Investigations of metacognition – and also the application of the storehouse and correspondence metaphors – seem as appropriate for laboratory research as for naturalistic research. In terms of measurement, the only quantitative difference between the “input-bound percent correct” and “output-bound percent correct” is the inclusion versus exclusion (respectively) of omission errors in the denominator of the percentages.

Several conclusions depend on a version of signal detection theory that assumes performance is based on underlying equal-variance normal distributions of trace strength. Such conclusions are questionable without empirical justification for that assumption. A thought experiment is presented to show how the assumption is probably invalid, and empirical evidence is cited for the assumption's invalidity in research on human memory.