David William Stephens

David William Stephens
University of Minnesota Twin Cities | UMN · Department of Ecology, Evolution and Behaviour

D. Phil.

About

82
Publications
21,609
Reads
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10,763
Citations
Additional affiliations
September 1999 - present
University of Minnesota Twin Cities
Position
  • Professor (Full)
September 1989 - September 1998
University of Nebraska at Lincoln
Position
  • Professor (Associate)
January 1984 - December 1986
University of Utah
Position
  • PostDoc Position

Publications

Publications (82)
Article
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This paper considers the relevance of so-called "Lewisian conventions" to the study of nonhuman animals. Conventions arise in coordination games with multiple equilibria, and the apparent arbitrariness of conventions occurs when processes outside the game itself determine which of several equilibria is ultimately chosen. Well-understood human conve...
Chapter
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This chapter considers foraging behavior and its connections with learning and memory. The chapter reviews the basic models of foraging that behavioral ecologists have developed over the last 40 years. These models provide an economic framework for the study of foraging. Animals forage in a changing environment, and they must adjust their foraging...
Article
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Preferences are the foundation of economics. Preferences are taken by economists as fixed by some implicitly biological process. In recent decades, behavioral economics has documented the divergence between the nature of human preferences and the assumptions of standard economics. In this study, we use the tool of experimental evolution to study th...
Article
The hypothesis that prey organisms can reduce the risk of predation by overtly signalling their unprofitability, or aposematism, has a long history in behavioural and evolutionary biology. To fully understand this longstanding idea, we need to measure and manipulate traits of aposematic prey, such as their distinctiveness from other prey, from the...
Article
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Animals are selective about when to learn by observing others. Models predict that social information becomes less reliable in uncertain environments, and therefore animals should reduce their use of social information in these environments; however, these parameters are often difficult to manipulate and control. We investigated how information rel...
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Multimodal signals are widespread in animal communication. Theoreticians have noted that, from an informational perspective, it is often not clear why multimodal signals should offer any benefit over unimodal complex signals. One possibility is that multimodal signals provide psychological benefits to receivers by virtue of the fact that they stimu...
Article
Animal signals commonly consist of many components. Students of signaling have suggested that these complex, multicomponent signals are beneficial because they are more effective at influencing receiver behavior. This “more is better” view, however, is at odds with economic models, which predict that a single signal component is often sufficient to...
Chapter
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Animal signals commonly consist of multiple components—say a sound and a display—and students of signaling have offered many perceptual and cognitive explanations for why compound signals should be more effective. Yet, the economic benefits that receivers obtain by following multiple signal components remain unclear. Superficially, it would seem th...
Article
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This is a theory paper that advocates experimental evolution as a novel approach to study economic preferences. Economics could benefit because preferences are exogenous, axiomatic, and contentious. Experimental evolution allows the empirical study of preferences by placing organisms in designed environments and studying their genotype and phenotyp...
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This paper presents an alternative approach to studying signaller–receiver interactions. The conventional approach focuses on signal reliability; instead, we focus on receivers' willingness to tolerate imperfect reliability (receiver tolerance). Both approaches aim to explain what promotes and maintains communication. We define receiver tolerance a...
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Animals learn some things more easily than others. To explain this so-called prepared learning, investigators commonly appeal to the evolutionary history of stimulus-consequence relationships experienced by a population or species. We offer a simple model that formalizes this long-standing hypothesis. The key variable in our model is the statistica...
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Communication depends on reliability. Yet, the existence of stable honest signalling presents an evolutionary puzzle. Why should animals signal honestly in the face of a conflict of interest? While students of animal signalling have offered several theoretical answers to this puzzle, the most widely studied model, commonly called the 'handicap prin...
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Laboratory studies of decision making often take the form of two-alternative, forced-choice paradigms. In natural settings, however, many decision problems arise as stay/go choices. We designed a foraging task to test intertemporal decision making in rats via stay/go decisions. Subjects did not follow the rate-maximizing strategy of choosing only f...
Article
In this paper we develop a simplified and experimentally tractable version of Andersson & Krebs’s (1978, Animal Behaviour, 26, 707–711) classical model of caching behaviour. We conducted three experiments using captive blue jays, Cyanocitta cristata, to test the predictions of this model. These experiments explored the effects of three theoreticall...
Article
In the present paper, we explore a novel preparation for the study of animal choice behaviour designed to capture some aspects of naturally occurring patch exploitation. Although one can cast the problem of patch exploitation as a binary choice, naturally occurring patch-leaving decisions are inevitably asymmetric. We asked whether captive blue jay...
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Introduction Uncertainty is an unavoidable product of any encounter between two or more animals. Although the level of uncertainty may vary as a function of many factors – including species, sex, age and condition – even at its minimum it still presents a challenge that must be overcome over the course of every animal’s life (Dall, 2010). This proc...
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This paper investigates the effect of three important variables on signal use, theoretically and experimentally. We present a simple model and a corresponding experiment that investigates the combined effects of uncertainty about action, signal reliability and signal cost. Our experiment uses techniques drawn from the psychology laboratory to test...
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An old joke circulates among animal behavior instructors. One can, the joke goes, divide the topics of animal behavior into four Fs: fighting, fleeing, feeding, and reproduction. This somewhat tired joke carries considerable truth. Animals behaving in nature surely must make decisions about conflicts, predator avoidance, feeding, and mating. Male c...
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Several phenomena in animal learning seem to call for evolutionary explanations, such as patterns of what animals learn and do not learn. While several models consider how evolution should influence learning, we have very little data testing these models. Theorists agree that environmental change is a central factor in the evolution of learning. We...
Article
This study compares two procedures for the study of choices that differ in time and amount, namely the self-control and patch procedures. The self-control procedure offers animals a binary mutually exclusive choice between a smaller-sooner and larger-later option. This procedure dominates the choice literature. It seems to address the idea of choic...
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In this article, I review the approach taken by behavioral ecologists to the study of animal foraging behavior and explore connections with general analyses of decision making. I use the example of patch exploitation decisions in this article in order to develop several key points about the properties of naturally occurring foraging decisions. Firs...
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What is patience? Humans and other animals often make decisions that trade off present and future benefits. Should a monkey eat an unripe fruit or wait for it to ripen? Should I purchase the iPhone at its debut or wait for the price to drop in a few months? In these dilemmas, large gains often require long waits, so decision makers must choose betw...
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Experimental animals often prefer small but immediate rewards even when larger-delayed rewards provide a higher rate of intake. This impulsivity has important implications for models of foraging and cooperation. Behavioral ecologists have hypothesized that animals discount delayed rewards because delay imposes a collection risk. According to this l...
Article
Foraging is fundamental to animal survival and reproduction, yet it is much more than a simple matter of finding food; it is a biological imperative. Animals must find and consume resources to succeed, and they make extraordinary efforts to do so. For instance, pythons rarely eat, but when they do, their meals are large—as much as 60 percent larg...
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We investigated the roles of signal reliability and environmental uncertainty in animal signal use. We developed a simple model that predicted when animals should switch between choosing the most common option (which we call environment tracking) and following a signal. The model predicts signal following when signal reliability exceeds environment...
Article
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Animals show impulsiveness when they prefer a smaller more immediate option, even though a larger more delayed option produces a higher intake rate. This impulsive behavior has implications for several behavioral problems including social cooperation. This paper presents two experiments using captive blue jays (Cyanocitta cristata) that consider th...
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Information is a crucial currency for animals from both a behavioural and evolutionary perspective. Adaptive behaviour relies upon accurate estimation of relevant ecological parameters; the better informed an individual, the better it can develop and adjust its behaviour to meet the demands of a variable world. Here, we focus on the burgeoning inte...
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Observed animal impulsiveness challenges ideas from foraging theory about the fitness value of food rewards, and may play a role in important behavioural phenomena such as cooperation and addiction. Behavioural ecologists usually invoke temporal discounting to explain the evolution of animal impulsiveness. According to the discounting hypothesis, d...
Article
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The current study examined the economics of cooperation in controlled-payoff games by using captive blue jays, Cyanocitta cristata. This investigation used a special feeding apparatus to test for the stability of cooperative choice in a series of iterated games. The jays experienced experimentally determined game theoretical payoff matrices, which...
Article
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Animals frequently raise their heads to check for danger. In a group, individuals generally raise their heads independently. Earlier models suggest that all group members could gain by coordinating their vigilance, i.e., each member raising its head when others are not. We re-examine these suggestions, considering groups of different sizes, in ligh...
Article
Psychological studies of animal choice show that the immediate consequences of choice strongly influence preference. In contrast, evolutionary models emphasize the longer-term fitness consequences of choice. Building on recent work by Stephens & Anderson (2001, Behavioral Ecology12, 330–339), this study presents two experiments that address this co...
Article
We derived a model to predict site selection by drifting prey in streams. This model considers the conflicting demands between feeding and avoiding both benthic and drift predators. Our analysis suggests a ranking of site qualities based on the ratio of food acquisition rate to benthic predation risk (termed site value). Drifting organisms should a...
Article
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The Iterated Prisoner's Dilemma (IPD) is a central paradigm in the study of animal cooperation. According to the IPD framework, repeated play (repetition) and reciprocity combine to maintain a cooperative equilibrium. However, experimental studies with animals suggest that cooperative behavior in IPDs is unstable, and some have suggested that stron...
Article
Psychological studies of animal choice show that the immediate consequences of choice strongly influence preference. In contrast, evolutionary models emphasize the longer-term fitness consequences of choice. Building on recent work by Stephens & Anderson (2001, Behavioral Ecology12, 330–339), this study presents two experiments that address this co...
Article
Full-text available
Feeding animals often prefer small, quickly delivered rewards over larger, more delayed rewards. Students of feeding behaviour typically explain this behaviour by saying that animals discount delayed benefits. Temporal discounting implies that delayed benefits are worth less than immediate benefits. This paper presents a new explanation of short-si...
Article
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Most analyses of food-sharing behavior invoke complex explanations such as indirect and delayed benefits for sharing via kin selection and reciprocal altruism. However, food sharing can be a more general phenomenon accounted for by more parsimonious, mutualistic explanations. We propose a game theoretical model of a general sharing situation in whi...
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Results from the operant laboratory suggest that short-term benefits guide animal feeding decisions. These results appear to contradict evolutionarily-motivated models of foraging that emphasize long-term benefits. Because of this contradiction, some behavioral ecologists argue that natural selection must favor short-term benefits in some unknown w...
Article
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This investigation presents a simple spatially explicit analysis of the ideal-free distribution. The traditional ideal-free distribution assumes discrete sites with definite boundaries, and predicts how many individuals should occupy each site. In contrast, the present analysis assumes that a forager’s gains gradually decline with distance from a s...
Article
Experimental studies with captive animals show strong preferences for immediate reward. Several authors have argued that these tendencies to discount delayed reward may severely limit the Iterated Prisoner's Dilemma game as a model of animal cooperation. This paper explores a simple mechanism, dubbed cumulative games, that can, in principle, promot...
Article
The iterated Prisoner's Dilemma (IPD) is usually analysed by evaluating arithmetic mean pay-offs in an ESS analysis. We consider several points that the standard argument does not address. Finite population size and finite numbers of matches in the IPD game lead us to consider both pay-off variance and the sampling process in the evolutionary game....
Article
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Many animals search in a saltatory fashion: they move forward, pause briefly, and move forward again. Although many optimal-foraging models bare been developed, most do not address how an animal searches for food. We view search strategies as 'time-distance' functions to allow not only for the possibility of oscillations in body speed, as implied b...
Article
An experimental analysis of the movements of predator-approaching fish is presented. The experiments evaluated two competing hypotheses. (1) Predator-approaching fish play the game-theoretical strategy Tit for Tat. Alternatively, (2) the movements of predator-approaching fish superficially resemble Tit for Tat, because fish independently orient to...
Article
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Variance in amount of rewards has been the focus of many studies and models of risk sensitivity. However, the timing of rewards has received much less attention. Animals tend to prefer immediate rewards, even when this preference reduces the long term rate of gain. This implies future rewards are devalued, a phenomenon known as time discounting. Th...
Article
Since 1981 a large body of research has focused on the Iterated Prisoner's Dilemma as a “basic paradigm” for the study of non-kin cooperation. Current evidence, however, shows that animals consistently defect in controlled Prisoner's Dilemmas. In this paper, an attempt is made to understand this by studying the effects of error and discounting (the...
Article
We present two models of optimal resource exploitation for sit-and-wait foragers. The first model assumes immediate recognition of site quality and that site quality does not change over time. This model predicts a forager's minimum acceptable site quality. We present a graphical analysis to show how (1) the distribution of site qualities, (2) the...
Article
Since 1981, the iterated Prisoner's Dilemma has dominated studies of non-kin cooperation. Alternative models have received relatively little attention. The simplest alternative is mutualism, in which mutual cooperation always pays best. The behaviour of three pairs of blue jays,Cyanocitta cristata, was tested in precisely controlled iterated mutual...
Article
Blue jays (Cyanocitta cristata) were presented with a foraging situation in which half of the patches they encountered contained no prey and half contained a single prey item. Experimentally determined probability distributions controlled prey arrival times in those patches that contained prey. Patch residence in empty patches was studied during fo...
Article
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The mathematical technique of dimensional analysis is presented in the context of behavioral ecology. Dimensional analysis transforms the variables in a problem to a reduced set of unitfree variables. This transformation helps to reveal the nature of relationships among variables, simplifies modeling, and produces predictions that are readily compa...
Chapter
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When a foraging notonecif bug extracts the juices from a prey item, it will, at some point, stop extracting and begin to search for another prey item. Behavioral ecologists have found that predators, like my hypothetical notonectid, will extract a high proportion of the available resources from a given prey, taking a long time to do it, when prey a...
Article
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I present a simple model that considers how three factors—change, regularity, and value— influence the evolution of animal learning. Change and regularity are considered by introducing two terms that measure environmental persistence. One term, “between-generation persistence, ” defines the extent to which states in the parental generation predict...
Article
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A simple way to approximate the value of information is proposed. Two kinds of quantities are important in determining the value of information: 1) the optimal behaviors that would be chosen if the decision maker knew which subtype (or state) of the resource it faced; and 2) the costs of small deviations from these subtype optima. The value of info...
Article
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Host selection by solitary parasitoids is modeled as a problem in life-historical evolution. The basic approach is to assume fitness maximization in the face of trade-offs. Two kinds of trade-offs are considered: 1) patchy versus fine-grained host distribution, and 2) an egg-production rate that is either negatively related to adult survival or sim...
Article
The problem of how animals keep track of unpredictable changes in the profitability of foraging sites was studied. An optimality model was used to predict the frequency with which a forager should sample a foraging site in which the probability of reward fluctuates randomly between high and low. The alternative foraging site is stable and offers an...
Article
This paper presents a simple model of how an animal should best use experience to track a changing environment. The model supposes that the environment switches between good and bad states according to a first-order Markov chain. The optimal sampling behavior is characterized in terms of the stability of runs (the probability that the environment w...
Article
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Attempts to integrate the related problems of patch choice and prey choice within patches. Two models of prey choice within patches are discussed. One based on momentary rate maximizing (the take-the-most-profitable rule) has been presented previously. An alternative long-term rate-maximizing rule, the discrete-marginal-value theorem, is developed....
Article
Orians & Pearson (1979) present models of optimal behaviour for central place foragers. The models for single-prey and multiple-prey loaders are superficially similar, but fundamentally different. The similarity appears to have led Orians & Pearson to a mistake in the formulation of the single-preyloader model. We present the correct form of the gr...
Article
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Some simple stochastic models of optimal foraging are considered. Firstly, mathematical renewal theory is used to make a general model of the combined processes of search, encounter, capture and handling. In the case where patches or prey items are encountered according to a Poisson process, the limiting probability distribution of energy gain is f...
Article
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Reviews the findings of T. Caraco et al (see record 1981-05141-001) that the foraging preferences of animals are sensitive to variance in the proability distribution of a food reward. Also examined was T. Caraco's (1980) suggestion that some aspects of risk sensitivity may be explained by minimization of the probability of starvation. The present...
Article
Thesis (D. Phil)--University of Oxford, 1982. Includes bibliographical references.

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