Problem-solving

Carrying out a reasoning task can be interpreted as a problem-solving activity, while problem-solving frequently requires reasoning. The following tasks are classified as problem-solving tasks in that they require several steps to solution, and they require Ss to generate a strategy. Task solution is likely to require reasoning, but it is less certain what type of inferences Ss might draw and when, since the tasks are less constrained than the reasoning tasks described above.

2.3.8.2.4.1 Clinical samples

Watts MacLeod and Morris (1988) used the Tower o f London task (Shallice, 1982) to examine problem-solving ability in depressed and nondepressed Ss. In this task, three beads are arranged in various starting positions on sticks of unequal length, and Ss are required to move them to a goal position in the minimum number of moves, with certain constraints on the types of possible move. The groups did not differ significantly in the number of problems solved, but time taken both to plan and execute the moves was significantly longer for the depressed Ss. Beats et al. (1996) compared depressed and normal controls on a computerised version of this task. The depressed Ss took significantly more moves overall to solve the problems than controls, although the groups did not differ significantly in the number of problems solved in the minimum number of moves. The depressed Ss were significantly slower than controls for both initial and subsequent movement times. Beats et al. (1996) calculated a measure o f thinking times from the movement time data, and found the groups did not differ in initial thinking time, but depressed Ss did spend significantly longer than the controls thinking about the task after making the first move. There was evidence o f improvement in performance when depressed Ss were re-tested on recovery, but they remained significantly slower than the controls. These two studies (Beats et al., 1996; Watts et al., 1988) are similar in finding the accuracy of depressive performance tended to be less impaired than latency. Elliott et al. (1996) reported a different pattern, with depressed Ss showing global impairment in performance accuracy, but no difference in movement time. When thinking times were calculated, depressed Ss were found to spend more time than controls planning the simpler problems, but less time planning the more difficult problems. The depressed Ss spent significantly longer than the controls thinking about the task after making the first move.

2.3.8.2.4.2 Nonclinical samples

anagrams o f equal length are arranged in a standard letter sequence. Whilst they can be solved individually, recognition of the standard sequence considerably improves performance, assessed in terms of response latency, number o f unsolved anagrams, and number of trials to learn the pattern. This task was originally developed to test the learned helplessness model o f depression described in section 2.1.3.3.3, and a series of studies employed 'helplessness' manipulations in nondepressed Ss by exposing them to uncontrollable aversive events, and assessing subsequent task performance. Some of these studies have also included a straightforward comparison of dysphoric and nondysphoric Ss on the task. Of these, several have found evidence of deficits in task performance in dysphoric compared with control Ss (Klein, Fencil-Morse & Seligman, 1976; Miller & Seligman, 1975; Willis & Blaney, 1978, Experiment 3), while others have not (Gotlib & Asamow, 1979; Sacco & Hokanson, 1978). All five of these studies used similar methods of S recruitment, and Ss showed similar scores on the BDI. The tasks used in each study were also very similar, although the studies did vary experimental conditions such as the addition of a 'helplessness' condition. The variability o f the findings therefore suggests any depressive deficit on this task is not robust, at least when nonclinical Ss are used.

Hertel and Knoedler (1996, Experiments 1, 2A & 2B) compared dysphoric and nondysphoric students selected on the basis of the BDI on their ability to solve problems by analogy. In Experiment 1, Ss first solved a series of training problems that were analogous to subsequent target problems. In the hint condition, the relationship between the target problem and the preceding training problem was made explicit in the task instructions. In the no-hint condition no reference was made to this relationship. The nondysphoric Ss solved more target problems in the no-hint relative to the hint condition, suggesting the hints inhibited performance, perhaps by focusing efforts on remembering irrelevant details of the training problems. In contrast, the dysphoric Ss solved a similar number o f target problems in the two conditions. O f more interest, while there was no difference between the groups in the no-hint condition, the dysphoric Ss solved more target problems than the nondysphoric Ss in the hint condition. Hertel and Knoedler (1996) suggest post-hoc that the dysphoric Ss failed to concentrate on trying to recall the training problems when prompted to by the hints, and therefore did not experience the disadvantage shown by the non dysphoric Ss. In Experiment 2B, dysphoric and nondysphoric Ss were compared on the same set of problems with all Ss receiving hints, but during the training phase Ss were either instructed to attempt solution of the training

problems (as in Experiement 1) or they were instructed to try to remember the training problems. The results showed nondysphoric Ss solved more problems in the memory- oriented versus the problem-oriented training, while dysphoric Ss showed no difference between the two conditions. When comparing the groups, dysphoric Ss solved more problems than nondysphoric Ss in the problem-oriented condition, replicating the findings of Experiment 1, but the groups did not differ in the memory-oriented condition. The authors suggest the memory-oriented training provided a better basis, for the nondysphoric Ss at least, for transfer of the solution, reducing the interfering effects o f remembering irrelevant details, while the results suggest dysphoric Ss did not attempt to make use of the strategies built into the experimental design, and therefore showed an advantage in performance when these strategies proved to be unhelpful.

In summary, there have been relatively few studies of reasoning and problem-solving on neutral tasks, and many o f those carried out are difficult to interpret due to problems of design. For example, some studies (e.g. King & Phillips, 1985; Salzman et al., 1966) have compared depressed patients with groups o f other psychiatric diagnoses, but have not included a normal control group, while others have included both manic and depressed Ss in the same group (e.g. Gruzelier et al., 1988). Overall, the weight of evidence suggests a deficit <jin reasoning and problem-solving tasks associated with depression, but the studies reviewed above provide very little information about the qualitative nature of any deficits, and have made little attempt to explore the processes which might underlie depressive performance on these tasks.