Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:…Task (Stroop, 1935) is probably the task that has been the most extensively used in a wide variety of fields in psychology, including the experimental, developmental, psychopathological and neuropsychological ones (see Dyer, 1973; MacLeod, 1991; MacLeod and MacDonald, 2000, for detailed reviews).
Category: