The literature reviewed above has demonstrated that more work needs to be done on developing measures of real-life-type problem-solving in order to assess the deficits shown in patients with frontal lobe involvement. Studies have highlighted that everyday problem-solving is a multidimensional concept, and that many factors potentially contribute to performance including executive skills, prioritising and planning abilities, comprehension and judgement of interpersonal issues, and prior experience of similar problems. The current thesis attempts to address these issues in a series o f related experiments using new real-life-type measures as described below.
6.1 STUDY 1: REAL-LIFE PROBLEM-SOLVING
The first study is split into two parts. The first part describes the development of a test designed to assess multiple dimensions of interpersonal problem-solving. The problems were intended to be open-ended, with no absolute right or wrong answers, and were administered with little direct cueing or feedback, in order to have greater ecological validity than most abstract standardised measures. Ecological validity was also increased by presenting half of the scenarios on videotape. A battery of standardised executive measures was included in the study. The performance of participants with anterior structural lesions, those with posterior structural lesions, and a matched healthy control group, was compared. It was anticipated that the anterior group would show impairment relative to the other groups on a range o f aspects of problem-solving, and that these would relate to the factors outlined above, including executive function, ability to prioritise and make decisions, comprehension and judgement of interpersonal issues, and previous experience.
Part B of study 1 describes an adapted version o f the real-life problem-solving measure. This was designed to be more sensitive to the deficits shown by patients with
anterior lesions, and to be shorter and more user-friendly than the original measure. The performance of participants with anterior lesions was compared with that of the matched healthy control group.
6.2 STUDIES 2 AND 3: CONTRIBUTION OF PRIOR KNOWLEDGE AND EXPERIENCE TO PROBLEM-SOLVING
Studies 2 and 3 primarily address the contribution of experience to real-life-type problem-solving performance, using the measure developed in part B of study 1. Assessing the amount of previous experience that people have with particular situations is complex, and there are no existing reliable methods to achieve this. Rather than attempting to measure previous experience directly, the strategy followed in the current thesis was to assess groups of participants who are likely to differ in the extent/quality of their experience.
Two studies were carried out, both involving participants with postulated frontal lobe involvement. Study 2 compared the performance of adults with Tourette’s Syndrome (TS), with that of a matched control group. As TS develops early in life, it would be predicted that these participants would have reduced or less effective knowledge stores, both due to the primary effects of fronto-striatal dysfunction, and to the secondary effects o f the disorder, as discussed above in section 3. The main aim of study 2 was to determine whether participants with TS showed impairments in real- life-type problem-solving, as would be predicted if experience plays a crucial role in this.
Study 3 examined the performance o f a group of healthy older people, compared with a matched group o f younger adults. Although ageing is associated with differential changes in frontal cortex, it has been argued that the extensive experience and wisdom acquired by older people throughout the life span can have a protective effect in everyday problem-solving situations, as discussed above in section 4. The aim of study
3 was to examine whether the older group showed intact real-life-type problem solving performance, as predicted on the basis of their greater experience.
Studies 2 and 3 also allowed further elucidation of the contribution o f executive processes to performance, since TS is associated with a narrower range of executive deficits than that seen in people with anterior lesions, to the extent that some authors have argued that people with uncomplicated TS have no executive deficits (Yeates & Bomstein 1994; Ozonoff, 1997). By contrast, impairment relative to younger people has been reported on a range of standardised executive measures in older people, as described in section 4.2. Therefore, the battery of executive measures used in study 1 was also administered in studies 2 and 3, and the relationships between performance on these measures, and aspects of the real-life problem-solving test were examined.
6.3 STUDY 4: CONTRIBUTION OF SPEC IFIC INTERPERSONAL PROCESSES TO REAL-LIFE PROBLEM -SOLVING
Previous work, as described in section 2.5.4.2 above, has indicated that the frontal lobes are implicated in functions involved in understanding and relating to other people, such as pragmatic language processing, theory of mind and empathy. Study 4 describes an adaptation o f the test used in the previous studies, in order to assess the contribution of specific interpersonal difficulties to problem-solving performance. New problems were developed focussed on practical difficulties that minimised the need to comprehend or consider interpersonal issues. These were compared with a subset of the original problems in which interpersonal issues were central to the problem. This study compared the performance of participants with focal anterior lesions with a group of control participants. The aim was to discover whether those with anterior lesions continued to show deficits on the practical problems when these did not involve interpersonal issues.
6.4 STUDY 5: CONTRIBUTION OF SPECIFIC DEFICITS IN PRIORITISATION AND PLANNING TO REAL-LIFE PROBLEM-SOLVING
Study 5 describes the development of new measures designed to address the selection of courses of action in more detail. The new measures focussed on prioritisation and planning skills, and participants’ ability to evaluate consequences. Real-life materials were used, and there was little direct feedback on performance, and no absolute right or wrong answers, in order to increase the ecological validity o f the tests. The performance of participants with anterior lesions was compared with that of a matched control group. In addition, a sample of adults with Tourette’s Syndrome was also compared with a matched control group. The aim o f the study was to determine whether anterior lesions and Tourette’s Syndrome are associated with deficits in prioritisation and planning on a range of types o f different tasks.