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:To date, these reactions have primarily been investigated on an interpersonal level – the level of individual profiles (e.g., Hooper & Kalidas, 2012; McLaughlin & Vitak, 2012; Peña & Brody, 2014).
Category: