Matching Items (13)

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The Rhythm of Running: An Analysis of Preferred Running Tempo

Description

The action of running is difficult to measure, but well worth it to receive valuable information about one of our most basic evolutionary functions. In the context of modern day,

The action of running is difficult to measure, but well worth it to receive valuable information about one of our most basic evolutionary functions. In the context of modern day, recreational runners typically listen to music while running, and so the purpose of this experiment is to analyze the influence of music on running from a more dynamical approach. The first experiment was a running task involving running without a metronome and running with one while setting one's own preferred running tempo. The second experiment sought to manipulate the participant's preferred running tempo by having them listen to the metronome set at their preferred tempo, 20% above their preferred tempo, or 20% below. The purpose of this study is to analyze whether or not rhythmic perturbations different to one's preferred running tempo would interfere with one's preferred running tempo and cause a change in the variability of one's running patterns as well as a change in one's running performance along the measures of step rate, stride length, and stride pace. The evidence suggests that participants naturally entrained to the metronome tempo which influenced them to run faster or slower as a function of metronome tempo. However, this change was also accompanied by a shift in the variability of one's step rate and stride length.

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Date Created
  • 2017-05

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Sit-to-stand task with physical and cognitive perturbations: A comparison of linear and nonlinear methods of analyzing postural data

Description

Variability is inherent in human movement, and poses a challenge to researchers attempting to measure balance. Human movement variability was analyzed using two methods: standard deviation and largest Lyapunov exponent.

Variability is inherent in human movement, and poses a challenge to researchers attempting to measure balance. Human movement variability was analyzed using two methods: standard deviation and largest Lyapunov exponent. The experiment was a sit-to-stand task with physical and cognitive perturbations. The physical perturbation consisted of stable and unstable platform conditions, while the cognitive perturbation consisted of a counting task. The data were collected from 24 healthy young adults. The purpose of this study was to compare the standard deviation and largest Lyapunov exponent as measures of stability, and to determine the Lyapunov exponent's sensitivity to cognitive perturbation. Evidence suggests that the Lyapunov exponent serves as a more accurate indicator of stability than standard deviation, and that it lacks sensitivity to the counting task.

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Date Created
  • 2016-12

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The Trajectory of Thought: Lévy Flight Patterns and Dynamical Systems in Human Memory Foraging

Description

Recent work in free-recall tasks suggest that human memory foraging may follow a Lévy flight distribution – a random walk procedure that is common in other activities of cognitive agents,

Recent work in free-recall tasks suggest that human memory foraging may follow a Lévy flight distribution – a random walk procedure that is common in other activities of cognitive agents, such as animal and human food foraging. This study attempts to draw parallels between memory search and physical search, with the assumption that humans follow similar search patterns in both. To date, research merely equates the two processes (foraging in memory and the physical world) based on a similarity in statistical structure. This study starts with demonstrating a relationship between physical distance traveled and IRIs by having participants list countries. An IRI, inter-retrieval interval, is the time interval between items recalled. The next experiment uses multidimensional scaling (MDS) to derive a Euclidean perceptual space from similarity ratings of freely-recalled items and then maps the trajectory of human thought through this perceptual space. This trajectory can offer a much more compelling comparison to physical foraging behavior. Finally, a possible correlate of Lévy flight foraging is explored called critical slowing down. Statistically significant evidence was found in all three experiments. The discussion connects all three experiments and what their results mean for human memory foraging.

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Date Created
  • 2016-12

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Effects of Videotaped and/or Written Instructions on Learning to Slackline

Description

The human body is a complex system that links mental learning processes and developed muscular capabilities to produce novel movements or refine existing movements. It is well known that skills

The human body is a complex system that links mental learning processes and developed muscular capabilities to produce novel movements or refine existing movements. It is well known that skills are learned and become more refined with practice, however motor skills can develop by watching others perform an action. The current study aims to test the utility of videotaped and/or written instructional methods in teaching novice slackliners. Results showed a significant interaction between group and trial. The video+word group had significantly longer balance times than the control and video groups in trial two. The word group had significantly longer balance times than the control and video groups in trials three and four. A cumulative skill score was not found to be significantly correlated with balance times. Limitations of the current study are discussed, as well as recommendations for future study and applications.

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Date Created
  • 2018-05

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Exploring Intentional and Unintentional Coordination Within Dyads

Description

Humans achieve coordination within and across themselves through the use of coupling. Coupling is the term for an informational linkage that allows two independent processes to eventually coordinate together. Coupling

Humans achieve coordination within and across themselves through the use of coupling. Coupling is the term for an informational linkage that allows two independent processes to eventually coordinate together. Coupling between the motor and respiratory system is evident within people through the signaling of the nervous system. However, little has been known about the degree of coordination that can be attained across two people regarding their respiratory patterns. The current study tested whether unintentional coordination of respiration across two people could be achieved when both people were intentionally coordinating their motor movements. Participants were assigned the position of leader or follower, where the leader followed the rhythm of a metronome to lift their leg to and the follower coordinated their leg-lift with the leader’s using their vision, as instructed. During the experiment the movements of each participant’s knee and their respiration were recorded. Relative phase was used as a measure of coordination. Results show that motor coordination was achieved, consistent with past studies, but that there was no coordination of respiration across the participants. This is most likely due to individual differences in physiology and the lack of coupling between the two separate respiratory systems. Although internal motor-respiratory patterns may have coordinated in a multi-frequency manner within each participant, the outward phasing of their respiration showed no such relationship. This study highlights the importance of a multi-frequency approach when observing coordination within and across physiological systems.

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  • 2020-12

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Causes and consequences of queen-number variation in the California harvester ant Pogonomyrmex californicus

Description

Social insect colonies exhibit striking diversity in social organization. Included in this overwhelming variation in structure are differences in colony queen number. The number of queens per colony varies both

Social insect colonies exhibit striking diversity in social organization. Included in this overwhelming variation in structure are differences in colony queen number. The number of queens per colony varies both intra- and interspecifically and has major impacts on the social dynamics of a colony and the fitness of its members. To understand the evolutionary transition from single to multi-queen colonies, I examined a species which exhibits variation both in mode of colony founding and in the queen number of mature colonies. The California harvester ant Pogonomyrmex californicus exhibits both variation in the number of queens that begin a colony (metrosis) and in the number of queens in adult colonies (gyny). Throughout most of its range, colonies begin with one queen (haplometrosis) but in some populations multiple queens cooperate to initiate colonies (pleometrosis). I present results that confirm co-foundresses are unrelated. I also map the geographic occurrence of pleometrotic populations and show that the phenomenon appears to be localized in southern California and Northern Baja California. Additionally, I provide genetic evidence that pleometrosis leads to primary polygyny (polygyny developing from pleometrosis) a phenomenon which has received little attention and is poorly understood. Phylogenetic and haplotype analyses utilizing mitochondrial markers reveal that populations of both behavioral types in California are closely related and have low mitochondrial diversity. Nuclear markers however, indicate strong barriers to gene flow between focal populations. I also show that intrinsic differences in queen behavior lead to the two types of populations observed. Even though populations exhibit strong tendencies on average toward haplo- or pleometrosis, within population variation exists among queens for behaviors relevant to metrosis and gyny. These results are important in understanding the dynamics and evolutionary history of a distinct form of cooperation among unrelated social insects. They also help to understand the dynamics of intraspecific variation and the conflicting forces of local adaptation and gene flow.

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Created

Date Created
  • 2011

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Psychology of a superorganism

Description

For over a century, researchers have been investigating collective cognition, in which a group of individuals together process information and act as a single cognitive unit. However, I still know

For over a century, researchers have been investigating collective cognition, in which a group of individuals together process information and act as a single cognitive unit. However, I still know little about circumstances under which groups achieve better (or worse) decisions than individuals. My dissertation research directly addressed this longstanding question, using the house-hunting ant Temnothorax rugatulus as a model system. Here I applied concepts and methods developed in psychology not only to individuals but also to colonies in order to investigate differences of their cognitive abilities. This approach is inspired by the superorganism concept, which sees a tightly integrated insect society as the analog of a single organism. I combined experimental manipulations and models to elucidate the emergent processes of collective cognition. My studies show that groups can achieve superior cognition by sharing the burden of option assessment among members and by integrating information from members using positive feedback. However, the same positive feedback can lock the group into a suboptimal choice in certain circumstances. Although ants are obligately social, my results show that they can be isolated and individually tested on cognitive tasks. In the future, this novel approach will help the field of animal behavior move towards better understanding of collective cognition.

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Date Created
  • 2013

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Coordinating Individual Behavior in Collective Processes; Seed Choice in Harvester Ants (Pogonomyrmex californicus)

Description

Social animals benefit from the aggregation of knowledge and cognitive processing power. Part of this benefit comes from individual heterogeneity, which provides the basis to group-level strategies, such as division

Social animals benefit from the aggregation of knowledge and cognitive processing power. Part of this benefit comes from individual heterogeneity, which provides the basis to group-level strategies, such as division of labor and collective intelligence. In turn, the outcomes of collective choices, as well as the needs of the society at large, influence the behavior of individuals within it. My dissertation research addresses how the feedback between individual and group-level behavior affects individuals and promotes collective change. I study this question in the context of seed selection in the seed harvester ant, Pogonomyrmex californicus. I use both field and laboratory studies to explore questions relating to individual behavior: how forager decision-making is affected through information available in the nest and at the seed pile; how workers interact with seeds in the nest; and how forager preferences diverge from each other’s and the colony’s preference. I also explore the integration between individual and colony behavior, specifically: how interactions between the foraging and processing tasks affect colony collection behavior; how individual behavior changes affect colony preference changes and whether colony preference changes can be considered learning behavior. To answer these questions, I provided colonies with binary choices between seeds of unequal or similar quality, and measured individual, task group, and colony-level behavior. I found that colonies are capable of learning to discriminate between seeds, and learned information lasts at least one month without seed interaction outside of the nest. I also found that colony learning was coordinated by foragers receiving updated information from seeds in the nest to better discriminate and make choices between seed quality during searches for seeds outside of the nest. My results show that seed processing is essential for stimulating collection of novel seeds, and that foraging and processing are conducted by behaviorally and spatially overlapping but distinct groups of workers. Finally, I found that foragers’ preferences are diverse yet flexible, even when colonies are consistent in their preference at the population level. These combined experiments generate a more detailed and complete understanding of the mechanisms behind the flexibility of collective colony choices, how colonies incorporate new information, and how workers individually and collectively make foraging decisions for the colony in a decentralized manner.

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  • 2020

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Decoding brood pheromone: the releaser and primer effects of young and old larvae on honey bee (Apis mellifera) workers

Description

How a colony regulates the division of labor to forage for nutritional resources while accommodating for changes in colony demography is a fundamental question in the sociobiology of social insects.

How a colony regulates the division of labor to forage for nutritional resources while accommodating for changes in colony demography is a fundamental question in the sociobiology of social insects. In honey bee, Apis mellifera, brood composition impacts the division of labor, but it is unknown if colonies adjust the allocation of foragers to carbohydrate and protein resources based on changes in the age demography of larvae and the pheromones they produce. Young and old larvae produce pheromones that differ in composition and volatility. In turn, nurses differentially provision larvae, feeding developing young worker larvae a surplus diet that is more queen-like in protein composition and food availability, while old larvae receive a diet that mimics the sugar composition of the queen larval diet but is restrictively fed instead of provided ad lib. This research investigated how larval age and the larval pheromone e-β ocimene (eβ) impact foraging activity and foraging load. Additional cage studies were conducted to determine if eβ interacts synergistically with queen mandibular pheromone (QMP) to suppress ovary activation and prime worker physiology for nursing behavior. Lastly, the priming effects of larval age and eβ on worker physiology and the transition from in-hive nursing tasks to outside foraging were examined. Results indicate that workers differentially respond to larvae of different ages, likely by detecting changes in the composition of the pheromones they emit. This resulted in adjustments to the foraging division of labor (pollen vs. nectar) to ensure that the nutritional needs of the colony's brood were met. For younger larvae and eβ, this resulted in a bias favoring pollen collection. The cage studies reveal that both eβ and QMP suppressed ovary activation, but the larval pheromone was more effective. Maturing in an environment of young or old larvae primed bees for nursing and impacted important endocrine titers involved in the transition to foraging, so bees maturing in the presence of larvae foraged earlier than control bees reared with no brood.

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Date Created
  • 2014

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Proximate and ultimate mechanisms of nestmate recognition in ants

Description

The most abundantly studied societies, with the exception of humans, are those of the eusocial insects, which include all ants. Eusocial insect societies are typically composed of many dozens to

The most abundantly studied societies, with the exception of humans, are those of the eusocial insects, which include all ants. Eusocial insect societies are typically composed of many dozens to millions of individuals, referred to as nestmates, which require some form of communication to maintain colony cohesion and coordinate the activities within them. Nestmate recognition is the process of distinguishing between nestmates and non-nestmates, and embodies the first line of defense for social insect colonies. In ants, nestmate recognition is widely thought to occur through olfactory cues found on the exterior surfaces of individuals. These cues, called cuticular hydrocarbons (CHCs), comprise the overwhelming majority of ant nestmate profiles and help maintain colony identity. In this dissertation, I investigate how nestmate recognition is influenced by evolutionary, ontogenetic, and environmental factors. First, I contributed to the sequencing and description of three ant genomes including the red harvester ant, Pogonomyrmex barbatus, presented in detail here. Next, I studied how variation in nestmate cues may be shaped through evolution by comparatively studying a family of genes involved in fatty acid and hydrocarbon biosynthesis, i.e., the acyl-CoA desaturases, across seven ant species in comparison with other social and solitary insects. Then, I tested how genetic, developmental, and social factors influence CHC profile variation in P. barbatus, through a three-part study. (1) I conducted a descriptive, correlative study of desaturase gene expression and CHC variation in P. barbatus workers and queens; (2) I explored how larger-scale genetic variation in the P. barbatus species complex influences CHC variation across two genetically isolated lineages (J1/J2 genetic caste determining lineages); and (3) I experimentally examined how CHC development is influenced by an individual’s social environment. In the final part of my work, I resolved discrepancies between previous findings of nestmate recognition behavior in P. barbatus by studying how factors of territorial experience, i.e., spatiotemporal relationships, affect aggressive behaviors among red harvester ant colonies. Through this research, I was able to identify promising methodological approaches and candidate genes, which both broadens our understanding of P. barbatus nestmate recognition systems and supports future functional genetic studies of CHCs in ants.

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Date Created
  • 2016