A meta-analysis on uncertainty monitoring in four non-primate animal species: Pigeons, rats, large-billed crows, and bees

Humans have the metacognitive capacity to be aware of what they do and do not know. While uncertainty monitoring has long been regarded as uniquely human, researchers in search of the polygenetic root of this ability have gathered evidence that primate species possess functional features parallel to humans. However, there were no systematic studies that quantitively take into account of extant data for these non-primate animals. Through a meta-analysis, we collected published data reported in 11 articles from 55 individual non-primate animals spanning over four species on the “opt-out” paradigm, the most prevailing paradigms used to test nonhuman animals’ uncertainty monitoring. We used chosen-forced advantage and opt-out rate to quantify animals’ performance results for computing the aggregated effect size for this literature. We found that these four NPA species process a significantly positive effect size for both scores and identified the moderators that have contributed to the inconsistencies across these studies. Implications for theories on metacognition are discussed.