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:using the Reading Span [40], and the Digit Span, a subtest of the WAIS; Visual-motor processing and attention (VSM), was assessed with the Digit Symbol Test, a subtest of the WAIS, the Trailmaking test, part B (TMT; [41]) and the Color-WordInterference test [42], one of the most widely used paradigms for the evaluation of selective attention; Abstraction and conceptual flexibility (ABS) were assessed by means of the modified Wisconsin Card Sorting Test (number categories and perseverative
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