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:Similarly, in a study on 60 subjects, blinks were measured at the beginning and end of a working day (Caffier et al., 2003). Although no significant difference between alert and drowsy phases was found, a slightly decreased blink rate during drowsy phase was reported. However, these results contradict the findings of Morris and Miller (1996) about the efficiency of F in a moving base-flight simulator with 10 sleep-deprived pilots.
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