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:All experiments included blocks of auditory stimuli and blocks of visual stimuli, delivered with different presentation rates (e.g. auditory blocks repetitions and visual blocks repetitions were not the same), in a semi-overlapped manner (Hertz & Amedi, 2010).
Category: