Patient HM: Implicit Learning and the Mirror Drawing Test

 This post was inspired by a classmate's post on the Mirror Drawing Test (thanks Angelina!). Their post discussed the Mirror Drawing Test's general use in testing motor skills and development in children and adults. Where my post differs is that it reminded me of patient HM, a man who could not form any long-term or explicit memories due to damage to his Hippocampus. 

In researching patient HM's abilities to form new skills (and therefore, some type of memory that functions outside of the Hippocampus' role), they had HM do the Mirror Drawing Test 10 times a day, everyday for 3 days. To remind anyone who may have forgotten or does not know, the mirror drawing test is a task that require an individual to simply trace a star within the boundaries of two lines. The catch is that they must do this task while looking in a mirror, not their hands directly. This reverses our movements and makes the task fairly difficult. What they found with HM is that, despite not being able to form explicit long-term memories, he became progressively better at the task. Each time he came to the task, he had the impression that it was his very first time performing it, even noting in one later session how it turned out to be easier than he expected.

Below is a video shortly summarizing HM and the Mirror Drawing Test: