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:Brain imaging (Altmann et al., 2003; Kourtzi et al., 2003; Qiu et al., 2016; Tanskanen et al., 2008) and electrophysiological (Chen et al., 2014) studies have shown that multiple cortical areas are involved in integrating discrete contour fragments into global contours.
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