Extrinsic feedback facilitates mental chronometry abilities in stroke patients.

One 30-minute session, measured to the next day only. Nothing here shows whether the improvement in imagined timing lasts longer than that, or whether repeated training changes anything a patient can do with their arm. The 60 patients were all within six months of their stroke and all able to grasp and release blocks. People who could not understand instructions, or who had aphasia, dementia, hemianopia, spatial neglect or another neurological disease, were excluded, so the result does not speak to many of the patients on a stroke ward. Only the person doing the assessment was kept unaware of group allocation. The trainers and the patients both knew whether feedback had been given, and expectation could have shaped how patients performed the imagined task. The affected hand was measured before the unaffected hand in every patient, so by the time the unaffected hand was tested the patient had already practised the task. The authors say they cannot rule this out as the reason for the difference between hands. The difference between the affected and unaffected hand was statistically significant but the average scores were nearly the same (0.34 and 0.31 on a ratio where 0 is a perfect match), so it may not be a difference a therapist would notice in practice. The patients were in one German rehabilitation department and the authors report no calculation showing the study was large enough to detect small differences.

The authors declare no conflicts of interest. The text supplied gives no funding statement.

Do not read this as proof that mental practice or feedback improves arm function. The only thing that improved was how accurately patients judged the timing of a movement in their head, and how fast the hand actually moved improved in all three groups, including the control group that did no mental practice at all.