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Unequal Access to Opportunity in the Workplace Peer Reviewed Articles

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The motivational toll of inequality: Opportunity gaps reduce the willingness to work

  • Filip Gesiarz,
  • January-Emmanuel De Neve,
  • Tali Sharot

PLOS

x

  • Published: September four, 2020
  • https://doi.org/10.1371/journal.pone.0237914

Abstract

Factors beyond a person'due south control, such as demographic characteristics at birth, oft influence the availability of rewards an private can look for their efforts. Nosotros know surprisingly little how such differences in opportunities impact human motivation. To test this, we designed a report in which we arbitrarily varied the reward offered to each participant in a group for performing the same task. Participants then had to determine whether or not they were willing to exert effort to receive their reward. Across three experiments, we found that the unequal distribution of offers reduced participants' motivation to pursue rewards even when their relative position in the distribution was high, and despite the conclusion being of no do good to others and reducing the reward for oneself. Participants' feelings partially mediated this human relationship. In particular, a large disparity in rewards was associated with greater unhappiness, which was associated with lower willingness to work–even when decision-making for absolute advantage and its relative value, both of which also affected decisions to work. A model that incorporated a person's relative position and unfairness of rewards in the group fit improve to the data than other popular models describing the furnishings of inequality. Our findings propose opportunity-gaps can trigger psychological dynamics that hurt productivity and well-being of all involved.

Introduction

Randomness plays a surprisingly important role in determining the barriers and opportunities encountered by individuals on their path to a prosperous life [1]. Country of birth alone explains 66% of global variation in living standards [two]. Other non-meritocratic factors, such as cypher code [3], parental socio-economical condition [four], gender [5], or a person's name [6] accept been shown to have a significant issue on earnings, fifty-fifty after accounting for inter-private differences in merit. Economic inequality arising due to random circumstances is ofttimes viewed as unfair [7], and previous studies have shown that people support redistribution of wealth in such situations [viii]. However, much less is known almost how opportunity gaps influence human motivation. Such knowledge could shed lite on psychological mechanisms that lead to differences in aspirations, that in turn might contribute to higher unemployment [9–11] and lower university application rates of people from disadvantaged backgrounds [12–14]. Here, we examine how randomly assigned unequal advantage prospects can influence a person'south willingness to exert try in substitution for rewards–a proxy measure of motivation in labour supply decisions.

Due to a lack of experimental research on the bear upon of inequality on motivation, the underlying mechanisms of this relationship remain unknown. We hypothesize that arbitrary differences in opportunities to earn rewards tin can negatively impact non only disadvantaged individuals but also those who are offered relatively high rewards. This is because facing opportunity gaps can involve two separate mechanisms: relative comparisons and reactions to unfairness, representing cocky-regarding and grouping-regarding reactions to inequality, respectively [15]. Outset, because people engage in spontaneous social comparisons, evaluating their rewards relative to those of others [16–19], opportunity gaps tin can increase motivation to pursue rewards of those offered relatively loftier rewards and reduce the motivation of those offered relatively low rewards. Still, at the same fourth dimension people may have a negative response to the unfairness of arbitrary distributions of rewards in their group regardless of which side of the distribution they are at, and exist less willing to pursue rewards in situations that are unfair. Indeed, it has been shown that subjects are less happy when they themselves win in a gambling task, just the other field of study loses, in comparison to when both subjects win [twenty]. We hypothesize that such a negative reaction may take consequences across a person's melancholia country. Specifically, negative feelings tin lead to apathy as well as a reduction in the subjective value of rewards [21], leading to a reduced motivation of all members of the group. Thus, individuals at the lesser of the distribution may be negatively affected twice, beginning due to their lower relative position and 2d due to their reaction to unfair distribution.

We formalize the to a higher place hypotheses in a model that characterizes the motivational response to rewards as a linear combination of advantage'due south absolute value, relative value, and statistical dispersion of all rewards in the group. Based on the constabulary of decreasing marginal utility, we assume that absolute reward has a non-linear effect on decisions to engage in an attempt to earn the reward [22]. Every bit previous studies have shown that people accept a tendency to engage in ordinal rather than absolute comparisons [23], we ascertain the relative value of rewards as the rank of the offered reward. Statistical dispersion is calculated in our model every bit Gini coefficient, post-obit other studies suggesting a relation between this measure out and well-being in national surveys [24].

In three experiments, we were able to dissociate and quantify the influence unfairness, reward'south rank, its absolute value, while studying them independently from other factors that are oftentimes associated with opportunity gaps, such every bit demographics or stereotypes. In all three studies, participants fabricated decisions on whether to exert cognitive effort in exchange for a reward while observing the rewards offered to others for completing the same job. In these experiments we manipulated: (i) the departure of payments in the group from an equal distribution (thereafter 'unfairness'), and (ii) the relative position of the offer in the distribution (thereafter 'rank'). Experiment one aimed to establish if the motivation to work for rewards is influenced by unfairness and rank of offered rewards. Experiments 2 and iii aimed to test the mechanisms underlying the influence of relative value and unfairness on motivation, including the mediating function of emotions, and the moderating role of uncertainty.

Methods Experiment one

Overview

Experiment i used a one-shot pattern (Fig 1) and was conducted on Prolific—an online labour marketplace platform. Participants were offered £0.24 for an optional task of transcribing 1/iii of a page of text from a displayed paradigm and were fabricated to believe that this reward offering was fatigued at random. The offered reward was displayed in the context of iv other rewards assigned randomly to other workers on the platform. Seven hundred participants were assigned to separate conditions in a 2x5 design that determined the context of their offered reward: the five rewards could be either relatively every bit distributed or unequally distributed, and participant'due south reward of £0.24 could be presented either as vth, 4th, 3rd, twond or 1st best-offered reward.

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Fig 1. Behavioural task in Experiment one.

(A) The online task had a one-shot design. The job was advertised on an online labour market platform as a uncomplicated transcribing job. After completing the mandatory cognitive task, participants were informed that they would take an opportunity to complete an optional transcribing chore for a randomly fatigued fee. The random describe was determined by spinning a bicycle of fortune that assigned a participant 1 out of v different colours. After the color assignment, participants were presented with the advantage offers for all 5 colours, and were told that the other rewards were assigned to other people who drew those colours. Participants then decided to either take or pass up the reward offer for the optional task. If they accepted it, they had to transcribe an boosted text. If they declined it, the chore ended, and they were granted their base fee. Unbeknownst to participants, the reward offer was always equal to £0.24, and the random colour assignment determined if the offer was presented either as 5th, 4th, 3rd, 2nd or onest best advantage. Independently, participants were randomly assigned to i of two levels of unfairness (Gini coefficient = 0.three or Gini coefficient = 0.v) of advantage distribution. (B) The task had a 5x2 design (10 conditions in total): ii levels of inequality, and five levels of relative value. Each participant viewed only one of these conditions. Panel B illustrates example atmospheric condition. The example a) shows a state of affairs where £0.24 was presented as the second-all-time reward in an unfair context, and example b) where information technology was presented as the second-best advantage in a off-white context. The example c) shows a situation where £0.24 was presented as the center advantage in an unfair context, and the instance d) shows a situation where £0.24 was presented as the middle advantage in a fair context.

https://doi.org/10.1371/journal.pone.0237914.g001

Participants

In experiment one, seven hundred participants were recruited to take office in the online study, spread evenly beyond ten weather (70 participants per condition). All participants provided written informed consent. The experiment was approved past the UCL ethics commission. Participants were recruited through the Prolific platform–an online platform for offering web-based tasks. Eighty participants were excluded due to failing attending check that asked them almost the color that they have been assigned to. This exclusion benchmark was necessary, as the colour indicated which reward a participant was offered. All participants in the online task were currently UK residents (hateful age 26.two[five.0], age range 18–35, 487 women). The average self-identified political orientation was 4.61(1.61) on a scale ranging from 1 (extremely right-fly) to 7 (extremely left-wing), significantly more left-fly than the centre of the calibration (t(699) = 18.27, p < 0.001).

Procedure

Participants responded to an ad on Prolific platform that recruited people for a short transcribing task–a common job on online labour markets. The display of the ad was restricted to current U.k. residents aged eighteen–35. After signing up to consummate the chore, participants were informed that the task will consist of a mandatory transcribing job, for which they will be paid the advertised wage (£0.25), and an optional transcribing task for which they volition be paid a bonus payment. The mandatory transcribing chore required participants to transcribe a 1/5 of a page from an erstwhile cookbook. The optional job was to transcribe a unlike text from the same cookbook, which was approximately 3 times longer. The instructions emphasized that participants had to be 99% accurate to receive the bonus payment. There was no fourth dimension limit.

They were also informed that the wage for the optional task would be randomly fatigued. The random draw was determined by a bike of fortune that later on spinning for iii seconds picked one colour out of 5 colours. Subsequently the participant was assigned 1 of 5 colours, the bonus wages for the optional task were revealed all at once for all 5 colours. Participants were told that data about the other wages was displayed to inform other Prolific users who drew different colours. Unbeknownst to participants, the offered wage for the optional task was always equal to £0.24, and each participant was assigned to ane condition in a 2x5 design that adamant the context in which the reward was displayed. In particular, the reward could be presented either as 5th, 4th, 3rd, 2nd or ist all-time reward, and was presented either in a context of a roughly fair distribution of rewards betwixt participants (corresponding to a 0.ii Gini coefficient) or an unfair distribution (corresponding to a 0.five Gini coefficient). Total list of reward distributions is included in the S2 Tabular array. After seeing the reward offers, participants had to decide to either accept or reject the optional task. If they decided to accept it, they had to transcribe an additional text and were paid their bonus wage (£0.24) plus base wage (£0.25). If they decided to reject it, they were paid only their base of operations wage (£0.25).

Data analysis

To examination the influence of reward's rank and unfairness of the distribution, we used a Generalized Linear Model (GLM) that included decisions to work every bit the categorical dependent variable, and unfairness (measured as Gini coefficient) and rank (normalized to range from 0 to 1, for everyman and highest rank respectively) as independent variables. Both independent variables were standardized prior to the analysis. The GLME model assumed a binomial distribution of the dependent variable.

Participant's offer rank was normalized to range from 0 to 1 as follows: Where i is the reward offer index in a set of offers ordered from lowest to highest and n is the number of participants in the group (in our case five). The above rank mensurate assigns 1 to the person with the all-time offer, 0 to the person with the lowest offer, and 0.5 to the person with the intermediate offering. Unfairness was measured as the Gini coefficient, calculated equally follows: Where north is the number of participants in the group, x i and x j is the reward offers received by each person, and is the mean reward offer.

To illustrate the results from experiment i, we plotted the number of participants who decided to pursue additional reward divided past the number of all participants in the condition separately for each rank and level of unfairness (Fig 2).

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Fig two. Motivation to work is higher when the distribution of rewards is off-white and the rank of the reward is high, despite the same level of absolute reward.

The plot illustrates the results from a one-shot experiment conducted on an online labour market platform. Each dot represents the proportion of participants who decided to perform an additional task for a bonus advantage of £0.24, which was presented either in a relatively fair (blue) or unfair (red) context, and either as the 5th, fourth, 3rd, iind or ist best reward. The lines represent the best fitting line based on the Ordinary Least Squares method. Participants were more likely to have the offer of £0.24 when its rank was high than when it was low, and when the rewards of all participants were fairly distributed than when they were unfairly distributed.

https://doi.org/10.1371/journal.pone.0237914.g002

Results Experiment one

Overall, 77.33% of participants decided to perform the optional task in exchange for an boosted fee of £0.24. However, nosotros plant that participants were less willing to work for the additional reward when they believed that the distributions of offered rewards were unfair vs. fair (β = -0.31, p < 0.01), and when the rank of their reward was low vs. high (β = 0.twoscore, p < 0.001), despite accented reward beingness the same across all conditions in this experiment (Fig 2). On average, an increase of 0.3 in Gini coefficient resulted in ten.six% less accustomed offers, and increase of i rank resulted in 5.three% more than accepted offers.

Procedure for onsite experiments (Experiments 2 & three)

Overview.

Experiments 2 and 3 followed a similar logic as experiment 1, but used a repeated measure out pattern (Fig 3), in which the same person was exposed to different distributions of rewards. Repeated measure out designs reach greater statistical power with fewer participants, allowing united states of america to test more efficiently a larger number of hypotheses regarding the mechanisms underlying the furnishings observed in Experiment ane. Experiments 2 and 3 aimed to test the robustness of the effects observed in Experiment 1 when translated to a different context. Both experiments included a greater variety of distributions (both positively skewed and negatively skewed) and a unlike cognitive attempt job. Different distributions immune us to test the predictions of different models describing the impact of inequality on the evaluation of rewards. Additionally, the experiments: a) gathered data about participants' electric current feelings later on seeing the distribution of rewards, allowing usa to test if the observed furnishings are mediated by the impact of rank and unfairness on person's emotional state, and b) manipulated the incertitude about the value of rewards, by either introducing a known (Experiment 2) or an unknown (Experiment three) exchange charge per unit of earned points with £, allowing u.s. to test if reliance on the social context in ane'south decisions to work is moderated by doubtfulness.

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Fig 3. Behavioural task in Experiment 2 and three.

(A) Both Experiment two and 3 used a repeated measures design. Participants were invited to the lab in groups of five. To hands identify themselves during the experiment, each participant selected a cartoon avatar that would represent them throughout the task. They and then retired to private cubicles to complete the study. There were 60 trials in total. Each trial started with a brandish of all participants' reward offers, that differed in rank, absolute advantage, and level of unfairness between participants. Subsequently seeing the distribution of rewards, participants rated their electric current feelings and indicated whether they were willing to exert cognitive attempt for their offered reward on that specific trial. If they decided to do and then, they would complete 3 mathematical problems. If non, they would move on to the adjacent trial. If a participant gave an incorrect answer to the mathematical problem, they would accept to solve an additional ane, until they completed three problems correctly. (B) For the repeated measure out experiments, we created 30 income distributions based on a log-normal probability density function (corresponding to 10 levels of Gini alphabetize uniformly distributed between 15 and 55, with 3 different median values) Log-normal distribution approximates reward distributions encountered in existent-world, such as income distributions within countries [25] and companies [26]. Because these distributions are always positively skewed, we too created thirty distributions that were negatively skewed and a mirror prototype of the positively skewed distributions. For illustration purposes, we plot four of these distributions. Each dot on the line represents one of v reward offers presented to participants. Numbers above the dots refer to the advantage's rank. Numbers in the rectangles refer to unfairness level, expressed in the Gini coefficient. Distribution a) is an example of a fair positively skewed distribution with a low median reward; distribution b) is an case of similarly fair distribution, just with a college median value; Distribution c) is an example of an unfair positively skewed distribution, and distribution d) is an instance of a negatively skewed distribution that is a mirror image of c).

https://doi.org/ten.1371/journal.pone.0237914.g003

Participants.

In Experiment 2 and 3, one hundred and ten participants from University College London subject puddle were recruited to take office in two onsite studies: 60 in experiment 2 (mean age 22.1[iii.2], historic period range 18–35; 38 women) and fifty in experiment iii (hateful historic period 21.four[2.0]; age range 18–35; 34 women). All participants provided written informed consent. The experiment was approved by the UCL ethics committee. Across these two experiments, 67% of participants originated from Western countries. The boilerplate cocky-identified political orientation was 3.52(ane.38) on a scale ranging from 1 (extremely right-fly) to 7 (extremely left-wing) and was not significantly different from the centre of the calibration (t(87) = 0.12, p = 0.91). All participants started with an initial endowment of £x and were paid an additional bonus based on their decision to accept or pass up reward offers in exchange for performing a cognitive job in one randomly selected trial. Participants who accepted all reward offers were excluded from the data analysis as we could not identify the factors influencing their decisions due to lack of behavioral variability, beyond the fact that they were maximizing their bonus reward at the end (eight subjects in experiment ii and seven subjects in experiment 3), leaving 52 and 43 participants in each experimental sample respectively. None of the subjects rejected all offers.

Procedure.

In both experiments, nosotros invited participants to the lab in groups of five (N = 110 in total). To easily place themselves during the chore, participants were asked to choose a drawing avatar that would represent them in the study. A randomly drawn lot number determined the social club of choosing avatars. Participants were informed that each person volition exist offered a dissimilar reward on each trial and that these rewards were randomly decided on each trial by a computer plan. Next, participants retired to dissever cubicles where they were given additional instructions.

Participants first completed one practice trial. Both experiments consisted of 60 trials. In each of lx trials, we presented to participants the reward points offered to each of the five members of the group on that trial. On each trial, we independently manipulated: (i) the deviation of payments in the grouping from an equal distribution ('unfairness'), (ii) the rank of the advantage offered to each person within the group (ranging from i to 5 - 'rank') and (iii) the absolute reward offered (i.e., points—'accented reward').

We created 60 dissimilar distributions of reward offers in total and presented them in random order. Nosotros generated 30 advantage distributions based on a log-normal probability density function. Log-normal distribution was chosen every bit it fits closely real-earth income structures inside firms [26] and countries [25]. To vary the levels of reward magnitude range and statistical dispersion we used a combination of iii unlike median values (0.55, ane, i.45) and 10 different standard deviations, corresponding to values of the Gini coefficient varying uniformly from 20 to 65, resulting in 30 different distributions. Log-normal distributions are always positively skewed. To generalize our findings, nosotros as well included 30 negatively skewed distributions that were a mirror-epitome of the positively skewed distributions past applying the following transformation of representative values: Where x northward is subject northward payment offer in each trial, x positive and ten negative are payment offers of all participants in trials with positively and negatively skewed distributions, respectively.

To generate reward offers representative of the in a higher place distributions, we used an inverse cumulative density part of these distributions, which assigns maximal pay value earned by each pct of the population. We side by side took an average pay from subsequent twenty percentiles of this function, with the exclusion of top 1 percentile, resulting in 5 values reflecting an average pay of each 20% of the population. The final percentile was excluded as it approaches infinity. Unfairness was quantified based on these five representative values. To innovate variability to the middle pay (that otherwise would be the same for all distributions generated from the aforementioned median value) we additionally subtracted a number between 0 and nine from each representative value in each distribution (in each distribution the same number was subtracted for each value). This resulted in the pay offers shown in S1 Table.

Afterward seeing the distribution of advantage offers, participants and then rated their feelings by clicking on a continuous sliding calibration ranging from very unhappy to very happy. The slider started in the middle of the scale on every trial. After the feeling ratings, participants indicated whether they were willing to complete iii mathematical problems to earn their reward. If they decided to do so, they were asked to solve the problems (the instructions emphasized that the mathematical problems were the same for all). If they decided not to, they would move on to the next trial. Each problem required adding two 3-digit numbers. To ensure equal difficulty of mathematical problems throughout the task, each improver had exactly two carryovers (sum of ones, tens or hundreds greater than 10). E.thou., problems included sums like 118 + 197. If participants provided an incorrect answer, they had to solve an additional problem. Participants connected until they got three problems correct. On average, 89% of attempts were correct, and it took subjects 17 seconds (SD = 7.56s) on average to solve each problem.

At the end of the study, nosotros selected one trial at random for compensation–a common process used to avoid the furnishings of reward accumulation during the task [27]. If the participant had decided non to work on that trial, no bonus reward was received. If the participant decided to work for a reward on that trial, they would receive the reward offered on that trial. The decision of whether to piece of work did not influence the rewards offered on futurity trials or pay-out of other members of the group. This data was emphasized in the instructions, and participants had to laissez passer a comprehension check to ensure that they understood the details of the task.

The difference between the two onsite experiments was that in one experiment the participants knew the exchange rate between advantage points offered and Smashing British Pounds (one point was worth £0.04), in the other experiment it was unknown and said to differ on each trial (ranging from £0.001 to £0.08). The total bonus reward (subsequently exchanging earned points from a selected trial to £) could range from £0 to £18.64 in Experiment 2 and from £0 to £37.28 in Experiment 3. We hypothesized that when the value of points was unknown, participants would rely more heavily on social context when deciding to piece of work for a displayed reward. Nosotros replicated the core findings across both studies. Thus, we initially report results from the combined dataset, and then formally test if the effects differed in strength betwixt both experiments. A separate assay of each dataset is presented in the Supporting Information.

Data analysis

Although participants on average accustomed 54% of reward offers in experiment two and 3, we found a considerable variability between participants, with some participants accepting/rejecting as petty as just ane offer, limiting inferences that can be drawn from a single participant. To account for this upshot, as well as within-subject correlations of responses related to repeated measures in our design, we used Generalized Linear Mixed Effects (GLME) model arroyo, in which fixed effects describe the effect common for all participants and random furnishings describe idiosyncrasies specific for an private. The GLME model included decisions to work as the categorical dependent variable and assumed a binomial distribution of the dependent variable. The independent variables were unfairness (measured as Gini coefficient), rank (normalized to range from 0 to 1, for lowest and highest rank respectively), and reward magnitude (expressed as a ability part, see beneath). All variables were standardized prior to the analysis. Post-obit methodological recommendations past Barr and colleagues [28], all models included fixed and random effects for intercept and all independent variables.

Rank and unfairness were calculated equally in Experiment 1. To business relationship for a possibility of diminishing marginal utility of each boosted awarded point, nosotros tested if the event of reward magnitude was ameliorate expressed as a linear or a power office (as it is in the prospect theory [22]): Where x is the reward offer, and ρ represents parameter describing the curvature of the reward function, ranging from 0 to 1 (at which point information technology is linear). To fit the higher up part, nosotros estimated non-linear mixed-effects model with stochastic Expectation-Maximization algorithm [29]. The ρ value maximizing the R 2 of the model describing the relationship between advantage magnitude and motivation to work (including the variables listed in the section beneath) was equal to 0.43, suggesting a non-linear relationship between accented reward and its value, and was subsequently used in all analyses.

We additionally tested if skewness of the distribution could separately influence participants' decisions, by including in the above model an Adapted Pearson's Coefficient of Skewness, calculated equally follows: Where is the average reward offer, n is the number of participants in the group, x i is the advantage offer received past each person.

To illustrate the size of the effect of unfairness and rank nosotros plotted predicted values of the higher up GLME model across dissimilar levels of unfairness (Fig 4A) and separately, across different ranks (Fig 4B), with the result of trial number, rank (only for Fig 4A) and unfairness (only for Fig 4B) ready to 0. To illustrate the issue of unfairness and rank in isolation from reward magnitude (Fig 4C), we estimated the probability of pursuing rewards on each trial from a GLME model including absolute reward and trial number (with other factors fixed to 0). Nosotros then calculated the residuals, past subtracting observed decisions and their predicted probability. Nosotros categorized residuals into 5 ranks and ii levels of unfairness (based on the middle value of the tested range) and calculated the boilerplate residuum value for each participant within each category and plotted the averages over participants within each category.

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Fig four. Motivation to work is higher when the distribution of rewards is off-white; the rank is loftier, and the accented advantage is high.

To illustrate the effect of factors influencing the motivation to work in repeated measures experiments, we plotted the probability of participants' decision to work from a GLME model predicting choice from reward magnitude and either different levels of (A) unfairness or (B) rank. (C) We also plotted average residuals for the v rank categories and 2 levels of unfairness from a GLME model predicting choice just from absolute reward and trial number. We observe that participants are more likely to make up one's mind to piece of work when (A, C) rewards are fairly distributed and (B, C) when the rank is high than low. Error confined = SEM.

https://doi.org/ten.1371/journal.pone.0237914.g004

The fit of the model including rank and unfairness was compared to two other popular models describing the effects of inequality on the evaluation of reward: the adaptation model [xxx], and inequality aversion model [31]. All compared models included accented value equally 1 of the independent variables. Adaptation model additionally included the difference between absolute value of the offered advantage and the average reward offered to all people in the grouping on a specific trial. Inequality aversion additionally model included advantageous and disadvantageous inequality, calculated as follows [31]: Where x i is an individual's payment offer and 10 j are payment offers received by other grouping members. All models were compared based on their Bayesian Information Criterion (BIC) which simultaneously assesses the model's fit, while penalizing it for its complexity.

To investigate if person's electric current emotional state mediated the effect of rank and unfairness on decisions to piece of work, we used a multi-level mediation analysis approach [32], which nests trial-level observations inside upper-level units (individual participants), similarly to the GLME approach described above. The analysis was performed using M3 Mediation Toolbox for MATLAB [33]. Bootstrapping approach, a non-parametric method based on resampling with replacement, was used to judge the significance of the effects, using the standard yard samples [34]. To control for the fact that independent variables in our design were correlated and ensure that the conclusion of the mediation analysis relates specifically to the investigated variable, each mediation model was performed on residuals from a GLME model regressing out the issue of the variable non tested. That is regressing out trial number, and: (i) reward magnitude and rank for the mediation model describing the effect of unfairness, or (two) reward magnitude and unfairness for the arbitration model describing the effect of rank; on both feelings and decisions to work. Prior to the analysis, feelings ratings were transformed to range from 0 to 1, with 0 indicating a low score (i.e., very unhappy).

Results Experiments two and 3

Opportunity gaps reduce the motivation to work

Beyond 2 onsite experiments, participants chose to work on 54% of trials. To test whether the hypothesized factors influenced participants' choices, we used a generalized linear mixed-furnishings model (GLME) predicting decisions to piece of work for reward on every trial from unfairness level of all offers, rank of individual's offered reward (from 1 to 5), and the accented value of the offered reward (expressed as a ability office to business relationship for diminishing marginal utility; run across Methods for details). Additionally, we examined if participants reacted to reward offers differently when the minority of individuals are at the summit of the distribution and the majority at the bottom or vice versa, by including in the model the signed skewness of the distribution (measured by Adapted Pearson'due south Coefficient of Skewness). The possible effect of fatigue was accounted for past including trial number. All three hypothesized factors significantly influenced decisions to work in exchange for rewards. In particular, the likelihood of pursuing rewards was greater when (i) unfairness was depression (β = -0.29, p < 0.001), (ii) rank was loftier (β = 0.92, p < 0.001) and (3) absolute reward was high (β = 2.82, p < 0.001). In add-on, the likelihood of pursuing rewards decreased over time (β = -i.04, p < 0.001), presumably due to fatigue. Skewness of the distribution did not have a pregnant outcome (β = 0.01, p = 0.92).

To illustrate the touch on of unfairness, nosotros calculated each participant's probability of pursuing rewards at unlike levels of unfairness and advantage magnitudes (based on the estimated fixed and random effects from a GLME model predicting decision to work but from these two factors, setting the other factors to 0). The estimated probabilities were then averaged over participants (Fig 4A). As can be observed, for the same reward magnitude, participants were more likely to work when unfairness was low rather than loftier. The indifference indicate (i.e., the advantage magnitude for which participants cull to work with l% probability) was 27.5 points greater for the highest level of unfairness than for the lowest level.

Adjacent, we plotted the likelihood of pursuing rewards for each advantage magnitude across the five offer ranks, using the same method as above. Equally can be observed in Fig 4B the likelihood of pursuing rewards was greater when the rank of the offer is loftier than when it was depression for the same absolute value of the reward. For the lowest rank, participants required an additional 66.4 points to exist indifferent on whether to pursue reward than for the highest rank.

To illustrate the upshot of unfairness and rank in isolation from the reward magnitude, nosotros plotted the residuals from the above GLME model with the effect of unfairness and rank set to 0. These residuals were then divided into five ranks and two levels of unfairness (high and low based on a median split; Fig 4C). This practice demonstrates that participants were less likely to work when unfairness was loftier (ruby line) than low (blue line) across different ranks. Moreover, participants were more probable to work when the rank of their advantage offering was high than when information technology was depression, across unlike levels of unfairness.

While large unfairness in the group had a negative effect on motivation, it may be that when looking downwards at the less fortunate, big unfairness might increase motivation. To test for this possibility, we added to the higher up GLME model 2 covariates for each subject and trial: the sum of distances between the participant and anybody beneath them (advantageous inequality) and the sum of the distances between the participant and anybody higher up them (disadvantageous inequality). While all three main effects from the original model remained pregnant (unfairness: β = -0.33, p < 0.001; rank: β = 0.87, p < 0.001; absolute reward: β = two.67, p < 0.001), neither upward (β = -0.04, p = 0.67) nor down (β = -0.29, p = 0.08) comparisons significantly influenced the willingness to work. In other words, while the relative ranking of a participant'south pay offer affects motivation, as does the general level of unfairness, once we account for these two factors, having people's pay be at a greater distance from others' in either direction does not additionally impact their willingness to work.

Finally, we compared the original model to two well-known models in the literature that respectively depict the effect of relative value and inequality on utility: (i) the accommodation model, which is based on the assumption that people compare their income to an average value for their reference group [xxx], and (ii) the Fehr-Schmidt inequality aversion model, which assumes that people have a separate reaction to advantageous and disadvantageous inequality [31]. In both, we include accented reward and trial number equally covariates. Our original model (the 'rank-unfairness model') (BIC = 3661.9) outperformed both the accommodation model (BIC = 3765.8) and the Fehr-Schmidt inequality model (BIC = 3780.1), as well as models consisting of only rank (BIC = 3681.3), merely unfairness (BIC = 3687.3), or but absolute advantage (BIC = 3833.4). Together, the results suggest that high unfairness, low rank and low accented advantage all take significant, negative and independent effects on the willingness to work and that both unfairness and relative value components are necessary to explain the reactions to unequal opportunities.

Across two experiments, we manipulated the level of uncertainty near the monetary value of points by either disclosing or non disclosing the exchange rate (£ per point). To examination if the effects differed in these two cases, we added to our GLME model interaction effects betwixt the version of the experiment and the iii primary factors: rank, unfairness, and absolute advantage. Nosotros constitute that the effect of rank and unfairness was stronger when the value of points was unknown than when it was known (interaction with rank: β = 0.97, p < 0.01; interaction with unfairness: β = -0.27, p = 0.019), while remaining significant in both experiments (see Supporting Data). The effect of absolute reward was weaker when the value of points was unknown than when it was known (interaction between experiment version and absolute reward: β = -one.7, p < 0.001). This suggests that participants relied more heavily on social context when they were uncertain almost monetary value.

Feelings partially mediate the furnishings of opportunity gaps on decisions to exert endeavor

To examine whether feelings mediated the effects of opportunity gaps on decisions to work, nosotros performed two multi-level mediation analyses. Each of the mediation analysis examined whether feelings mediate the outcome of i of the factors identified above (i.e., rank or unfairness) while controlling for the absolute reward magnitude, trial number and the other factor.

Nosotros establish that the furnishings of unfairness and rank on conclusion to work were both partially mediated by feelings (run into Fig five). First, as we already reported, low unfairness and high rank were related to greater likelihood to work (full issue: unfairness: β = -0.019, p < 0.001; rank: β = 0.029, p < 0.001). This event was partially mediated by feelings (path ab: unfairness: β = -0.002, p < 0.001; rank: β = 0.010, p <0.001) with positive feelings related to depression unfairness and high rank (path a: unfairness: β = -0.012, p < 0.001; rank: β = 0.038, p <0.001). Additionally, feelings predicted decisions to work fifty-fifty when unfairness and rank were deemed for (path b: unfairness: β = 0.318, p < 0.001; rank: β = 0.327, p <0.001). This suggests that incidental fluctuations of feelings, unrelated to task variables, also had a unique consequence on the decision to work. Conversely, the two task related variables had direct outcome on the decision to work that could non be deemed for past changes in feelings (path c': unfairness: β = -0.014, p < 0.01; rank: β = 0.013, p <0.001).

