Understanding ambiguous texts has been widely accepted as an indicator of conceptual thinking efficiency. As a kind of ambiguous texts, fables are promising as a tool for measuring cognitive abilities, but rarely used in intelligence research. In this study, we aimed to reveal: 1) the degree to which healthy adults experience difficulties in fables comprehension; 2) the role that psychometric IQ plays in understanding fables’ metaphorical meanings (gists). We hypothesized that: 1) the higher the level of psychometric IQ, the better the understanding of fables’ gists; 2) the higher the level of fables understanding, the higher the ability to pair single fables in accordance to their gists. Twenty-four participants were presented with 3 sets of Aesop’s fables and an IQ test. During in-depth interviews, they were asked to interpret the gist of each fable and pair any two of them within each set. It was shown that healthy adults experience major difficulties with understanding fables’ gists at a highly generalized, abstract level. We found no correlation of psychometric IQ and fables understanding; and no correlation between comprehension depth and fables pairing. This suggests that 1) there is a lack of conceptual thinking in healthy adults and 2) the ability to understand a fable’s gist is not reflected in the results of current psychometric tools but may require more advanced approaches.