Cognitive bias and memory performance in patients with persistent insomnia

Abstract

Twenty patients with primary insomnia were compared with 20 normal controls, matched for age, sex, and educational level, on a modified version of the emotional Stroop test, and tests of explicit and implicit memory for threat words and non-threat words. The results showed that the insomniacs had a prolonged Stroop latency for sleep words, but so did the controls, and there was no group difference on Stroop interference of sleep words. The insomniacs showed no explicit or implicit memory bias for threat words, and they did not differ from the controls on explicit or implicit memory performance. They did differ from the controls, however, by scoring lower on the WAIS-R vocabulary test, and by having lower expectations of their explicit memory performance before testing, although they did not differ from the controls on how they evaluated their memory performance after testing. The results are discussed in terms of a possible deficit in semantic memory in insomniacs.