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:…the sexes may differ in which signal feature they pay most attention to (i.e., body posture vs motion displays; Martins et al. 2005; Nava et al. 2009) or which signal type elicits a stronger behavioral response (i.e., conspecific vs heterospecific; Searcy and Brenowitz 1988; Bernal et al. 2007).
Category: