According to prospect-refuge theory, humans prefer to be in spaces that afford protection from threat (refuge), but also provide large fields of view (prospect). These preferences are said to arise from the adaptive advantages of such locations with respect to both avoidance of predation from refuge and survey of opportunities for resource collection by prospect. Prospect-refuge theory in the past has traditionally only been applied to human beings, but many of the same contingencies governing spatial preference ought to also hold true in other animals. If people's spatial preferences are influenced by prospect-refuge considerations, then such preferences ought to be found in other animals that are subject to the same pressures to find safety and resources. The overall objective of this study was to explore spatial preferences of the Mongolian gerbil in situations in which prospect-refuge theory makes specific predictions about which regions of an environment will be preferred. Gerbils were placed in an arena containing three dome shaped refuges that varied in the amount of prospect and refuge. A predator was released during the trial to examine how contextual factors may influence the degree of prospect and refuge preferred. There was a preference for an enclosed refuge at stimulus onset even though this was not reflective of what happened prior to stimulus onset, which suggests there was a shift in preferring refuges with greater concealment upon exposure to a threatening stimulus. These results indicate that shelter preference does in fact depend on contextual factors. An explicit comparison of these preferences in widely divergent species may help to place theories of spatial preference on a firmer biological footing, and may provide a greater understanding of how the principles of spatial cognition might underpin parts of the design process.

In two experiments we evaluated whether memory for item locations across trials can improve visual search performance. Measuring both response times and eye movements we examined how visual search performance is influenced by a progressive change in item locations across successive search trials. The positions of items in the search displays were slightly shifted across successive displays and the degree of shift (trial-to-trial stability) was varied across participants. In addition, at the beginning of a trial we either presented only the current target (no-preview) or current and the next target (preview). This allowed us to evaluate performance under preview and under load, as participants on some trials held a future target in working memory. We found that search performance improved with increased stability. In addition, we demonstrate direct links between the accuracy with which an item is observed on one trial and the facility of search for that item during later trials, implicating a strong influence of trial-to-trial memory. Finally, we found that previewing a target improved performance particularly under load. Overall, our results support a model of search in which relatively slow top-down information guides and constrains the deployment of fast perceptual processes.

According to prospect-refuge theory, humans prefer to be in spaces that afford protection from threat (refuge), but also provide large fields of view (prospect). These preferences are said to arise from the adaptive advantages of such locations with respect to both avoidance of predation from refuge and survey of opportunities for resource collection by prospect. Prospect-refuge theory in the past has traditionally only been applied to human beings, but many of the same contingencies governing spatial preference ought to also hold true in other animals. If people's spatial preferences are influenced by prospect-refuge considerations, then such preferences ought to be found in other animals that are subject to the same pressures to find safety and resources. The overall objective of this study was to explore spatial preferences of the Mongolian gerbil in situations in which prospect-refuge theory makes specific predictions about which regions of an environment will be preferred. Gerbils were placed in an arena containing three dome shaped refuges that varied in the amount of prospect and refuge. A predator was released during the trial to examine how contextual factors may influence the degree of prospect and refuge preferred. There was a preference for an enclosed refuge at stimulus onset even though this was not reflective of what happened prior to stimulus onset, which suggests there was a shift in preferring refuges with greater concealment upon exposure to a threatening stimulus. These results indicate that shelter preference does in fact depend on contextual factors. An explicit comparison of these preferences in widely divergent species may help to place theories of spatial preference on a firmer biological footing, and may provide a greater understanding of how the principles of spatial cognition might underpin parts of the design process.

In two experiments we evaluated whether memory for item locations across trials can improve visual search performance. Measuring both response times and eye movements we examined how visual search performance is influenced by a progressive change in item locations across successive search trials. The positions of items in the search displays were slightly shifted across successive displays and the degree of shift (trial-to-trial stability) was varied across participants. In addition, at the beginning of a trial we either presented only the current target (no-preview) or current and the next target (preview). This allowed us to evaluate performance under preview and under load, as participants on some trials held a future target in working memory. We found that search performance improved with increased stability. In addition, we demonstrate direct links between the accuracy with which an item is observed on one trial and the facility of search for that item during later trials, implicating a strong influence of trial-to-trial memory. Finally, we found that previewing a target improved performance particularly under load. Overall, our results support a model of search in which relatively slow top-down information guides and constrains the deployment of fast perceptual processes.

We examined how explicit instructions to encode visual context information accompanying visually-presented unrelated target words affected later recognition of the targets presented alone, in younger and older adults. In Experiments 1 and 3, neutral context scenes, and in Experiments 2 and 4, emotionally salient context scenes, were paired with target words during encoding. Experiments 1 and 2 data were collected using within subject design; in Experiments 3 and 4 we used a between subjects design. Across all four experiments, instructions to explicitly make a link (associate) between simultaneously presented context and target words always led to significantly better recognition memory in both younger and older adults compared to deep or shallow levels of processing (LoP) instructions for the context information. In all experiments the age-related deficit in overall memory remained. There was no consistent difference in the effect of a shallow versus deep processing of context in the first three experiments in young adults, although a standard LoP effect, with better memory performance following deep than shallow processing, was demonstrated with both age groups in Experiment 4. Results suggest that an instruction to explicitly link target words to context information will significantly and consistently improve memory recognition for targets. This was demonstrated in all four experiments, in both younger and older adults. Importantly, results suggest that memory in older adults can be improved with specific instructional manipulations during encoding.

Repeated focal electrical stimulation of the brain results in kindling, the development of generalized seizures that progress in length and severity as more seizures are elicited. Barnes et al. (2001) paired one context (CS+) with kindling stimulation of the amygdala, and another context (CS-) with sham stimulation. They found conditioned anticipatory fear responses in the CS+, a conditioned place aversion to the CS+, and more intense convulsions in the CS+ than in the CS- in a probe trial. The present experiment was an attempt to replicate the findings, and to extend them by recording electroencephalographs (EEG). As well, I tested for conditioned effects on afterdischarge threshold (ADT). Rats received 45 pairings in each context before a conditioned place preference/aversion test, to determine whether the stimulation and seizures were rewarding or punishing. After more pairings, rats received suprathreshold stimulation in each context (switch test). Ictal measures in this test included afterdischarge duration, clonus duration, latency to clonus, class of convulsion, and falls. After more pairings, ADT was measured in each context. I partially replicated the findings of Barnes et al., in that conditioned anticipatory responses and conditioned place aversion were found. However, there were no conditioned effects on any ictal measures, including ADT. I conclude that conditioning is unlikely to play a major role in epileptogenesis.

We examined how explicit instructions to encode visual context information accompanying visually-presented unrelated target words affected later recognition of the targets presented alone, in younger and older adults. In Experiments 1 and 3, neutral context scenes, and in Experiments 2 and 4, emotionally salient context scenes, were paired with target words during encoding. Experiments 1 and 2 data were collected using within subject design; in Experiments 3 and 4 we used a between subjects design. Across all four experiments, instructions to explicitly make a link (associate) between simultaneously presented context and target words always led to significantly better recognition memory in both younger and older adults compared to deep or shallow levels of processing (LoP) instructions for the context information. In all experiments the age-related deficit in overall memory remained. There was no consistent difference in the effect of a shallow versus deep processing of context in the first three experiments in young adults, although a standard LoP effect, with better memory performance following deep than shallow processing, was demonstrated with both age groups in Experiment 4. Results suggest that an instruction to explicitly link target words to context information will significantly and consistently improve memory recognition for targets. This was demonstrated in all four experiments, in both younger and older adults. Importantly, results suggest that memory in older adults can be improved with specific instructional manipulations during encoding.

Over two decades of patient and neuroimaging data have provided increasing support for a role of the posterior cerebellum in cognition, particularly attention. Contralateral connections between the prefrontal cortex and the cerebellum are a probable basis for this effect. It is the purpose of this thesis to understand the contribution of the fronto-cerebellar system to cognitive and attentional processes. The first aim of this thesis was to localize areas of the cerebellum that participate in non-motor behaviour. After transient disruption of cerebellar activity using continuous theta burst stimulation (cTBS), a form of transcranial magnetic stimulation, Study 1 and 2 identified the right posterior-lateral cerebellum as a contributor to a network involved in two non-motor tasks; word generation and the attentional blink. The aim of Study 3 was to investigate if manipulating task demands increased fronto-cerebellar recruitment. The final study of this thesis employed electroencephalography (EEG) and cTBS to probe the neural events disrupted during the attentional blink task when the left frontal- right cerebellar system was transiently disrupted. Understanding the manner in which these neural events are affected by transient perturbation is integral to the understanding of the fronto-cerebellar contribution to cognitive and attentional processes. Together these studies help elucidate the role of the fronto-cerebellar system in non-motor functions.

Everyday experience suggests that certain people can find their way to a destination easily, while others have considerable difficulty. This dissertation focused on gaining a greater understanding of navigational strategies that can facilitate or hinder an individual’s wayfinding performance. The first study was conducted to gain a broad idea of various factors that may influence navigational performance. Participants were guided through a building and then asked to find their way to a destination. It was found that good navigators made fewer errors in traversing a learned route than did poor navigators. They were also better at recognizing landmarks they had seen along the route, recalling the appropriate directions to be turned at each landmark, and at drawing the correct pathways on a map drawing task. A discriminant analysis revealed that the best predictor of determining navigational performance was the ability to form spatial relationships between landmarks. Results from the first study demonstrated that good navigators were better at determining spatial relationships between landmarks, but it did not address whether this was due to spatial relationships between distances and/or angles. The focus of the second study was to gain a greater understanding of the degree to which distance and angular information are used by good and poor navigators in determining spatial relationships between landmarks. Results showed that neither a distance nor an angular strategy were preferred in either group of wayfinders. An analysis of navigators initial heading angle error to a target location suggested that good wayfinders may be more efficient at finding their way because they appear to plan routes prior to initiating self-locomotion. Such pre-planning was confirmed by the fact that good wayfinders’ initial heading direction error was significantly less than in poor wayfinders. Poor wayfinders appear to head in a random direction and then attempt to determine target locations. The use of landmark information may be useful in certain contexts, but this may not always be the most efficient strategy. The last experiment was aimed at determining whether good navigators adjust strategies used (landmark vs. street), depending on contextual factors. Differences in strategies used were not found, however the results suggest that good navigators appear to be more skilled at navigating in environments rich with streets compared to poor wayfinders. Good and poor navigators were equally skilled at navigating in environments rich in landmarks. It appears that the ability to determine spatial relationships between landmarks is the strongest predictor of navigational performance compared to a wide range of other navigational skills.

Over two decades of patient and neuroimaging data have provided increasing support for a role of the posterior cerebellum in cognition, particularly attention. Contralateral connections between the prefrontal cortex and the cerebellum are a probable basis for this effect. It is the purpose of this thesis to understand the contribution of the fronto-cerebellar system to cognitive and attentional processes. The first aim of this thesis was to localize areas of the cerebellum that participate in non-motor behaviour. After transient disruption of cerebellar activity using continuous theta burst stimulation (cTBS), a form of transcranial magnetic stimulation, Study 1 and 2 identified the right posterior-lateral cerebellum as a contributor to a network involved in two non-motor tasks; word generation and the attentional blink. The aim of Study 3 was to investigate if manipulating task demands increased fronto-cerebellar recruitment. The final study of this thesis employed electroencephalography (EEG) and cTBS to probe the neural events disrupted during the attentional blink task when the left frontal- right cerebellar system was transiently disrupted. Understanding the manner in which these neural events are affected by transient perturbation is integral to the understanding of the fronto-cerebellar contribution to cognitive and attentional processes. Together these studies help elucidate the role of the fronto-cerebellar system in non-motor functions.