ABSTRACT
Error is defined here as the deviation of human performance from some intended, desired or ideal standard. Such deviations may have bad outcomes, but they can also be inconsequential or even benign — as in trial-and-error learning. Errors are not intrinsically bad, though their consequences and the conditions provoking them may be. Systematic error forms arise from highly adaptive cognitive processes. It is the circumstances of their occurrence rather than the underlying mechanisms that largely determine the nature of the outcome.
