UNDERLYING CAUSE BIAS (RUMINATION BIAS):

Individuals, such as cases in a case-control study, may ruminate about possible causes for their illnesses and thus exhibit different recall or prior exposure than others, such as controls in a case-control study¹. This bias is similar to Recall Bias, but also eludes to behaviors exhibited by some individuals due to biased recall, vs. just the description of past events due to biases recall. Also see: Recall Bias, and Availability Bias.

Reference:

1. Sackett DL. Bias in analytic research. J Chronic Dis. 1979;32 (1-2):51-63. (Link to Reference)