systems that distinguish different stimuli. Separate functions of the reward system such as anticipation, evaluation, consummation and identification; all contain function-specific elements. The level of the stimulus also influences the participation of the elements of the reward system, there are possible reactions to even below threshold stimuli, and excessive stimuli can change reward to aversion involving parts of the system. Learning and memory of past reward is an important integral element of reward and addictive behavior. Many of the reward elements are altered by repeated or chronic stimuli, and chronic exposure to one drug is likely to alter the response to another stimulus. To evaluate and identify the reward stimulus thus requires heterogeneity of the reward components in the brain.

Rewards Communication in Australia and the United States: A Survey of Policies and Programs

Human resources (HR) and compensation professionals in Australia were surveyed to determine how they communicate rewards information to employees. The rewards communications survey examined five reward components: organization reward strategy and philosophy, base pay, base-pay increases, short-term variable pay and benefits. This research found that HR and compensation professionals believe that rewards communication is important, even to the degree that it affects organizational performance, employee satisfaction with pay, employee retention and employee motivation. They also believe that most employees have limited understanding of the purpose of reward programs and how they work; in fact, many do not understand aspects of the pay system that directly affect them such as pay ranges, average pay rates and performance targets. Comparisons between Australian and United State reward communication policies and practices are reported.

How Many Calories Are on Our Plate? Expected Fullness, Not Liking, Determines Meal‐size Selection

The availability of highly palatable food is thought to stimulate the selection of larger meals (leading to weight gain and obesity). In this article, we explore aspects of this proposition. Specifically, we scrutinize two basic assumptions: (i) palatable energy-dense foods are more rewarding (desired), and (ii) these palatable foods are selected in relatively larger portions. In combination with palatability, we also consider the relative role for "expected satiation"-the extent to which a food is expected to deliver satiation. A total of 17 commonly consumed foods were assessed by 28 normal-weight participants at lunchtime. Critically, our measure of food reward and expected satiation involves comparisons between foods based on equicaloric portions. When assessed in this way, we find that food reward and ideal portion sizes (in kcal) are both closely associated with expected satiation, but not with "expected liking." Low expected satiation (not expected liking) predicts the selection of large portion sizes (in kcal) and foods with this characteristic tend to be more energy dense and are regarded as less (not more) rewarding (when compared calorie for calorie). Together, these findings challenge the role of palatability in meal-size selection and they highlight the importance of expected satiation, a "nonaffective" component of food reward.

Plasticity of addiction: a mesolimbic dopamine short-circuit?

The development of drug addiction progresses along a continuum from acute drug use to compulsive use and drug seeking behavior. Many researchers have focused on identifying the physiological mechanisms involved in drug addiction in order to develop effective pharmacotherapies. Neuroplasticity, the putative mechanism underlying learning and memory, is modified by drugs of abuse and may contribute to the development of the eventual addicted state. Innovative treatments directly targeting these drug-induced changes in brain reward components and circuits may be efficacious in reducing drug use and relapse.

Dissecting components of reward: ‘liking’, ‘wanting’, and learning

In recent years significant progress has been made delineating the psychological components of reward and their underlying neural mechanisms. Here we briefly highlight findings on three dissociable psychological components of reward: 'liking' (hedonic impact), 'wanting' (incentive salience), and learning (predictive associations and cognitions). A better understanding of the components of reward, and their neurobiological substrates, may help in devising improved treatments for disorders of mood and motivation, ranging from depression to eating disorders, drug addiction, and related compulsive pursuits of rewards.

Sexual reward in male rats: Effects of sexual experience on conditioned place preferences associated with ejaculation and intromissions

Various behavioral models and studies have provided evidence suggesting that male rat sexual behavior has rewarding and reinforcing properties. However, there is little information regarding the rewarding values of the different components of sexual behavior. Therefore, this study used a conditioned place preference (CPP) paradigm to address whether ejaculation and intromissions differ in their rewarding incentive values. We also addressed whether the differential rewarding values were dependent on prior sexual experience. Sexually naïve and experienced males received one pairing of either intromissions or ejaculation with one of the chambers in the CPP box. The amount of time spent in each chamber of the CPP apparatus after conditioning was then measured. Both sexually naïve and sexually experienced males formed a CPP for ejaculation, while only sexually naïve, and not sexually experienced, males formed a CPP for intromissions. Moreover, in sexually naïve males, multiple pairings of ejaculation with the designated chamber resulted in a CPP relative to the control chamber paired with display of intromissions. These data support the hypothesis that there is a hierarchy of rewarding sexual behavior, with ejaculation being the most rewarding component, and that the rewarding incentive value of other components of sexual behavior is dependent upon prior sexual experience.

Effects of sucrose, glucose and fructose on peripheral and central appetite signals

In the Western world, consumption of soft drinks has increased the last three decades and is partly responsible for the epidemic-like increase in obesity. Soft drinks, originally sweetened by sucrose, are now sweetened by other caloric sweeteners, such as fructose. In this study, we investigated the short-term effect of sucrose, glucose or fructose solutions on food intake and body weight in rats, and on peripheral and central appetite signals. Rats received water containing either of the sugars and standard rat chow for two weeks. Rats receiving water alone and standard chow were controls. All rats offered the sugar solutions increased their total caloric intake. The increased caloric intake occurred despite the fact that the rats offered either of the sugar solutions consumed less chow. As a consequence of the increased caloric intake, the sugar-drinking rats had elevated serum levels of free fatty acids, triglycerides and cholesterol. In addition, consuming sugar solutions resulted in increased serum leptin, decreased serum PYY and down-regulated hypothalamic NPY mRNA. Serum ghrelin was increased in rats receiving fructose solution. Moreover, consumption of sucrose or fructose solution resulted in up-regulated hypothalamic CB1 mRNA. Hypothalamic POMC mRNA was down-regulated in rats receiving glucose or fructose. In conclusion, consumption of glucose, sucrose or fructose solution results in caloric overconsumption and body weight gain through activation of hunger signals and depression of satiety signals as well as activation of reward components. The weight-promoting effect of these sugar solutions may possibly be ameliorated by the down-regulation of NPY mRNA and increased serum leptin.