Test re-test reliability of the semi-structured interview 79-

The results of the test re-test reliability analysis although good, were slightly less satisfactory; four of the 45 items being rated significantly differently at the two time points. Closer inspection of these differences revealed that some participants reported more thoughts during the second interview whilst others reported fewer, and some belief ratings increased whilst others decreased. A number of factors might account for these discrepancies.

The situations recalled during the second interview may have simply been more or less significant for the participant concerned. Alternatively, where the same situations were discussed during both interviews, the interim may have allowed participants to contemplate the situations discussed and questions posed, resulting in variation in the amount o f information recalled during the second interview.

It is also possible that during the second interview participants were less motivated to talk about the finer details of their concerns, having already discussed them a few weeks earlier. This, coupled with the knowledge that denying the existence of concerns would result in faster progression through the interview, may have led some second interviews to be less fruitful than their first round counterparts.

Despite expecting a reliable interview to elicit similar assumption and core belief ratings at different points over time, the confounding variables discussed suggest that it is perhaps an over simplification to assume that differences in test re-test reliability necessarily indicate inadequacy in the interview’s structure. Although the reliability analyses carried out in the present study produced promising results, limitations such as those'previously discussed should be borne in mind when assessing a measure’s psychometric properties.

4.2.8 Concurrent validity of the semi-structured interview

Items from the EAT and the EDBQ sub-scales that were used to check concurrent validity generally correlated well with the corresponding number of negative automatic thoughts and assumptions elicited by the interview. Items from the BDI, BAI, RSE and EDBQ-NS sub-scale also correlated well with the mean emotion and negative self-belief ratings.

The above discussions give prominence to a number of important issues concerning the use of semi-structured interviews, particularly with clinical populations. However, given the promising reliability and validity checks, and the fact that no known measure

assesses cognitions to the necessary specificity, it was felt that this interview was the most appropriate choice of measure for the present study. It is however, acknowledged that additional psychometric investigation would be required if this instrument were to be further developed as a useful research and clinical tool.

4.3 Interpretation of the Results

4.3.1 Negative automatic thoughts

The finding that patients with anorexia nervosa reported more eating related negative automatic thoughts when discussing an eating related incident, compared to non-clinical participants, supports earlier studies (M.J. Cooper & Fairbum, 1992) as well as the theoretical ideas proposed by Gamer & Bemis (1982). Findings that patients with anorexia nervosa reported longer duration of thoughts and higher levels of belief and associated distress than non-symptomatic dieters and female controls also supports and extends the findings of Clark et al. (1989), who found that individuals with anorexia nervosa found their eating, weight and shape related thoughts more emotionally laden and plausible than controls.

However, the clear distinction between the female controls and both the patients with anorexia nervosa and the non-symptomatic dieters becomes slightly less evident when discussing concerns about weight and shape. Here, the non-symptomatic dieters reported eating, and weight and shape related automatic thoughts that were in some ways intermediate in characteristics between those identified by patients with anorexia nervosa and those identified by female controls. This finding gives prominence to the importance of separating areas of concern, whilst also indicating that eating related

thoughts may be more specific to anorexia nervosa than weight and shape related automatic thoughts. The latter may also be characteristic of non-symptomatic dieters, though to a lesser extent than patients with anorexia nervosa.

4.3.2 Underlying assumptions related to eating, and weight and shape as a means to acceptance by self and others

The finding that patients with anorexia nervosa reported significantly more second order assumptions related to eating, and weight and shape as a means to acceptance by self and others than non-symptomatic dieters and female controls supports earlier studies (M.J. Cooper et al.f 1997; M.J. Cooper et al., 1998; Geller et al., 1998; Mizes, 1992). Current findings also indicated that patients with anorexia nervosa found their eating, and weight and shape related assumptions significantly more believable and distressing than non-symptomatic dieters and female controls. This suggests that these assumptions may be more elaborated in clinical participants. However, the findings that non- symptomatic dieters reported significantly more self- and other-referent second order weight , and shape related assumptions than the females controls (similar differences being reported in degree of belief and distress), suggests that these assumptions may also be characteristic of non-symptomatic dieters, though again to a lesser extent than patients with anorexia nervosa.

These results support the theoretical proposal that weight-related self-schemata are central to the psychopathology of anorexia nervosa (Vitousck & Hollon, 1990). However, they also give prominence to the potential importance of assumptions linking weight and shape to acceptance by others, and assumptions linking eating to acceptance

by self and others. Indeed, these findings raise the question of whether current thinking is in danger of becoming overly focused upon weight and shape at the expense of potentially pivotal eating related concerns.

4.3.3 Control over eating

The finding that patients with anorexia nervosa reported significantly more cognitions related to control over eating than non-symptomatic dieters and female controls, corroborates the earlier work of M.J. Cooper et al. (1997) and Fairbum & M.J. Cooper (1992): In addition to existing empirical evidence, the current findings also indicated that patients with anorexia nervosa found these cognitions significantly more believable and distressing than non-clinical participants. Whilst not marginalising the importance of weight and shape related assumptions, these findings again give prominence to the potential importance of eating related assumptions.