The effect of practice on inhibition in task switching: Controlling for episodic retrieval

Previous work has shown that extended practice leads to a reduction in a key measure of cognitive inhibition during task switching: The n–2 task repetition cost. However, it has been demonstrated that this n–2 task repetition cost is increased by a non-inhibitory process—namely episodic retrieval—raising the question of whether the observed reduction of the cost with practice is driven by a reduction in inhibition, episodic retrieval effects, or a combination of both. The current study addresses this question by utilising a practice protocol using a task switching paradigm capable of controlling for episodic retrieval. The results showed a reduction in the n–2 task repetition cost with extended practice. The results also showed a clear increase of the n–2 task repetition cost due to episodic retrieval effects. The reduction of the cost with practice was driven by a reduction in inhibition and episodic retrieval contributions to the cost with practice, although there was a larger reduction in the episodic retrieval contribution with practice. The results are discussed with reference to current theoretical models of inhibition in task switching, which need to accommodate episodic retrieval and practice effects.