Benefit valuation predicts gratitude

Gratitude is an emotion that promotes cooperative relationships and is elicited when an act reveals that an actor values the recipient, especially when the benefit conferred is greater than the recipient expected. But, recipient expectations might vary depending on how much the benefactor is perceived to value the recipient — all else equal, the greater the benefactor is perceived to value the recipient's welfare, the greater the recipient's expectations of benefit delivery. Thus, at a given benefit level, it might be easier to exceed the threshold of expectation in a relationship for which the recipient holds low expectations (e.g., a stranger) as compared to a relationship for which the recipient holds high expectations (e.g., a sibling). This leads to the prediction that cognitive representations of welfare valuation inversely correlate with gratitude: The greater the expected welfare valuation, the more difficult it is to exceed expectations of benefit delivery and, therefore, the less felt gratitude. To test this prediction, we conducted two experiments in which subjects estimated how much they perceived a particular person in their social network to value the subject's welfare. Next, subjects estimated how grateful they would feel if this person provided them with differing levels of benefits. Contrary to our model, we found that gratitude was predicted by the magnitude of the benefit, but not by the recipient's perception of the benefactor's valuation of the recipient.     

Gratitude Depends on the Relational Model of Communal Sharing

We studied the relation between benefits, perception of social relationships and gratitude. Across three studies, we provide evidence that benefits increase gratitude to the extent to which one applies a mental model of a communal relationship. In Study 1, the communal sharing relational model, and no other relational models, predicted the amount of gratitude participants felt after imagining receiving a benefit from a new acquaintance. In Study 2, participants recalled a large benefit they had received. Applying a communal sharing relational model increased feelings of gratitude for the benefit. In Study 3, we manipulated whether the participant or another person received a benefit from an unknown other. Again, we found that the extent of communal sharing perceived in the relationship with the stranger predicted gratitude. An additional finding of Study 2 was that communal sharing predicted future gratitude regarding the relational partner in a longitudinal design. To conclude, applying a communal sharing model predicts gratitude regarding concrete benefits and regarding the relational partner, presumably because one perceives the communal partner as motivated to meet one''s needs. Finally, in Study 3, we found in addition that being the recipient of a benefit without opportunity to repay directly increased communal sharing, and indirectly increased gratitude. These circumstances thus seem to favor the attribution of communal norms, leading to a communal sharing representation and in turn to gratitude. We discuss the importance of relational models as mental representations of relationships for feelings of gratitude.     

Dynamically engaged smiling predicts cooperation above and beyond average smiling levels

Smiling has been conceptualized as a signal of cooperative intent, yet smiles are easy to fake. We suggest that contextually appropriate, dynamically engaged smiling imposes an attentional cost, thereby making engaged smiling a plausible “honest signal” of cooperative intent. To test this hypothesis, we analyzed data from 123 pairs of same-sex strangers having “getting-to-know-you” conversations who subsequently played a one-shot prisoner's dilemma together. We calculated the strength of engagement in smiling using a cross-lagged auto-regressive model for dyadic data. We found that when an individual's partner (the signaler) tended to smile in a more responsive way, that individual (the receiver) was more likely to cooperate. Conversely, when a signaler tended to smile in a less responsive way, the receiver was less likely to cooperate. These effects were present over-and-above the effects of average levels of smiling and self-reported liking, which also predicted likelihood of cooperation. However, dynamically engaged smiling did not predict cooperation on the part of the signaler, suggesting that receivers weight the importance of engagement more highly than they should, or even that engaged smiling might be a manipulative display. These results illustrate how conversational dynamics can influence evolutionary signaling.     

