Mapping introspection's blind spot: reconstruction of dual-task phenomenology using quantified introspection.

Psychologists often dismiss introspection as an inappropriate measure, yet subjects readily volunteer detailed descriptions of the time and effort that they spent on a task. Are such reports really so inaccurate? We asked subjects to perform a psychological refractory period experiment followed by extensive quantified introspection. On each trial, just after their objective responses, subjects provided no less than four subjective estimates of the timing of sensory, decision and response events. Based on these subjective variables, we reconstructed the phenomenology of an average trial and compared it to objective times and to predictions derived from the central interference model. Introspections of decision time were highly correlated with objective measures, but there was one point of drastic distortion: subjects were largely unaware that the second target was waiting while the first task was being completed, the psychological refractory period effect. Thus, conscious perception is systematically delayed and distorted while central processing resources are monopolized by another task.