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 average magnitude of the NBR increases with increasing stimulus intensity and duration (Klingner et al., 2010; Shmuel et al., 2002), suggesting that NBR reflects neuronal inhibition required to optimise task performance, by reducing sensitivity and allocation of processing resources to the…
Category: