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Full-Text Articles in Biological Psychology

Sex Differences In Lateral Hypothalamic Extracellular Glucose Concentrations During Cumulative Dosing Of Methamphetamine In Rats, Joshua A. Jolton Apr 2022

Sex Differences In Lateral Hypothalamic Extracellular Glucose Concentrations During Cumulative Dosing Of Methamphetamine In Rats, Joshua A. Jolton

Honors Theses

The present study experimentally investigated sex differences in lateral hypothalamic glucose concentrations following cumulative dosing of methamphetamine. Male (n=17) and female (n=11) rats were surgically implanted with enzyme-based glucose biosensors in the lateral hypothalamus. Rats then received a saline injection followed by four methamphetamine doses (0.025 mg/kg, 0.05 mg/kg, 0.1 mg/kg, and 0.2 mg/kg) spaced 55 minutes apart. We found that while there was a general decrease in glucose baseline throughout the study for both sexes, the magnitude of the decrease was significantly greater in females compared to males. On a rapid timescale, fixed sex effects existed at the lower …


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 …


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 …


No Association Between An Oxytocin Receptor Genetic Variant And Depressive Symptoms, Rachel Sisley, Grace Sullivan, Scott Stoltenberg Ph. D. Apr 2020

No Association Between An Oxytocin Receptor Genetic Variant And Depressive Symptoms, Rachel Sisley, Grace Sullivan, Scott Stoltenberg Ph. D.

UCARE Research Products

• Depression has the greatest impact on daily functioning capability of all diseases and adversely effects individuals globally (Flint & Kendler, 2014). • Human capital value of these losses has been about $40 billion dollars annually (Kessler, 2012). • Analysis of the genetic and biological systems associated with depressive symptoms, such as the oxytocin system, could lead to identifying risk variants and possible treatment development. • Genetic Variation in OXTR is associated with a variation in depressive symptoms including low selfesteem, pessimism, and low self-efficacy, etc. (Conner et al., 2018). • The A allele of the SNP rs53576 is considered …


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 …


Examination Of Methamphetamine Reinstatement In Female And Male Rats: A Pre-Clinical Model Of Relapse, Steven T. Pittenger Jun 2016

Examination Of Methamphetamine Reinstatement In Female And Male Rats: A Pre-Clinical Model Of Relapse, Steven T. Pittenger

Department of Psychology: Dissertations, Theses, and Student Research

Methamphetamine (meth) dependence is often characterized by persistent and chronic relapse (i.e., return to drug use). There is growing pre-clinical and human evidence suggesting females are at greater risk to relapse. The set of studies presented in this dissertation extended this limited evidence by identifying sex-dependent neural substrates correlated with meth-triggered reinstatement (Experiment 1) and by examining sex-differences in reinstatement triggered by drugs of abuse that are commonly co-abused with meth (Experiment 2). Female and male rats were trained to self-administer meth, received subsequent extinction sessions, and then tested for reinstatement. In Experiment 1, rats were perfused following reinstatement testing …


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 …


Oprm1 Rs1799971 Genotype Predicts Drinking Behavior In Males, But Not Females, Sarah Hughes Berheim, Carmen Ochoa, Grace Sullivan, Scott F. Stoltenberg Apr 2015

Oprm1 Rs1799971 Genotype Predicts Drinking Behavior In Males, But Not Females, Sarah Hughes Berheim, Carmen Ochoa, Grace Sullivan, Scott F. Stoltenberg

UCARE Research Products

• The prevalence of alcohol disorders costs Americans $223.5 billion yearly due mostly from losses in workplace productivity, as well as health care and criminal justice expenses (CDC, 2016).

• Maximum number of drinks consumed in a 24 hour period is a valid indicator of dangerous drinking behavior and may reflect an increased tolerance for high levels of alcohol (Edenberg, 2016).

• Awareness of factors related to such heavy drinking is important for targeting interventions for dangerous alcohol use.

• Men drink significantly more than women, with about 4.5% of men and 2.5% of women meeting the diagnostic criteria for …


Repeated Effects Of The Neurotensin Receptor Agonist Pd149163 In Three Animal Tests Of Antipsychotic Activity: Assessing For Tolerance And Cross-Tolerance To Clozapine, Shinnyi Chou, Collin Davis, Sean Jones, Ming Li Jan 2015

Repeated Effects Of The Neurotensin Receptor Agonist Pd149163 In Three Animal Tests Of Antipsychotic Activity: Assessing For Tolerance And Cross-Tolerance To Clozapine, Shinnyi Chou, Collin Davis, Sean Jones, Ming Li

Department of Psychology: Faculty Publications

Neurotensin is an endogenous neuropeptide closely associated with the mesolimbic dopaminergic system and shown to possess antipsychotic-like effects. In particular, acute neurotensin receptor activation can inhibit conditioned avoidance response (CAR), attenuate phencyclidine (PCP)-induced prepulse inhibition (PPI) disruptions, and reverse PCP-induced hyperlocomotion. However, few studies have examined the long term effects of repeated neurotensin receptor activation and results are inconsistent. Since clinical administration of antipsychotic therapy often requires a prolonged treatment schedule, here we assessed the effects of repeated activation of neurotensin receptors using an NTS1 receptor selective agonist, PD149163, in 3 behavioral tests of antipsychotic activity. We also investigated whether …


A Quantitative Analysis Of The Value-Enhancing Effects Of Nicotine, Bupropion, And Varenicline In Male And Female Rats, Scott Barrett Dec 2014

A Quantitative Analysis Of The Value-Enhancing Effects Of Nicotine, Bupropion, And Varenicline In Male And Female Rats, Scott Barrett

Department of Psychology: Dissertations, Theses, and Student Research

Smoking and tobacco dependence are serious health concerns in the United States and globally. Reward via the pharmacological effects of nicotine are believed to be the principal motivating factor that drive tobacco dependence. Research reveals differences in sensitivity between males and females to the motivational effects of nicotine in tobacco use. Enhancement of reinforcement value of non-nicotine rewards contributes to overall nicotine reward. Similar value-enhancing effects have been observed by the two most commonly prescribed smoking cessation aids, bupropion and varenicline. The present dissertation investigated the value-enhancing effects of nicotine, bupropion and varenicline in both male and female rats using …


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 …


Effects Of 5-Hydroxytryptamine 2c Receptor Agonist Mk212 And 2a Receptor Antagonist Mdl100907 On Maternal Behavior In Postpartum Female Rats, Weihai Chen, Qi Zhang, Wenxin Su, Yu Yang, Jing Qiao, Nan Sui, Ming Li Feb 2014

Effects Of 5-Hydroxytryptamine 2c Receptor Agonist Mk212 And 2a Receptor Antagonist Mdl100907 On Maternal Behavior In Postpartum Female Rats, Weihai Chen, Qi Zhang, Wenxin Su, Yu Yang, Jing Qiao, Nan Sui, Ming Li

Department of Psychology: Faculty Publications

Maternal behavior in rats is a highly motivated and well-organized social behavior. Given the known roles of serotonin (5-HT) in emotion, motivation, social behavior, and major depression – and its known interaction with dopamine – it is likely that serotonin also plays a crucial role in this behavior. So far, there are surprisingly few studies focusing on 5-HT in maternal behavior, except for maternal aggression. In the present study,we examined the effects of 5-HT2C receptor agonism and 5-HT2A receptor antagonism on maternal behavior in postpartum female rats.We hypothesized that activation of 5-HT2C receptors and blockade of 5-HT …


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 …


Iptakalim Attenuates Self-Administration And Acquired Goal-Tracking Behavior Controlled By Nicotine, S. Charntikov, N. Swalve, Steven T. Pittenger, K. Fink, S. Schepers, G. C. Hadlock, A. E. Fleckenstein, G. Hu, Ming Li, Rick A. Bevins Dec 2013

Iptakalim Attenuates Self-Administration And Acquired Goal-Tracking Behavior Controlled By Nicotine, S. Charntikov, N. Swalve, Steven T. Pittenger, K. Fink, S. Schepers, G. C. Hadlock, A. E. Fleckenstein, G. Hu, Ming Li, Rick A. Bevins

Department of Psychology: Faculty Publications

Iptakalim is an ATP-sensitive potassium channel opener, as well as an a4b2-containing nicotinic acetylcholine receptor (nAChR) antagonist. Pretreatment with iptakalim diminishes nicotine-induced dopamine (DA) and glutamate release in the nucleus accumbens. This neuropharmacological profile suggests that iptakalim may be useful for treatment of nicotine dependence. Thus, we examined the effects of iptakalim in two preclinical models. First, the impact of iptakalim on the interoceptive stimulus effect of nicotine was evaluated by training rats in a discriminated goal-tracking task that included intermixed nicotine (0.4 mg/kg, SC) and saline sessions. Sucrose was intermittently presented in a responseindependent manner only on nicotine sessions. …


Repeated Asenapine Treatment Produces A Sensitization Effect In Two Preclinical Tests Of Antipsychotic Activity, Rongyin Qin, Yingzhu Chen, Ming Li Dec 2013

Repeated Asenapine Treatment Produces A Sensitization Effect In Two Preclinical Tests Of Antipsychotic Activity, Rongyin Qin, Yingzhu Chen, Ming Li

Department of Psychology: Faculty Publications

Among several commonly used atypical antipsychotic drugs, olanzapine and risperidone cause a sensitization effect in the conditioned avoidance response (CAR) and phencyclidine (PCP)- induced hyperlocomotion paradigms – two well established animal tests of antipsychotic drugs, whereas clozapine causes a tolerance effect. Asenapine is a novel antipsychotic drug recently approved for the treatment of schizophrenia and manic disorders. It shares several receptor binding sites and behavioral features with other atypical antipsychotic drugs. However, it is not clear what type of repeated effect (sensitization or tolerance) asenapine would induce, and whether such an effect is transferrable to other atypicals. In this study, …


Olanzapine Sensitization And Clozapine Tolerance: From Adolescence To Adulthood In The Conditioned Avoidance Response Model, Jing Qiao, Hong Li, Ming Li Jan 2013

Olanzapine Sensitization And Clozapine Tolerance: From Adolescence To Adulthood In The Conditioned Avoidance Response Model, Jing Qiao, Hong Li, Ming Li

Department of Psychology: Faculty Publications

Disruption of conditioned avoidance response (CAR) in rodents is one trademark feature of many antipsychotic drugs. In adult rats, repeated olanzapine (OLZ) treatment causes an enhanced disruption of avoidance response (sensitization), whereas repeated clozapine (CLZ) treatment causes a decreased disruption (tolerance). The present study addressed (1) whether OLZ sensitization and CLZ tolerance can be induced in adolescent rats, and (2) the extent to which OLZ sensitization and CLZ tolerance induced in adolescence persists into adulthood. Male adolescent Sprague–Dawley rats (approximate postnatal days (BP) 43–47) were first treated with OLZ (1.0 or 2.0 mg/kg, subcutaneously (sc)) or CLZ (10 or 20 …


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 …


Conditioned Response Evoked By Nicotine Conditioned Stimulus Preferentially Induces C-Fos Expression In Medial Regions Of Caudate-Putamen, Sergios Charntikov, Matthew E. Tracy, Changjiu Zhao, Ming Li, Rick A. Bevins Jan 2012

Conditioned Response Evoked By Nicotine Conditioned Stimulus Preferentially Induces C-Fos Expression In Medial Regions Of Caudate-Putamen, Sergios Charntikov, Matthew E. Tracy, Changjiu Zhao, Ming Li, Rick A. Bevins

Department of Psychology: Faculty Publications

Nicotine has both unconditioned and conditioned stimulus properties. Conditioned stimulus properties of nicotine may contribute to the tenacity of nicotine addiction. The purpose of this experiment was to use neurohistochemical analysis of rapidly developing c-Fos protein to elucidate neurobiological loci involved in the processing of nicotine as an interoceptive conditioned stimulus (CS). Rats were injected (SC) in an intermixed fashion with saline or nicotine (16 sessions of each) and placed in conditioning chambers where they were given one of the three conditions depending on group assignment: (a) nicotine paired 100% of the time with intermittent access to sucrose (nicotine-CS condition), …


Iptakalim Preferentially Decreases Nicotine-Induced Hyperlocomotion In Phencyclidine-Sensitized Rats: A Potential Dual Action Against Nicotine Addiction And Psychosis, Nick Volf, Gang Hu, Ming Li Jan 2012

Iptakalim Preferentially Decreases Nicotine-Induced Hyperlocomotion In Phencyclidine-Sensitized Rats: A Potential Dual Action Against Nicotine Addiction And Psychosis, Nick Volf, Gang Hu, Ming Li

Department of Psychology: Faculty Publications

Objective: Iptakalim is a putative ATP-sensitive potassium (KATP) channel opener. It is also a novel nicotinic acetylcholine receptor (nAChR) blocker and can antagonize nicotine-induced increase in dopamine release in the nucleus accumbens. Our recent work also shows that iptakalim exhibits a clozapine-like atypical antipsychotic profile, indicating that iptakalim may possess a dual action against nicotine addiction and schizophrenia.

Methods: The present study examined the potential therapeutic effects of iptakalim on nicotine use in schizophrenia. We created an animal model of comorbidity of nicotine addiction and schizophrenia by injecting male Sprague-Dawley rats with nicotine (0.40 mg/kg, subcutaneously[sc]) or saline, in combination …


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 …


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 …