mirror therapy

The brain is, at heart, a prediction machine that trusts its eyes. Mirror therapy is a clever exploitation of that trust. A mirror is placed upright between the two limbs, reflective side facing the good limb, so that when the person looks toward where their affected limb should be, they instead see the mirror image of the good limb — appearing to be the affected one, moving normally and painlessly.

The setup hides the affected hand or foot behind the mirror and shows the reflection of the healthy one in its place. The person then moves the good limb (sometimes trying to move both) while watching the reflection. The brain, seeing what looks like the affected limb moving smoothly, receives a flood of positive visual feedback that contradicts the real situation — and that mismatch seems to do useful work. It is used in two main settings: to help reactivate movement in a weak limb after stroke, by feeding the brain the image of successful movement; and to ease phantom limb pain after amputation, where the reflection of the intact limb can convince the brain the missing limb is present and unclenched, calming the pain.

Mirror therapy is cheap, safe, and simple — little more than a mirror and instruction — which is part of its appeal. The evidence is moderate and mixed: it appears genuinely helpful for some people with post-stroke weakness and for some with phantom limb pain, but effects vary and it is no cure-all. It works best as one ingredient in a broader programme, and its reliance on visual illusion means it suits people who can attend to and be convinced by the reflection.