An implicit memory test assesses retention without requiring the person to consciously recollect the prior experience. Performance, not deliberate recall, reveals the memory.

Common forms include stem-completion and fragment-completion tasks, in which participants fill in word stems or fragments; prior exposure to a word increases the probability that it will be produced, even if the person does not remember seeing it. Perceptual identification tasks measure how briefly a stimulus can be presented and still be recognized; prior exposure improves performance. Skill-learning tasks measure improvement in speed or accuracy across practice trials. In each case the instructions do not ask the participant to remember; they ask the participant to perform.

Implicit tests are especially useful in the study of amnesia, aging, and the cognitive effects of anesthesia or trauma, because they can detect preserved memory when explicit tests show impairment. They also help map the boundary between conscious and unconscious influences on behavior.

When memory is present but not reportable, an implicit test can still reveal it.