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 current trendsetters in predictive coding are the motor control crowd who have developed, empirically validated, and promoted the notion of internal forward models as a neural mechanism necessary for smooth, efficient motor control (Kawato, 1999; Shadmehr et al. 2010; Wolpert et al. 1995).
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