It is often assumed that cross-linguistically more prevalent distinctions are easier to learn (Typological Prevalence Hypothesis - TPH). Prior work supports this hypothesis in phonology, morphology and syntax but has not addressed semantics. Using an Artificial Language Learning paradigm, we explore the learnability of semantic distinctions within the domain of evidentiality (i.e. the linguistic encoding of information sources). Our results support the TPH, since the most prevalent evidential system was learned best while the most rare evidentiality system yielded the worst learnability results. Furthermore, our results indicate that, cross- linguistically, indirect information sources seem to be marked preferentially (and acquired more easily) compared to direct sources. We explain this pattern in terms of the pragmatic need to mark indirect, potentially more unreliable sources over direct sources of information.