Changes in cognitive status occur with aging and significant attention has been placed on developing interventions to possibly delay cognitive decline and identifying risk factors that exacerbate cognitive deficits. One issue that arises when studying interventions is that they do not always effectively translate from animal models to human subjects. When testing potentially modifiable risk factors related to cognitive impairment, more sensitive metrics could help in identifying targets for intervention at earlier time-points. Therefore, the aims of the current dissertation were twofold. The first study examined the ability to translate between species using a common behavioral paradigm, the Morris water maze (MWM). The second study evaluated human MWM performance and commonly used neuropsychological test performance in relation to a marker of glucose regulation, HbA1c. The first study tested translation between rats and humans using the MWM paradigm. Using secondary data sources from a study of nutrition, inflammation, and aging among rats and the Czech Brain Aging Study among humans, differences in average performance and across trial learning were examined between young (3 months; n=10) and aged (20 months; n=13) rats as well age young-old (age 53-70; n=47) and old-old (age 71-85; n=30) human subjects. The cumulative distance was measured in rats and distance error to the hidden goal was measured in human subjects. Results indicated that age-related deficits in performance are greater in magnitude for rats than human subjects. Further, the across trial learning data is more sensitive to change in performance than average performance metrics. Across learning trials indicated poorer performance for aged rats than young rats. Significant effects of age were also observed for human subjects using with the allocentric and egocentric subtests. The second study examined the influence of a measure of glucose regulation (HbA1c) on commonly used neuropsychological tests and a test of spatial navigation abilities among human subjects. Participants classified as cognitively normal, subjective cognitive decline, amnestic mild cognitive impairment (aMCI), and Alzheimer’s disease (AD) were evaluated on verbal memory, nonverbal memory, working memory, visuospatial skills, and executive function in addition to the virtual and real space versions of a human MWM paradigm. A total of 116 participants were included in the complete data sample and 133 participants were included in the multiple imputation sample. Results indicated that HbA1c influenced executive function but not any other measures of cognition. Higher HbA1c levels were associated with poorer performance. A significant interaction was observed between cognitive status and HbA1c. Those with cognitive impairment and higher HbA1c levels had poorer executive function performance. This effect, however, was not observed with the imputation sample. Results of the first study indicated that the MWM paradigm serves as a good tool to assess translation between rats and human subjects. This would be helpful in examining interventions designed to improve normal age-related changes in cognition. It is important to note, however, that the differences observed among animals tend to be greater than human subjects. Therefore, the margin of improvement may be greater following treatment with studies utilizing animals rather than human subjects. The second study indicated that glucose levels may have an impact on cognitive abilities, particularly those related to executive function. Targeting blood glucose levels may be one effective way to keep executive function abilities more intact with age. Taken together, these studies will better inform future work related to delaying cognitive decline among older adults.

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This research explores how computers may be used by individual researchers engaged in cognitive activity and creating original outputs, specifically, how one of the emerging information technologies, hypertext, is able to provide suggestions for the understanding to support and empower human cognitive activity.The study investigates the possibility of a new model within which to approach that part of research that seeks to make connections to what has been done previously, and to stimulate new thoughts.Imagine swimming in a vast sea of potentially useful information. How can one possibly begin to make sense of it? Engage in a phenomenological experience in which the data is permitted to speak to you. Immerse yourself, navigate around with the ability to backtrack, search, explore trails of associative thought, all with a prepared mind. The mind is prepared, or sensitised, due to the previous research and learning ? the culture to which one belongs. The process will gradually cause an uncluttering of the sea of information resulting eventually in what in this thesis is termed Generative Conceptualisation. The tools and techniques used to do this (for it is impossible to work unaided with large amounts of data) will have provided the empowerment to generate and create. The tyranny of linear order has been replaced by the dynamically varying structure of selected, sometimes hierarchical and othertimes herterarchic or network views of the data, forming or exposing (primarily through juxtaposition) insights, new ideas, and new knowledge. These are some characteristics of working in a hypertext paradigm.Generative Conceptualisation is introduced to describe the intermingling of human mind and computer hypertext, which, it is argued, results in a greater degree of original output by researchers. A hypertext paradigm, the definition of which emerges in the thesis, is ++ / suggested as being an environment for Generative Conceptualisation. A theory (substantive) of knowledge creation is offered in the concluding chapter, in the light of which existing formal theories of knowledge creation may be reviewed or elaborated.

The problem addressed in this thesis is the nature of design expertise and the role of visual mental imagery in design. The problem is addressed firstly, by examining the nature of problems, including design problems. It is argued that design problems are complex and ill-defined and can be distinguished from non-design problems. Secondly, design expertise is examined. It was found that design experts have a large store of design knowledge in a form that is readily accessible, and engage in extensive problem-finding prior to generating design solutions. Thirdly, the role of visual mental images as a component of design problem-solving and design expertise is examined. It is argued that visual mental images are important features of both design expertise and the transition from novice to expert. A number of case studies are designed and conducted. The findings of these studies are interpreted as supporting the theoretical ideas developed in the thesis. The introduction of design-based technology programs into Australian high schools has created the need for teachers to be able to assist students to generate creative solutions to design problems. Currently, technology teachers are experiencing difficulty in helping students to generate creative solutions to design problems. Hence a better understanding of design process may help to shape teaching and learning in design-based subjects. Furthermore, many complex everyday problems share similar properties with design problems. The research may therefore contribute to the understanding of the way people solve problems that have some characteristics in common with design problems. It is argued in this thesis that existing theories and models explaining the nature of problems and of the processes of solving problems are adequate in explaining many categories of problems and problem-solving but are inadequate in explaining the process of solving design problems. A new model of a problem space is proposed and justified. It is argued that design problems occur within a problem space that consists of a problem zone, a search and construction space and a satisficing zone. To establish, theoretically, the role of visual mental imagery in designing, two bodies of cognitive research literature are employed. Firstly, research into the utility of sketches in problem-solving are examined. This research indicates that external images assist problem-solving. Secondly, research into the relationship between perception and imagery is examined. This research suggests that visual mental images are functionally equivalent to perceived images. Thirdly, by combining the findings on sketches in problem-solving with the findings on imagery and perception, it is then possible to argue that visual mental images can assist problem-solving, and may play an important role in the resolution of complex design problems. The cognitive theory explaining the role of visual mental imagery in problem-solving in design is used to develop predictions for testing in two practical studies. Designers use visual imagery to represent and transform complex design problems within the problem space, and visual images are theorised as capable of providing more efficient representations for solving design problems than other forms of representation such as propositions. In the two studies undertaken in this thesis, a case study methodology was employed. The findings of the two studies support the arguments developed in this thesis that expert designers are able to form more complete and more detailed images of design problems and solutions than novices. Expert designers have a large store of previous solutions that can be retrieved from long-term memory as visual mental images. Expert designers are able to recognise when their existing solutions can be used, how they might be modified for use, and where something new is required. The study examined designing in terms of the deployment of procedures and the relationship among these procedures, and with images usage. It was found that designers traverse the design problem space using generative and exploratory procedures and that these procedures are facilitated by and facilitate, the production of visual mental images. The study provides a model of a problem space that can be used to explain the process of solving complex ill-defined problems, the cognitive processing involved in creative thinking and the role of mental imagery in an information processing theory of problem-solving. Conceptualising the problem space as containing a problem zone, search and construction space and satisficing zone makes it possible to apply the concept of a problem space to problems that do not contain well specified problem and goal states and with a limited number of operators. Integrating imagery theories with information processing theories provides an account of the process of solving complex design problems and the generation of novel solutions.

This masters thesis examines the hemispheric activation pattern of the cognitive processes involved in a complex mental rotations test (MRT) (Vandenberg and Kuse, 1978) using Steady-State Probe Topography (SSPT) (Silberstein et al, 1990) as a method to index brain activity. The Steady State Visually Evoked Potential (SSVEP) was recorded from 64 electrode sites using a multichannel electrode helmet, and elicited by a 13 Hz sinusoidal visual flicker, whilst the subjects were performing a visual vigilance Baseline task and the MRT. Forty-one right handed subjects (twenty male and twenty-one female) were used. In the MRT the subjects were required to choose the two figures which correctly matched the criterion figure in the centre. The figures were three-dimensional objects represented in two-dimensions on a computer screen. A significant finding of this study was that when all the subjects were considered as one group, no noticeable lateralization in cerebral activation associated with mental rotation was evident. When analyzing the results for the subjects, partitioned into two groups according to gender, evidence was found suggesting that the cortical processing associated with mental rotation may be more localized bilaterally in the males than the females. However, no noticeable lateralization effects for mental rotation were found in the males or females, and hence no gender differences in hemispheric lateralization was evident. An important finding was the emergence of gender differences in hemispheric lateralization in subsets of subjects performing with higher spatial ability. A left hemisphere lateralization for mental rotation was associated with the Best Performance Male group. The Best Performance Female group showed the opposite effect, where a right hemisphere lateralization was associated with better performance on the task. The lateralization effect appeared to be stronger in the Best Performance Males than the Best Performance Females. An important conclusion from this study is that when examining for hemispheric lateralization effects in mental rotation, and possibly other visual-spatial tasks, not only gender effects need to be considered, but the level of spatial ability in the comparison groups needs also to be taken into account.

Research in neuropsychology has found depression to be related to impaired right hemisphere (RH) functioning. How clinical depression affects brain lateralized functioning for each sex, however, is not clear. The main aim of this thesis was to investigate how clinical depression impacts brain lateralized functioning for each sex. Additionally, this thesis investigates brain lateralization for emotional processing in a non-depressed group, as well as sex differences in brain lateralization for spatial, verbal, and emotional processing in a non-depressed group. In order to examine each of these research areas, sixty non-depressed participants, and thirty-nine dilnically depressed patients were recnjited to complete a set of neuropsychological tasks that measure brain lateralized spatial, verbal, and emotional functioning. The neuropsychological tasks that were selected also measure the brain regions known to be involved with depression (frontal lobe and right parietal lobe). The tasks were: the mental rotation task (MRT) to measure RH spatial functioning; the verbal fluency task (phonemic and semantic) to measure left hemisphere (LH) verbal functioning; and the chimeric faces task to measure frontal lobe emotional functioning. The data from these tasks were reported as two separate experiments. Experiment One examined sex differences in brain lateralization for spatial and verbal processing in a non-depressed group. Experiment One also investigates brain lateralization for emotional processing in a non-depressed group, in particular to determine whether there is a sex difference in brain lateralization for emotional processing. The aim of Experiment One was to replicate the male advantage in spatial processing and the female advantage in verbal processing, which have previously been interpreted as reflecting sex differences in brain lateralization for these functions. It was also the aim to differentiate between the competing RH and valence hypotheses of brain lateralization for emotional processing and further investigate sex differences in brain lateralization for emotional processing. Sex differences in brain lateralization for spatial, verbal, and emotional processing were examined by comparing the performance of thirty non-depressed males and thirty non-depressed females on the MRT, verbal fluency task, and chimeric faces task respectively. The hypothesis that males would mentally rotate the stimuli of the MRT faster than the females was not supported, as no significant sex differences in performance were observed on the MRT. Failure to replicate the male advantage in spatial functioning was attributed to a possible sex difference in level of spatial ability, which has been found to mediate hemispheric functioning. The hypothesis that the females would generate significantly more words than the males on the verbal fluency task was supported, thus replicating the female advantage in verbal processing. For the chimeric faces task, the group findings supported the RH hypothesis for brain lateralization for emotional processing, with responses being significanfly faster and more accurate to happy and sad expressions shown in the LVF than in the RVF. No consistent sex differences in performance were observed between the RT and accuracy rate analyses of the chimeric faces task. Reaction times to the chimeric faces showed a LVF advantage in emotional processing for the males, and no hemispheric bias for emotional processing for the females. In contrast, recognition accuracy of the chimeric faces showed a LVF advantage for emotional processing for both the males and the females. The inconsistent sex differences on the chimeric faces task suggests that there is not a strong sex difference in brain lateralization for emotional processing. Expertment Two investigated brain lateralization for spatial, verbal, and emotional functioning in a clinically depressed group. It was the aim of Experiment Two to determine whether clinical depression is associated with impaired RH functioning, as suggested by the literature. It was also the aim of Experiment Two to examine more specifically, how clinical depression affects brain lateralized functioning for each sex separately. To examine the effect of clinical depression on brain lateralized functioning, the performance of thirty-six (fifteen males, twenty-one females) clinically depressed patients (three excluded from the recruited thirty-nine) and thirty-six (eighteen males, eighteen females) non-depressed control participants was compared on the MRT, verbal fluency task, and chimeric faces task. The hypothesis that clinical depression would be associated with impaired RH functioning was partially supported by the results of Experiment Two. The depressed group performed signiflcantiy poorer than the control group on both the RH task (the MRT intercept and overall R and the LH task (semantic verbal fluency). Therefore, impaired RH and LH functioning on the spatial and verbal task was evidenced for the clinically depressed group in Experiment Two. A RH impairment in emotional functioning with clinical depression could not be clearly ascertained from the results of the chimeric faces task. The RT analyses of the chimeric faces task showed a LVF advantage for emotional processing for both the control and depressed groups. In contrast to the RT analyses, the accuracy rate analyses of the chimeric faces task showed a LVF advantage in emotional processing for the control group, and no hemispheric bias for emotional processing for the depressed group, As the depressed group were significantly impaired for both RH and LH functioning in Experiment Two, it is possible that the findings of Experiment Two are reflective of a generalised performance deficit associated with clinical depression, rather than to a disturbance in brain lateralized functioning. The depressed group was also found to respond significantly slower than the control group in overall RT on the MRT and chimeric faces task. The significant group difference on the intercept of the FART implicates impaired information encoding for the clinically depressed group. The slowed Ris of the depressed group may also reflect impaired pre-motor organization with clinical depression, thus resulting in delayed motor responses. In relation to the affect of clinical depression on brain lateralizaflon for each sex, it was hypothesised that the depressed males would perform significantly poorer than the depressed females on tasks measuring functions lateralized to the cerebral hemisphere impaired due to clinical depression. The premise for this hypothesis lies in the evidence from past unilateral brain lesion research, which suggests that the stronger brain ateralization of males restricts assistance from the unimpaired hemisphere to perform the task of the impalred hemisphere. The bilateralization of females however, allows greater assistance of the unimpaired hemisphere to perform the task at hand. In contrast to the hypothesis however, there was no evidence from the results of Experiment Two that clinical depression had a greater impact on the brain lateralized functioning of males than females. No significant sex differences in performance on the FART were observed for either the non-depressed control group or clinical depressed group. For the verbal fluency task, a female advantage in word generation was observed for both phonemic and semantic fluency, regardless of group. Also regardless of group, the RT analyses of the chimeric faces task showed that the males responded significantly faster to emotional expressions shown in the LVF than in the RVF. For the females however, there was no hemispheric bias in RT for emotional processing. The accuracy rate analyses from the chimeric faces task also showed no sex differences for either group. The similar findings of sex differences between the control and depressed groups across each task suggests that clinical depression had a similar impact on both the males and the females, regardless of brain late ralization. The results of Experiment Two could be indicative of impaired LH and RH functioning with clinical depression, or of a generalised performance deficit with clinical depression. A generalised performance deficit for the clinically depressed group in Experiment Two may explain why a sex difference in the effects of clinical depression on brain lateralized functioning was not observed. Future research observing a RH impairment with clinical depression is encouraged to further examine the affect of clinical depression on brain lateralization for each sex separately. Further understanding of the affect of clinical depression on brain lateralization for each sex could provide addiional information on sex difference in the prevalence of clinical depression.

Theory of mind has been described in philosophical and psychological literature as "folk psychology", and is the tacit understanding that our behaviour is driven by our thoughts, desires and beliefs (Wellman, Cross, & Watson, 2001). Children are widely considered to have attained theory of mind understanding when they are able to pass the test of false belief understanding devised by Wimmer and Perner (1983), at around 4 years of age. There are many theories as to how a child comes to hold a folk psychology, including innate modularism (Leslie, 1987, 1988, 1994), theory change (Gopnik & Wellman 1992), developing representational understanding (Perner, 1991, 1995, 2000), and experiential understanding developed in a socio-linguisitic context (Nelson, 1996). In addition, theory of mind has been linked to the development of symbolic understanding (Deloache & Smith, 1999; Perner, 1991), pretend play (Leslie, 1987; Taylor & Carlson, 1997; Youngblade & Dunn, 1993), language (Astington & Jenkins, 1999; Nelson, 1996; Olson, 1988) and executive function (e.g. Hughes, 1998a; Kochanska et al., 1996; Reed et al., 1984). The present study sought to bring together these diverse findings and to attempt to provide an integrated account of the emergence of theory of mind understanding during the preschool years. Sixty-four New Zealand children were assessed on their mental state understanding, deceptive abilities, symbolic functioning, language, and executive skills, when they were aged 30, 36, 42 and 48 months of age. There were a number of key findings in the present study. Language was a powerful predictor of false belief performance both within and across time, and was also related to many of the other variables included in the study. Performance on the scale model test of symbolic functioning was related across time to children�s concurrent and later false belief understanding. Scale model performance was also intertwined in a bidirectional relationship with language, and language appeared to play an increasingly important role in mediating the relationship with false belief understanding across time. False belief understanding and scale model performance were also related within and across time to executive function. There was evidence to suggest that the importance of working memory was due to its role in conflict inhibition. Although deception has sometimes been posited to be a precocious manifestation of theory of mind (Chandler, Fritz, & Hala, 1989), in the present study deceptive ability lagged false belief understanding. Furthermore, false belief understanding was related to children�s subsequent (but not earlier) responses to a protagonist�s intention. This supports the hypothesis that false belief understanding allows a qualitative change in the execution of deception, whereby children can move from simple physical strategies to more sophisticated mentalist strategies. Overall, the present study provides some evidence to suggest that symbolic functioning, language, and later theory of mind may form part of a single developing skill set of symbolic representation. In dynamic interaction with social understanding, and supported by cognitive abilities such as executive function, and the socio-linguistic context, it is argued that understanding of one�s own and other minds emerges. Children�s ability to solve the false belief problem at 4 years of age is presented as a milestone on a developmental continuum of social understanding.