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:…ranges of sensitivity estimates (Additive: 23.44 to 10.58; Subtractive: 21.95 to 8.42) were well outside the usual range of sensitivity to reinforcement estimates (a) obtained from human detection experiments which studied the effects of reinforcers alone (e.g., 20.01 to 0.58; Lie & Alsop, 2009).
Category: