Amount Of Reward Research Articles

Enhanced Population Coding for Rewarded Choices in the Medial Frontal Cortex of the Mouse.

Instrumental behavior is characterized by the selection of actions based on the degree to which they lead to a desired outcome. However, we lack a detailed understanding of how rewarded actions are reinforced and preferentially implemented. In rodents, the medial frontal cortex is hypothesized to play an important role in this process, based in part on its capacity to encode chosen actions and their outcomes. We therefore asked how neural representations of choice and outcome might interact to facilitate instrumental behavior. To investigate this question, we imaged neural ensemble activity in layer 2/3 of the secondary motor region (M2) while mice engaged in a two-choice auditory discrimination task with probabilistic outcomes. Correct choices could result in one of three reward amounts (single, double or omitted reward), which allowed us to measure neural and behavioral effects of reward magnitude, as well as its categorical presence or absence. Single-unit and population decoding analyses revealed a consistent influence of outcome on choice signals in M2. Specifically, rewarded choices were more robustly encoded relative to unrewarded choices, with little dependence on the exact magnitude of reinforcement. Our results provide insight into the integration of past choices and outcomes in the rodent brain during instrumental behavior.

Feeding behaviour, risk-sensitivity and response control: effects of 5-HT2C receptor manipulations.

People, like animals, tend to choose the variable option when given the choice between a fixed and variable delay to reward where, in the variable delay condition, some rewards are available immediately (Laura-Jean et al. 2019 Phil. Trans. R. Soc. B 374, 20180141. (doi:10.1098/rstb.2018.0141)). This bias has been suggested to reflect evolutionary pressures resulting from food scarcity in the past placing a premium on obtaining food quickly that can win out against the risks of sometimes sustaining longer delays to food. The psychologies mediating this effect may become maladaptive in the developed world where food is readily available contributing, potentially, to overeating and obesity. Here, we report our development of a novel touchscreen task in mice allowing comparisons of the impact of food delay and food magnitude across species. We show that mice exhibit the typical preference, as shown by humans, for variable over fixed delays to rewards but no preference when it comes to fixed versus variable reward amounts and further show that this bias is sensitive to manipulations of the 5-HT2C receptor, a key mediator of feeding and impulse control. We discuss the data in terms of the utility of the task to model the psychologies and underlying brain mechanisms impacting on feeding behaviours.This article is part of the theme issue ‘Risk taking and impulsive behaviour: fundamental discoveries, theoretical perspectives and clinical implications’.

Better, Not Just More-Contrast in Qualitative Aspects of Reward Facilitates Impulse Control in Pigs.

Delay-of-gratification paradigms, such as the famous “Marshmallow Test,” are designed to investigate the complex cognitive concepts of self-control and impulse control in humans and animals. Such tests determine whether a subject will demonstrate impulse control by choosing a large, delayed reward over an immediate, but smaller reward. Documented relationships between impulsive behavior and aggression in humans and animals suggest important implications for farm animal husbandry and welfare, especially in terms of inadequate social behavior, tail biting and maternal behavior. In a preliminary study, we investigated whether the extent of impulse control would differ between quantitatively and qualitatively different aspects of reward in pigs. Twenty female piglets were randomly divided into two groups, with 10 piglets each. After a preference test to determine individual reward preference among six different food items, a discrimination test was conducted to train for successful discrimination between different amounts of reward (one piece vs. four pieces) and different qualitative aspects of reward (highly preferred vs. least preferred food item). Then, an increasing delay (2, 4, 8, 16, 24, 32 s) was introduced for the larger/highly preferred reward. Each piglet could choose to get the smaller/least preferred reward immediately or to wait for the larger/highly preferred reward. Piglets showed clear differences in their preference for food items. Moreover, the “quality group” displayed faster learning in the discrimination test (number of sessions until 90% of the animals completed the discrimination test: “quality group”−3 days vs. “quantity group”−5 days) and reached a higher level of impulse control in the delay-of-gratification test compared to the “quantity group” (maximum delay that was mastered: “quality group”−24 s vs. “quantity group”−8 s). These results demonstrate that impulse control is present in piglets but that the opportunity to get a highly preferred reward is more valued than the opportunity to get more of a given reward. This outcome also underlines the crucial role of motivation in cognitive test paradigms. Further investigations will examine whether impulse control is related to traits that are relevant to animal husbandry and welfare.

Orexin 1 receptors in the anterior cingulate and orbitofrontal cortex regulate cost and benefit decision-making

Orexin neurons are discretely localized within the lateral hypothalamus and have widespread projections into all areas of the brain. In addition, several lines of evidence specify that orexins may also participate in the regulation of a variety of affective and cognitive processes. The Orexin-1 receptor (OX1r) is distributed extensively throughout the prefrontal cortex (PFC). Delay-based decision- making is mediated largely by the orbitofrontal cortex (OFC) while effort- based decision-making is controlled by the anterior cingulated cortex (ACC). Hence, in the present study, a series of experiments were conducted to clarify the role of OX1r in the mPFC (ACC and/or OFC) in cost and benefit decision-making. The rats were trained in a delay and/or effort-based form of cost-benefit T-maze decision-making task. Two goal arms were different in the amount of accessible reward and cost. Before surgery, all animals were selecting the high reward arm and pay the cost on almost every trial. During the test days, the rats received local injections of either DMSO 20% /0.5 μl, as a vehicle, or SB334867 (3, 30 and 300 nM/0.5 μl), as a selective OX1r antagonist, within the ACC and/or OFC. The results of this study showed that the bilateral microinjection of SB334867 into ACC and/or OFC changed the preference to a low reward arm with no cost, indicating the role of OX1 receptors in cost and benefit decision- making. From these results, it can be implied that OX1 receptors in the mPFC play a crucial role for allowing the animal to evaluate and pay the cost to acquire greater rewards.

The effect of reward on listening effort as reflected by the pupil dilation response

Listening to speech in noise can be effortful but when motivated people seem to be more persevering. Previous research showed effects of monetary reward on autonomic responses like cardiovascular reactivity and pupil dilation while participants processed auditory information. The current study examined the effects of monetary reward on the processing of speech in noise and related listening effort as reflected by the pupil dilation response. Twenty-four participants (median age 21 yrs) performed two speech reception threshold (SRT) tasks, one tracking 50% correct (hard) and one tracking 85% correct (easy), both of which they listened to and repeated sentences uttered by a female talker. The sentences were presented with a single male talker or, in a control condition, in quiet. Participants were told that they could earn a high (5 euros) or low (0.20 euro) reward when repeating 70% or more of the sentences correctly. Conditions were presented in a blocked fashion and during each trial, pupil diameter was recorded. At the end of each block, participants rated the effort they had experienced, their performance, and their tendency to quit listening. Additionally, participants performed a working memory capacity task and filled in a need-for-recovery questionnaire as these tap into factors that influence the pupil dilation response. The results showed no effect of reward on speech perception performance as reflected by the SRT. The peak pupil dilation showed a significantly larger response for high than for low reward, for the easy and hard conditions, but not the control condition. Higher need for recovery was associated with a higher subjective tendency to quit listening. Consistent with the Framework for Understanding Effortful Listening, we conclude that listening effort as reflected by the peak pupil dilation is sensitive to the amount of monetary reward.

Rewarding objects appear larger but not brighter.

Whether reward can accentuate the perception of visual objects, that is, makes them appear larger than they really are, is a long-standing and controversial question. Here, we revisit this issue with a novel two-alternative forced-choice paradigm combining asymmetric reward schedule and task reversal. In a first experiment, participants (n = 27) choose the larger of two unequally rewarded objects in some sessions and the smaller one in other sessions. Response biases toward the most rewarding object differ significantly between the reversed tasks, revealing an influence of reward on perceived sizes. In a second experiment, participants (n = 27) indicate either the brighter or darker object. In contrast with the first experiment, response biases are similar between those reversed tasks, indicating that the perceived luminance is immune to reward manipulation. Together, these results reveal that if two objects are associated with different amounts of reward, participants will perceive the more rewarded object to be slightly larger, but not brighter, than the less rewarded one.

Impact of referral reward program on innovative customers’ follow-up e-referral

PurposeWith the rise of customer engagement in online products and services innovation, enterprises are seeking effective referral reward program (RRP) to encourage customers’ follow-up electronic-referral (e-referral) behaviors. Therefore, how to stimulate more customers to participate in the RRP is very important to enterprises. However, little empirical work has systemically investigated the impact of RRP on customers’ follow-up e-referral, as well as the moderating effects of customers’ characteristics. To fill those research gaps, the purpose of this paper is to explore the effects of RRP (particularly, reward amount and reward type) on customers’ follow-up e-referral, and the role of creative self-efficacy.Design/methodology/approachBased on the self-perception theory and the context of online customer innovation, this paper establishes a theoretical model and uses an experiment with 160 participants to test the hypotheses on the role of reward (amount and type) and the moderating effect of creative self-efficacy.FindingsThe results of the experiment suggest that both reward amount and reward type in RRP positively impact customers’ follow-up e-referral. Furthermore, customers’ creative self-efficacy moderates the relationship between rewards and customers’ follow-up e-referral. Customers with low creative self-efficacy, reward amount significantly stimulate their follow-up e-referral, but such effect is insignificant when customers’ creative self-efficacy is high. In terms of reward type, gift reward has more positive effect on customers’ follow-up e-referral when they have high (rather than low) creative self-efficacy, but cash reward has more positive effect on those with low (rather than high) creative self-efficacy.Originality/valueFirst, based on the self-perception theory, the study clarifies the inconsistent relationship between reward and customers’ e-referral and contributes to related research. Second, the study broadens the existing research perspective by introducing creative self-efficacy, which shows interesting and powerful moderating effect but has been ignored in previous studies. Third, the study provides valuable advice on how enterprises design an effective RRP to enhance customers’ follow-up e-referral.

Opposing pupil responses to offered and anticipated reward values.

Previous studies have shown that the pupils dilate more in anticipation of larger rewards. This finding raises the possibility of a more general association between reward amount and pupil size. We tested this idea by characterizing macaque pupil responses to offered rewards during evaluation and comparison in a binary choice task. To control attention, we made use of a design in which offers occurred in sequence. By looking at pupil responses after choice but before reward, we confirmed the previously observed positive association between pupil size and anticipated reward values. Surprisingly, however, we find that pupil size is negatively correlated with the value of offered gambles before choice, during both evaluation and comparison stages of the task. These results demonstrate a functional distinction between offered and anticipated rewards and present evidence against a narrow version of the simulation hypothesis; the idea that we represent offers by reactivating states associated with anticipating them. They also suggest that pupil size is correlated with relative, not absolute, values of offers, suggestive of an accept-reject model of comparison.

A revenue sharing contract for reverse supply chain coordination under stochastic quality of returned products and uncertain remanufacturing capacity

Abstract This paper investigates a two-echelon reverse supply chain (RSC) consisting of a single remanufacturer and a single collector. The collector by offering a reward persuades consumers to take back their used products. Only items that meet the minimum quality level are accepted to be refurbished. There are two sources of uncertainties in the investigated RSC: (1) uncertainty in quality of returned products, (2) uncertainty in remanufacturing capacity. Under these circumstances, the amount of offered reward to consumers is a key problem. To optimize the whole RSC, the collector should determine the reward amount by considering the possibility of idle/overload capacity of the remanufacturing process. In the investigated RSC, the quality of returned products follows a uniform distribution and remanufacturing capacity follows a normal distribution. A customized revenue sharing mechanism is developed to share the risk of uncertainties between two members, fairly. The results indicate that, when remanufacturing capacity is limited, the suggested revenue sharing contract is able to share risks between participants and creates a win-win situation. In addition the suggested scheme is able to achieve channel coordination.

The amount-based deformation of the [formula omitted]-exponential discount function: A joint analysis of delay and magnitude effects

The magnitude effect is one of the main anomalies shown by people in the context of intertemporal choice. Thus, the main objective of this paper is to provide a general procedure to obtain a general discount function able to explain this paradox. By this methodology, we will to mathematically deform time in a discount function, more specifically to multiply the variable “time” by a certain power of the reward amount. However, in most cases, the existing literature presents some ad hoc discounting models to describe a unique anomaly. In order to solve this limitation, we will apply the former methodology to the q-exponential discount function introduced by Cajueiro (2006). In this way, we will obtain a mathematical setting able to jointly explain the delay and the magnitude effects, depending on the values of parameters q and α involved in the model. Moreover, another advantage of this amount-based q-exponential function is its convergence to the time-deformed exponential, hyperbolic and linear discounting, depending on the value of q in the joint interval (−∞,1)∪(1,+∞).

Dynamic Encoding of Effort and Reward throughout the Execution of Action by External Globus Pallidus Neurons in Monkeys.

Humans and animals must evaluate the costs and expected benefits of their actions to make adaptive choices. Prior studies have demonstrated the involvement of the basal ganglia in this evaluation. However, little is known about the role of the external part of the globus pallidus (GPe), which is well positioned to integrate motor and reward-related information, in this process. To investigate this role, the activity of 126 neurons was recorded in the associative and limbic parts of the GPe of two monkeys performing a behavioral task in which different levels of force were required to obtain different amounts of liquid reward. The results first revealed that the activity of associative and limbic GPe neurons could be modulated not only by cognitive and limbic but also motor information at the same time, both during a single period or during different periods throughout the trial, mainly in an independent way. Moreover, as a population, GPe neurons encoded these types of information dynamically throughout the trial, when each piece of information was the most relevant for the achievement of the action. Taken together, these results suggest that GPe neurons could be dedicated to the parallel monitoring of task parameters essential to adjusting and maintaining goal-directed behavior.

Belief state representation in the dopamine system

Learning to predict future outcomes is critical for driving appropriate behaviors. Reinforcement learning (RL) models have successfully accounted for such learning, relying on reward prediction errors (RPEs) signaled by midbrain dopamine neurons. It has been proposed that when sensory data provide only ambiguous information about which state an animal is in, it can predict reward based on a set of probabilities assigned to hypothetical states (called the belief state). Here we examine how dopamine RPEs and subsequent learning are regulated under state uncertainty. Mice are first trained in a task with two potential states defined by different reward amounts. During testing, intermediate-sized rewards are given in rare trials. Dopamine activity is a non-monotonic function of reward size, consistent with RL models operating on belief states. Furthermore, the magnitude of dopamine responses quantitatively predicts changes in behavior. These results establish the critical role of state inference in RL.

Collection and Remanufacturing of Waste Products under Patent Protection and Government Regulation

There is increasing academic and pragmatic interest in leveraging patent rights to invigorate remanufacturing for waste products under governmental interventions via regulations and reward–penalty instruments. In practice, many original manufacturers that are possessed with intellectual property rights allow third-party remanufacturers to implement reproducing operations through authorization and charging licensing fees. The general purpose of this paper is to explore favorable strategies for a closed-loop supply chain (CLSC) system of waste product collection and remanufacturing, in the context of either manufacturer-remanufacturing or remanufacturer-remanufacturing. To achieve such an objective, game theory is adopted to establish models of three collection and remanufacturing modes among channel members involving a manufacturer, a seller, and a remanufacturer. In so doing, the results show that a government’s allocations of elementary remanufacturing ratio and the unit amount of reward–penalty count significantly in CLSC operations, especially for the manufacturer, who acts as the leader in the system and makes mode selections.

Reverse supply chain coordination under stochastic remanufacturing capacity

In this paper, a two-stage reverse supply chain (RSC) is analyzed where the retailer pays rewards to customers to return obsolete products and the manufacturer refurbishes eligible returned items through remanufacturing process. Remanufacturing capacity is assumed as a stochastic variable. Under the uncertainty of remanufacturing capacity, it is possible that some inspected and eligible items could not be processed. If a bought item could not be processed, it should be salvaged at low prices and be considered a lost profit. In such situations, increasing the number of returned obsolete products is suitable where there is a high probability for enough capacity in the remanufacturing process. In this study, a stochastic model is developed to find the optimal paid reward to customers under both scenarios, including decentralized (where the retailer decides independently on reward amount) and centralized (where reward amount is determined based on the whole channel interest). By sharing the manufacturer’s capacity risk, a revenue sharing contract is proposed to convince the retailer to consider uncertainty of remanufacturing capacity in deciding reward amount. Under the proposed contract, a part of retailer revenue is postponed until the remanufacturing process is completed. Non-eligible items, as well as those that cannot be processed due to insufficient capacity are not involved in revenue sharing with the retailer. Our numerical investigations reveal that the proposed scheme is able to coordinate the investigated RSC under the uncertainty of remanufacturing capacity. Contrary to the decentralized scenario, the proposed model recommends fewer paid rewards to customers when there is a high possibility of insufficient capacity in the remanufacturing process.

Emphasizing the "positive" in positive reinforcement: using nonbinary rewarding for training monkeys on cognitive tasks.

Nonhuman primates constitute an indispensable model system for studying higher brain functions at the neurophysiological level. Studies involving these animals elucidated the neuronal mechanisms of various cognitive and executive functions, such as visual attention, working memory, and decision-making. Positive reinforcement training (PRT) constitutes the gold standard for training animals on the cognitive tasks employed in these studies. In the laboratory, PRT is usually based on application of a liquid reward as the reinforcer to strengthen the desired behavior and absence of the reward if the animal's response is wrong. By trial and error, the monkey may adapt its behavior and successfully reduce the number of error trials, and eventually learn even very sophisticated tasks. However, progress and success of the training strongly depend on reasonable error rates. If errors get too frequent, they may cause a drop in the animal's motivation to cooperate or its adaptation to high error rates and poor overall performance. We introduce in this report an alternative training regime to minimize errors and base the critical information for learning on graded rewarding. For every new task rule, the feedback to the animal is provided by different amounts of reward to distinguish the desired, optimal behavior from less optimal behavior. We applied this regime in different situations during training of visual attention tasks and analyzed behavioral performance and reaction times to evaluate its effectiveness. For both simple and complex behaviors, graded rewarding was found to constitute a powerful technique allowing for effective training without trade-off in accessible task difficulty or task performance. NEW & NOTEWORTHY Laboratory training of monkeys usually builds on providing a fixed amount of reward for the desired behavior, and no reward otherwise. We present a nonbinary, graded reward schedule to emphasize the positive, desired behavior and to keep errors on a moderate level. Using data from typical training situations, we demonstrate that graded rewards help to effectively guide the animal by success rather than errors and provide a powerful new tool for positive reinforcement training.

Neurons in the Pigeon Nidopallium Caudolaterale Display Value-Related Activity

We recorded from neurons in the nidopallium caudolaterale, the avian equivalent of the mammalian prefrontal cortex, in four birds. The birds were required to peck a stimulus that indicated the amount of reward they would receive (small or large) after a certain delay (short or long). We found that the activity of neurons in the nidopallium caudolaterale was modulated by the value of the reward that would be received based on the reward amount and the delay to reward. We found that value coding was most prominent during the presentation of the sample period, and less so during the delay period and during the presentation of the reward itself. Our findings support the view that activity in nidopallium caudolaterale reflects the encoding of the value of reward based on a combination of reward amount and delay to a reward.

