Effective decisions and their verbal justification

Recent experimental work on human control of complex systems has drawn attention to the discrepancy that may exist between the person's reported knowledge of the system and their ability to control it. Sometimes people act correctly but cannot answer questions about what they are doing; sometimes they can say verbally what they should do (perhaps having had verbal instruction in the right answers), but still do not do it. This discrepancy is of major practical importance, for example in designing training programmes or in eliciting expert knowledge for incorporation in a mechanical 'expert system'. It is also puzzling for psychological theory, as it rules out certain plausible models of the functioning of the brain. This paper considers what mechanisms are still possible.