 Nondeclarative memory is usually defined in negative terms: a form of memory is declarative if it involves the encoding, storage, and retrieval of content that the subject can, at least in principle, bring to consciousness; it is nondeclarative if it does not (Squire 2009). Beyond this negative feature, the various kinds of nondeclarative memory may not have much in common with each other. For example, nondeclarative memory includes priming, which occurs when a subject’s response to a given stimulus is affected by his previous exposure to related stimuli (e.g., I recognize the word “Toronto” more quickly after seeing “CN Tower” than after seeing “Colosseum”). It also includes procedural memory, corresponding roughly to habit memory, the kind of memory at work when a subject manifests his ability to perform a skilled action (I remember how to ride a bicycle).