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:…processes, such as incentive salience (Knutson et al, 2000; Knutson et al, 2001; Knutson et al, 2003), the hedonic experience of reward (O’Doherty et al, 2001), and reward learning (Asaad and Eskandar, 2011; Berns et al, 2001; McClure et al, 2003; O’Doherty et al, 2003; Schultz, et al,…
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