Temporal judgments and contextual change

Three experiments investigated effects of environmental context on temporal memory judgments. An equal number of items occurred within each of two equal durations (D1 and D2). Subjects subsequently were asked to judge the length of a given duration in comparison with the other, then to discriminate the correct list and serial position for each recognized item on a test. If environmental context was unchanged, D1 was remembered as being longer than D2; if the context was disrupted during the interval separating D1 and D2, this effect was reduced; and if the context prevailing during D2 also was changed, the effect was eliminated. List discrimination was improved only if the context was changed. Serial-position judgment was not affected by either manipulation. Changes in process context--the internal context produced by the performance of specific cognitive processes--lengthened remembered duration, but the effect did not simply add on to the effects of environmental context. Results are discussed in terms of a contextual-change hypothesis.