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:…negative correlation, such that more positive mean PBR occurred concurrently with a more negative mean NBR, is in agreement with previous studies (Klingner et al., 2010; Shmuel et al., 2002), suggesting that the magnitude of ipsilateral inhibition increases with the magnitude of increasing…
Category: