Simplificación para la apertura de un negocio en México

In the following empirical chapters the principal method of investigation is the group study though some issues are explored through single case analysis. Although the merits of both o f these approaches has been widely debated the combination of group studies and single-case investigations is increasingly being accepted as perhaps the most fruitful way to pursue clinical research (Burgess, 1997).

From a purely theoretical perspective one would ideally use localised lesion cases, but this was not practicable. The experimental subjects were in fact mostly individuals who had sustained severe head injuries (and therefore fairly diffuse brain damage), although some of the single case investigations were undertaken with individuals with other aetiologies (principally stroke, anoxia and herpes simplex encephalitis). This composition and the fact that all were undergoing rehabilitation at the time of the study reflects the nature of the author’s clinical work. The advantage of this approach, aside from ease of subject availability, is that the investigations were strongly motivated by a desire to understand more about the real life problems associated with disturbed temporal experience that are so rarely made explicit in rehabilitation.

There are also obvious limitations of this strategy. Clearly, the unavailability of unilateral/selectively lesioned subjects precludes investigation of the neurological underpinnings of the many different facets of psychological time (Godefroy et al., 1998). Yet because temporal experience is an area of cognition which has received very limited neuropsychological attention it was decided to pursue a series o f iterative exploratory studies which would have the potential to be applied to specific lesioned cases in future

investigations. Given the current embryonic status of research in the field, the fact that there are few systematic clinical studies and no clinically-derived theoretical frameworks, the present approach was inevitably an exploratory venture concerned with several different issues regarding the nature of time experience. Future research will be able to refine key methodological and conceptual issues raised in the thesis.

A primary aim of the present research therefore was to develop a set of tasks which could be employed in future studies to examine some of the more promising empirical findings. For example, a core objective was to design a series of practical easily administered tests which would be sensitive to brain damage. Such tasks could then be undertaken with unilateral lesion groups which would allow more specific investigation of interesting theoretical issues raised by the present research (see final chapter). Another potential development lies with equating performance on the relatively short cognitive tasks developed in the thesis with temporal awareness over much longer time periods in everyday functional situations.

In order to provide an assessment of task performance which could be normatively evaluated and against which concurrent time estimation could be compared, standard neuropsychological measures were used as much as possible. This meant that many of the tasks employed would be already familiar to clinicians as tests used in clinical practice. At this point it is also worth clarifying what is meant by the notion of a ‘task. ’ In contrast to standard neuropsychological assessments when a subject is engaged in one activity at a time, most time estimation studies are really dual task experiments. There is a primary task (usually the process of keeping track of time) and a secondary task (the activity one is engaged in during the interval which is to be timed). The validity of this distinction is an issue which will arise in several chapters and will be discussed in the final section. Throughout the research the secondary tasks were essentially familiar clinical tools which were employed according to novel procedures involving temporal judgements.

With regard to the design of the group studies, it was decided to compare the performances of two groups of severely head injured individuals vsath one another and with a ‘normal’ control group. In this way it is possible to distinguish between the specificity of a test for brain damage (ie. where control subjects outperform two similarly-performing groups of head injured subjects) and its sensitivity to severity of brain dysfunction (where the less severe head injured subjects performance is superior to the more severely disturbed group). The theoretical justification for this distinction is discussed in the next section.

In the research both the head injury groups comprise people who have technically sustained severe brain injures and so it is worth commenting at this stage on the clinical basis for making a distinction between them. Initially this decision reflected the differences in clinical presentation between members of the two groups. However, the subjects’ neurological history confirmed that this clinical judgement was well-founded by revealing a significant disparity in the duration of post-traumatic amnesia exhibited by members of the two groups. Thus, not only did the mean length of PTA differ across groups but there was no overlap between them. Within this general design, slight differences occurred in the subject composition for each study and these are described in the relevant chapters.

One notable feature of the brain injured subjects employed in the present research is that they sustained very serious injuries and were very severely cognitively disturbed as a result. Consequently they represent only a minority of the brain injured population, but there are several advantages to studying this somewhat unrepresentative group. The investigation of subjects who in some sense represent ‘extreme’ cases is a useful means of establishing tasks and procedures which can later be refined for use with less severe cases. Appropriate case material for this approach can be either selectively lesioned cases or very severe generalised injuries. Theoretically too, one can develop hypotheses from the study of grossly disturbed patients, the generality of which can then be tested within less severe populations. Equally importantly, more o f the severely brain injured

come to the attention of clinicians and therefore investigation in this population is more directly applicable to the working climate of brain injury services. Finally, a better understanding of temporal disturbance is really an initial step in trying to intervene to alleviate such problems, and since head injury is the most common kind o f brain injury amongst most age groups and certainly the most debilitating economically, it seems appropriate to pursue this enterprise with this population.