Stimulus specificity in combined action observation and motor imagery of typing

Combined action observation and motor imagery (AO+MI) can improve movement execution in healthy adults and certain patient populations. However, it is unclear how the specificity of the observation component during AO+MI influences performance. As generalised observation could result in more flexible AO+MI rehabilitation programs, this study investigated whether specific or general AO+MI would have different effects on keyboard typing in healthy young adults. In Experiment 1, 51 students imagined typing a target word while watching a video of either the target word (specific AO+MI), or non-matching words (general AO+MI), being typed. There were no performance differences between AO+MI conditions, though participants typed more slowly after both AO+MI conditions compared to no observation or imagery. Experiment 2 replicated Experiment 1 in 20 students, but with a faster stimulus speed in the AO+MI conditions and increased cognitive difficulty in the control condition. This showed that the slowed typing after AO+MI in Experiment 1 was due to a strong influence of task-switching between imagery and execution, as well as an automatic imitation effect. Both experiments demonstrate that general and specific AO+MI comparably impact performance. Whilst AO+MI was not suitable for facilitating typing in this sample, it may still be effective in a rehabilitative context.