Response time is used to interpret choice in decision problems. It is first establishes that there is a correlation between short response time and choices that are clearly a mistake. It is then determines whether a correlation also exists between response time and behavior that is inconsistent with some standard theories of decision making. The lack of such a correlation is interpreted to imply that such behavior does not reflect a mistake. It is also shown that a typology of slow and fast responders may, in some cases, be more useful than standard typologies.