Why Desirable Difficulties 'Work': A Review of the Evidence From Cognitive and Educational Psychology and Some Caveats for the Health Professions Education Field.

BACKGROUND: 'Desirable difficulties', a concept that originated in the cognitive psychology literature, are practices that tend to impede initial learning but that promote long-term retention and transfer of knowledge and skills. Educators in the health professions have been enjoined to employ and integrate desirable difficulties in their classroom and clinical teaching practice, with assurances that they 'work'. But how do they work? Insights into the mechanisms of desirably difficult practices may enrich the practice of educators and provide impetus for further research into how and when such practices might be effectively deployed in health professions education.

AIM: In this paper, I review the evidence from the cognitive psychology and educational literatures not only for evidence of the effectiveness and boundary conditions of the desirable difficulties, but for their proposed mechanisms. I also review reports on how these practices have been deployed and investigated within health professions education.

RESULTS: Desirable difficulties for which there is ample robust evidence across fields and disciplines are formative testing, or assessment-for-learning as opposed to assessment-of-learning, interleaved or mixed practice, or problem-solving, distributed or spaced practice, and various productive failure approaches. These practices are hypothesised to have various cognitive, meta-cognitive, motivational and affective mechanisms at the level of the individual. Within the health professions education literature, there is some evidence of lack of clarity as to how these practices are defined and as to their theoretical underpinnings.

CONCLUSIONS: While there is ample evidence supporting the efficacy of desirable difficulties, it is crucial to approach their implementation with caution. Greater perceived difficulty or disfluency should not be conflated uncritically with greater educational benefit. Lack of clarity as to what is, and what is not, a desirably difficult practice has been evident in published health professions education literature. Educators and researchers alike should have a clear understanding of the definitions and theoretical bases of desirable difficulties to advance practice and theory.