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:For example, healthy SN? adults exhibit normal performance on pegboard tests (Berg et al. 1999a, 2001b, 2002; Mehnert et al. 2010) and normal (Berg et al. 1999a, 2002) or impaired (Berg et al. 2001b) performance on maximal finger tapping tests.
Category: