Shared Evidence: It all depends...

AbstractWhen reasoning about evidence, we must carefully consider the impact of different structures. For instance, if in the process of evaluating multiple reports, we find they rely on the same, shared evidence, then the support proffered by those reports is dependent on that evidence. Critically, normative accounts suggest that such a dependency results in redundant information across reports (reducing evidential support), relative to reports based on distinct items of evidence. In the present work we disentangle the structural and observation-based indicators of this form of dependency. In so doing, we present novel findings that lay reasoners are not only insensitive to shared evidence structures when updating their beliefs, but also that reasoners do not necessarily prefer more diverse sources of evidence. Finally, we replicate prior effects in reasoning under uncertainty, including conservative sequential updating, and difficulty in integrating contradictory reports.


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