Mechanisms underlying training-induced cognitive change

The prospect of enhancing cognition through behavioural training interventions, for example, the repetitive practice of cognitive tasks or metacognitive strategy instruction, has seen a surge in popularity over the past 20 years. Although overwhelming evidence demonstrates that such training interventions increase performance in the trained tasks, controversy remains over whether these benefits transfer to other tasks and abilities beyond the trained context. In this Review, we provide an overview of the effectiveness of cognitive training to induce transfer to untrained tasks, with a particular focus on the theoretical mechanisms that have been proposed to underlie training and transfer effects. We highlight that there is relatively little evidence that training enhances cognitive capacity, that is, the overall cognitive resources available to an individual. By contrast, substantial evidence supports training-induced improvements in cognitive efficiency, that is, optimized performance within existing cognitive capacity limits. We conclude that shifting research towards identifying the cognitive mechanisms underlying gains in cognitive efficiency offers a fruitful avenue for developing effective cognitive training interventions. However, to advance our understanding of human cognition and cognitive plasticity we must strive to develop and refine theories that generate testable hypotheses.