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Full-Text Articles in Behavior and Ethology

Between Choice And Compulsion: An Examination And Critique Of The Evolution Of 'Original Sin', Matthew James Wynn Jan 2023

Between Choice And Compulsion: An Examination And Critique Of The Evolution Of 'Original Sin', Matthew James Wynn

MSU Graduate Theses

“Why are we the way that we are?” is one of the hardest questions to answer because it requires grasping the origin of human beings. This has left philosophers and theologians in century-long debates on forming a “cosmogony of ontology” (i.e., how the origin of the universe informs the human condition). The concept, “original sin” was developed by a North African theologian named Augustine (354 – 430 CE). Augustine’s reading of Genesis 3, and inaccurate translation of Romans 5:12, taught that a person is born morally culpable for a fault antecedent to their existence. This way of thinking about the …


Uncovering 'Hidden' Signals: Previously Presumed Visual Signals Likely Generate Air Particle Movement, Pallabi Kundu, Noori Choi, Aaron S. Rundus, Roger D. Santer Jul 2022

Uncovering 'Hidden' Signals: Previously Presumed Visual Signals Likely Generate Air Particle Movement, Pallabi Kundu, Noori Choi, Aaron S. Rundus, Roger D. Santer

Psychology Faculty Publications

Wolf spiders within the genus Schizocosa have become a model system for exploring the form and function of multimodal communication. In terms of male signaling, much past research has focused on the role and importance of dynamic and static visual and substrate-borne vibratory communication. Studies on S. retrorsa, however, have found that female-male pairs were able to successfully mate in the absence of both visual and vibratory stimuli, suggesting a reduced or non-existent role of these signaling modalities in this species. Given these prior findings, it has been suggested that S. retrorsa males may utilize an additional signaling modality during …


Cross-Modal Perception Of Identity By Sound And Taste In Bottlenose Dolphins, Jason N. Bruck, Sam F. Walmsley, Vincent M. Janik May 2022

Cross-Modal Perception Of Identity By Sound And Taste In Bottlenose Dolphins, Jason N. Bruck, Sam F. Walmsley, Vincent M. Janik

Faculty Publications

While studies have demonstrated concept formation in animals, only humans are known to label concepts to use them in mental simulations or predictions. To investigate whether other animals use labels comparably, we studied cross-modal, individual recognition in bottlenose dolphins (Tursiops truncatus) that use signature whistles as labels for conspecifics in their own communication. First, we tested whether dolphins could use gustatory stimuli and found that they could distinguish between water and urine samples, as well as between urine from familiar and unfamiliar individuals. Then, we paired playbacks of signature whistles of known animals with urine samples from either the same …


The Evolution Of Quantitative Sensitivity, Margaret A H Bryer, Sarah E. Koopman, Jessica F. Cantlon, Steven T. Piantadosi, Evan L. Maclean, Joseph M. Baker, Michael J. Beran, Sarah M. Jones, Kerry E. Jordan, Salif Mahamane, Andreas Nieder, Bonnie M. Perdue, Friederike Range, Jeffrey R. Stevens, Masaki Tomonaga, Dorottya Ujfalussy, Jennifer Vonk Jan 2022

The Evolution Of Quantitative Sensitivity, Margaret A H Bryer, Sarah E. Koopman, Jessica F. Cantlon, Steven T. Piantadosi, Evan L. Maclean, Joseph M. Baker, Michael J. Beran, Sarah M. Jones, Kerry E. Jordan, Salif Mahamane, Andreas Nieder, Bonnie M. Perdue, Friederike Range, Jeffrey R. Stevens, Masaki Tomonaga, Dorottya Ujfalussy, Jennifer Vonk

Jeffrey Stevens Publications

The ability to represent approximate quantities appears to be phylogenetically widespread, but the selective pressures and proximate mechanisms favouring this ability remain unknown. We analysed quantity discrimination data from 672 subjects across 33 bird and mammal species, using a novel Bayesian model that combined phylogenetic regression with a model of number psychophysics and random effect components. This allowed us to combine data from 49 studies and calculate the Weber fraction (a measure of quantity representation precision) for each species. We then examined which cognitive, socioecological and biological factors were related to variance in Weber fraction. We found contributions of phylogeny …


Big Five Personality Traits And Political Orientation: An Inquiry Into Political Beliefs, Ian E. Phillips May 2021

Big Five Personality Traits And Political Orientation: An Inquiry Into Political Beliefs, Ian E. Phillips

The Downtown Review

Personality research centered on the Big Five personality traits has heavily impacted our understanding in regards to what forces orient a person on a political spectrum. Examining how personality differences interact with political orientation, this research seeks to provide information on what makes someone either more or less likely to be liberal or conservative based on their temperament. In this paper, previous personality research is synthesized into one discussion, centered on what the effects of each trait are and how they impact political orientation, the heritability of personality, and what implications there are for such research in the realm of …


Dog And Owner Characteristics Predict Training Success, Jeffrey R. Stevens, London M. Wolff, Megan Bosworth, Jill Morstad Jan 2021

Dog And Owner Characteristics Predict Training Success, Jeffrey R. Stevens, London M. Wolff, Megan Bosworth, Jill Morstad

Jeffrey Stevens Publications

Teaching owners how to train their dogs is an important part of maintaining the health and safety of dogs and people. Yet we do not know what behavioral characteristics of dogs and their owners are relevant to dog training or if owner cognitive abilities play a role in training success. The aim of this study is to determine which characteristics of both dogs and owners predict success in completing the American Kennel Club Canine Good Citizen training program. Before the first session of a dog training course, owners completed surveys evaluating the behavior and cognition of their dog and themselves. …


Are Capuchin Monkeys (Sapajus Spp.) Sensitive To Lost Opportunities? The Role Of Opportunity Costs In Intertemporal Choice, Elsa Addessi, Valeria Tierno, Valentina Focaroli, Federica Rossi, Serena Gastaldi, Francesca De Petrillo, Fabio Paglieri, Jeffrey R. Stevens Jan 2021

Are Capuchin Monkeys (Sapajus Spp.) Sensitive To Lost Opportunities? The Role Of Opportunity Costs In Intertemporal Choice, Elsa Addessi, Valeria Tierno, Valentina Focaroli, Federica Rossi, Serena Gastaldi, Francesca De Petrillo, Fabio Paglieri, Jeffrey R. Stevens

Jeffrey Stevens Publications

Principles of economics predict that the costs associated with obtaining rewards can influence choice. When individuals face choices between a smaller, immediate option and a larger, later option, they often experience opportunity costs associated with waiting for delayed rewards because they must forego the opportunity to make other choices. We evaluated how reducing opportunity costs affects delay tolerance in capuchin monkeys. After choosing the larger option, in the High cost condition, subjects had to wait for the delay to expire, whereas in the Low cost different and Low cost same conditions, they could perform a new choice during the delay. …


Effects Of Human-Animal Interactions On Affect And Cognition, Elise L. Thayer, Jeffrey R. Stevens Jan 2021

Effects Of Human-Animal Interactions On Affect And Cognition, Elise L. Thayer, Jeffrey R. Stevens

Jeffrey Stevens Publications

Human-animal interaction has clear positive effects on people’s affect and stress. But less is known about how animal interactions influence cognition. We draw parallels between animal interactions and exposure to natural environments, a research area that shows clear improvements in cognitive performance. The aim of this study is to investigate whether interacting with animals similarly enhances cognitive performance, specifically executive functioning. To test this, we conducted two experiments in which we had participants self-report their affect and complete a series of cognitive tasks (long-term memory, attentional control, and working memory) before and after either a brief interaction with a dog …


Bottlenose Dolphin (Tursiops Truncatus) Vocal Responses To Sonar And Spectrally Pink Background Noise, Maria Zapetis May 2019

Bottlenose Dolphin (Tursiops Truncatus) Vocal Responses To Sonar And Spectrally Pink Background Noise, Maria Zapetis

Dissertations

As human populations rise, the level of man-made noise increases globally. Naval sonar and boat traffic are underwater sound sources of particular concern to marine mammal welfare. To better understand the impact of these noise increases on cetaceans, studies can explore animals’ behavioral changes in response to noise. Studies have investigated the ‘dose-response’ relationship between the received sound pressure level of sonar signals and the behavior of cetaceans in the wild, but exposure studies in controlled environments are limited. The studies in this dissertation examined bottlenose dolphin vocal modifications during various experimental noise treatments. Acoustic recordings previously obtained for bottlenose …


Behavioral Assessment Of Social Structure And Guest Provisioning Program Participation Of Zoo-Housed Giraffes (Giraffa Camelopardalis) Under Varying Spatial Availability., Fatima Ramis Jan 2019

Behavioral Assessment Of Social Structure And Guest Provisioning Program Participation Of Zoo-Housed Giraffes (Giraffa Camelopardalis) Under Varying Spatial Availability., Fatima Ramis

UNF Graduate Theses and Dissertations

Close encounters with animals are considered integral for visitors and are trademark components of traditional educational engagement in zoological parks. As capacity for up-close encounters continue to increase with a simultaneous development in the field of animal welfare science, behavioral assessments on the role of common close encounters is timely. Giraffes (Giraffa camelopardalis) visitor feeding programs are established in approximately 57% of institutions accredited by Association of Zoos and Aquariums. Due to successful breeding and capacity building for zoological giraffe populations, this percentage will likely continue to increase. There is a great deal of variation in the environmental …


Bubble Stream Production By Belugas (Delphinapterus Leucas), Megan Slack Aug 2018

Bubble Stream Production By Belugas (Delphinapterus Leucas), Megan Slack

Theses

Bubble stream production in belugas has been poorly characterized and its function is not well understood. I examined behavioral states when producing bubble streams (“bubbling”), and when bubbling calls, to determine whether bubbling was significantly associated with a particular call category or behavioral state. Using 19 hours of video and audio recordings collected over a two-day period, I quantified bubble streams of a 4-month old calf and an unrelated adult female housed together. Based on the overall activity budgets and pool of vocalizations for both animals, I calculated the expected counts of bubble streams with and without vocalizations, assuming that …


Social Contact Patterns Can Buffer Costs Of Forgetting In The Evolution Of Cooperation, Jeffrey R. Stevens, Jan K. Woike, Lael J. Schooler, Stefan Lindner, Thorsten Pachur Jan 2018

Social Contact Patterns Can Buffer Costs Of Forgetting In The Evolution Of Cooperation, Jeffrey R. Stevens, Jan K. Woike, Lael J. Schooler, Stefan Lindner, Thorsten Pachur

Jeffrey Stevens Publications

Analyses of the evolution of cooperation often rely on two simplifying assumptions: (i) individuals interact equally frequently with all social network members and (ii) they accurately remember each partner's past cooperation or defection. Here, we examine how more realistic, skewed patterns of contact—in which individuals interact primarily with only a subset of their network's members—influence cooperation. In addition, we test whether skewed contact patterns can counteract the decrease in cooperation caused by memory errors (i.e. forgetting). Finally, we compare two types of memory error that vary in whether forgotten interactions are replaced with random actions or with actions from previous …


A New Taxonomy Of Altruism In Terms Of Prosocial Behaviors, Kristin Kaiser Jun 2017

A New Taxonomy Of Altruism In Terms Of Prosocial Behaviors, Kristin Kaiser

Dialogue & Nexus

The definition of altruism has been studied, explained, and even confused by many scholars in various fields. The term itself has been inappropriately used to describe prosocial behaviors that do not fall within the definition of altruism. An evaluation of Grant Ramsey’s taxonomy of altruism, which includes biological altruism, psychological altruism, and helping altruism, proves that it is not adequate in categorizing organism’s behaviors. A new taxonomy, with the branches of kin selection, reciprocity, and aesthetic altruism, is presented and explained to clarify the definition of altruism and alleviate confusion about how to describe prosocial behaviors. Both naming systems are …


Cognitive Phenotypes And The Evolution Of Animal Decisions, Tamra C. Mendelson, Courtney L. Fitzpatrick, Mark E. Hauber, Charles H. Pence, Rafael L. Rodríguez, Rebecca J. Safran, Caitlin A. Stern, Jeffrey R. Stevens Jan 2016

Cognitive Phenotypes And The Evolution Of Animal Decisions, Tamra C. Mendelson, Courtney L. Fitzpatrick, Mark E. Hauber, Charles H. Pence, Rafael L. Rodríguez, Rebecca J. Safran, Caitlin A. Stern, Jeffrey R. Stevens

Faculty Publications

Despite the clear fitness consequences of animal decisions, the science of animal decision making in evolutionary biology is underdeveloped compared with decision science in human psychology. Specifically, the field lacks a conceptual framework that defines and describes the relevant components of a decision, leading to imprecise language and concepts. The ‘judgment and decision-making’ (JDM) framework in human psychology is a powerful tool for framing and understanding human decisions, and we apply it here to components of animal decisions, which we refer to as ‘cognitive phenotypes’. We distinguish multiple cognitive phenotypes in the context of a JDM framework and highlight empirical …


Evidence For Animal Grief?, Carolyn Ristau Jan 2016

Evidence For Animal Grief?, Carolyn Ristau

Animal Sentience

The nature of evidence appropriate to the study of animal emotion (and cognition) is discussed in this review with reference to Barbara King’s book. How Animals Grieve is beautifully written, but it intermixes examples meeting King’s criteria for evidence of grief with other poignant but far less convincing examples. Yet, as noted earlier by Griffin (1958/1974), “Excessive caution can sometimes lead one as far astray as rash enthusiasm.” King cites strong evidence from long-term scientific field studies, often involving known individuals; from videotapes; from convergent evidence in neurophysiological studies; and, notwithstanding possible emotional bias, from animals living closely with humans. …


The Domain Specificity Of Intertemporal Choice In Pinyon Jays, Jeffrey R. Stevens, Bryce Kennedy, Dina Morales, Marianna Burks Jan 2016

The Domain Specificity Of Intertemporal Choice In Pinyon Jays, Jeffrey R. Stevens, Bryce Kennedy, Dina Morales, Marianna Burks

Jeffrey Stevens Publications

When choosing between a piece of cake now versus a slimmer waistline in the future, many of us have difficulty with self-control. Food-caching species, however, regularly hide food for later recovery, sometimes waiting months before retrieving their caches. It remains unclear whether these long-term choices generalize outside of the caching domain. We hypothesized that the ability to save for the future is a general tendency that cuts across different situations. To test this hypothesis, we measured and experimentally manipulated caching to evaluate its relationship with operant measures of self-control in pinyon jays (Gymnorhinus cyanocephalus). We found no correlation …


Reflections Of The Social Environment In Chimpanzee Memory: Applying Rational Analysis Beyond Humans, Jeffrey R. Stevens, Julian N. Marewski, Lael J. Schooler, Ian C. Gilby Jan 2016

Reflections Of The Social Environment In Chimpanzee Memory: Applying Rational Analysis Beyond Humans, Jeffrey R. Stevens, Julian N. Marewski, Lael J. Schooler, Ian C. Gilby

Jeffrey Stevens Publications

In cognitive science, the rational analysis framework allows modelling of how physical and social environments impose information-processing demands onto cognitive systems. In humans, for example, past social contact among individuals predicts their future contact with linear and power functions. These features of the human environment constrain the optimal way to remember information and probably shape how memory records are retained and retrieved. We offer a primer on how biologists can apply rational analysis to study animal behaviour. Using chimpanzees (Pan troglodytes) as a case study, we modelled 19 years of observational data on their social contact patterns. Much …


Intertemporal Similarity: Discounting As A Last Resort, Jeffrey R. Stevens Jan 2016

Intertemporal Similarity: Discounting As A Last Resort, Jeffrey R. Stevens

Jeffrey Stevens Publications

Standard models of intertemporal choice assume that individuals discount future payoffs by integrating reward amounts and time delays to generate a discounted value. Alternative models propose that, rather than integrate across them, individuals compare within attributes (amounts and delays) to determine if differences in one attribute outweigh differences in another attribute. For instance, Leland (2002) and Rubinstein (2003) propose models that 1) compare the two reward amounts to determine whether they are similar, 2) compare the similarity of the two time delays, and then 3) make a decision based on these similarity judgments. Here, I tested discounting models against attribute-based …


Evolutionary Pressures On Primate Intertemporal Choice, Jeffrey R. Stevens May 2014

Evolutionary Pressures On Primate Intertemporal Choice, Jeffrey R. Stevens

Department of Psychology: Faculty Publications

From finding food to choosing mates, animals must make intertemporal choices that involve fitness benefits available at different times. Species vary dramatically in their willingness to wait for delayed rewards. Why does this variation across species exist? An adaptive approach to intertemporal choice suggests that time preferences should reflect the temporal problems faced in a species' environment. Here, I use phylogenetic regression to test whether allometric factors (relating to body size), relative brain size, and social group size predict how long 13 primate species will wait in laboratory intertemporal choice tasks. Controlling for phylogeny, a composite allometric factor that includes …


Visual Search And Attention In Blue Jays (Cyanocitta Cristata): Associative Cuing And Sequential Priming, Kazuhiro Goto, Alan B. Bond, Marianna Burks, Alan C. Kamil Apr 2014

Visual Search And Attention In Blue Jays (Cyanocitta Cristata): Associative Cuing And Sequential Priming, Kazuhiro Goto, Alan B. Bond, Marianna Burks, Alan C. Kamil

Alan Bond Publications

Visual search for complex natural targets requires focal attention, either cued by predictive stimulus associations or primed by a representation of the most recently detected target. Because both processes can focus visual attention, cuing and priming were compared in an operant search task to evaluate their relative impacts on performance and to determine the nature of their interaction in combined treatments. Blue jays were trained to search for pairs of alternative targets among distractors. Informative or ambiguous color cues were provided before each trial, and targets were presented either in homogeneous blocked sequences or in constrained random order. Initial task …


Direct And Relational Representation During Transitive List Linking In Pinyon Jays (Gymnorhinus Cyanocephalus), Cynthia Wei, Alan Kamil, Alan B. Bond Feb 2014

Direct And Relational Representation During Transitive List Linking In Pinyon Jays (Gymnorhinus Cyanocephalus), Cynthia Wei, Alan Kamil, Alan B. Bond

Alan Bond Publications

The authors used the list-linking procedure (Treichler & Van Tilburg, 1996) to explore the processes by which animals assemble cognitive structures from fragmentary and often contradictory data. Pinyon jays (Gymnorhinus cyanocephalus) were trained to a high level of accuracy on two implicit transitive lists. They were then given linkage training on the single pair that linked the two lists into a composite, 10-item hierarchy. Following linkage training, the birds were tested on nonadjacent probe pairs drawn both from within (B-D and 2–4) and between (D-1, E-2, B-2, C-3) each original list. Linkage training resulted in a significant transitory disruption in …


Timing Of Developmental Stress And Phenotypic Plasticity: Effects Of Nutritional Stress At Different Developmental Periods On Physiological And Cognitive-Behavioral Traits In The Zebra Finch (Taeniopygia Guttata), Buddhamas Kriengwatana Aug 2013

Timing Of Developmental Stress And Phenotypic Plasticity: Effects Of Nutritional Stress At Different Developmental Periods On Physiological And Cognitive-Behavioral Traits In The Zebra Finch (Taeniopygia Guttata), Buddhamas Kriengwatana

Electronic Thesis and Dissertation Repository

Developmentally plastic organisms can respond to stressful environmental conditions by altering multiple aspects of their phenotype, often in a permanent fashion. The timing of developmental stress influences these phenotypic alterations because the prioritization of resources to traits necessary to overcome the stressor may be costly for the development of other traits. Despite the importance of this timing, few studies in birds have accounted for it, and those that have usually examined the effect on a single or few variables. This dissertation addresses the outstanding issues regarding i) the effects of timing of developmental stress on developmental plasticity, and ii) the …


The Effect Of Visual Wulst Lesions And Trigeminal Nerve Sectioning On The Discrimination Of Magnetic Inclination In The Homing Pigeon (Columba Livia), Merissa Acerbi Jan 2013

The Effect Of Visual Wulst Lesions And Trigeminal Nerve Sectioning On The Discrimination Of Magnetic Inclination In The Homing Pigeon (Columba Livia), Merissa Acerbi

Honors Projects

The ability of homing pigeons to return to their loft from unknown places has fascinated scientists for centuries. It is well established that homing pigeons, like migratory birds, posses an innate magnetic inclination compass to determine direction by measuring the angle between the magnetic field vector and the Earth's surface. Recent work has indicated that the avian magnetic compass is light mediated and appears to mediate magnetic information to the brain. This occurs via a visual pathway with processing in the visual Wulst area of the forebrain. There is, however, also evidence from other avian species that magnetic direction may …


The Lives Of Others: Social Rationality In Animals, Jeffrey R. Stevens, Andrew J. King Jan 2013

The Lives Of Others: Social Rationality In Animals, Jeffrey R. Stevens, Andrew J. King

Jeffrey Stevens Publications

Darwin (1871) boldly claimed that humans and other animals differ very little in their cognition; a statement that has raised the ire of many scientists (Bolhuis & Wynne, 2009; Penn, Holyoak, & Povinelli, 2008). Rather than stating this continuity as a fact, we will explore the similarities and differences between humans and animals in the social rationality of their decision making. We find this a fruitful exercise because it can profit researchers of both humans and animals. Our purpose here is to provide an evolutionary background of social rationality: Why do animals attend to the lives of others? To this …


Picture Recognition Of Food By Macaques (Macaca Silenus), Peter G. Judge Sep 2011

Picture Recognition Of Food By Macaques (Macaca Silenus), Peter G. Judge

Faculty Journal Articles

Pictorial representations of three-dimensional objects are often used to investigate animal cognitive abilities; however, investigators rarely evaluate whether the animals conceptualize the two-dimensional image as the object it is intended to represent. We tested for picture recognition in lion-tailed macaques by presenting five monkeys with digitized images of familiar foods on a touch screen. Monkeys viewed images of two different foods and learned that they would receive a piece of the one they touched first. After demonstrating that they would reliably select images of their preferred foods on one set of foods, animals were transferred to images of a second …


Parental Precaution: Neurobiological Means And Adaptive Ends, Jennifer Hahn-Holbrook, Colin Holbrook, Martie G. Haselton Jan 2011

Parental Precaution: Neurobiological Means And Adaptive Ends, Jennifer Hahn-Holbrook, Colin Holbrook, Martie G. Haselton

Psychology Faculty Articles and Research

Humans invest precious reproductive resources in just a few offspring, who remain vulnerable for an extended period of their lifetimes relative to other primates. Therefore, it is likely that humans evolved a rich precautionary psychology that assists in the formidable task of protecting offspring. In this review, we integrate precautionary behaviors during pregnancy and postpartum with the adaptive functions they may serve and what is known of their biological mediators, particularly brain systems motivating security and attachment. We highlight the role of reproductive hormones in (i) priming parental affiliation with young to incentivize offspring protection, (ii) focusing parental attention on …


Mechanisms For Decisions About The Future, Jeffrey R. Stevens Jan 2011

Mechanisms For Decisions About The Future, Jeffrey R. Stevens

Jeffrey Stevens Publications

Evolutionary and psychological perspectives on decision making remain largely separate endeavors. The bounded rationality approach integrates these two perspectives by focusing on simple, plausible mechanisms of decision making and the cognitive capacities needed to implement these mechanisms. Decisions about the future provide a class of decisions that lend themselves to a bounded rationality approach. Though many different mechanisms may exist for making decisions about the future, only a subset of these mechanisms actually require a representation of the future. The bounded rationality approach helps focus on the cognitive capacities and decision mechanisms that are necessary for a full understanding of …


Application Of Microsatellite Dna Markers To Discriminate Maternal And Genetic Effects On Scalation And Behavior In Multiply-Sired Garter Snake Litters, Gordon Burghardt Jan 2007

Application Of Microsatellite Dna Markers To Discriminate Maternal And Genetic Effects On Scalation And Behavior In Multiply-Sired Garter Snake Litters, Gordon Burghardt

Gordon Burghardt

Incomplete knowledge of pedigrees sometimes limits the methods of estimating quantitative genetic parameters (heritability, genetic correlation) in nature and may result in estimates that are inflated by nongenetic sources of variation. North American garter snakes and their allies provide a model system for investigating evolutionary quantitative genetics, but estimates of quantitative genetic parameters in these snakes are mostly based on offspring-dam regression and full-sib analysis, methods that fail to discriminate between maternal genetic, maternal environmental, and direct genetic effects on traits of interest. Using data from the garter snake Thamnophis sirtalis, we demonstrate that microsatellite DNA markers can be used …


The Selfish Nature Of Generosity: Harassment And Food Sharing In Primates, Jeffrey R. Stevens Jan 2004

The Selfish Nature Of Generosity: Harassment And Food Sharing In Primates, Jeffrey R. Stevens

Jeffrey Stevens Publications

Animals may share food to gain immediate or delayed fitness benefits. Previous studies of sharing have concentrated on delayed benefits such as reciprocity, trade and punishment. This study tests an alternative model (the harassment or sharing–under–pressure hypothesis) in which a food owner immediately benefits because sharing avoids costly harassment from a beggar. I present an experiment that varies the potential ability of the beggar to harass, and of the owner to defend the food, to examine the effects of harassment on food sharing in two primate species: chimpanzees (Pan troglodytes) and squirrel monkeys (Saimiri boliviensis). For …


Discounting And Reciprocity In An Iterated Prisoner’S Dilemma, David W. Stephens, Colleen M. Mclinn, Jeffrey R. Stevens Jan 2002

Discounting And Reciprocity In An Iterated Prisoner’S Dilemma, David W. Stephens, Colleen M. Mclinn, Jeffrey R. Stevens

Jeffrey Stevens Publications

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 strong preferences for immediate benefits (that is, temporal discounting) might explain the fragility of cooperative equilibria. We studied the effects of discounting and strategic reciprocity on cooperation in captive blue jays. Our results demonstrate an interaction between discounting and reciprocity. Blue jays show high stable levels of cooperation in treatments with …