Recall bias in reporting medically unexplained symptoms comes from semantic memory.

OBJECTIVE: When people report somatic complaints retrospectively, they depend on their memory. Therefore, retrospective reports can be influenced by general beliefs on sickness and health from semantic memory. We hypothesized that individuals with medically unexplained symptoms (MUS) would have recall biases stronger than those of people without complaints when reporting symptoms retrospectively, and that this effect would be a function of time between symptom experience and report.
METHODS: To compare two time frames, 37 participants who were high and low on MUS reported momentary symptoms combined by daily recall and weekly recall using an electronic diary.
RESULTS: Both groups reported more symptoms when recalling the entire week than what could be expected from average momentary reports. However, participants high on MUS also reported more symptoms when recalling a week than when recalling a day. For this group, recall bias was not associated with peak heuristic or symptoms variability.
CONCLUSION: Symptom reports in people high on MUS increases as time passes by, probably as a results of a shift in memory retrieval strategy from using episodic knowledge to using semantic beliefs.