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 fact that others have shown that continued experience or exposure can modify when perceptual narrowing (or perceptual attenuation) occurs (Pascalis et al., 2005; Scott & Monesson, 2009), and the current results that perceptual discrimination is possible after narrowing has occurred, demonstrate…
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