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:Consistent with previous characterizations, these neurons respond only to vestibular stimulation and are insensitive to eye movements (Roy and Cullen, 2001b, 2004, Sadeghi et al., 2011).
Category: