Fabricación de las espumas 65

Design

The design o f this study incorporated two features whicl^ formed signficant inqjrovements on previous studies. These included:

1. The use o f a depressed control group. This was a major improvement on previous studies o f self-focus in panic in that it allowed the exclusion o f depression as an explanation for any positive results.

2. Use of several measures of self-focus m the same study. As is evident from the present study, results do not necessarily generalise over different types o f measure. The few previous studies have not compared performance on different measures o f self-focus in the same sample, therefore making it difficult to compare studies using differing measures on different populations.

One possible drawback of the design o f the present study was the use o f a group of panickers with concurrent depression. Because the panickers used in this study were also depressed, it could be argued that comorbidity or an interaction o f depression with panic may have been at least partly responsible for the nature of the results. However, there were clear advantages to using depressed panickers and the substitution o f a pure panic group would not have been satisfactory for the reasons discussed in Section 1.2.1. However, if time and resources had allowed, the addition o f a pure panic group would have been useful in clarifying these issues further.

Measures

Thought-Sampling Task

Overall, the thought-sampling task worked well - respondents were able to report enough thoughts for a satisfactory sample to be obtained and levels o f each type o f response were

sufficiently high to allow valid between group comparisons. However, there were two areas in which the task was not wholly satisfactory.

First, as discussed above, it was not clear that the induction o f physical sensations was sufficiently powerfiil for the hypotheses to be adequately tested and some form of physiological monitoring would have been desirable to eliminate this lack o f clarity. Second, the task required participants to write down their thoughts and some participants found this difficult or disturbing because of low confidence with literacy (despite

reassurances from the experimenter). This type o f task has been used with success in other studies (reviewed by Singer & Kolligian, 1987) and significant difficulties were therefore not anticipated. An alternative method would have been to record participants’ verbal accounts o f their thinking. This method was used by Borden et al. (1993) with an American sample and was considered for the present study. It was felt however, that a British sample may find giving a verbal report o f their thoughts rather embarrassing and intrusive and the choice was therefore made to use a written task. On balance, this was probably the right choice - ninety per cent of participants produced 14 or more responses and no participant produced fewer than five responses, indicating that even the least confident were able to give some indication o f their thinking. Also, although some participants expressed worries about writing their thoughts, none appeared seriously distressed.

Sentence-completion

The sentence-completion measure was unsatisfactory for the purposes of this study in that it elicited very low levels o f somatic self-focus. Possible reasons for this have been

discussed above. It was also noted as a matter o f some concern that Exner’s (1973) sentence-completion task produced distress in some participants. This problem was not anticipated as previous studies using this measure have not reported any adverse effects and the items do not require in-depth responses. Nevertheless, around seven per cent o f participants (three patients and two controls) commented that they had found the

sentence-stems emotionally distressing to complete and the measure precipitated crying in three individuals.

BCG

The Body Consciousness Questionnaire was used to assess trait somatic self-focus as this is the only available measure. However, as discussed above, the subscale most relevant to the hypotheses (Private Body Consciousness) is not ideal. It is very short and this may mean that it is relatively insensitive to gradations o f somatic self-focus. A more

comprehensive instrument would certainly have been preferable.

BC6"

This is a well-used measure with good psychometric properties. Scheier & Carver (1985) developed a simplified version o f the SCS on the grounds that that some previous studies had reported difficulties with the administration o f the SCS - specifically that respondents had been unable to understand the wording o f some items and that this had caused distress. However, the decision was made to use the original version both because the psychometric properties o f the revised version have not been well-documented and because potential participants with serious language or literacy problems would have been

excluded (because the thought-sampling task required a minimum standard o f linguistic competence). In fact, no significant dif&culties with administration were noted.

Sample

The nature of the samples accessed for each group was considered to be satisfactory. The groups performed as expected on the screening measures and were adequately matched for age, sex ratio and educational level. The sample size o f eighty participants was also considered to be satisfactory on the basis of the power calculations, although obviously, a larger sample might have allowed smaller effect sizes to be demonstrated.