Can subjects maintain a constant criterion in a memory task?

In two recognition memory experiments, subjects rated how certain they were that a given test item had been shown previously. Subjects either received standard instructions about their rating criteria or were explicitly instructed to maintain criteria defined in the manner of Healy and Jones (1973) or along the lines of signal detection theory. When a priori probability varied, subjects in all instruction groups held constant the criteria defined by signal detection theory at the expense of shifting the criteria proposed by Healy and Jones. The results were taken as evidence for the psychological validity of recognition memory analyses based on signal detection theory.