Aggression in young men high in threat potential increases after hearing low-pitched male voices: two tests of the retaliation-cost model

Research suggests that male voice pitch is an honest dominance signal because it indexes men's physicality and because lower-pitched voices are more costly to develop and maintain. Rather than considering these signaler-dependent mechanisms, we tested a receiver-dependent mechanism hypothesized by M. Enquist's (1985) retaliation-cost model of aggressive signaling. The model predicts that, given a competitive scenario, low-pitched male voices will elicit aggression from male listeners (i.e., signal receivers) who are relatively high in threat potential. We confirmed this hypothesis in two experiments. Under a sexual but not control prime and after listening to low- but not average-pitched male voices, increases in heterosexual male participants' trait dominance predicted stronger aggressive cognitions (Experiment 1), and increases in male participants' handgrip strength predicted stronger aggressive intent (Experiment 2). These findings provide the first direct support for the retaliation-cost model in humans, extend research on the effects of male voice pitch on receiver psychology, and demonstrate an additional cost mechanism that explains why voice pitch is an honest signal of dominance in men.     

The unsteady continuous culture of phosphate-limited Monochrysis lutheri droop: Experimental and theoretical analysis

A three-state variable model for phosphate-limited phytoplankton growth in a continuously lit continuous culture is proposed. In the model, the phosphate uptake rate per cell is a Michaelis-Mententype hyperbolic function of ambient nutrient concentration and the growth rate is a Droop-type hyperbolic function of cell quota. Steady-state and short-term uptake experiments with unialgal cultures of Monochrysis lutheri Droop, a marine chrysophyte, were used to calibrate the proposed model. For the long-term unsteady experiments, the model predicts well the culture's dynamic response in terms of cell density to steps down and up in influent concentration of limiting nutrient. For step changes in dilution rate, the model predicts well the culture's response to a step down but predicts poorly the culture's response to a step up. The long-term responses of the cultures to impulses in influent concentration show that the model fails to predict, even qualitatively, the behavior of the phytoplankton. Not unexpectedly, the model fails most dramatically in those experiments involving a rapid increase in cell quota, thereby demonstrating both the inherent flaws in the concept of the instantaneous growth rate as a function of instantaneous cell quota and the need for further dynamic characterization of phytoplankton behavior.     

Gratefully Received,Gratefully Repaid: The Role of Perceived Fairness in Cooperative Interactions

It is well documented that people would remunerate fair behaviours and penalize unfair behaviours. It is argued that individuals’ reactions following the receipt of a gift depend on the perceived intentions of the donors. Fair intentions should prompt positive affect, like gratitude, triggering cooperative behaviours; while intended unfairness should trigger negative affect, like anger, fostering anti-social actions. It is, however, contended that when people lack information to infer others’ intention they may use ‘normative’ beliefs about fairness - what a typical fair individual ‘should’ do in these circumstances – to guide their behaviour. In this experiment we examined this assertion. We had 122 participants play a one-shot, double-anonymous game with half playing as potential helpers (P1s) and half as recipients (P2s). Whether a participant was a P1 or P2 was chance-determined and all participants knew this. P1s decided whether to help P2s and whether to make their help unconditional (no repayment needed) or conditional (full or ‘taxed’ repayment). P2s decided whether to accept the offer and whatever conditions attached but were blind to the list of helping options available to P1s. We anticipated that recipients would refer to the ‘injunctive norm’ that ‘fair people should help “for free” when it is only by chance that they are in a position to help’. Therefore, without knowing P1s’ different helping options, unconditional offers should be rated by recipients as fairer than conditional offers, and this should be linked to greater gratitude with greater gratitude linked to greater reciprocation. Path analyses confirmed this serial mediation. The results showed that recipients of unconditional offers, compared to conditional ones, interpreted the helpers’ motives as more helpful, experienced greater gratitude and were more eager to reciprocate. The behavioural data further revealed that, when given a latter option to default, 38% of recipients of conditional offers did so.     

The emotion–valuation constellation: Multiple emotions are governed by a common grammar of social valuation

Social emotions are hypothesized to be adaptations designed by selection to solve adaptive problems pertaining to social valuation—the disposition to attend to, associate with, and aid a target individual based on her probable contributions to the fitness of the valuer. To steer between effectiveness and economy, social emotions need to activate in precise proportion to the local evaluations of the various acts and characteristics that dictate the social value of self and others. Supporting this hypothesis, experiments conducted in the United States and India indicate that five different social emotions all track a common set of valuations. The extent to which people value each of 25 positive characteristics in others predicts the intensities of: pride (if you had those characteristics), anger (if someone failed to acknowledge that you have those characteristics), gratitude (if someone convinced others that you have those characteristics), guilt (if you harmed someone who has those characteristics), and sadness (if someone died who had those characteristics). The five emotions track local valuations (mean r = +.72) and even foreign valuations (mean r = +.70). In addition, cultural differences in emotion are patterned: They follow cultural differences in valuation. These findings suggest that multiple social emotions are governed (in part) by a common architecture of social valuation, that the valuation architecture operates with a substantial degree of universality in its content, and that a unified theoretical framework may explain cross-cultural invariances and cultural differences in emotion.     

Distribution of Posterior Corneal Astigmatism According to Axis Orientation of Anterior Corneal Astigmatism

Purpose

To investigate the distribution of posterior corneal astigmatism in eyes with with-the-rule (WTR) and against-the-rule (ATR) anterior corneal astigmatism.

Methods

We retrospectively examined six hundred eight eyes of 608 healthy subjects (275 men and 333 women; mean age ± standard deviation, 55.3 ± 20.2 years). The magnitude and axis orientation of anterior and posterior corneal astigmatism were determined with a rotating Scheimpflug system (Pentacam HR, Oculus) when we divided the subjects into WTR and ATR anterior corneal astigmatism groups.

Results

The mean magnitudes of anterior and posterior corneal astigmatism were 1.14 ± 0.76 diopters (D), and 0.37 ± 0.19 D, respectively. We found a significant correlation between the magnitudes of anterior and posterior corneal astigmatism (Pearson correlation coefficient r = 0.4739, P<0.001). In the WTR anterior astigmatism group, we found ATR astigmatism of the posterior corneal surface in 402 eyes (96.6%). In the ATR anterior astigmatism group, we found ATR posterior corneal astigmatism in 82 eyes (73.9%). Especially in eyes with ATR anterior corneal astigmatism of 1 D or more and 1.5 D or more, ATR posterior corneal astigmatism was found in 28 eyes (59.6%) and 9 eyes (42.9%), respectively.

Conclusions

WTR anterior astigmatism and ATR posterior astigmatism were found in approximately 68% and 91% of eyes, respectively. The magnitude and the axis orientation of posterior corneal astigmatism were not constant, especially in eyes having high ATR anterior corneal astigmatism, as is often the case in patients who have undergone toric IOL implantation.     

Whether to have a second child or not? An integrative approach to women's reproductive decision-making in current China

The transition to low fertility worldwide has led to introduction of diverse frameworks across disciplines to understand its causes and consequences. Previous attempts to compare the relative importance of the key factors influencing women's fertility decision-making largely focused on a single rather than multiple steps of decision-making—an important problem if different factors are associated with different steps. Furthermore, insufficient attention has been paid explicitly to husband's and already-born children's influences, two potentially important factors. Here we introduce a framework covering three steps of reproductive decision-making—ideal family size, fertility desire and fertility intention—and test it using multi-level survey data collected from Chinese one-child mothers. Mother's attitudes towards having two children were paramount factors underlying her ideal family size, and husband's and the firstborn child's attitudes were critical to her desire to have a second child, which in turn played a decisive role in her intention to have a second child. Although husband's attitude was related to all steps, most factors were only relevant to one step; e.g., perceived child mortality and value for old-age security predicted ideal family size, admiration—a prerequisite for social learning—for two-child families predicted fertility desire, and physical/economic constraints primarily predicted fertility intention. Our study emphasizes multiple decision-makers in family reproduction; indicates the relative importance of fertility-influencing factors could vary with steps of decision-making; and has important implications for population policy in low-fertility societies.     

Decisions for Others Become Less Impulsive the Further Away They Are on the Family Tree

Background

People tend to prefer a smaller immediate reward to a larger but delayed reward. Although this discounting of future rewards is often associated with impulsivity, it is not necessarily irrational. Instead it has been suggested that it reflects the decision maker’s greater interest in the ‘me now’ than the ‘me in 10 years’, such that the concern for our future self is about the same as for someone else who is close to us.

Methodology/Principal Findings

To investigate this we used a delay-discounting task to compare discount functions for choices that people would make for themselves against decisions that they think that other people should make, e.g. to accept $500 now or $1000 next week. The psychological distance of the hypothetical beneficiaries was manipulated in terms of the genetic coefficient of relatedness ranging from zero (e.g. a stranger, or unrelated close friend), .125 (e.g. a cousin), .25 (e.g. a nephew or niece), to .5 (parent or sibling).

Conclusions/Significance

The observed discount functions were steeper (i.e. more impulsive) for choices in which the decision-maker was the beneficiary than for all other beneficiaries. Impulsiveness of decisions declined systematically with the distance of the beneficiary from the decision-maker. The data are discussed with reference to the implusivity and interpersonal empathy gaps in decision-making.     

Inoculation and recovery rates in the malaria model of Dietz,Molineaux, and Thomas

In the malaria model of Dietz, Molineaux, and Thomas [Bull. WHO 50:347–357 (1974)] the iroculation rate depends on a pseudoequilibrium approximation to a differential equation describing mosquito dynamics. By biasing a key parameter, the approximation can match the predictions of the differential equation; with fixed parameters, the approximation sometimes predicts qualitatively different disease behavior than does its approximand. The model's recovery rate depends on an approximation to a full time-dependent formulation of Macdonald's superinfection hypothesis. Judged by the ability to fit data, the approximation performs better than its approximand. Alternative implementations of the model yield significantly different estimates of scientifically meaningful parameters.     

No Evidence That Gratitude Enhances Neural Performance Monitoring or Conflict-Driven Control

It has recently been suggested that gratitude can benefit self-regulation by reducing impulsivity during economic decision making. We tested if comparable benefits of gratitude are observed for neural performance monitoring and conflict-driven self-control. In a pre-post design, 61 participants were randomly assigned to either a gratitude or happiness condition, and then performed a pre-induction flanker task. Subsequently, participants recalled an autobiographical event where they had felt grateful or happy, followed by a post-induction flanker task. Despite closely following existing protocols, participants in the gratitude condition did not report elevated gratefulness compared to the happy group. In regard to self-control, we found no association between gratitude—operationalized by experimental condition or as a continuous predictor—and any control metric, including flanker interference, post-error adjustments, or neural monitoring (the error-related negativity, ERN). Thus, while gratitude might increase economic patience, such benefits may not generalize to conflict-driven control processes.     

Are dogs able to recognize their handler's voice? A preliminary study

Abstract

A number of studies have dealt with the ability of dogs to rely on olfactory cues to recognize their owner or handler. However, in the absence of these cues (e.g., when working at a distance from their owner) dogs have to use other senses to interact with their owner. Considering the high sensitivity of their auditory system, we can hypothesize that dogs are able to use vocal cues for this purpose. Certainly, it is commonly assumed that dogs can discriminate between people on the basis of their voice, and yet there is a clear lack of empirical data on this subject. The present study assesses the importance of the handler's olfactory and visual cues versus the importance of his/her vocal cues to the working behavior of dogs. I compare the ability of working dogs to obey different vocal commands issued either by their handler (HV) or by a stranger (SV) via loudspeakers in different olfactory contexts: presence of their handler (H) or of a stranger (S). The dogs' performance (percentage of correct responses) decreased when the acoustic cues were modified (H+HV tended to differ from the H+SV—p = 0.09—and differed from the S+SV conditions—p = 0.05) but not when only the olfactory cues were changed (no difference between H+HV and S+HV conditions—p > 0.1). Consequently, we can assume that dogs rely, at least in part, on acoustic parameters of voices to recognize and cooperate with their handler.     

Evolution and gradualness

Evolutionary systems are commonly considered to have two fundamental properties: (1) elements (or organisms) in the system reproduce with mutation and (2) only the fit elements survive. I propose that evolutionary systems have a third property — the property of gradualness. A system has gradualness, if, and only if, small changes in an element usually lead to small changes in that element's fitness.I have formalized a framework from which attempts to design evolutionary systems might proceed. Of particular importance are the criteria, based on the notion of perpetuation, which a system's behavior must satisfy in order to be considered evolutionary. By my standards, no computer programs have been designed that manifest meaningful evolutionary behavior.     

Subjective optimality in finite sequential decision-making

Many decisions in life are sequential and constrained by a time window. Although mathematically derived optimal solutions exist, it has been reported that humans often deviate from making optimal choices. Here, we used a secretary problem, a classic example of finite sequential decision-making, and investigated the mechanisms underlying individuals’ suboptimal choices. Across three independent experiments, we found that a dynamic programming model comprising subjective value function explains individuals’ deviations from optimality and predicts the choice behaviors under fewer and more opportunities. We further identified that pupil dilation reflected the levels of decision difficulty and subsequent choices to accept or reject the stimulus at each opportunity. The value sensitivity, a model-based estimate that characterizes each individual’s subjective valuation, correlated with the extent to which individuals’ physiological responses tracked stimuli information. Our results provide model-based and physiological evidence for subjective valuation in finite sequential decision-making, rediscovering human suboptimality in subjectively optimal decision-making processes.     

Partner choice creates competitive altruism in humans

Reciprocal altruism has been the backbone of research on the evolution of altruistic behaviour towards non-kin, but recent research has begun to apply costly signalling theory to this problem. In addition to signalling resources or abilities, public generosity could function as a costly signal of cooperative intent, benefiting altruists in terms of (i) better access to cooperative relationships and (ii) greater cooperation within those relationships. When future interaction partners can choose with whom they wish to interact, this could lead to competition to be more generous than others. Little empirical work has tested for the possible existence of this 'competitive altruism'. Using a cooperative monetary game with and without opportunities for partner choice and signalling cooperative intent, we show here that people actively compete to be more generous than others when they can benefit from being chosen for cooperative partnerships, and the most generous people are correspondingly chosen more often as cooperative partners. We also found evidence for increased scepticism of altruistic signals when the potential reputational benefits for dishonest signalling were high. Thus, this work supports the hypothesis that public generosity can be a signal of cooperative intent, which people sometimes 'fake' when conditions permit it.     

Water flux and energy use in wild house mice (Mus domesticus) and the impact of seasonal aridity on breeding and population levels

Summary Water turnover rate (WTR), urine concentration and field metabolic rate (FMR) were examined in house mice, Mus domesticus, permanently inhabiting roadside verge areas and seasonally invading crops in semi-arid wheatlands in South Australia. FMR was approximately proportional to body mass^0.5 and mean values varied from 4.8 ml CO₂ g^–1h^–1 (2.9 kJ g^–1d^–1) in autumn and winter, to 7.0 ml CO₂ g^–1h^–1 (4.2 kJ g^–1d^–1) in maturing crops during spring. WTR was independent of body mass, indicating that larger mice were selecting a diet containing moister foods. WTR was low in summer and high in winter, and in mice from crops varied from 165 ml l^–1 body water d^–1 (122 ml kg^–1d^–1) to 1000 ml l^–1d^–1 (725 ml kg^–1d^–1). Seasonal changes in WTR were less extreme on the roadside, where a greater diversity of food was available. In the crops, breeding occurred throughout summer during two of three years, but the population increased only in the one summer when mice had marginally higher WTR. On the roadside breeding and population growth were continuous during summer, except in a drought year. Avcrage urine concentration was inversely related to WTR, and varied from 2.0 to 4.8 Osm l^–1. The data indicate that the water conserving abilities of mice equal those of many desert rodents. The water conserving abilities of mice living in crops during summer were fully extended, and in some years aridity limited breeding success and population levels. The degree of moisture stress to which mice are exposed during summer appears to depend not only on rainfall but also on other factors such as availability of food and shelter, and the level of weed infestation in crops.     

Who is the fairest of them all? The independent effect of attractive features and self-perceived attractiveness on cooperation among women

The present paper analyzes the extent to which attractiveness-related variables affect cooperative behavior in women. Cooperativeness is evaluated through a Prisoner's Dilemma Game (PDG). We consider several morphometric variables related to attractiveness: fluctuating asymmetry (FA), waist–hip ratio (WHR), body mass index (BMI) and facial femininity (FF). These variables have been shown to predict human behavior. We also include as a control variable a score for self-perceived attractiveness (SPA). We test differences in these variables according to behavior in the PDG. Our results reveal that low-FA women cooperate less frequently in the PDG. We also find that women with lower WHR are more cooperative. This result contradicts the expected relation between WHR and behavior in the PDG. We show that this effect of WHR on cooperation operates through its influence on the expectation that participants hold on the cooperative intent of their counterpart. In addition, we show that the effect of attractive features on cooperation occurs independently of the participants' perception of their own appeal. Finally, we discuss our results in the context of the evolution of cooperative behavior and under the hypothesis that attractiveness is a reliable indicator of phenotypic quality.     

Modulation of social behavior and dominance status by chronic pain in mice

The potential influence of pain on social behavior in laboratory animals has rarely been evaluated. Using a new assay of social behavior, the tube co‐occupancy test (TCOT), we assess propinquity—the tendency to maintain close physical proximity—in mice exposed to pain using subcutaneous zymosan or spared nerve injury as noxious stimuli. Our previous experience with the TCOT showed that outbred mouse sibling dyads show higher levels of tube co‐occupancy than stranger dyads. We find here that long‐lasting pain from spared nerve injury given to both mice in the dyad abolishes this effect of familiarity, such that strangers also display high levels of propinquity. We performed a separate experiment to assess the effect on dominance behavior of nerve injury to one or both mice of a dyad in which relative dominance status had been previously established via the confrontation tube test. We find that neuropathic pain given only to the dominant mouse reverses the relationship in male but not female mice, such that the previously subordinate mouse becomes dominant. These observations bolster the scant but growing evidence that pain can robustly affect social behavior in animals.     

Differences between Adiposity Indicators for Predicting All-Cause Mortality in a Representative Sample of United States Non-Elderly Adults

Background

Adiposity predicts health outcomes, but this relationship could depend on population characteristics and adiposity indicator employed. In a representative sample of 11,437 US adults (National Health and Nutrition Examination Survey, 1988–1994, ages 18–64) we estimated associations with all-cause mortality for body mass index (BMI) and four abdominal adiposity indicators (waist circumference [WC], waist-to-height ratio [WHtR], waist-to-hip ratio [WHR], and waist-to-thigh ratio [WTR]). In a fasting subsample we considered the lipid accumulation product (LAP; [WC enlargement*triglycerides]).

Methods and Findings

For each adiposity indicator we estimated linear and categorical mortality risks using sex-specific, proportional-hazards models adjusted for age, black ancestry, tobacco exposure, and socioeconomic position. There were 1,081 deaths through 2006. Using linear models we found little difference among indicators (adjusted hazard ratios [aHRs] per SD increase 1.2–1.4 for men, 1.3–1.5 for women). Using categorical models, men in adiposity midrange (quartiles 2+3; compared to quartile 1) were not at significantly increased risk (aHRs<1.1) unless assessed by WTR (aHR 1.4 [95%CI 1.0–1.9]). Women in adiposity midrange, however, tended toward elevated risk (aHRs 1.2–1.5), except for black women assessed by BMI, WC or WHtR (aHRs 0.7–0.8). Men or women in adiposity quartile 4 (compared to midrange) were generally at risk (aHRs>1.1), especially black men assessed by WTR (aHR 1.9 [1.4–2.6]) and black women by LAP (aHR 2.2 [1.4–3.5]). Quartile 4 of WC or WHtR carried no significant risk for diabetic persons (aHRs 0.7–1.1), but elevated risks for those without diabetes (aHRs>1.5). For both sexes, quartile 4 of LAP carried increased risks for tobacco-exposed persons (aHRs>1.6) but not for non-exposed (aHRs<1.0).

Conclusions

Predictions of mortality risk associated with top-quartile adiposity vary with the indicator used, sex, ancestry, and other characteristics. Interpretations of adiposity should consider how variation in the physiology and expandability of regional adipose-tissue depots impacts health.