The same task as the forward digit span, done in reverse. This means when answering, you need to type the digits in the reverse order in which you saw them. Just as you probably thought, this is a harder task than the forward digit span, as it requires manipulation of items in the working memory, requiring a greater role of the executive functions. Normally, your backwards digit span will be a few less than your forward digit span, along with an expected slowdown of response time. How much slower?