Strength Of Aversion Research Articles

Medial prefrontal cortex suppresses reward-seeking behavior with risk of punishment by reducing sensitivity to reward.

Reward-seeking behavior is frequently associated with risk of punishment. There are two types of punishment: positive punishment, which is defined as addition of an aversive stimulus, and negative punishment, involves the omission of a rewarding outcome. Although the medial prefrontal cortex (mPFC) is important in avoiding punishment, whether it is important for avoiding both positive and negative punishment and how it contributes to such avoidance are not clear. In this study, we trained male mice to perform decision-making tasks under the risks of positive (air-puff stimulus) and negative (reward omission) punishment, and modeled their behavior with reinforcement learning. Following the training, we pharmacologically inhibited the mPFC. We found that pharmacological inactivation of mPFC enhanced the reward-seeking choice under the risk of positive, but not negative, punishment. In reinforcement learning models, this behavioral change was well-explained as an increase in sensitivity to reward, rather than a decrease in the strength of aversion to punishment. Our results suggest that mPFC suppresses reward-seeking behavior by reducing sensitivity to reward under the risk of positive punishment.

Brief environmental enrichment elicits metaplasticity on the insular cortex in vivo and reduces the strength of conditioned taste aversion

Environmental enrichment (EE) is known to improve memory and cognition and modulate the impact of aversive stimuli in animals, promoting the development of resilience to stressful situations. Likewise, it is known that EE can modulate synaptic plasticity as is the case of long-term potentiation (LTP). These findings have been described initially in ex vivo preparations, suggesting that the effects of EE are the result of an early modification of the synaptic excitability and transmission. In this regard, it is known that metaplasticity refers to the persistent modification, by previous activity, in the ability to induce synaptic plasticity. Our previous studies have shown that prior training in conditioned taste aversion (CTA) prevents the subsequent induction of LTP in the projection from the basolateral nucleus of the amygdala (Bla) to the insular cortex (IC) in vivo. In addition, we have shown that CTA extinction allows the induction but not the maintenance of IC-LTP of the Bla-IC pathway. Recently, we also showed that prior exposure to environmental enrichment for three weeks reduces the strength of CTA, restoring the brain-derived neurotrophic factor (BDNF) levels in the IC. The present study aimed to analyze the effects of brief exposure to an enriched environment on the strength of aversive memory, as well as on the in vivo IC-LTP. To do so, adult rats were exposed for seven days to an EE, either before CTA training or LTP induction in the Bla-IC pathway. Our results demonstrate that a seven-day exposure to an enriched environment attenuates the aversive response to a strong CTA and allows the induction but not the maintenance of LTP in the insular cortex. These findings provide evidence that metaplastic regulation in a neocortical region takes part in the mechanisms through which brief exposure to enriched environments attenuates an aversive response.

Partial reinforcement effects on acquisition and extinction of a conditioned taste aversion.

Four experiments with rat subjects asked whether a partial reinforcement extinction effect (PREE) occurs in taste aversion learning. The question has received little attention in the literature, and to our knowledge no taste aversion experiment has previously demonstrated a PREE. In each of the present experiments, experimental groups received a taste mixed in drinking water for 20 min; such taste exposures were sometimes paired with a lithium chloride (LiCl) injection and sometimes not. Control groups received only taste-LiCl pairings. There was evidence that each reinforced and non-reinforced trial produced increments and decrements in aversion strength (respectively), and trials mattered more than accumulated time during the conditioned stimulus and during the background (as emphasized in time-accumulation models like those of Gallistel and Gibbon, Psychological Review, 107, 289-344, 2000, and Gibbon and Balsam, Autoshaping and conditioning theory, Academic Press, New York, pp. 219-235, 1981). In addition, a partial reinforcement extinction effect was observed when there was a relatively large number of conditioning trials. The results extend our understanding of extinction in taste aversion learning and provide more evidence that aversion learning might follow rules that are qualitatively similar to those of other forms of learning.

Risk aversion, downside risk aversion, and the transition to entrepreneurship

In this paper, we discuss the transition from secure employment to risky self-employment (entrepreneurship) caused by a small increase in wealth. Building on the apportioning risk literature, we prove that the transition from secure employment to risky entrepreneurship is based on a measure of the difference between the strength of downside risk aversion and the strength of risk aversion. This result highlights the idea that using the behavioral approach of risky lotteries to study entrepreneurship can produce different results from the traditional economic theory of entrepreneurship, which can have policy implications that must be considered with caution.

Evidence for consistent individual differences in rat sensitivity to carbon dioxide.

Carbon dioxide (CO2) gradual-fill is commonly used to kill laboratory rats, but this use remains controversial due to a lack of agreement between studies. Inconsistencies may arise from differences in behaviors measured (e.g. active versus passive behaviors), in how rats cope with threats, or in rat sensitivity to CO2. The aims of the current study were to 1) describe active and passive responses during CO2 forced exposure, 2) determine if these responses are consistent within individuals and across aversive stimuli, 3) assess individual differences in aversion to CO2 in aversion-avoidance and approach-avoidance tests and 4) determine how responses in aversion tests relate to individual differences in behavior during forced exposure. Twelve Sprague Dawley female rats were exposed twice to three treatments: CO2, oxygen (O2), and fox scent, and were exposed to CO2 twice in each aversion test. The change in behavior from baseline was higher for rearing and locomotion when rats were exposed to CO2 than when exposed to O2 and fox scent. Responses varied among rats but were consistent across multiple tests within rats. For example, rearing was consistent within individuals between two exposures to CO2. Similarly, the strength of aversion was consistent within individuals across multiple exposures to CO2 in aversion-avoidance and approach-avoidance testing. Latency to avoid CO2 in aversion-avoidance tests was negatively correlated with rearing during CO2 forced exposure. Collectively, these results indicate that rat responses to CO2 vary between (but are consistent within) individuals, suggesting that rats vary in CO2 sensitivity. However, even the less responsive rats avoided CO2 concentrations far below those necessary to achieve unconsciousness, indicating that all rats likely experience negative states when euthanized with CO2.

Recursive non-expected utility: Connecting ambiguity attitudes to risk preferences and the level of ambiguity

I study how risk preferences and the level of ambiguity influence ambiguity attitudes in Uzi Segal's recursive second-order non-expected utility model. It is shown that the negative certainty independence axiom for risk preferences is equivalent to a global form of ambiguity aversion that entails ambiguity averse behavior irrespective of the state space and the decision maker's second-order belief. Thus, the second-order version of the cautious expected utility model is the only subclass of Segal's theory that robustly predicts ambiguity aversion. Moreover, a mean-preserving spread operation over second-order beliefs, which corresponds to a particular way of increasing the level of ambiguity, is equivalent to increasing the relative strength of ambiguity aversion for each possible specification of risk preferences within the cautious expected utility model. An application of the latter result establishes a negative relation between participation rates in an asset market and the level of ambiguity concerning the distribution of returns.

Acquisition and retention of conditioned aversions to context and taste in laboratory mice.

We compared the rate of acquisition and strength of retention of conditioned context aversion (CCA) with conditioned taste aversion (CTA) using pigmented, genetically heterogeneous mice (derived from Large and Small strains). Extending previous findings, in Experiment 1, mice accustomed to drinking from large glass bottles in the colony room learned to avoid graduated tubes after a single conditioning trial when drinking from these novel tubes was paired with injections of LiCl. The results also showed that CCA could be developed even when there was a 30-minute delay between conditioned stimulus and unconditioned stimulus. Retention of the aversion lasted for 4 weeks in both Immediate and Delay groups. Studies of conditioned saccharin aversion were conducted in Experiment 2. CTA acquisition was very similar to that observed in CCA and duration of aversion retention was similar in the CCA and CTA Delay groups, although at least 2 weeks longer in the Immediate group. Thus, CCA acquisition and retention characteristics are closer to those seen for CTA than has previously been reported. In Experiment 3, we examined whether albino mice (which are known to have weaker visual abilities compared to pigmented mice) would develop CCA comparable to those of pigmented mice. The development of conditioned aversion and its duration of retention was similar in albinos and pigmented mice. Nonspecific aversion emerged as an important contributor to strength of aversion during retention trials in both CCA and CTA paradigms with pigmented (but not albino) mice and deserves additional scrutiny in this field of inquiry.

Consumer Choices Based on Online Ratings: The Diagnosticity of a Discrepant Rating

This paper examines how consumers integrate other people’s opinions to evaluate an unknown product or service. The use of these ratings has mushroomed with the prevalence of online ratings by consumers in domains ranging from restaurants to movies. However, their credibility or diagnosticity is unknown and/or even skeptical, since they are given by anybody. We examine how consumers judge which ratings are more diagnostic among inconsistent ratings without knowing who the rating providers are. Specifically we focus on how consumers judge a discrepant rating’s diagnosticity, because a discrepant rating, a rating very different from other ratings, can be either negligible or influential on product evaluations. A two-stage aggregation process (rating screening stage and rating integration stage) is proposed to explain when a discrepant rating is discounted as an outlier and when valued as a loss or gain signal. Four experiments show that the diagnosticity judgment is moderated by the rating’s discrepancy level (Study 1,2,3). When a rating is highly discrepant, it is discounted as an outlier, but when a rating is less discrepant, it is judged to be valid and valued as a loss or gain signal (Study 1). Consumers discount a rating, if it is highly discrepant, even when data size is very small (Study 2). When ratings are negatively skewed, discrepancy discounting and loss aversion generate conflicted weights for a discrepant rating. Whether the rating is discounted or valued depends on the relative strength of discrepancy and loss aversion (Study 3). As a psychological factor affecting the diagnosticity judgment, a consumer’s expectation of ratings’ similarity was examined (Study 4). The greater the expected heterogeneity of preferences, the greater the value assigned to majority ratings, the smaller the value assigned to a discrepant ratings. Marketing implications for the format and display of online ratings are discussed.

Choice set, relative income, and inequity aversion: An experimental investigation

Inequity aversion preference has been widely applied in interpretations of various economic behaviors. A rapidly growing literature has been attempting to measure the strength of inequity aversion preferences as accurately as possible. We vary two factors that might affect the accuracy of the measurement of inequity aversion preference, i.e., choice sets with different underlying inequity aversion strength ranges and with different relative income inequities while absolute income inequities remain fixed. We find that unidirectional changes in the choice sets for disadvantageous and advantageous inequity aversion preferences significantly bias the measured strength of both preferences in the same directions of the changes and that the variance in inequity aversion increases with the range of choice sets. Moreover, a decrease in relative income inequity raises the measured strength of advantageous inequity aversion but does not affect disadvantageous inequity aversion preference. Our results suggest controlling for choice sets and relative income inequity between players to improve the measurement accuracy of inequity aversion preference.

Extinction of conditioned taste aversion is related to the aversion strength and associated with c-fos expression in the insular cortex

Taste aversion learning is a type of conditioning where animals learn to associate a novel taste (conditioned stimulus; CS) with a stimulus inducing symptoms of poisoning or illness (unconditioned stimulus; US). As a consequence animals later avoid this taste, a reaction known as conditioned taste aversion (CTA). An established CTA extinguishes over time when the CS is repeatedly presented in the absence of the US. However, inter-individual differences in CTA extinction do exist. Using a model of behavioral conditioning with saccharin as CS and the immunosuppressant cyclosporine A as US, the present study aimed at further elucidating the factors underlying individual differences in extinction learning by investigating whether extinction of an established CTA is related to the strength of the initially acquired CS–US association. In addition, we analyzed the expression of the neuronal activation marker c-fos in brain structures relevant for acquisition and retrieval of the CTA, such as the insular cortex and the amygdala. We here show that animals, displaying a strong CS–US association during acquisition, maintained a strong CTA during unreinforced CS re-exposures, in contrast to animals with moderate CS–US association. Moreover, the latter animals showed increased c-fos mRNA expression in the insular cortex. Our data indicate that CTA extinction apparently depends on the strength of the initially learned CS–US association. In addition, these findings provide further evidence that the memory for the initial excitatory conditioning and its subsequent extinction is probably stored in those structures that participate in the processing of the CS and the US.

Conflicting risk attitudes

This paper examines whether differences in individual risk attitudes are related to interpersonal conflict. In more than thirty villages of rural Uganda, we conduct a social survey to document social links between pairs of individuals within a village, and separately elicit individual risk attitudes using an incentivized task. Our findings reveal that the difference in risk attitudes between two individuals is significantly and positively related to the presence of interpersonal conflict between them. This relationship is particularly strong among kin. By contrast, the strength of risk aversion per se is not related to conflict. Further, we conduct simulations that suggest that the relationship cannot be solely explained by diverging attitudes after the severing of social ties as a result of interpersonal conflict.

Increasing trial number produces augmentation, not blocking, in flavor-aversion conditioning

Typically, A+→AX+ conditioning yields significantly weaker responding to CS X, a phenomenon known as blocking. Yet, in flavor-aversion conditioning, A+→AX+ conditioning yields a significantly stronger response to X, termed augmentation. Two flavor-aversion experiments with rat subjects and rotationally induced illness were conducted to determine if trial number was a factor that affected the expression of augmentation. An increase in the number of A+ preconditioning trials resulted in a stronger augmented aversion (Experiment 1). Similarly, an increase in the number of AX+ compound conditioning trials also produced a significantly stronger augmentation effect (Experiment 2). Therefore, these data show that variations in trial number are not the determining factor in the expression of augmentation or blocking, and they confirm that the strength of augmented aversions are directly related to the strength of the aversion of the preconditioned cue. Finally, these results are the first to show odor-aversion conditioning and augmented taste aversions produced via rotational stimulation.

Aversive conditioning of Steller's Jays to improve marbled murrelet nest survival

ABSTRACTPredation on eggs of marbled murrelets (Brachyramphus marmoratus) has been linked to poor recruitment of young, especially in California, Oregon, and Washington. Corvids have been implicated as the most influential egg predators on murrelets. Remnant murrelet nesting habitats in California and elsewhere support a high population density of opportunistic corvids like the Steller's jay (Cyanocitta stelleri). We exposed Steller's jays to eggs mimicking murrelet eggs in color and size that contained the emetic carbachol. In laboratory tests, we effectively induced aversive conditioning subsequent to exposure to the murrelet‐mimic eggs. Attack latencies on murrelet‐mimic eggs increased following exposure to carbachol eggs and the strength of aversion was consistent over the range of retention periods tested (8 weeks). We conducted field trials on murrelet‐mimic eggs and control eggs deployed across a systematic 428‐ha grid in murrelet breeding habitat. After a period of aversive conditioning, the percentage of murrelet‐mimic eggs that were attacked by corvids in the field experiment was reduced by at least 37% in comparison to control eggs. We concluded that corvid predation can be reduced significantly using aversive training in the field, and could be practically applied to jay territories within murrelet breeding habitat. We suggest that aversive conditioning treatment may be a cost‐effective emergency tool to improve reproductive success of murrelets in the Pacific Northwest. © 2014 The Wildlife Society.

Fitness Costs Predict Inbreeding Aversion Irrespective of Self-Involvement: Support for Hypotheses Derived from Evolutionary Theory

It is expected that in humans, the lowered fitness of inbred offspring has produced a sexual aversion between close relatives. Generally, the strength of this aversion depends on the degree of relatedness between two individuals, with closer relatives inciting greater aversion than more distant relatives. Individuals are also expected to oppose acts of inbreeding that do not include the self, as inbreeding between two individuals posits fitness costs not only to the individuals involved in the sexual act, but also to their biological relatives. Thus, the strength of inbreeding aversion should be predicted by the fitness costs an inbred child posits to a given individual, irrespective of this individual’s actual involvement in the sexual act. To test this prediction, we obtained information about the family structures of 663 participants, who reported the number of same-sex siblings, opposite-sex siblings, opposite-sex half siblings and opposite-sex cousins. Each participant was presented with three different types of inbreeding scenarios: 1) Participant descriptions, in which participants themselves were described as having sex with an actual opposite-sex relative (sibling, half sibling, or cousin); 2) Related third-party descriptions, in which participants’ actual same-sex siblings were described as having sex with their actual opposite-sex relatives; 3) Unrelated third-party descriptions, in which individuals of the same sex as the participants but unrelated to them were described as having sex with opposite-sex relatives. Participants rated each description on the strength of sexual aversion (i.e., disgust-reaction). We found that unrelated third-party descriptions elicited less disgust than related third-party and participant descriptions. Related third-party and participant descriptions elicited similar levels of disgust suggesting that the strength of inbreeding aversion is predicted by inclusive fitness costs. Further, in the related and unrelated conditions alike, the strength of inbreeding aversion was positively associated with the degree of relatedness between those described in the descriptions.

Measurement-induced focusing and the magnitude of loss aversion: The difference between comparing gains to losses and losses to gains

AbstractResearch has identified loss aversion as a strong and robust phenomenon, but has also revealed some moderators affecting the magnitude of its effect on decision making. In the current article, we draw attention to the fact that even the measurement of loss aversion itself may affect its magnitude by inducing a focus on either losses or gains. In three studies, we provide empirical evidence for such a measurement-induced focus. In all studies we used coin-toss gambles—in which there is a 50/50 chance to win or to lose—to assess gain/loss ratios as a measure of loss aversion. Participants either filled out the loss side or the gain side of this gain/loss ratio. The studies consistently showed that—using within- and between-subject designs and anticipated and real coin-toss gambles—the strength of loss aversion depended on the measurement format (fill-in-the-loss versus fill-in-the-gain); filling in the loss side increased loss aversion. Moreover, loss aversion was more affected by the stakes of the gamble in the fill-in-the-loss format than in the fill-in-the-gain format.

Experience-dependent flexibility in collective decision making by house-hunting ants

When making a decision, solitary animals often adjust to local conditions by using flexible evaluation and decision criteria, even though these may occasionally lead to irrationality. By contrast, collective decision making in large animal groups—such as, nest choice by emigrating ant colonies—is usually considered to rely on robust, fixed preference rules and to be immune to irrationality. Here, we show that familiarization with available nest sites prior to emigration can lead to flexible collective decisions in the house-hunting ant Temnothorax albipennis. Colonies allowed to inspect a mediocre nest site while their home nest is still intact usually develop an aversion toward that nest. We found that aversion strength was not determined by the quality of the familiar nest only but was also influenced by the quality of the home nest. As a result, nest choice in later emigrations depended strongly on the quality of the previously experienced home nest, allowing colonies to adjust to the local quality of available sites. Additionally, we found that in a worst-case scenario where the only alternatives are of even lower quality, developing an aversion toward a mediocre nest can occasionally lead to poor collective decisions. We discuss whether the observed flexibility in collective choices necessarily requires experience-dependent changes in individual decision criteria and develop a new analytical model of nest choice in house-hunting ants showing that a fixed-threshold decision strategy at the individual level can lead to experience-dependent, flexible decisions at the colony level. Key words: ants; collective decision making, irrationality, nest choice; previous experience. [BehavEcol]

A Structural Analysis of Disappointment Aversion in a Real Effort Competition

We develop a novel computerized real effort task, based on moving sliders across a screen, to test experimentally whether agents are disappointment averse when they compete in a real effort sequential-move tournament. We predict that a disappointment averse agent, who is loss averse around her endogenous choice-acclimating expectations-based reference point, responds negatively to her rival's effort. We find significant evidence for this discouragement effect, and use the Method of Simulated Moments to estimate the strength of disappointment aversion on average and the heterogeneity in disappointment aversion across the population. (JEL C91, D12, D81, D84)

Dopamine, norepinephrine and serotonin transporter gene deletions differentially alter cocaine-induced taste aversion

Although cocaine is primarily known for its powerful hedonic effects, there is evidence that its affective experience has a notable aversive component that is less well understood. A variety of pharmacological and molecular approaches have implicated enhanced monoamine (MA) neurotransmission in the aversive effects of cocaine. Although numerous studies have yielded data supportive of the role of the monoamines (indirectly and directly), the specific system suggested to be involved differs across studies and paradigms (Freeman et al., 2005b; Grupp, 1997; Roberts and Fibiger, 1997). Monoamine transporter knockout mice have been useful in the study of many different aspects of cocaine effects relevant to human drug use and addiction, yet an assessment of the effects of deletion of the genes for the dopamine, norepinephrine and serotonin transporters (DAT, NET, and SERT, respectively) on cocaine's aversive properties has yet to be performed (Uhl et al., 2002). In the current investigation, the strength of cocaine-induced aversions was compared among three groups of transgenic mice with deletions of the genes responsible for the production of one of the monoamine transporters. When compared to their respective WT controls, dopamine transporter deletion slightly attenuated cocaine-induced aversion while deletion of SERT or NET resulted in a more significant delay in the onset and strength of cocaine-induced taste aversions. The data lead us to conclude that the action of cocaine to inhibit NET contributes most substantially to its aversive effects, with some involvement of SERT and minimal contribution of DAT.

Interactions of temperature and taste in conditioned aversions

The influence of temperature on taste cues and the ability to discriminate and learn about different temperatures of foods are important factors regulating ingestion. The goal of this research was to demonstrate that thermal orosensory input can serve as a salient stimulus to guide ingestive behavior in the rat, and also that it interacts with gustatory input during choice and conditioned aversion experiments. A novel apparatus with Peltier refrigerators was used to control the temperature of solutions in 10-min, 2-bottle tests. It was determined that naive rats preferred cold water (10 °C) to warm water (40°). When cold water was paired with a toxic LiCl injection, rats avoided cold water and drank warm water, thus demonstrating that cold water could serve as the conditioned stimulus in a conditioned temperature aversion. Rats conditioned against cold water could discriminate 10 °C water from 16 °C water, but not from 13 °C water, thus showing an ability to discriminate orosensory thermal cues to within 3–6 °C. Rats also generalized conditioned aversions from cold water to cold saccharin and cold sucrose solutions. However, if rats were conditioned against a compound taste and thermal stimulus (10 °C, 0.125% saccharin), the rats could distinguish and avoid each component individually, i.e., by avoiding cold water or warm saccharin. Finally, daily 2-bottle extinction tests were used to assess the strength of aversions conditioned against a taste cue (0.25 M sucrose), a thermal cue (10 °C water), or the combination. Aversions to taste or temperature alone persisted for 7–14 days of extinction testing, but the combined taste–temperature aversion was stronger and did not extinguish after 20 days of extinction testing. These results demonstrate that temperature can serve as a salient cue in conditioned aversions that affect ingestion independent of taste cues or by potentiating taste cues.

A Structural Analysis of Disappointment Aversion in a Real Effort Competition

We develop a novel computerized real effort task, based on moving sliders across a screen, to test experimentally whether agents are disappointment averse when they compete in a real effort sequential-move tournament. Our theory predicts that a disappointment averse agent, who is loss averse around her endogenous expectations-based reference point, responds negatively to her rival's effort. We find significant evidence for this discouragement effect, and use the Method of Simulated Moments to estimate the strength of disappointment aversion on average and the heterogeneity in disappointment aversion across the population.