Explicit memory doesn’t come online until around age 3, so much of what a child experiences before that is implicit. For instance, George Santayana, the philosopher to whom the above quote is attributed, probably had implicit memories from his first few years of life when his mother left him in Spain to start a new life in the United States. However, he may have explicit memories of when he was 8-years-old and was abandoned by his father. Both memories likely had a heavy hand in shaping his life, but each would be experienced in different ways.
Implicit memory relies on structures in our brain that are fully developed before we are born. Because it’s an unconscious, bodily memory, when it gets triggered in the present, it does not seem like it’s coming from the past. Instead, it feels like it’s happening now. Thus, we react as if we are back in the original situation.
Unlike an explicit memory, an implicit memory does not involve the internal experience of recalling. It’s been described as “retention without remembering” and as “nondeclarative, nonverbal memory.” It can be behavioral, emotional, perceptual, or somatosensory, and is often felt in the body. A good example of implicit memory is hopping on a bike and instinctively remembering how to ride, whereas an explicit memory would be the recollection of someone teaching you to ride.