| Summary: | This thesis presents an investigation of cognitive aspects of a perceptual motor skill. In particular the relationship between covert rehearsal (mental practice), imagery and memory is considered. An analysis of past studies of mental practice suggested that some form of imagery is used by subjects to mentally rehearse certain aspects of various tasks. It appears that mental practice produces relatively consistent performance improvements in tasks which are predominantly perceptual or motor in nature, rather than symbolic. Two different types of imagery have been suggested; one based on the visual/perceptual system, the other based on the motor system. A review of the mental imagery literature considered the various methods of investigating imagery and outlined several hypothetical models of mental imagery. It was concluded that selective interference techniques offered the greatest potential for investigating mental imagery, as might be employed in mental practice procedures. A technique for investigating mental imagery was derived from a recent study by Finko (1979) in which the functional equivalence between images and actions was inferred from the presence or absence of imagery induced biasing or after-effects. The present research used a linear positioning task, with novel movements interpolated between the learning and recall of a standard movement as the basic perceptual-motor task to be investigated. In past research such tasks have boon shown to be biased by characteristics of the interpolated movement. It was hypothesised that if imagery of movements and movements were functionally equivalent, then biasing errors produced by making a novel interpolated movement should also be present with instructions to imagine but not execute such a movement. The results showed that instructions to execute or imagine linear movements produced similar effects on subjects’ memory for other linear movements. A series of five further experiments then investigated the nature of imagery used in this task, by means of a selective interference paradigm, used to suppress any imagery effects. The results of these experiments suggested that this type of imagery primarily involved a spatial information processing system. The seventh experiment investigated the relationship between images of linear movements and subjects' memory for such movements. It was found that tasks which suppressed images also interfered with subjects' memory for linear movements. It was concluded from this that subjects' images of linear movements and their memory for that class of movement primarily involved the representation of spatial information. The final experiment investigated the effects of instructions to form images of a non-spatial task on subjects' memory for a similar non-spatial task. Instructions to imagine a novel pressure, interpolated between the learning and recall of a standard pressure, failed to produce a predicted biasing effect. However, it appeared, from subjective reports, that subjects were generating spatial images which had little or no significant effect on how the task had been remembered. This research shows that imagery of linear movements involves a spatial information processing system and that even in a task with little spatial informational content it is the spatial aspects of the tasks which are reported in subjects' imagery. It is suggested that this may reflect the importance of spatial information in action control. Mental practice appears to be a procedure in which subjects use images consisting largely of spatial information to represent the environmental conditions for and consequences of action.
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