Human behavior and decision-making depend largely on past experiences that generate specific action patterns (i.e., scripts, Gioia & Manz, 1985) for specific situations. In an ideal world, in which changes in the environment do not conflict with these action patterns, humans would be able to operate consistently, efficiently, and automatically. However, real-world environments are dynamic and fluid, thus altering behavior and forcing changes in scripts. Research suggests that to implement alternate solutions to changing situations, humans select from a "library" of learned scripts. Since humans tend to implement scripts to the degree that these are successful over a period of time, implementing alternate scripts can be difficult. That is, unless one has the cognitive flexibility to adapt scripts, implementing a new solution to a problem can be difficult and/or unsuccessful. Cognitive flexibility allows one to restructure knowledge to form an adaptive response to changes set forth by the environment. At issue is the difference between possessing a repertoire of scripts that can be selected and implemented to solve a problem, and having the cognitive flexibility to effectively switch between scripts when a change in context occurs. The purpose of this dissertation is to: (a) evaluate the effectiveness of possessing alternate scripts to respond to situations, and (b) assess the effectiveness of cognitive flexibility training on the ability to switch between scripts. The ultimate goal is to improve mental flexibility in situations where a specific approach should be revised and adjusted to conform to changes in context. A total of 48 participants were randomly assigned to one of four conditions in a 2 (number of scripts) x 2 (training present or absent) design: (a) single script, (b) single script and cognitive flexibility training, (c) two scripts, and (d) two scripts and cognitive flexibility training. Participants either learned one script or two scripts on how to respond to a car engine overheat. In addition, depending on the study condition, participants completed a cognitive flexibility training that used a mental simulation approach. The cognitive flexibility training was intended to allow participants to imagine a number of different scenarios that may impact that task, evaluate assumptions, check assumptions against the situation, imagine a response to such scenarios, and review the effectiveness of the developed solutions. The results of this research suggested that for situations requiring a change or an adaptation to an alternate script, possessing two scripts facilitated correct decision-making, whereas cognitive flexibility training may have hindered decision-making. In addition, for situations requiring a standard script, possessing two scripts was detrimental to decision-making performance, regardless of cognitive flexibility training. Theoretical implications in terms of script-processing and cognitive flexibility, as well as practical implications for training design are provided.

Older adults experience more difficulties completing goal directed movements than younger adults. The reasons for this have not been completely elucidated within the research literature; however, it is thought that age related movement differences are due to at least one of three possible reasons. The current study investigated the influence of these three hypotheses: (1) biomechanical changes (limbs, joints, or muscles), (2) sensory feedback processing ability, or (3) differences in overall movement strategy on movement kinematics. Additionally, physical activi-ty is known to improve both physical and cognitive functioning and staying cognitively active may also attenuate age-related declines in cognitive ability; thus the current study also examined the impact of physical and mental fitness on movement performance across the lifespan. Both active and sedentary young and old adults completed different experimental conditions to de-termine how biomechanical ability, sensory processing ability, and individual differences impact different kinematic aspects of movement performance. Participants completed two different Fitts' pointing tasks where difficulty was manipulated by either increasing biomechanical effort and/or amount of feedback processing needed to complete each movement. Results indicated that distance impacted movement more than width for all participants indicated by a greater ID-MT slope. While increasing age was associated with an increases slope, the larger finding was that age increased the overall time. Thus, it was concluded that distance and width constraints are processed by similar processes regardless of age, but these processes slow with age. Cardio-vascular fitness attenuated declines in the distance condition while mental fitness attenuated those in the width condition. Further supporting a theory of differential movement constraints.

The redundant signals effect, or redundancy gain, is an increase in human processing efficiency when target redundancy is introduced into a display. An advantage for two visual signals over one has been found in a wide variety of speeded response time tasks, but does not always occur and may be weakened by some task parameters. These disparate results suggest that visual redundancy gain is not a unitary effect, but is instead based on different underlying mechanisms in different tasks. The current study synthesizes previous theories applied to redundancy gain into the three-conditions hypothesis, which states that visual redundancy gain depends on the presence of at least one of three factors: visual identicalness between multiple targets, familiarity with multiple similar targets, or prepotentiation for multiple different targets. In a series of four simple response time experiments, participants responded to single targets presented to one side of the visual field, or to bilateral targets presented to both sides of the visual field. The first three experiments each explored one condition, the first experiment by comparing identical to non-identical random shapes to examine visual identicalness, the second by comparing familiar to unfamiliar letters to examine familiarity, and the third by comparing previewed with non-previewed random shapes to examine prepotentiation. Finally, the fourth experiment employed letters that varied in familiarity, identicalness, and preview, to examine whether or not the three hypothesized causes have multiplicative effects on redundancy. Results indicated that participants were able to benefit equally from redundancy regardless of identicalness, familiarity, or prepotentiation, but that they did so by ignoring one target in the redundant-target trials. These results suggest that redundancy gain may need to be even further divided into more than three underlying mechanisms, with a serial processing mechanism that can be used for stimuli that are not familiar, prepotentiated, or identical.

The present study empirically examined the effects of working memory capacity (WMC) and executive attention on distracted driving. Study 1 examined whether a Grocery List Task (GLT) distractor would load onto WMC. Forty-three participants completed a series of WMC tasks followed by the GLT. They then completed two driving trials: driving without the GLT and driving while completing the GLT. It was hypothesized that WMC would positively correlate with GLT performance. A bivariate correlation indicated that WMC was positively associated with performance on the GLT. Study 2 tested a series of distractor tasks (GLT, Tone Monitoring, and Stop Signal) to examine whether these three distractor tasks were also related to WMC, and if each of the distractor tasks would result in poor driving performance. Eighty-four participants were randomly assigned to the distractor conditions. Results indicated that GLT was related to WMC, but Tone Monitoring was not related to WMC. Also, engaging in each of the three distractor tasks led to significantly poorer driving performance. Study 3 evaluated whether rainy or clear weather conditions would affect the relationship between WMC and distracted driving using the same three distractor tasks (GLT, Tone Monitoring, and Stop Signal) as used in Study 2. Ninety-six participants were randomly assigned to the distractor conditions. Results showed that engaging in GLT while driving led to slower braking response times compared to not engaging in GLT driving while driving. Furthermore, WMC moderated the degree to which distraction impaired performance. The present findings clearly indicate that all three distractor tasks had a deleterious effect on driving performance. Furthermore, this effect of distraction on driving depends on many factors, including the type of distraction, the driving performance measure, and the individual's cognitive capabilities. Both theoretical and practical implications are discussed and directions for future research are presented.

Categorization is an essential survival skill that we engage in daily. A multitude of behavioral and neuropsychological evidence support the existence of multiple learning systems involved in category learning. COmpetition between Verbal and Implicit Systems (COVIS) theory provides a neuropsychological basis for the existence of an explicit and implicit learning system involved in the learning of category rules. COVIS provides a convincing account of asymptotic performance in human category learning. However, COVIS – and virtually all current theories of category learning – focus solely on categories and decision environments that remain stationary over time. However, our environment is dynamic, and we often need to adapt our decision making to account for environmental or categorical changes. Machine learning addresses this significant challenge through what is termed concept drift. Concept drift occurs any time a data distribution changes over time. This dissertation draws from two key characteristics of concept drift in machine learning known to impact the performance of learning models, and in-so-doing provides the first systematic exploration of concept drift (i.e., categorical change) in human perceptual category learning. Four experiments, each including one key change parameter (category base-rates, payoffs, or category structure [RB/II]), investigated the effect of rate of change (abrupt, gradual) and awareness of change (foretold or not) on decision criterion adaptation. Critically, Experiments 3 and 4 evaluated differences in categorical adaptation within explicit and implicit category learning tasks to determine if rate and awareness of change moderated any learning system differences. The results of these experiments inform current category learning theory and provide information for machine learning models of decision support in non-stationary environments.

Vigilance, or the ability to maintain attention to stimuli over a prolonged period of time (Davies & Parasuraman, 1982; Warm & Jerison, 1984), has been a troublesome research topic since World War II. Scientists have sought to counteract performance declines in vigilance tasks by training observers on these tasks. Though an extensive literature has been developed to examine the effectiveness of these techniques, the mechanisms by which many forms of vigilance training help performance are largely unknown. The present dissertation seeks to further the understanding of how two forms of training for vigilance, practice and knowledge of result, function to improve observers' ability to remain vigilant as time on task increases. In addition to understanding these forms of training, this dissertation seeks to develop a training protocol that would train observers for vigilance without adversely affecting their cognitive resources. Finally, this dissertation utilizes this new training protocol to examine the potential for transfer of training, which has been a question for vigilance researchers for decades. Results relating to these three research questions are presented, as well as a discussion of how these results may inform or influence vigilance research in the future.

Episodic memory retrieval is believed to require recovering a slowly changing spatiotemporal context. Two findings supporting this view are the recency effect (recent events are more likely to be remembered) and the contiguity effect (after recollecting an event, things that occurred near the event are more likely to be remembered). Critically, contiguity and recency effects are similar across time scales (i.e., they are scale-invariant). As a result, a scale-invariant model of context was proposed which makes several empirical predictions about the brain and behavior. Neurally, this model predicts neurons that respond shortly after an event and exponentially return to baseline at various rates. Experiment~1 analyzed single-unit recordings from the entorhinal cortex of 2~male rhesus macaques as they freely viewed images. In support of this hypothesis, I report units that fired in response to image onset and then relaxed their firing with a spectrum of rates. Behaviorally, this model suggests that the time required to initiate memory retrieval can increase logarithmically with recency. Experiment~2 analyzed results from 6~continuous recognition experiments, where 202~human adults judged on each trial if a stimulus is new or old without separate study and test phases. Response time distributions demonstrated that the time required to initiate memory retrieval increased as a logarithmic function of that memory's recency out to at least 8~minutes, supporting this behavioral hypothesis. Finally, although there is a spectrum of decay rates, there must be a fastest decay rate—items presented at a rate faster than this fastest decay rate should disrupt the contiguity effect. Experiment~3 analyzed behavioral results from 330~human adults performing an immediate free recall task in which lists were presented at 2, 4, or 8~Hz. In immediate free recall, participants studied a list of items and began recall as soon as the list ended. Critically, for lists presented at 8~Hz, the contiguity effect was eliminated, consistent with the hypothesis that the contiguity effect does not occur at very short time scales. Together these results suggest that temporal context is scale-invariant and offer additional constraints to the form of this representation.

It is unclear whether or not older adults experience more difficulty managing cognitive conflict by inhibiting distracting stimuli and/or ignoring irrelevant information than younger adults. A common procedure used to measure inhibitory function is through the use of congruent and incongruent stimuli. Specifically, past literature that used tasks like the Simon and flanker have found differing effects on reaction times and various event-related potential (ERP) amplitudes and latencies, suggesting that either inhibitory function is a unitary mechanism or multifaceted. Moreover, research exhibits uncertainty for whether or not age influences deficits to inhibitory function. Another way to measure inhibitory deficits with these two tasks is through the use and measurements of conflict adaptation. Previous literature that have used such tasks support the notion that higher-conflict trials that precede lower-conflict trials result in smaller congruency effects, or what is known as conflict adaptation. While conflict processing has been associated with activity in the medial prefrontal cortex, it is typically considered a measure of the lateral prefrontal cortex and cognitive control. To date, no study has investigated age-related conflict processing and conflict adaptation effects between the Simon and Flanker tasks simultaneously. Therefore, the present study utilized an original combined Simon and flanker task to measure age-related inhibitory differences by measuring reaction time, accuracy, and various ERP (P1, N1, N2, P3) amplitudes to determine if older adults experience inhibitory deficits during the Simon and flanker tasks and whether inhibitory function is a unitary mechanism. Results of the present study indicate that older adults experience greater inhibitory deficits during cognitive conflict as compared to younger adults. Additionally, it was found that the combination of Simon and flanker effects significantly modulated inhibitory deficits for both age groups, but especially for older adults, as seen through both behavioral and electrophysiological means. Specifically, such deficits were most prominent during later processing (i.e. N2 and P3) as compared to early processing. Therefore, the study provides support for age-related changes in inhibitory function and conclude that inhibitory function is comprised of a unitary mechanism. Although these findings deem promising, future research should be conducted to provide conclusive evidence. Regardless, these findings are an important step towards better understanding how inhibitory function manifests and how older adults experience inhibitory deficits. Further, these results provide an initial framework into the identification and understanding of age-related changes during the normal aging process for the field of cognitive neuroscience.

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This work on trust in human-robot interaction describes a series of three experiments from which a series of predictive models are developed. Previous work in trust and robotics has examined HRI components related to robots extensively, but there has been little research to quantify the influence of individual differences in trust on HRI. The present work seeks to fill that void by measuring individual differences across a variety of conditions, including differences in robot characteristics and environments. The models produced indicate that the main individual factors predicting trust in robotics include pre-existing attitudes towards robots, interpersonal trust, and personality traits.