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Transfer, the use of acquired knowledge, skills and abilities across tasks and contexts, is a key and elusive goal of learning. Most evidence available in literature is based on a limited number of tasks, predominantly open-ended problems, game-like problems and taught school subjects (e.g. maths, physics, algebra). It is not obvious that findings from this work can be extended to the domain of decision making problems. This thesis, which aims to broaden the understanding of enhancing and limiting factors of transfer, examines transfer of binary decision making problems (analogs of the Monty Hall problem) under various conditions of semantic distance between learning and target problems, contextual shifts, and delay between learning and target. Our results indicate that not all findings of the classic analogical transfer studies based on open problem solving tasks extend to binary decision making transfer. Specifically, analogical encoding (i.e. learning two analogs by comparing them) did not lead to higher transfer than summarization. Furthermore, in our experiments, transfer rates were never significantly higher for participants learning two analogs by comparison (thus presumably forming a schema) than for those learning one analog by summarization (thus presumably not forming a schema). This leads us to cautiously hypothesize that the role of schema in mediating transfer could be less relevant in binary decision making than it is in open-ended problem solving. Finally, context shifts up to medium level, even coupled with several days delay, did not significantly reduce transfer, although high context shifts did. On the other hand, semantic distance, quality of learning and explicit recognition, were confirmed to have a significant relationship with transfer.

The ways in which listeners, engineers and musicians communicate the character of sounds to others is not well understood. When describing sounds, aspects of the perceived sound character are often associated with descriptive words and phrases. The first claim studied in this thesis is that, with the presentation of the same sounds to different listeners, there is a consistency in human responses when judging sounds for particular descriptors of sound character. The second claim studied is that these human responses can lead to the development of clear relationships between character descriptors and features e~1racted from the physical form ofthe sounds used. This thesis studies the form and consistency of these relationships. The use of qualitative descriptive terminology is found to be highly context sensitive. With careful choice of terminology, sounds and listening tests, some commonality is found between listeners. By using different listening tests, increasing consistency is demonstrated between some of the most common terms and simple sounds. With specific character descriptors and carefully controlled sounds, this leads to cases where there is sufficient confidence in listener responses that patterns could be established. A further study of brightness and harshness establishes links with features extracted from the sounds used, giving new insight into the commonly held understanding and use ofthose character descriptors.

Deciding where to direct our gaze is one of the most ubiquitous decisions we make, and this process can be viewed as a competition between objects in the visual scene (Findlay & Walker, 1999). Here we investigated the decision making process involved in target selection, and the impact it has on saccade metrices and dynamics such as latency, landing position and trajectory. We manipulated the evidence available for selecting one target over another, by varying the motion coherence level in a random dot kinematogram (RDK). In chapter two, we investigated the quantity of evidence available, and the period over which it was accumulated, to ascertain the effect this had on eye movements. The results suggest that increasing the quality (motion coherence) of the evidence had a larger effect on saccade trajectories than increasing the quanity (duration) of the evidence, and that the last piece of evidence viewed has the largest impact. In chapter three the role of confidence was examined and we successfully dissociated confidence ratings from the evidence underlying the decision, suggesting that confidence is not based on the same neural structures which are involved in eye movement control.

Humans are used as recording instruments in many areas of scientific experimentation. However, their responses are susceptible to bias due to the context in which the sensory stimuli are presented. One recognised source of bias is carryover, i.e. the effect of the previous stimuli on the current judgement. It is therefore important to take account of carryover effects in both the design and analysis of the experiments in order to obtain precise and bias free estimates of experimental treatment effects. In this study we investigate carryover in two areas: sensory profiling of food products and the assessment of crop disease severity. A series of experiments are designed, conducted and analysed for both applications, in order to ascertain the form, frequency and magnitude of carryover. Alternatives to the standard additive carryover model are proposed for the sensory profiling responses. The proposed model has carryover effects which are proportional to direct treatment effects. In visual assessment carryover is found to depend on whether the previous stimulus is higher than the current stimulus and an appropriate model is developed to describe this relationship. Results for optimal and efficient change-over designs for estimating direct treatment effects in the presence of carryover, in addition to repeat treatment effects, are derived for the proportional carryover model analytically. Balanced uniform designs with or without a circular pre-period for specified design parameters are determined to be optimal within their respective classes of competing designs. The search for optimal and efficient change-over designs is extended to all possible designs using a computer search algorithm. However, the relative efficiency of designs is shown to depend on the value of the proportional scalar linking carryover effects to direct treatment effects, and knowledge of this parameter will influence the optimal design.

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Visual search is a commonly used experimental procedure to explore human processing of visual multiple object scene (Wolfe, 1998b). This thesis introduces a new computational model of visual search, termed Selective Attention for Identification model (SAIM). SAIM aims to solve translation invariant object identification in a connectionist modelling framework. The thesis demonstrates that SAIM can successfully simulate the following experimental evidence: symmetric searches (L amongst Ts and/or upside down Ts (Duncan & Humphreys, 1989; Egeth & Dagenbach, 1991)), asymmetric searches of oriented lines (Treisman & Gormican, 1988), line size (Treisman & Gormican, 1988), item complexity (Treisman & Souther, 1985; Rauschenberger & Yantis, 2(06)) and familiarity (Wang, Cavanagh, & Green, 1994; Shen & Reingold, 2(01)), the influence of distractor (non-targets) orientation (Foster & Ward, 1991; Foster & Westland, 1995), effects of priming (Hodsoll & Humphreys, 2001; Mueller, Reimann, & Krummenacher, 2003; Wolfe, Butcher, Lee, & Hyle, 2003; Anderson, Heinke, & Humphreys, 2(06)) and 'contextual cueing' (Chun & Jiang, 1998). Crucially, SAIM's success emerges from the competition of objects for object identification. This competition is chiefly influenced by three factors: the similarity between search targets and non-targets (distractors), the visual features of the distractors, e.g., line orientation, and the influence of the object identification stage on the selection process (top-down modulation). On the other hand, a detailed reView in this thesis highlights that none of the existing computational models and theories can satisfactorily account for these experimental results. Instead, each theoretical account contains only a subset of the factors suggested by SAIM and, therefore, can explain only a subset of the experimental data. In SAIM these factors are pulled together into a unifying approach of parallel competitive interaction towards visual search.

The research reported here centres on two interesting memory phenomena: the von Restorff and release effects. A variety cf theoretical interpretations of these phenomena has been offered in the experimental literature, and it has sometiimes, indeed, been proposed that a single interpretation might account for both phenomena. A case can be made for dividing up the theoretical interpretations into those emphasizing encoding processes, those emphasizing storage and rehearsal processes, and those emphasizing the processes of retrieval. With the above distinction in mind, a total of seven experiments were conducted; some variables were investigated in relation to both of the phenomena in the attempt to ascertain more closely the similarity betweeen the two effects. In essence, the results obtained indicated that a common process does not underlie the two phenomena: the con Restorff effect appears to depend upon encoding processes, whereas the release effect does rather seem to depend upon retrieval processes.