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This work reports a series of experiments designed to investigate the effects of non-verbal ('mere presence') social situations on the performance of routine, sensitive tasks. The particular conditions examined are coaction, competition and audience presence. Other variables of interest are individual differences (personality, sex and ability) and type of task (motor, cognitive and perceptual). The experiments are primarily based on theories of social facilitation, particularly Zajonc's interpretation of mere presence effects and their relationship to arousal level. However, these social situations are also considered in a broader context and effort is made to theoretically integrate this area of research with the larger body of literature concerning stress and human performance. Bearing this latter concern in mind, a central and somewhat unique feature of this work is the use of 'sensitive' performance tasks and the analysis of data in terms of task strategies and shifts in attention, rather than overall measures which sometimes mask effects. It is concluded that social comparison processes and inter-subject pacing of performance provide a better explanation of the present data than do arousal theories. The generality of these effects across different tasks and subject populations is considered, as is the role of individual differences. A model is offered which outlines the typical sequence of performance related behaviours in mere presence situations and suggestions are made, in terms of this model, for future research.

This thesis has been concerned with the neuromagnetic fields associated with the processing of faces and sentences in humans. In four, largely independent sub-projects, results were obtained using novel methods of analysis to extract neurophysiologically relevant information from magnetoencephalographic MEG readings. Using the MEG facility of the Helsinki University of Technology, Finland, the research has led to four main suggestions: a) there are early latency face-specific neural systems in humans that are predominantly in right inferior occipito-temporal cortex, b) MEG recordings are useful in the study of autism, in that autistic subjects exhibit different responses to normal subjects following face presentation, c) phase-locked y-band activity has a specific role in semantic processing of sentences in normal subjects, and d) the late components of responses to face images are modified by endogenous priming, which is detectable before stimulus arrival in normal subjects. In order to pursue these neuroscience objectives, new methods for treating MEG data were developed, implemented and used. These comprise: a) an improved parameterisation of signal power over regions of interest, b) the use of re-sampling strategies to achieve statistical assessment of spectral coefficients within subjects, and c) a prestimulus method for the study of face processing using a tailored state-space representation approach.

The understanding of information encoding and retrieval processes in working memory is one of the fundamental problems of cognitive psychology. Information monitoring tasks, in which the current status of changing information is tracked, are claimed to require the use of updating processes in working memory. This thesis examines updating in the running ' memory span task (Pollack, Johnson, & Knaff, 1959), a task requiring the reporting of the most recent items from a continuous stream of spoken information. The aim is to better understand updating of working memory in terms of the processes that are employed during encoding and the memory structures associated with recall. Empirical data and ACT-R . cognitive models are used to compare one theory ~laiming that verbal information . is stored in the phonological loop, and updated via associated positional information under the control of a supervisory central executive (Morris & Jones, 1990), with a recency-based account, in which updating arises from storage of items in episodic memory (Ruiz, Elosua, & Lechuga, 2005). This research argues against a unitary account of updating. Examining the impact of a range of different rehearsal strategies on recall revealed significant improvements in running memory span when participants were trained to use active rehearsal strategies compared with recall following the passive encoding of items. Further increases in span were observed with increasing organisation in rehearsal. Six major strategies were identified by self-report, when varying presentation rate and memory load. These included shadowing of the current item, updating rehearsal of a list ofrecently presented items and rehearsing adhoc lists when memory load restricted the use o~task specific strategies. The key finding is that the selection ofrehearsal strategies depends systematically on task conditions. ACT-R models of encoding and retrieval supported empirical findings demonstrating that key rehearsal strategies were associated with complex patterns of recall, requiring encoding of items into both a phonological loop and episodic memory. These findings reveal a varied and diverse account of memory updating processes, based around the use of rehearsal strategies and the availability of working memory structures for tracking and updating of verbal working memory.

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No description available.

The human ability to recognise a voice is important for social interaction and speech comprehension. In everyday recognitions, the voice can be encountered alone (e.g. over a telephone) or with a face, and ~e person being recognised can be familiar or unfamiliar (such as a witness choosing a perpetrator from a lineup). This thesis - presents 7 studies cov~ring each of these situations. The first paper presents 3 studies on recognition of unfamiliar voices when there is a change in emotional tone between learning and test phases. A tone change reduces recognition accuracy when there is no specific encoding strategy at the learning phase. Familiaris.ation at the learning phase reduces the tone change effect but concentrating on word content at the learning phase does not. The second paper presents 3 studies investigating the limitations of the face overshadowing effect (voice recognition is worse when the voice is learned with a face than if it is learned alone). Blurring faces made face recognition more qifficult but did not affect voice recognition. In experiment 2, participants learned a sentence repeated 3 times, either with the face changing on each repetition or staying the same. Face recognition accuracy was lower when there were 3 faces, but this did not affect voice recognition. In experiment 3, inverting faces' made face recognition more difficult but did not affect voice recognition. The third paper reports that episodic memory for a celebrity is improved when a face and voice are given compared to just a face. A model of person recognition is presented that builds on existing models (e.g. Burton, Bruce & Johnston, 1990; Belin, 2004). It accounts for unfamiliar and familiar voice recognition and the benefits and costs of auditory-visual integration.

Learning to drive a car poses novel and demanding problems for the nervous system. In this task the brain must utilise sensory modalities in conjunction with implicit knowledge and learning mechanisms to produce several, almost instantaneous, motor commands. The process' by which the brain achieves this has its basis in vision and perception, which are largely influenced by movements of the eyes. This thesis investigates the role of eye movements in learning to drive. Using a head mounted Camera, three learners were taken for their first three driving lessons and their eye and head movements were recorded. These were then analysed and compared to three experienced drivers who had driven the same rural-suburban circuit. Analysis revealed that learner drivers have a smaller area of visual search and . . longer mean fixation duration compared to the experienced drivers, as seen in previous studies of novice drivers (with some driving experience). In addition, when turning a comer learner drivers do not look into the bend as the experienced drivers do. Instead learners use information about the road in front of the car to guide steering which demonstrates a 'search strategy that is less anticipatory and denies them the opportunity to prepare for the road ahead. This work explores the use of eye movements in extracting useful visual information for learning to drive. In addition it looks at the time scale of learning to elucidate any patterns of eye-movements that may develop in this 'natural' task, as seen in other activities of daily life.

A female advantage is observed in the accurate recognition of mental and emotional states from the face (Hall, 1978, 1984). The psychological mechanisms that may underlie this advantage have not been addressed systematically by researchers. The present thesis discusses the potential mechanisms underlying the female advantage by considering the Extreme Male Brain (EMB) hypothesis of autism (Baron-Cohen, 2002). Several possible directions for research are presented, including sex differences in i) automaticity of processing facial expressions; ii) attention to the eyes; iii) configural versus featural processing of faces; and iv) stimulation of emotion. The first three of these directions are addressed in experimental chapters. A priming task and emotional face-word Stroop task were used to investigate sex differences in the automaticity of processing facial expressions. Sex differences in attention to the eyes were investigated in two eye tracking studies, and in two studies manipulating the eye region of emotional faces. Finally, a study with spatial frequency filtered emotional faces examined sex differences in the use of fine and coarse detail facial information. Overall, the investigations provide some evidence for greater female attention to the eye region in faces, and the possibility that this may explain an observed female advantage in facial expression recognition. Results are discussed in relation to the EMB hypothesis and sex differences in social cognition more generally. Potential directions for further research are outlined.