ABSTRACT
When we try to discover the quantitative rules that govern the human perceptual systems, we find ourselves faced with many-faceted problems of practical measurement. If the task of quantification in psychophysics impresses us as overly complicated, perhaps it is because we have not sampled the frustrations of scientists in other fields. Whenever a scientist refuses to settle for rough approximations and pushes instead toward exactitude, he is apt to find himself thwarted by those twin goblins, systematic errors and random errors. No scientist ever entirely escapes their jinx—provided he strives for the ultimate in accuracy.
