ABSTRACT
Psychophysicists and communications engineers use the notion of the ideal observer. An ideal observer is one who records events with utter faithfulness. There are no distortions in the recording system, and the record is a perfect rendering of the event. No such recording system, biological or artificial, exists in reality, but the ideal observer is a useful abstraction, a standard that the actual performances of real observers may be compared with. The memory systems of living organisms are real recording systems. Their operation may be described as distorting, marred by internal noise, faulty, incomplete, and prone to adding information that is not part of the event being recorded. Still, in evaluating the performance of human memory, assumptions are made as if it operated like an ideal observer most of the time. For instance, eyewitness testimony is still considered better than circumstantial evidence, even though psychologists have been demonstrating the unreliability of the memory of witnesses for the past 70 years or more (Buckhout, 1974; Loftus, 1979; Münsterberg, 1915; Wall, 1965).
