Yesterday, today and tomorrow

1260 American subjects were timed as they responded to one of the three questions ('What day of the week is today?' (Tod question), 'What day of the week was yesterday?' (Y question), and 'What day of the week will tomorrow be?' (Tom question)) at one of three times of the day (early morning, mid-day and the late evening). Response times as a function of the day on which the question was posed defined an inverted U-curve for all questions in all three conditions. The Tod question always triggered the fastest responses. In the morning, responses to the Y question were faster than responses to the Tom questions, whereas in the evening the converse was the case. At mid-day responses to the Y question were faster than responses to the Tom question at the beginning of the week and slower than those at its end. The patterns of introspection associated with the responses also defined reversed U-functions. The results are interpreted in the framework of a multi-channel spreading activation model.