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:‚Ä¶target on that trial would vanish (such a location was analogous to the location of distractors to the left or right of vertically moving targets in Kerzel, 2003a).2
 In each block, each participant received 216 trials (2 cues [present, absent] 9 probes [ 12, 9, 6, 3, 0, 3, 6, 9, 12] 2 directions‚Ä¶
Category: