Temporal experience after severe brain injury

Relatively little is known about the cognitive nature of temporal experience or 'psychological time' after brain damage, despite the importance of temporal regulation of action for normal social adaptive behaviour. Practising clinicians are confronted with a wide range of problems associated with disturbances of the subjective appreciation of time, all of which are central to the complex manner in which action is organised in temporal contexts. Yet in neuropsychological terms these different aspects of psychological time pertain to difference cognitive abilities. This thesis constitutes a preliminary' exploration of the nature of psychological time and how this may break down after severe brain injury in terms of the underlying cognitive processes. Experimental group studies are reported, supported by detailed single-case investigations, which suggest revisions to current theoretical accounts of time experience. In general, the empirical data support the notion of an internal timing system susceptible to attentional mediation, while translation of temporal awareness into a form useful for goal-directed behaviour entails the additional operation of executive skills. Episodic and semantic memory processes also contribute to temporal regulation of action in terms of sustaining a complex network of temporal representations based upon past events, knowledge about time and linguistic and numerical aspects which are necessary for communication about time. This in turn underlies the development of shared notions of time essential to social adaptation. It is argued that the psychological experience of time involves multiple temporal perspectives and that no single theory can provide an adequate conceptual framework for clinicians. Disturbances in temporal awareness can involve either dysfunction of a neural timing system sensitive to the operation of attention, or to impairments in a wide range of other general purpose information processing systems which contribute to the broader notion of psychological time