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Fig 5. Feelings partially mediate the consequence of opportunity gaps on decisions to work for the reward.

We examined whether the effect of the ii components of the motivational response to opportunity gaps, that is (A) unfairness and (B) rank, were mediated past feelings. In both cases, we controlled for the accented reward, trial number and either rank (A) or unfairness (B) respectively. In both cases, we found a significant indirect effect and direct effect (which represents the influence of the given cistron on determination to piece of work, while controlling for the indirect upshot), suggesting that feelings partially mediate the influence of each of the factors on decisions to piece of work.

https://doi.org/10.1371/periodical.pone.0237914.g005

Discussion

Circumstances across a person's command, such as socio-economic condition at nascency, often determine the rewards available to a person for their efforts. In the current study, nosotros investigated how decisions to work are altered by a person's awareness that some people in their group were luckier than others in the rewards they were offered for performing the aforementioned job. Nosotros hypothesized that the motivation to work would be influenced past the violation of the fairness principle and relative valuation of rewards. Across three experiments, we establish that unfair distribution of rewards betwixt group members had a negative impact on the decision to work not only of disadvantaged individuals simply also of advantaged individuals. Specifically, loftier unfairness was related to a reduction in the likelihood that participants agreed to piece of work for their reward irrespective of the magnitude of their reward and their relative position in the distribution. This is despite such refusal reducing the likelihood of receiving a bonus while having no impact on the rewards received by others.

2nd, the likelihood of agreeing to work in exchange for reward was reduced when the rank of the offering was low and vice versa (i.eastward., higher rank was related to greater motivation to piece of work), irrespective of the actual magnitude of the offered advantage. The third factor modulating motivation was the accented reward itself. The fact that accented advantage magnitude exerted influence even when decision-making for the level of unfairness and offer rank suggests that while people do care nearly the rewards of others, they only partially suit to nowadays social context when deciding whether to work [35].

Nosotros find that the rank-unfairness model outperformed the adaptation [30] and inequality-disfavor models [31] in explaining participants' reactions to opportunity-gaps. The adaptation model assumes that people focus on the difference betwixt their reward and the average reward, while the inequality aversion model assumes that people focus on 2 types of inequality: less heavily weighted advantageous and more heavily weighted disadvantageous inequality. The advantageous inequality is based on the absolute divergence between a person'due south reward and all other worse rewards, and the disadvantageous inequality is based on the difference between a person's advantage and all other meliorate rewards. All three models predict an increment of motivation with increasing relative value, just the rank-unfairness model is based on ordinal rather than accented comparisons. Predictions of these model substantially diverge for the issue of statistical dispersion: the rank-unfairness model predicts a uniform decrease of motivation with increased statistical dispersion across all unlike ranks, while the inequality aversion model predicts a greater drop of motivation for people with lower than higher ranks. On the other hand, the adaption model predicts that person at the top should e'er be more motivated past an increasing statistical dispersion, every bit statistical dispersion is associated with greater deviation of their advantage from the mean. In both cases, the observed design of results is more consequent with the predictions of the rank-unfairness model than the alternatives.

Past manipulating the unfairness of offers, offer's rank and absolute advantage in the second and third experiment, we were able to dissociate the influence of each of the 3 factors within the aforementioned individual. By doing and so, we overcome a difficulty in studying these variables in the "real-world", where individuals with different traits or experiences may populate dissimilar parts of the distribution [36]—making it difficult to isolate the influence of these components from factors correlating with them, such as negative effects of stereotypes on aspirations [37, 38]. Together, these findings suggest that individuals who are offered less than others are disadvantaged non just because the absolute reward they can peradventure obtain is lower, but too because they might suffer from a motivational cost that reduces the likelihood of pursuing the rewards that are within their reach. The latter may be due to a lower relative value of their rewards and a demotivating effect of participating in a situation that seems unfair.

Importantly, because the decisions to work were made in individual and did non bear upon others, the observed issue of unfairness on motivation cannot be attributed to reputation concerns [39], reciprocity [forty] or retribution motives [41]. Instead, our results suggest that unfairness and rank exert their consequence on motivation partially by influencing experienced feelings. We report a mediation that includes two links: the first is between each of the 2 factors (unfairness and low rank) and negative feelings; and the second between negative feelings and a reduction in the willingness to exert effort. As for the kickoff link, high unfairness and depression rank each triggered negative feelings even when controlling for the magnitude of the reward offered. The negative touch of opportunity gaps on feelings supports the notion that the perception of unfairness is reflected in emotional response [xx] and thus carries a cost to one's psychological well-being. The finding that rank influenced experienced feelings is consistent with studies showing that well-existence measures are influenced by a person'south standing relative to others [xvi–18].

The 2d link is between feelings and the willingness to work for the reward. Although the idea that unhappiness is related to depression motivation is intuitive, there has not been conclusive evidence for it in healthy individuals (for review come across: [42]). By studies have by and large examined the relationship between mood and functioning level, rather than the decision to engage in effort altogether, and produced mixed results. While some researchers found a beneficial effect of positive mood induction on performance [43], others plant that positive and negative emotions tin can improve or impair operation depending on the nature of the chore [44–47]. With regards to the motivation to pursue rewards, we find that unhappiness has a negative consequence. Such an consequence could be explained by the negative influence of bad mood on the perceived value of rewards, as suggested by previous experimental studies [21, 48]. Alternatively, rather than playing a causal part, lower happiness in our study could simply index reaction to lower the subjective value of offered rewards [49]. The effects of rank and unfairness were also observed in the first experiment, despite non request participants nigh their current emotional land. This suggests that the influence of unfairness and rank on motivation is not conditional on prompted introspection.

The mediatory effect of feelings in a relationship between unfairness and willingness to work for reward was partial, suggesting that additional mechanisms drive the negative influence of unfairness on motivation. One such possibility is that participants utilize data nearly the social environs to resolve incertitude nigh the value of their offers. In line with this suggestion, nosotros plant that in the condition in which the value of points was unknown, the effects of rank and unfairness were stronger than when the value of points was known.

Our study may accept implications for people's decisions and behaviour exterior the lab. We speculate that negative feelings caused past arbitrary reward disparities might exist i reason why disadvantaged individuals are more than likely to suffer from feet and low [50–52]. Furthermore, decreased motivation caused past unfairness and depression relative position might brand upward mobility particularly difficult, contributing to sustained poverty among disadvantaged groups [nine–11]. As such, the motivational phenomenon described in this study constitutes some other example of a poverty-trap, that is a situation where having worse prospects triggers boosted mechanisms ensuring that a person remains poor. Information technology besides suggests that whatever observed signs of decreased motivation among disadvantaged groups might be situational, rather than stemming from an individual'due south characteristics and could be a potential target of interventions.

The instructions of the studies made clear to participants that they had no control over the magnitude of the rewards offered. In contrast, in many everyday situations, there is ambiguity almost the role of randomness in success. Previous studies take shown that in such ambiguous situations, those who are advantaged are more probable to assume that their economic position is a result of talent and effort, while those who are disadvantaged assume it is a upshot of external circumstances [53, 54]. It remains to be tested whether similar effects to those reported here would be observed in such situations.

While by studies have suggested that people are generally balky to unfair distributions of rewards, here nosotros uncover their consequences beyond distribution preferences [31, 55] or bear on on the affective land [20, 56]. We bear witness that unequal opportunities accept a negative influence on the motivation to work for the reward of non merely disadvantaged individuals but likewise of others effectually them. Our findings provide an empirical framework for considering the affect of opportunity gaps on individuals, organizations, and societies, suggesting they tin trigger psychological dynamics that hurt the productivity of all involved.

