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:The classic formulation of the adaptation method assumes a decrease in the signal following repetitive presentation of the same stimulus and a signal recovery following presentation of the same adaptors with different test stimuli (Grill-Spector and Malach, 2001; Grill-Spector et al., 2006).
Category: