Reward Inequity Research Articles

Neurophysiological analysis of disadvantageous social inequity: Exploring emotional behavior changes and c-Fos expression in a male rat model

Humans and other animals exhibit aversive behavioral and emotional responses to unequal reward distributions compared with their conspecifics. Despite the significance of this phenomenon, experimental animal models designed to investigate social inequity aversion and delve into the underlying neurophysiological mechanisms are limited. In this study, we developed a rat model to determine the effects of socially equal or unequal reward and stress on emotional changes in male rats. During the training session, the rats were trained to escape when a sound cue was presented, and they were assigned to one of the following groups: all escaping rats [advantageous equity (AE)], freely moving rats alongside a restrained rat [advantageous inequity (AI)], all restrained rats [disadvantageous equity (DE)], and a rat restrained in the presence of freely moving companions [disadvantageous inequity (DI)]. During the test session, rats in the advantageous group (AE and AI) escaped after the cue sound (expected reward acquisition), whereas rats in the disadvantageous group (DE and DI) could not escape despite the cue being presented (expected reward deprivation). Emotional alteration induced by exposure to restraint stress under various social interaction circumstances was examined using an open field test. Notably, the DI group displayed reduced exploration of the center zone during the open field tests compared with the other groups, indicating heightened anxiety-like behaviors in response to reward inequity. Immunohistochemical analysis revealed increased c-Fos expression in the medial prefrontal and orbitofrontal cortices, coupled with reduced c-Fos expression in the striatum and nucleus accumbens under DI conditions, in contrast to the other experimental conditions. These findings provide compelling evidence that rats are particularly sensitive to reward inequity, shedding light on the neurophysiological basis for distinct cognitive processes that manifest when individuals are exposed to social equity and inequity situations.

Do wages underestimate the inequality in workers' rewards? The joint distribution of job quality and wages across occupations

AbstractInformation on both wages and job quality is needed in order to understand the occupational dispersion of wellbeing. We analyse subjective wellbeing in a large UK sample to construct a measure of ‘overall reward’, the sum of wages and the value of job quality, in 90 different occupations. If only wages are included, then labour market inequality is underestimated: the dispersion of overall rewards is one‐third larger than the dispersion of wages. Our findings are similar, and stronger, in data on US workers. We find a positive correlation between job quality and wages in all specifications, both between individuals in the cross‐section and within individuals in panel data. The gender and ethnic gaps in the labour market are larger than those in wages alone, and the overall rewards to education on the labour market are underestimated by earnings differentials alone.

Electrophysiological signatures of inequity-dependent reward encoding in the human OFC

Social decision making requires the integration of reward valuation and social cognition systems, both dependent on the orbitofrontal cortex (OFC). How these two OFC functions interact is largely unknown. We recorded intracranial activity from the OFC of ten patients making choices in a social context where reward inequity with a social counterpart varied and could be either advantageous or disadvantageous. We find that OFC high-frequency activity (HFA; 70-150Hz) encodes self-reward, consistent with previous reports. We also observe encoding of the social counterpart's reward, as well as the type of inequity being experienced. Additionally, we find evidence of inequity-dependent reward encoding: depending on the type of inequity, electrodes rapidly and reversibly switch between different reward-encoding profiles. These results provide direct evidence for encoding of self- and other rewards in the human OFC and highlight the dynamic nature of encoding in the OFC as a function of social context.

Novel 31-kHz calls emitted by female Lewis rats during social isolation and social inequality conditions

Whether commonly used experimental animals show aversion toward inequality of social rewards, as humans do remains unknown. We examined whether rats emitted the 22-kHz distress calls under social reward inequality. Rats showed affiliative behavior for a specific human who repeatedly stroked and tickled them. When experimenter stroked another rat in front of them and during social isolation, these rats emitted novel calls with acoustic characteristics different from those of calls emitted under physical stress, namely air-puff. Under inequality conditions, rats emitted calls with higher frequency (∼31kHz) and shorter duration (<0.5s) than those emitted when receiving air-puff. However, with an affiliative human in front of them, the number of novel calls was lower and rats emitted 50-kHz calls, indicative of the appetitive state. These results indicate that rats distinguish between conditions of social reward inequality and the presence of an experimenter, and emit novel 31-kHz calls.

Understanding the Inequality of Web Traffic and Engagement in Online Healthcare Communities.

The online healthcare community (OHC) is a kind of doctor-patient communication platform, in which doctors can share medical knowledge and provide various kinds of counsel for patients. However, if the OHC's web traffic is concentrated on a small number of doctors, or if only a few doctors are actively involved in the OHC's activities, this will not be conducive to the optimal development of the OHC. This study explores this issue of inequality and makes three main innovations. First, based on data on web traffic and engagement extracted from 139,037 doctors' web pages in one popular OHC, we point out how serious the inequality phenomenon is. Second, we confirm that the Matthew effect indeed exists in this context and leads to greater inequality. Third, we demonstrate that the inequality of psychological or material rewards causes the inequality of web traffic or engagement to become worse; hence, an appropriate reward mechanism should be designed to mitigate the Matthew effect rather than enhance it. Finally, we discuss the managerial implications of these results, as well as avenues for future studies.

The Gender Pay Gap in UK Medicine

In this study we quantify the size and drivers of the contemporary gender pay gap among medical doctors employed in the UK public sector. In using nationally representative data from the Annual Survey of Hours and Earnings, we make comparisons to doctors employed in the private sector, as well as to other public sector medical professionals. We find that the substantial 20 per cent hourly gender pay gap among public sector doctors is far larger than in either of these comparator occupations. Decomposing the mean gender pay gap for public sector doctors, we find that it is largely unexplained by personal and work-related characteristics, consistent with evidence of potential substantial gender inequality in rewards. It is at the top end of the wage distribution where this is most pronounced indicating the presence of a 'glass ceiling' in UK medicine.

Corticostriatal connectivity is associated with the reduction of intergroup bias and greater impartial giving in youth

Although prosocial behavior is preferentially directed toward the in-group across many species, prioritizing the outcomes of both the in- and out-group earlier in development can reduce intergroup biases. The current study examined the role of corticostriatal recruitment and connectivity in buffering the effect of intergroup bias on costly giving behavior during childhood and adolescence, a period when other-oriented preferences and associated brain functions undergo significant change. During functional magnetic resonance imaging, youth (n = 51; 8–16 years) made decisions that could potentially benefit in-group and out-group peers at a cost to themselves. Youth were more prosocial toward in-group relative to out-group peers, but were relatively more prosocial to out-group peers when there was a greater discrepancy between potential rewards for others over oneself (i.e., higher reward inequity). Although they showed no differences in corticostriatal activation, youth evinced greater connectivity between the ventral striatum (VS) and posterior superior temporal sulcus (pSTS) when considering more inequitable prosocial decisions that favored the outcomes of out-group peers, which attenuated intergroup biases in prosocial behavior. We found no age-related differences at the behavioral or neural level, suggesting that in-group preferences already bias prosocial behavior and its neurocognitive processes by late childhood and do not change across adolescence.

Scale and Skill in British Print Culture: Reading the Technologies, 1680–1820

Scale and Skill in British Print Culture: Reading the Technologies, 1680–1820 Jon Klancher (bio) In the long eighteenth century, a technology was something to read—a printed treatise or manual of skills that encompassed the whole range of what were then called the mechanical arts. The OED marks this meaning of the word as obsolete after 1860 (sense 1), but it flourished far and wide before then. Some of these works hewed closely to the ground of traditional artisan labor, like Joseph Moxon’s Mechanick Exercises (1683). Others deployed sophisticated idioms of mathematical measuring, like Benjamin Martin’s Logarithmologia (1740), and later, more spacious versions like Thomas Martin’s The Circle of the Mechanical Arts (1813) began to register the impact of steam technology on older and newer kinds of British skilled labor. At least one special case, Jeremy Bentham’s Chrestomathia (1816), would raise the level of these print technologies to an influential mode of social theory and a mapping of emergent disciplines of modern knowledge.1 Such works can be hard to read today (and are often not easy to find), but for us they have a two-fold importance. On the one hand, they speak to the new forms of modern work that were emerging in the long eighteenth century in what recent economic historians classify as lower, medium, and higher-skilled British labor, kinds of skill about which the print technologies [End Page 89] could teach readers during the early industrial revolution. Such books did not tell their readers about the wider theory of the division of labor adumbrated by Adam Smith, nor did they offer any critical (let alone radical) perspective with which to measure the increasing inequality of labor and rewards put in place by 1800 (fig. 1). Click for larger view View full resolution Figure 1. The third 1703 edition of Joseph Moxon’s Mechanick Exercises focused on six occupations, ECCO; Thomas Martin’s 1813 The Circle of the Mechanical Arts explored sixty-six fields of labor, GOOGLE. But with their microscopic attention to the rapidly shifting skills being empowered or disempowered by new technologies and capital investments, these books offer a rare inside look at the language of vocation and practice. This language did not provide the high-minded sense of vocation now usually associated with a calling to one of the modern professions, but the gritty vocabulary now customarily assigned to vocational schools and to everything beneath what colleges and universities have, since the nineteenth century, been calling the arts and sciences. The discourse of mechanical arts largely fell out of this latter category by the mid-nineteenth century, but it was robustly at the center of arts and sciences during the long eighteenth century.2 [End Page 90] Meanwhile, these print technologies were among the first to adapt an old word to a new modern usage: scale. Today we grapple with complex questions of scale in such realms as the digital, with its problematic of scalability in computing and visualizing; or in globalization, with what cultural geographers have called a “rescaling of social life.”3 With the advent of the Anthropocene, there is also the sense of scale-shock we experience when trying to grapple with the implications of climate change, pondering with Dipesh Chakrabarty the challenge to “think human agency over multiple and incommensurable scales at once” (earth’s history, human history, industrial history).4 This essay uses early-modern print technologies to begin to answer a more preliminary question: where did we get the modern language of scale from in the first place? And what did this language have to do with problems of scale posed by emerging disciplines in the nineteenth century, or by capitalist modernity more broadly? From the Latin word scala (or ladder), scale or scales had once denoted a fixed and balanced order of things: the great scale of being, the immutable scales of justice. Our historical print databases show the rise of a new and different sense of scale from the seventeenth- to the mid-nineteenth century: to measure weight, then space, then time. For natural philosophers of the Royal Society, there was little possibility of experiment without using a scale...

Inequality and risk-taking behaviour

This paper investigates social influences on attitudes to risk and reanalyses how risk taking varies with relative position and inequality. Individuals with low initial wealth, about to participate in a tournament with richer opponents, may take fair gambles even though they are risk averse in both consumption and tournament rewards. It is shown that this risk taking decreases in the inequality of initial endowments, but in contrast it increases in the inequality of tournament rewards.

Dogs\u2019 reaction to inequity is affected by inhibitory control

Inequity aversion is thought to act as a mechanism to ensure cooperation and has been studied in many different species, consistently revealing inter-individual variation. Inhibitory control has been proposed to act as one factor responsible for this variation since individuals need to inhibit performing the required action and/or refuse rewards in order to exhibit inequity aversion. Here, we investigated if dogs’ sensitivity to inequity is affected by their capacity for inhibitory control, assessed in a test battery and questionnaire. Overall, dogs showing high compulsivity scores (i.e. repetitive behaviours independent of feedback) were more motivated to participate in the inequity task independent of the rewarding scheme. Dogs were more sensitive to inequity and individual contrast if they exhibited a slower decision speed in the inhibition tasks. Furthermore, less persistent and more impulsive dogs were more sensitive to reward inequity, potentially due to having a lower tolerance level for frustration. Results indicate that aspects of inhibitory control can explain the variation in dogs’ inequity response, highlighting one of the mechanisms underlying responses to inequity. Emphasising the importance to design paradigms, which allow us to disentangle capacities to recognise inequity from the inability to react to it due to poor inhibitory control abilities.

Long-term assignment reward (dis)satisfaction outcomes: hearing women’s voices

Purpose – Drawing upon compensating differentials, equity theory, and the psychological contract, women’s voices illustrate how organisational policy dissemination, implementation and change can lead to unintended assignee dissatisfaction with reward. Implications arise for organisational justice which can affect women’s future expatriation decisions. The paper aims to discuss these issues. Design/methodology/approach – A qualitative case study methodology was employed. Reward policies for long-term international assignments (IAs) were analysed. In-depth semi-structured interviews were conducted confidentially with 21 female long-term assignees selected using stratified sampling, and with two managers responsible for international reward policy design/implementation. Findings – Policy transparency is required. Women perceive inequity when allowances based on grade are distorted by family status. Women in dual career/co-working couples expect reward to reflect their expatriate status. Reward inequity is reported linked to specific home/host country transfers. Policy change reducing housing and children’s education are major causes of reward dissatisfaction. Research limitations/implications – This case study research was cross-sectional and set within one industry. It addressed reward outcomes only for long-term IAs from the perspectives of women who had accepted expatriation in two oil and gas firms. Practical implications – Reward policy should be transparent. Practitioners might consider the inter-relationship between policy elements depending on grade and accompanied status, location pairings, and the effects of policy content delivery to dual career/co-working couples. Originality/value – This paper advances the field of IA reward by examining compensating differentials, equity and the psychological contract and takes these forward via implications for organisational justice. It identifies reward elements that support women’s expatriation and address their low share of expatriate roles, thereby fostering gender diversity. Future research themes are presented.

The role of inequality on effort in tournaments

We study the role of inequality using a tractable tournament model in which contestants with heterogeneous abilities are allocated a reward based on their relative effort. Using the Lorenz order, we focus on the effect of changing the degree of inequality in both the distribution abilities and rewards on the distribution of effort. When the Cumulative Density Function (CDF) of rewards is concave then reducing inequality of abilities increases effort at every rank, including aggregate effort. In general, aggregate effort increases (decreases) if the CDF of rewards has an increasing failure rate (decreasing failure rate). Further, unless the CDF of abilities is highly concave, increasing inequality of rewards always increases aggregate effort. Nonlinearity in the cost function also matters. The effect of changing the degree of inequality in either distribution of abilities or rewards, on aggregate effort, depends on the convexity of the cost function. In sum, our results challenge the current knowledge about the role of inequality in tournaments by showing how the distribution of effort–including aggregate effort–crucially depends on the convexity of the cost function and of the CDF of both rewards and abilities.

A neuronal reward inequity signal in primate striatum.

Primates are social animals, and their survival depends on social interactions with others. Especially important for social interactions and welfare is the observation of rewards obtained by other individuals and the comparison with own reward. The fundamental social decision variable for the comparison process is reward inequity, defined by an asymmetric reward distribution among individuals. An important brain structure for coding reward inequity may be the striatum, a component of the basal ganglia involved in goal-directed behavior. Two rhesus monkeys were seated opposite each other and contacted a touch-sensitive table placed between them to obtain specific magnitudes of reward that were equally or unequally distributed among them. Response times in one of the animals demonstrated differential behavioral sensitivity to reward inequity. A group of neurons in the striatum showed distinct signals reflecting disadvantageous and advantageous reward inequity. These neuronal signals occurred irrespective of, or in conjunction with, own reward coding. These data demonstrate that striatal neurons of macaque monkeys sense the differences between other's and own reward. The neuronal activities are likely to contribute crucial reward information to neuronal mechanisms involved in social interactions.

The role of the striatum in social behavior

Where and how does the brain code reward during social behavior? Almost all elements of the brain's reward circuit are modulated during social behavior. The striatum in particular is activated by rewards in social situations. However, its role in social behavior is still poorly understood. Here, we attempt to review its participation in social behaviors of different species ranging from voles to humans. Human fMRI experiments show that the striatum is reliably active in relation to others' rewards, to reward inequity and also while learning about social agents. Social contact and rearing conditions have long-lasting effects on behavior, striatal anatomy and physiology in rodents and primates. The striatum also plays a critical role in pair-bond formation and maintenance in monogamous voles. We review recent findings from single neuron recordings showing that the striatum contains cells that link own reward to self or others' actions. These signals might be used to solve the agency-credit assignment problem: the question of whose action was responsible for the reward. Activity in the striatum has been hypothesized to integrate actions with rewards. The picture that emerges from this review is that the striatum is a general-purpose subcortical region capable of integrating social information into coding of social action and reward.

The Influence of the Relationship and Motivation on Inequity Aversion in Dogs

One crucial element for the evolution of cooperation may be the sensitivity to others’ efforts and pay-offs in comparison with one’s own costs and gains. If an individual responds to a disadvantageous reward distribution, then it would likely increase its relative fitness compared with those who do not (Brosnan & de Waal, Nature 428:140, 2004). Recent experimental research indicates that sensitivity toward unequal reward distribution is not a uniquely human trait; non-human primates react to inequity if they witness a conspecific that obtains a more attractive reward for the same effort. However, primates are not the only species that cooperate and thus would benefit from inequity aversion. Canids also frequently cooperate with group members (e.g., wolves, wild dogs, etc.) or humans (domestic dogs), allowing for the possibility that they also are sensitive to the reward distribution. We report the findings of two studies of dogs’ responses to inequity and the social factors that mediate such responses. In the first study, we investigated whether domestic dogs showed a response to the inequity of rewards received for the same action in pairs of familiar dogs. We found that dogs showed significant behavioral differences when tested without food rewards when in the presence of a rewarded partner compared to the baseline and asocial control situations. This indicated that the presence of a rewarded partner matters (Range, Horn, Viranyi, & Huber, Proc Natl Acad Sci USA 106(1):340–345, 2009). In contrast to primates, dogs did not react to differences in the quality of food or effort. In the second study, we analyzed whether individual (motivational or personality) characteristics determined the response of each subject to unequal reward distributions or whether the subject’s responses depended on the specific relationship they had with its partner. We found that individual motivation and the quality of the relationship influenced the dogs’ performance in test conditions, but that these factors varied across the control and reward inequity conditions. Overall, our results suggest that inequity aversion in dogs is conditional on their and their partner’s rewards. Whether inequity aversion is based on the same mechanisms in both humans and non-human primates is still unclear.

Causes of social reward differences encoded in human brain

Rewards may be due to skill, effort, and luck, and the social perception of inequality in rewards among individuals may depend on what produced the inequality. Rewards due to skill produce a conflict: higher outcomes of others in this case are considered deserved, and this counters incentives to reduce inequality. However, they also signal superior skill and for this reason induce strong negative affect in those who perform less, which increases the incentive to reduce the inequality. The neurobiological mechanisms underlying evaluation of rewards due to skill, effort, and luck are still unknown. We scanned brain activity of subjects as they perceived monetary rewards caused by skill, effort, or luck. Subjects could subtract from others. Subtraction was larger, everything else being equal, in luck but increased more as the difference in outcomes grew in skill. Similarly, reward-related activation in medial orbitofrontal cortex was more sensitive to the difference in relative outcomes in skill trials. Orbitofrontal activation reflecting comparative reward advantage predicted by how much subjects reduced unfavorable reward inequality later on in the trial. Thus medial orbitofrontal cortex activity reflects the causes of reward and predicts actions that reduce inequality.

Which Inequality? The Inequality of Endowments versus the Inequality of Rewards

We introduce a new distinction between inequality in initial endowments (e.g., ability, inherited wealth) and inequality of what one can obtain as rewards (e.g., prestigious positions, money). We show that, when society allocates resources via tournaments, these two types of inequality have opposing effects on equilibrium behavior and well-being. Greater inequality of rewards hurts most people—both the middle class and the poor—who are forced into greater effort. Conversely, greater inequality of endowments benefits the middle class. Thus, the correctness of our intuitions about the implications of inequality is hugely affected by the type of inequality considered. (JEL D63, D82)

Mechanisms underlying responses to inequitable outcomes in chimpanzees, Pan troglodytes

Several species of nonhuman primates respond negatively to inequitable outcomes, a trait shared with humans. Despite previous research, questions regarding the response to inequity remain. In this study, we replicated the methodology from previous studies to address four questions related to inequity. First, we explored the impact of basic social factors. Second, we addressed whether negative responses to inequity require a task, or exist when rewards are given for 'free'. Third, we addressed whether differences in the experimental procedure or the level of effort required to obtain a reward affected responses. Finally, we explored the interaction between 'individual' expectations (based on one's own previous experience) and 'social' expectations (based on the partner's experience). These questions were investigated in 16 socially housed adult chimpanzees using eight conditions that varied across the dimensions of reward, effort and procedure. Subjects did respond to inequity, but only in the context of a task. Differences in procedure and level of effort required did not cause individuals to change their behaviour. Males were more sensitive to social than to individual expectation, while females were more sensitive to individual expectation. Finally, subjects also increased refusals when they received a better reward than their partner, which has not been documented previously. These results indicate that chimpanzees are more sensitive to reward inequity than procedures, and that there is interaction between social and individual expectations that depends upon social factors.

Managers' Tradeoffs Between Equality and Efficiency: Preferences and Emotional Responses

In a survey questionnaire, 81 Swedish managers working in the private and public sectors were presented with scenarios in which a manager chose among inefficient (i.e., economically worse) alternatives, implying equal rewards to subordinates; and efficient (i.e., economically better) alternatives, implying unequal rewards. The managers also rated 26 different emotion words, describing their responses to the inequality of rewards in the scenarios. The results showed stronger outward‐directed and inward‐directed negative emotions, and weaker inward‐directed positive emotions when the inequality of rewards increased. Furthermore, negative emotions were found to mediate the choices among efficient and inefficient alternatives.

Multiple Jobs and Inequality in Earnings

This paper shows that individual and structural factors which determine professors' salaries also influence, in various degrees, the accumulation of earnings from additional sources. As a result, those who receive greater rewards from their main work role are likely to have proportionately higher supplementary incomes. Thus, expanding occupational role‐sets increase the inequality in economic rewards in the academic system. It is proposed that the relative effect of each of the salary determinants on extra earnings depends on their ability to generate, directly or indirectly, extra earning opportunities.The examined factors are professorial rank, research productivity, departmental prestige and the length of academic experience. Professorial rank has been shown as the main determinant of institutional salary level, whereas research productivity is the most crucial factor in generating extra earning opportunities. It is likely that the importance of the latter, in our case, is mainly indirect in that it generates critical intervening resources such as professional reputation, visibility in the academic system and communication network.