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:A tentative explanation for the negative findings on the relationship between the cumulative dose of MA and ACC dysfunction is that the developmental stage exposed to MA rather than its dosage may play a more prominent role in determining the effects of MA on the developing brain (Lyoo et al. 2015).
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