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Full-Text Articles in Behavior and Ethology

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 …


Developing A Computer-Controlled Treat Dispenser For Canine Operant Conditioning, Walker Arce, Jeffrey R. Stevens Jan 2020

Developing A Computer-Controlled Treat Dispenser For Canine Operant Conditioning, Walker Arce, Jeffrey R. Stevens

Jeffrey Stevens Publications

When performing canine operant conditioning studies, the delivery of the reward can be a limiting factor of the study. While there are a few commercially available options for automatically delivering rewards, they generally require manual input, such as using a remote control, in accordance with the experiment script. This means that human reaction times and transmission distances can cause interruptions to the flow of the experiment. The potential for development of non-supervised conditioning studies is limited by this same factor. To remedy this, we retrofitted an off-the-shelf treat dispenser with new electronics that allow it to be remotely controllable as …


The Role Of Mesotocin On Social Bonding In Pinyon Jays, Juan Duque, Tanner Rasmussen, Anna Rodriguez, Jeffrey R. Stevens Jan 2020

The Role Of Mesotocin On Social Bonding In Pinyon Jays, Juan Duque, Tanner Rasmussen, Anna Rodriguez, Jeffrey R. Stevens

Jeffrey Stevens Publications

The neuropeptide oxytocin influences mammalian social bonding by facilitating the building and maintenance of parental, sexual, and same‐sex social relationships. However, we do not know whether the function of the avian homologue mesotocin is evolutionarily conserved across birds. While it does influence avian prosocial behavior, mesotocin's role in avian social bonding remains unclear. Here, we investigated whether mesotocin regulates the formation and maintenance of same‐sex social bonding in pinyon jays (Gymnorhinus cyanocephalus), a member of the crow family. We formed squads of four individually housed birds. In the first, “pair‐formation” phase of the experiment, we repeatedly placed pairs …


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 …


Mesotocin Influences Pinyon Jay Prosociality, Juan Duque, Whitney Leichner, Holly Ahmann, Jeffrey R. Stevens Jan 2018

Mesotocin Influences Pinyon Jay Prosociality, Juan Duque, Whitney Leichner, Holly Ahmann, Jeffrey R. Stevens

Jeffrey Stevens Publications

Many species exhibit prosocial behavior, in which one individual’s actions benefit another individual, often without an immediate benefit to itself. The neuropeptide oxytocin is an important hormonal mechanism influencing prosociality in mammals, but it is unclear whether the avian homologue mesotocin plays a similar functional role in birds. Here, we experimentally tested prosociality in pinyon jays (Gymnorhinus cyanocephalus), a highly social corvid species that spontaneously shares food with others. First, we measured prosocial preferences in a prosocial choice task with two different payoff distributions: Prosocial trials delivered food to both the subject and either an empty cage or a partner …


Is Cooperative Memory Special? The Role Of Costly Errors, Context, And Social Network Size When Remembering Cooperative Actions, Jeffrey R. Stevens, Tim Winke Oct 2017

Is Cooperative Memory Special? The Role Of Costly Errors, Context, And Social Network Size When Remembering Cooperative Actions, Jeffrey R. Stevens, Tim Winke

Jeffrey Stevens Publications

Theoretical studies of cooperative behavior have focused on decision strategies, such as tit-for-tat, that depend on remembering a partner’s last choices. Yet, an empirical study by Stevens et al. (2011) demonstrated that human memory may not meet the requirements that needed to use these strategies. When asked to recall the previous behavior of simulated partners in a cooperative memory task, participants performed poorly, making errors in 10–24% of the trials. However, we do not know the extent to which this task taps specialized cognition for cooperation. It may be possible to engage participants in more cooperative, strategic thinking, which may …


Replicability And Reproducibility In Comparative Psychology, Jeffrey R. Stevens May 2017

Replicability And Reproducibility In Comparative Psychology, Jeffrey R. Stevens

Jeffrey Stevens Publications

Psychology faces a replication crisis. The Reproducibility Project: Psychology sought to replicate the effects of 100 psychology studies. Though 97% of the original studies produced statistically significant results, only 36% of the replication studies did so (Open Science Collaboration, 2015). This inability to replicate previously published results, however, is not limited to psychology (Ioannidis, 2005). Replication projects in medicine (Prinz et al., 2011) and behavioral economics (Camerer et al., 2016) resulted in replication rates of 25 and 61%, respectively, and analyses in genetics (Munafò, 2009) and neuroscience (Button et al., 2013) question the validity of studies in those fields. Science, …


Review Of Bird Brain: An Exploration Of Avian Intelligence By Nathan Emery, Alan B. Bond Jan 2017

Review Of Bird Brain: An Exploration Of Avian Intelligence By Nathan Emery, Alan B. Bond

Avian Cognition Papers

Over the past 30 years, the study of bird behavior has been completely transformed by the ongoing revolution in cognitive psychology, opening up wholly new perspectives on the mental processes underlying such areas as foraging decisions, social intelligence, problem solving, memory encoding, and communication. Although these studies have contributed to a number of recent popular books, until now there has been no attempt to integrate avian cognition and recent findings in avian neuroanatomy and endocrinology into a single account that is attractive and accessible to a general readership. It is a steep challenge, but Nathan Emery has undertaken it in …


Intertemporal Choice And Delayed Gratification, Jeffrey R. Stevens Jan 2017

Intertemporal Choice And Delayed Gratification, Jeffrey R. Stevens

Jeffrey Stevens Publications

A parasitoid wasp has deposited half of her eggs in a host. She now faces the choice between depositing her remaining eggs in the same host or searching for another. Continuing to deposit in the current host provides the immediate payoff of completing her reproductive duties, allowing her to move on to other activities such as foraging or searching for another mate. Searching for another host, in contrast, delays the payoffs of reproducing until a suitable host is found. This wasp faces an intertemporal choice—that is, a choice between options that involve payoffs available at different times (Read, 2004; Stevens, …


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 …


Voluntary Food Sharing In Pinyon Jays: The Role Of Reciprocity And Dominance, Juan F. Duque, Jeffrey R. Stevens Jan 2016

Voluntary Food Sharing In Pinyon Jays: The Role Of Reciprocity And Dominance, Juan F. Duque, Jeffrey R. Stevens

Jeffrey Stevens Publications

Food sharing offers a clear example of prosocial behavior, in which one individual’s actions benefit another. Researchers have proposed a range of hypotheses that explain why food sharing may occur among unrelated individuals. Two such hypotheses, reciprocity and dominance, have been tested in many species, including fish, corvids, rats, bats, and primates, showing that (1) recipients sometimes reciprocate sharing back to previous donors and (2) dominant individuals share more than subordinates. Although primates dominate the study of prosocial behavior, active donation of food is actually quite rare in primates. In contrast, several corvid species spontaneously share food much more frequently. …


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

Jeffrey Stevens 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 …


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 …


Embracing Multiple Definitions Of Learning, Andrew B. Barron, Eileen A. Hebets, Thomas A. Cleland, Courtney L. Fitzpatrick, Mark E. Hauber, Jeffrey R. Stevens Jul 2015

Embracing Multiple Definitions Of Learning, Andrew B. Barron, Eileen A. Hebets, Thomas A. Cleland, Courtney L. Fitzpatrick, Mark E. Hauber, Jeffrey R. Stevens

Eileen Hebets Publications

Definitions of learning vary widely across disciplines, driven largely by different approaches used to assess its occurrence. These definitions can be better reconciled with each other if each is recognized as coherent with a common conceptualization of learning, while appreciating the practical utility of different learning definitions in different contexts.

Learning is a major focus of research in psychology, neuro- science, behavioral ecology, evolutionary theory, and computer science, as well as in many other disciplines. Despite its conceptual prevalence, definitions of learning differ enormously both within and between these disciplines, and new definitions continue to be proposed [1]. Ongoing disputes …


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 …


Changing Room Cues Reduces The Effects Of Proactive Interference In Clark’S Nutcrackers, Nucifraga Columbiana, Jody L. Lewis, Alan C. Kamil, Kate E. Webbink Jan 2013

Changing Room Cues Reduces The Effects Of Proactive Interference In Clark’S Nutcrackers, Nucifraga Columbiana, Jody L. Lewis, Alan C. Kamil, Kate E. Webbink

Avian Cognition Papers

To determine what factors are important for minimizing interference effects in spatial memory, Clark’s Nutcrackers, Nucifraga columbiana were tested for their spatial memory for two serial lists of locations per day. In this experiment two unique landmark sets were either different between List 1 and List 2 or the same. We found that Nutcrackers were most susceptible to interference when the landmark sets were the same. This study suggests that repeatedly testing animal memory in the same room, with the same cues, can hamper recall due to interference.


Differences In Relative Hippocampus Volume And Number Of Hippocampus Neurons Among Five Corvid Species, Kristy L. Gould, Karl E. Gilbertson, Andrew J. Hrvol, Joseph C. Nelson, Abigail L. Seyfer, Rose M. Brantner, Alan C. Kamil Jan 2013

Differences In Relative Hippocampus Volume And Number Of Hippocampus Neurons Among Five Corvid Species, Kristy L. Gould, Karl E. Gilbertson, Andrew J. Hrvol, Joseph C. Nelson, Abigail L. Seyfer, Rose M. Brantner, Alan C. Kamil

Avian Cognition Papers

The relative size of the avian hippocampus (Hp) has been shown to be related to spatial memory and food storing in two avian families, the parids and corvids. Basil et al. [Brain Behav Evol 1996;47: 156-164] examined North American food-storing birds in the corvid family and found that Clark’s nutcrackers had a larger relative Hp than pinyon jays and Western scrub jays. These results correlated with the nutcracker’s better performance on most spatial memory tasks and their strong reliance on stored food in the wild. However, Pravosudov and de Kort [Brain Behav Evol 67 (2006), 1-9] raised questions …


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 …


Do Clark’S Nutcrackers Demonstrate What-Where-When Memory On A Cache-Recovery Task?, Kristy L. Gould, Amy J. Ort, Alan C. Kamil Jan 2012

Do Clark’S Nutcrackers Demonstrate What-Where-When Memory On A Cache-Recovery Task?, Kristy L. Gould, Amy J. Ort, Alan C. Kamil

Avian Cognition Papers

What-where-when (WWW) memory during cache recovery was investigated in six Clark’s nutcrackers. During caching, both red- and blue-colored pine seeds were cached by the birds in holes filled with sand. Either a short (3 day) retention interval (RI) or a long (9 day) RI was followed by a recovery session during which caches were replaced with either a single seed or wooden bead depending upon the color of the cache and length of the retention interval. Knowledge of what was in the cache (seed or bead), where it was located, and when the cache had been made (3 or 9 …


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 …


Coaching Efficacy With Academic Leaders: A Phenomenological Investigation, Deanna Lee Vansickel-Peterson Nov 2010

Coaching Efficacy With Academic Leaders: A Phenomenological Investigation, Deanna Lee Vansickel-Peterson

College of Education and Human Sciences: Dissertations, Theses, and Student Research

The purpose of this psychological phenomenological research was to understand the efficacy of life coaching from the perspective of academic leaders. To date, not one investigation or attempt has been made towards the above stated purpose. This study includes a theoretical overview and a review of the coaching literature from Socrates (469-399 BC) to current day Humanistic theory presented in part by Roger (1902-1987).

This process included data collection from five academic leaders who have been coached for at least two years. Levels of analysis of 365 statements, quote and/or comments produced finding of efficacy in life coaching with academic …


Effects Of Gregariousness, Conspicuousness, And Novelty On Blue Jay (Cyanocitta Cristata) Learned Avoidance And Stimulus Generalization Of Unpalatable Prey, Joyce M. Dykema Apr 2008

Effects Of Gregariousness, Conspicuousness, And Novelty On Blue Jay (Cyanocitta Cristata) Learned Avoidance And Stimulus Generalization Of Unpalatable Prey, Joyce M. Dykema

Avian Cognition Papers

I examined a variety of factors hypothesized to be important in the evolution and maintenance of aposematism. Aposematism occurs when prey individuals advertise their toxic or otherwise aversive nature to potential predators via evolved conspicuous signals. I conducted three experiments in which blue jays (Cyanocitta cristata) were allowed to search a printed grayscale pixilated background for grayscale pixilated moths in an open room. I manipulated moth appearance and food reward, and recorded jay predation on the varying moth stimuli. In my first experiment, I repeated Alatalo & Mappes’ (1996) study examining the effects of prey gregariousness, or grouping, …


K-Means Clustering With Multiresolution Peak Detection, Guanshan Yu, Leen-Kiat Soh, Alan B. Bond May 2005

K-Means Clustering With Multiresolution Peak Detection, Guanshan Yu, Leen-Kiat Soh, Alan B. Bond

Avian Cognition Papers

Clustering is a practical data mining approach of pattern detection. Because of the sensitivity of initial conditions, k-means clustering often suffers from low clustering performance. We present a procedure to refine initial conditions of k-means clustering by analyzing density distributions of a data set before estimating the number of clusters k necessary for the data set, as well as the positions of the initial centroids of the clusters. We demonstrate that this approach indeed improves the accuracy and performance of k-means clustering measured by average intra to interclustering error ratio. This method is applied to the virtual ecology project to …


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 …