The Strength and Drivers of Bird-Mediated Selection on Fruit Crop Size: A Meta-Analysis

Fil: Palacio, Facundo Xavier. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Division Zoologia de Vertebrados. Seccion Ornitologia; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico - Tucuman. Unidad Ejecutora Lillo; Argentina

The Effect of Response Effort on Risk-Sensitive Decision Making in Pigeons (Columbia livia)

Foraging decisions are central to an organism’s survival in the unpredictable natural world. Recently, decision-making theories related to foraging have shifted focus from classic optimal rate maximization to ones that recognize risk as a prime factor that governs choice. For example, animals have been shown to adopt either risk-prone or risk-averse strategies, depending on their preference for variable or constant alternatives. The effects of variability in time or amount of reward have been consistently validated in animal models, establishing two main factors that affect choice behaviour. In the current study, we investigated response effort as a potential third factor that could produce risk sensitivity. Using operant conditioning, pigeons were trained to perform a colour discrimination task under two conditions. In the first condition, pigeons were exposed to stimuli associated with variable or constant response effort. In the second condition, pigeons experienced a time-matched delay before reinforcement to control for the concurrent effects of time. Preference for variable stimuli was measured in each condition using a probe trials method. We found that pigeons’ preference for a variable alternative in the response effort condition differed significantly from the time-matched control, such that time factors alone produced stronger risk-prone preferences over effort. These findings provide further evidence of the importance of assessing ecologically valid behaviour when using experimental methods. While incorporating foraging effort diminishes the effect of risk sensitivity, this may be more representative of the risk associated with delay that animals encounter in their natural environment.

An analysis of the energetic reward offered by field bean (Vicia faba) flowers: Nectar, pollen, and operative force.

Global consumption of crops with a yield that is dependent on animal pollinators is growing, with greater areas planted each year. However, the floral traits that influence pollinator visitation are not usually the focus of breeding programmes, and therefore, it is likely that yield improvements may be made by optimizing floral traits to enhance pollinator visitation rates. We investigated the variation present in the floral reward of the bee‐pollinated crop Vicia faba (field bean). We examined the genetic potential for breeding flowers with a greater reward into current commercial varieties and used bee behavioral experiments to gain insight into the optimal nectar concentration to maximize bee preference. There was a large range of variation in the amount of pollen and nectar reward of flowers in the genotypes investigated. Bee behavioral experiments using nectar sugar concentrations found in V. faba lines suggest that Bombus terrestris prefers 55% w/w sugar solution over 40% w/w, but has no preference between 55% w/w and 68% w/w sugar solution. We provide a first indication of the force required to open V. faba flowers. Our results provide a valuable starting point toward breeding for varieties with optimized floral reward. Field studies are now needed to verify whether the genetic potential for breeding more rewarding flowers can translate into higher yield and yield stability.

First-Pass Processing of Value Cues in the Ventral Visual Pathway

Real-world value often depends on subtle, continuously variable visual cues specific to particular object categories, like the tailoring of a suit, the condition of an automobile, or the construction of a house. Here, we used microelectrode recording in behaving monkeys to test two possible mechanisms for category-specific value-cue processing: (1) previous findings suggest that prefrontal cortex (PFC) identifies object categories, and based on category identity, PFC could use top-down attentional modulation to enhance visual processing of category-specific value cues, providing signals to PFC for calculating value, and (2) a faster mechanism would be first-pass visual processing of category-specific value cues, immediately providing the necessary visual information to PFC. This, however, would require learned mechanisms for processing the appropriate cues in a given object category. To test these hypotheses, we trained monkeys to discriminate value in four letter-like stimulus categories. Each category had a different, continuously variable shape cue that signified value (liquid reward amount) as well as other cues that were irrelevant. Monkeys chose between stimuli of different reward values. Consistent with the first-pass hypothesis, we found early signals for category-specific value cues in area TE (the final stage in monkey ventral visual pathway) beginning 81ms after stimulus onset-essentially at the start of TE responses. Task-related activity emerged in lateral PFC approximately 40ms later and consisted mainly of category-invariant value tuning. Our results show that, for familiar, behaviorally relevant object categories, high-level ventral pathway cortex can implement rapid, first-pass processing of category-specific value cues.