challengingness means Quality or degree of being challenging. Lexicurio rates it Rare gem — a strength score of 82 out of 100.
noun
- Quality or degree of being challenging.“Consequently, although the stimulus selection was clearly restricted, we propose that similar findings (at least in principle) should apply to a broader range of artistic artefacts despite potential variations in central stimulus-dimensions (such as subject matter, colorization, or image size) unless they alter the experience of processing ease or mental challengingness.”