Self-referential selective memory in pain patients.

The effect of self-reference on recall bias for pain stimuli was compared in chronic pain patients and controls. It was hypothesized that self-referential encoding would result in better recall of pain stimuli in chronic pain patients. In contrast, it was predicted that a non-pain control group would display no recall bias for pain-associated stimuli, regardless of the encoding reference. Subjects were tested in two conditions. The first condition (self-referential) involved encoding a list of words constructed from sensory pain, affective and neutral words. Elaboration at the encoding stage was achieved by asking subjects to imagine themselves in situations involving these words. Subjects were also asked to rate the likelihood of these situations occurring on a scale of 1 to 5 (from 1 = 'will not happen' to 5 = 'certain to happen'). The second condition (other-person reference) repeated this task in reference to another person with a matched list of words. A 2 x 2 x 3 factorial analysis of variance based on group x reference (self and other) x word type (sensory, affective and neutral) was carried out on recall scores, with the likelihood ratings as a covariate. Results reveal a significant three-way interaction. The analysis indicated that, while pain patients show an increase in recall of sensory words and a decrease in recall of neutral words when these are encoded in reference to themselves, control subjects show no difference in recall of these word types regardless of the encoding condition. The results support the notion that pain patients selectively recall more pain-associated words in comparison with other word types. However, this effect is only true for stimuli encoded in reference to themselves. It is proposed that this processing bias may contribute to the maintenance of a sense of helplessness and exacerbate the emotional impact of the pain experience.