Supporting information

References

  1. i. Pluchino A, Biondo AE, Rapisarda A. Talent versus luck: the role of randomness in success and failure. Advs Complex Syst. 2018;21: 1850014.
  2. 2. Milanovic B. Global Inequality of Opportunity: How Much of Our Income Is Determined past Where We Alive? The Review of Economic science and Statistics. 2014;97: 452–460.
  3. 3. Chetty R, Hendren N. The Impacts of Neighborhoods on Intergenerational Mobility I: Childhood Exposure Effects. Q J Econ. 2018;133: 1107–1162.
  4. iv. Duncan GJ, Magnuson M. Socioeconomic condition and cognitive functioning: moving from correlation to causation. Wiley Interdiscip Rev Cogn Sci. 2012;3: 377–386. pmid:26301469
  5. five. Blau FD, Kahn LM. The Gender Pay Gap: Have Women Gone as Far as They Can? University of Management Perspectives. 2007;21: vii–23.
  6. 6. Silberzahn R, Uhlmann EL. It Pays to Be Herr Kaiser: Germans With Noble-Sounding Surnames More Ofttimes Work as Managers Than as Employees. Psychol Sci. 2013;24: 2437–2444. pmid:24113624
  7. 7. Starmans C, Sheskin M, Bloom P. Why people adopt diff societies. Nat Hum Behav. 2017;1: 1–7.
  8. 8. McCall Fifty, Burk D, Laperrière M, Richeson JA. Exposure to rising inequality shapes Americans' opportunity behavior and policy support. PNAS. 2017;114: 9593–9598. pmid:28831007
  9. 9. Elmelech Y, Lu H-H. Race, ethnicity, and the gender poverty gap. Social Scientific discipline Research. 2004;33: 158–182.
  10. 10. Findlay J, Wright RE. Gender, Poverty and the Intra-Household Distribution of Resources. Review of Income and Wealth. 1996;42: 335–351.
  11. 11. Uhrig SN. SEXUAL ORIENTATION AND POVERTY IN THE UK: A REVIEW AND Summit-LINE FINDINGS FROM THE United kingdom of great britain and northern ireland HOUSEHOLD LONGITUDINAL Written report. Journal of Research in Gender Studies. 2015;5: 23–72.
  12. 12. Boliver V. How fair is access to more prestigious UK universities? The British Periodical of Folklore. 2013;64: 344–364. pmid:23713563
  13. thirteen. Crawford C, Macmillan L, Vignoles A. Progress made past high-attaining children from disadvantaged backgrounds: enquiry report. Social Mobility and Child Poverty Committee; 2014 [cited 27 Jul 2020]. Available: http://dera.ioe.air conditioning.u.k./20433/1/High_attainers_progress_report_final.pdf
  14. xiv. Thiele T, Pope D, Singleton A, Snape D, Stanistreet D. Experience of disadvantage: The influence of identity on date in working grade students' educational trajectories to an elite university. British Educational Research Journal. 2017;43: 49–67.
  15. fifteen. Clark AE, D'Ambrosio C. Chapter 13—Attitudes to Income Inequality: Experimental and Survey Bear witness. In: Atkinson AB, Bourguignon F, editors. Handbook of Income Distribution. Elsevier; 2015. pp. 1147–1208. https://doi.org/10.1016/B978-0-444-59428-0.00014-X
  16. xvi. Lyubomirsky S, Ross 50. Hedonic consequences of social comparison: a contrast of happy and unhappy people. J Pers Soc Psychol. 1997;73: 1141–1157. pmid:9418274
  17. 17. Hagerty MR. Social comparisons of income in one's community: evidence from national surveys of income and happiness. J Pers Soc Psychol. 2000;78: 764–771. pmid:10794379
  18. 18. Boyce CJ, Brown GDA, Moore SC. Money and Happiness: Rank of Income, Non Income, Affects Life Satisfaction. Psychological Science. 2010;21: 471–475. pmid:20424085
  19. 19. Bault Due north, Joffily M, Rustichini A, Coricelli G. Medial prefrontal cortex and striatum mediate the influence of social comparison on the determination procedure. Proceedings of the National University of Sciences of the The states of America. 2011;108: 16044–16049. pmid:21896760
  20. 20. Rutledge RB, de Berker AO, Espenhahn Due south, Dayan P, Dolan RJ. The social contingency of momentary subjective well-being. Nature Communications. 2016;7: i–eight. pmid:27293212
  21. 21. Eldar E, Niv Y. Interaction between emotional state and learning underlies mood instability. Nat Commun. 2015;6: i–10. pmid:25608088
  22. 22. Tversky A, Kahneman D. Advances in prospect theory: Cumulative representation of uncertainty. J Risk Uncertainty. 1992;v: 297–323.
  23. 23. Stewart N, Chater N, Brown GDA. Decision by sampling. Cogn Psychol. 2006;53: ane–26. pmid:16438947
  24. 24. Oishi S, Kesebir S, Diener East. Income Inequality and Happiness. Psychol Sci. 2011;22: 1095–1100. pmid:21841151
  25. 25. Pinkovskiy K, Sala-i-Martin X. Parametric Estimations of the Globe Distribution of Income. National Bureau of Economic Inquiry; 2009 Oct. Report No.: 15433.
  26. 26. Lazear EP, Shaw KL. The Structure of Wages: An International Comparison. University of Chicago Press; 2009.
  27. 27. Charness G, Gneezy U, Halladay B. Experimental methods: Pay one or pay all. Periodical of Economical Behavior & Organization. 2016;131: 141–150.
  28. 28. Barr DJ, Levy R, Scheepers C, Tily HJ. Random effects construction for confirmatory hypothesis testing: Keep it maximal. Journal of Memory and Language. 2013;68: 255–278. pmid:24403724
  29. 29. Delyon B, Lavielle M, Moulines Eastward. Convergence of a Stochastic Approximation Version of the EM Algorithm. The Annals of Statistics. 1999;27: 94–128.
  30. xxx. Helson H. Adaptation-level theory. Oxford, England: Harper & Row; 1964.
  31. 31. Fehr E, Schmidt KM. A Theory of Fairness, Competition, and Cooperation. Q J Econ. 1999;114: 817–868.
  32. 32. Kenny DA, Korchmaros JD, Bolger N. Lower level mediation in multi-level models. Psychol Methods. 2003;viii: 115–128. pmid:12924810
  33. 33. Wager TD, Davidson ML, Hughes BL, Lindquist MA, Ochsner KN. Prefrontal-subcortical pathways mediating successful emotion regulation. Neuron. 2008;59: 1037–1050. pmid:18817740
  34. 34. Hayes AF. Beyond Baron and Kenny: Statistical Arbitration Analysis in the New Millennium. Communication Monographs. 2009;76: 408–420.
  35. 35. Burke CJ, Baddeley Thou, Tobler PN, Schultz W. Fractional Adaptation of Obtained and Observed Value Signals Preserves Information virtually Gains and Losses. J Neurosci. 2016;36: 10016–10025. pmid:27683899
  36. 36. Gelissen J, de Graaf PM. Personality, social background, and occupational career success. Social Science Research. 2006;35: 702–726.
  37. 37. Migheli Yard. Gender at work: Incentives and self-sorting. Journal of Behavioral and Experimental Economic science. 2015;55: 10–18.
  38. 38. Riegle‐Crumb C, Moore C, Ramos‐Wada A. Who wants to have a career in science or math? exploring adolescents' time to come aspirations by gender and race/ethnicity. Scientific discipline Pedagogy. 2011;95: 458–476.
  39. 39. Engelmann D, Fischbacher U. Indirect reciprocity and strategic reputation building in an experimental helping game. Games and Economic Behavior. 2009;67: 399–407.
  40. 40. Kube South, Maréchal MA, Puppe C. The Currency of Reciprocity: Gift Exchange in the Workplace. American Economical Review. 2012;102: 1644–1662.
  41. 41. Expectations Suleiman R. and fairness in a modified Ultimatum game. Journal of Economic Psychology. 1996;17: 531–554.
  42. 42. Taris TW, Schaufeli WB, Schaufeli WB. Individual well-being and performance at work: A conceptual and theoretical overview. In: Well-existence and Functioning at Piece of work [Internet]. Psychology Press; 13 Nov 2014 [cited 27 Jul 2020] pp. 23–42.
  43. 43. Oswald AJ, Proto E, Sgroi D. Happiness and Productivity. Journal of Labor Economics. 2015;33: 789–822.
  44. 44. Grayness JR. Emotional modulation of cognitive control: arroyo-withdrawal states double-dissociate spatial from verbal two-dorsum job performance. J Exp Psychol Gen. 2001;130: 436–452. pmid:11561919
  45. 45. Phillips LH, Bull R, Adams E, Fraser L. Positive mood and executive office: testify from stroop and fluency tasks. Emotion. 2002;ii: 12–22. pmid:12899364
  46. 46. Dreisbach G. How positive affect modulates cognitive control: the costs and benefits of reduced maintenance capability. Brain Cogn. 2006;60: 11–19. pmid:16216400
  47. 47. Dreisbach Yard, Goschke T. How positive bear on modulates cerebral control: reduced perseveration at the cost of increased distractibility. J Exp Psychol Learn Mem Cogn. 2004;30: 343–353. pmid:14979809
  48. 48. Huys QJ, Pizzagalli DA, Bogdan R, Dayan P. Mapping anhedonia onto reinforcement learning: a behavioural meta-assay. Biol Mood Feet Disord. 2013;3: 1–16.
  49. 49. Rutledge RB, Skandali N, Dayan P, Dolan RJ. A computational and neural model of momentary subjective well-being. PNAS. 2014;111: 12252–12257. pmid:25092308
  50. 50. González HM, Tarraf Westward, Whitfield KE, Vega WA. The epidemiology of major depression and ethnicity in the The states. Journal of Psychiatric Inquiry. 2010;44: 1043–1051. pmid:20537350
  51. 51. Piccinelli Chiliad, Wilkinson Thou. Gender differences in depression: Disquisitional review. The British Journal of Psychiatry. 2000;177: 486–492. pmid:11102321
  52. 52. Lee C, Oliffe JL, Kelly MT, Ferlatte O. Depression and Suicidality in Gay Men: Implications for Health Care Providers. Am J Mens Health. 2017;11: 910–919. pmid:28103765
  53. 53. Hunt MO. Race/Ethnicity and Beliefs about Wealth and Poverty. Social Scientific discipline Quarterly. 2004;85: 827–853.
  54. 54. Kluegel JR, Smith ER. Beliefs About Inequality: Americans' Views of What Is and What Ought to Be. Transaction Publishers; 1986.
  55. 55. Dawes CT, Fowler JH, Johnson T, McElreath R, Smirnov O. Egalitarian motives in humans. Nature. 2007;446: 794–796. pmid:17429399
  56. 56. Tricomi E, Balleine BW, O'Doherty JP. A specific office for posterior dorsolateral striatum in homo habit learning. Eur J Neurosci. 2009;29: 2225–2232. pmid:19490086

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