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:Go trials occurred with probability p .75 to encourage hand preparation as in previous studies using the hybrid-choice RT go/no-go paradigm (e.g., Abdel Rahman et al., 2002; Miller & Hackley, 1992).
Category: