scholarly journals Irrational risk aversion in ants is driven by perceptual mechanisms

2019 ◽  
Author(s):  
Massimo De Agrò ◽  
Daniel Grimwade ◽  
Tomer J. Czaczkes
Keyword(s):  
Risk Aversion ◽  
Sucrose Solution ◽  
Risk Preference ◽  
Lasius Niger ◽  
Risk Sensitivity ◽  
Eusocial Insects ◽  
Collective Decisions ◽  
Y Maze ◽  
Equal Chance ◽  
Driving Risk

AbstractAnimals must often decide between exploiting safe options or risky options with a chance for large gains. While traditional optimal foraging theories assume rational energy maximisation, they fail to fully describe animal behaviour. A logarithmic rather than linear perception of stimuli may shape preference, causing animals to make suboptimal choices. Budget-based rules have also been used to explain risk-preference, and the relative importance of these theories is debated. Eusocial insects represent a special case of risk sensitivity, as they must often make collective decisions based on resource evaluations from many individuals. Previously, colonies of the ant Lasius niger were found to be risk-neutral, but the risk preference of individual foragers was unknown. Here, we tested individual L. niger in a risk sensitivity paradigm. Ants were trained to associate a scent with 0.55M sucrose solution and another scent with an equal chance of either 0.1 and 1.0M sucrose. Preference was tested in a Y-maze. Ants were extremely risk averse, with 91% choosing the safe option. Even when the risky option offered on average more sucrose (0.8M) than the fixed option, 75% preferred the latter. Based on the psychophysical Weber-Fechner law, we predicted that logarithmically balanced alternatives (0.3M vs 0.1M/0.9M) would be perceived as having equal value. Our prediction was supported, with ants having no preference for either feeder (53% chose the fixed option). Our results thus strongly support perceptual mechanisms driving risk-aversion in ants, and demonstrate that the behaviour of individual foragers can be a very poor predictor of colony-level behaviour.

scholarly journals Irrational risk aversion in an ant

2021 ◽  
Author(s):  
Massimo De Agrò ◽  
Daniel Grimwade ◽  
Richard Bach ◽  
Tomer J. Czaczkes
Keyword(s):  
Risk Aversion ◽  
Sucrose Solution ◽  
Lasius Niger ◽  
Risk Sensitivity ◽  
Eusocial Insects ◽  
Decisions Under Risk ◽  
Collective Decisions ◽  
Y Maze ◽  
Equal Chance ◽  
Relative Differences

AbstractAnimals must often decide between exploiting safe options or risky options with a chance for large gains. Both proximate theories based on perceptual mechanisms, and evolutionary ones based on fitness benefits, have been proposed to explain decisions under risk. Eusocial insects represent a special case of risk sensitivity, as they must often make collective decisions based on resource evaluations from many individuals. Previously, colonies of the ant Lasius niger were found to be risk-neutral, but the risk preference of individual foragers was unknown. Here, we tested individual L. niger in a risk sensitivity paradigm. Ants were trained to associate one scent with 0.55 M sucrose solution and another with an equal chance of either 0.1 or 1.0 M sucrose. Preference was tested in a Y-maze. Ants were extremely risk-averse, with 91% choosing the safe option. Based on the psychophysical Weber–Fechner law, we predicted that ants evaluate resources depending on their logarithmic difference. To test this hypothesis, we designed 4 more experiments by varying the relative differences between the alternatives, making the risky option less, equally or more valuable than the safe one. Our results support the logarithmic origin of risk aversion in ants, and demonstrate that the behaviour of individual foragers can be a very poor predictor of colony-level behaviour.

scholarly journals Quantitative tests of an associative theory of risk-sensitivity in honeybees

2001 ◽  
Vol 204 (3) ◽  
pp. 565-573 ◽  
Author(s):  
M.S. Shapiro ◽  
P.A. Couvillon ◽  
M.E. Bitterman
Keyword(s):  
Risk Aversion ◽  
Sucrose Solution ◽  
Discriminative Learning ◽  
Second Phase ◽  
Risk Sensitivity ◽  
Natural Conditions ◽  
Associative Theory ◽  
Mean Concentration

Risk-sensitivity was studied in free-flying honeybees trained individually to choose between two scented targets (A and B) with varying amounts and concentrations of sucrose solution as reward. In the first phase of experiment 1, the animals showed “risk-aversion,” preferring A, which provided 5 microl of a 40 % sucrose solution on every trial, to B, which provided 30 microl of the same solution once in every six trials (mean amount per trial 5 microl for each alternative). In the second phase, the preference reversed with reversal of the reward assignments. In experiment 2, the consistently rewarded A (5 microl of 40 % sucrose solution per trial) was again preferred, although the inconsistently rewarded B now provided twice the amount of sucrose solution on average (30 microl on two of every six trials, mean amount per trial 10 microl). In experiment 3, with A providing 10 microl of a 15 % sucrose solution on every trial and B providing 10 microl of a 60 % sucrose solution on two of every four trials (mean concentration per trial 30 %), the animals preferred B. In Experiment 4, patterned after experiment 1, similar results were obtained under more natural conditions in which the animals were no longer constrained (as they were in the first three experiments) to go equally often to each alternative. The results of all four experiments were predicted quantitatively and with considerable accuracy by a simple associative theory of discriminative learning in honeybees.

Connection Function and its Posture Analysis of Risk Preference

2013 ◽  
Vol 756-759 ◽  
pp. 1784-1787
Author(s):  
Ya Feng Yang ◽  
Huan Cheng Zhang ◽  
Li Nan Shi
Keyword(s):  
Risk Aversion ◽  
Decision Analysis ◽  
Utility Function ◽  
Risk Preference ◽  
Posture Analysis ◽  
Connection Degree ◽  
Risk Neutral

To make utility function reflect the comprehensive utility of things and decision, and consider the uncertainty in the decision analysis and things acknowledge, a deeply analysis of the set pair character of utility function is carried on from three aspects: risk aversion, risk neutral and risk pursuit, and then the set pair connection function of risk preference was constructed. Finally, the posture of preference connection degree was discussed.

Testing the Effect of Risk Attitude on Auditor Judgments Using Multiattribute Utility Theory

1993 ◽  
Vol 8 (1) ◽  
pp. 91-110 ◽  
Author(s):  
Timothy A. Farmer
Keyword(s):  
Risk Aversion ◽  
Internal Control ◽  
Utility Theory ◽  
Risk Preference ◽  
Risk Attitude ◽  
Test Results ◽  
Multiattribute Utility ◽  
Multiattribute Utility Theory ◽  
Auditor Judgments ◽  
The Individual

The scaling constant of multiattribute utility functions derived for each of 15 practicing auditors was used to measure risk attitude for the subjects. The risk preference or risk aversion indicated by this metric allowed categorization of the auditors to test for an effect of risk attitude on audit judgments. The sample showed both risk aversion and risk preference among the auditors. The correlations among auditor evaluations of hypothetical internal control compliance test results were generally high and were different for audit seniors than for audit managers. Risk attitude was not found to explain the differences across rank nor the individual differences in consensus.

scholarly journals Risk Aversion and Timber Harvest Strategies: A Case Study of Nonindustrial Private Forest Management in Louisiana

2022 ◽  
Author(s):  
Hua Wang ◽  
Naveen Adusumilli ◽  
Michael Blazier ◽  
Santosh Pathak
Keyword(s):  
Forest Management ◽  
Risk Aversion ◽  
Risk Premium ◽  
Policy Development ◽  
Forest Policy ◽  
Risk Preference ◽  
Timber Harvest ◽  
Forest Owners ◽  
Management Actions ◽  
Management Alternatives

AbstractForest owners face many challenges regarding forest management due to the long period from planting to harvest. Along with the economic and environmental factors that influence management actions, the owners' attitude to risk plays a crucial role in forest management decisions. This study shows that understanding the effects of the owner's risk preference for management actions is an important step to form an effective forest policy. The objectives of the study are to (1) assess the economic advantage of forest management alternatives over a range of risk aversion coefficients and (2) determine the financial incentive (risk premium) corresponding to a forest owners' risk attitude. We implemented the stochastic efficiency with respect to a function framework to evaluate a set of fertilization, herbicide, and thinning management alternatives at mid-rotation loblolly pine plantations in Louisiana. Results from this study indicate that forest owner's risk preference affects their decision to select management actions. Financial incentives are substantially different for specific management alternatives between risk-neutral and risk-averse forest owners. The results can guide forest policy development where agencies can modify financial assistance programs to improve the adoption of management actions.

scholarly journals Same length, different shapes: ants collectively choose a straight foraging path over a bent one

2018 ◽  
Vol 14 (3) ◽  
pp. 20180070 ◽  
Author(s):  
Olivier Bles ◽  
Thibault Boehly ◽  
Jean-Louis Deneubourg ◽  
Stamatios C. Nicolis
Keyword(s):  
Food Source ◽  
Abrupt Change ◽  
Food Sources ◽  
Lasius Niger ◽  
Straight Path ◽  
Change Of Direction ◽  
Collective Decisions ◽  
Different Shapes ◽  
Theoretical Results ◽  
Pheromone Trail

In socials insects, exploration is fundamental for the discovery of food resources and determines decision-making. We investigated how the interplay between the physical characteristics of the paths leading to food sources and the way it impacts the behaviour of individual ants affects their collective decisions. Colonies of different sizes of Lasius niger had access to two equal food sources through two paths of equal length but of different geometries: one was straight between the nest and the food source, and the other involved an abrupt change of direction at the midway point (135°). Both food sources were discovered simultaneously, but the food source at the end of the straight path was preferentially exploited by ants. Based on experimental and theoretical results, we show that a significantly shorter duration of nestbound travel on the straight path, which rapidly leads to a stronger pheromone trail, is at the origin of this preference.

scholarly journals Investors’ Risk Preference Characteristics and Conditional Skewness

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Fenghua Wen ◽  
Zhifang He ◽  
Xiaohong Chen
Keyword(s):  
Risk Aversion ◽  
Behavioral Finance ◽  
Stock Exchange ◽  
Risk Preference ◽  
Full Description ◽  
Risk Return ◽  
Risk Seeking ◽  
The Empirical Analysis ◽  
Composite Indexes ◽  
Current Risk

Perspective on behavioral finance, we take a new look at the characteristics of investors’ risk preference, building the D-GARCH-M model, DR-GARCH-M model, and GARCHC-M model to investigate their changes with states of gain and loss and values of return together with other time-varying characteristics of investors’ risk preference. Based on a full description of risk preference characteristic, we develop a GARCHCS-M model to study its effect on the return skewness. The top ten market value stock composite indexes from Global Stock Exchange in 2012 are adopted to make the empirical analysis. The results show that investors are risk aversion when they gain and risk seeking when they lose, which effectively explains the inconsistent risk-return relationship. Moreover, the degree of risk aversion rises with the increasing gain and that of risk seeking improves with the increasing losses. Meanwhile, we find that investors’ inherent risk preference in most countries displays risk seeking, and their current risk preference is influenced by last period’s risk preference and disturbances. At last, investors’ risk preferences affect the conditional skewness; specifically, their risk aversion makes return skewness reduce, while risk seeking makes the skewness increase.

scholarly journals Investors’ Risk Preference Characteristics Based on Different Reference Point

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Fenghua Wen ◽  
Zhifang He ◽  
Xu Gong ◽  
Aiming Liu
Keyword(s):  
Stock Market ◽  
Risk Aversion ◽  
Empirical Evidence ◽  
Reference Point ◽  
Risk Preference ◽  
Reference Points ◽  
Time Varying ◽  
Explanatory Variables ◽  
House Money Effect ◽  
Two Factors

Taking the stock market as a whole object, we assume that prior losses and gains are two different factors that can influence risk preference separately. The two factors are introduced as separate explanatory variables into the time-varying GARCH-M (TVRA-GARCH-M) model. Then, we redefine prior losses and gains by selecting different reference point to study investors’ time-varying risk preference. The empirical evidence shows that investors’ risk preference is time varying and is influenced by previous outcomes; the stock market as a whole exhibits house money effect; that is, prior gains can decrease investors’ risk aversion while prior losses increase their risk aversion. Besides, different reference points selected by investors will cause different valuation of prior losses and gains, thus affecting investors’ risk preference.

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