Implicit versus explicit memory

Implicit memory involves memories encoded and stored based on what we have learned from past experience. It is used without conscious awareness and is non-verbalized or non-declarative. Step-by-step tasks such as brushing teeth, riding a bike and tying shoe laces are procedural memory examples calling on this unconscious memory, in other words we know how to do something we have done many times before, but because we are not consciously aware of its use, it is non-accessible and hard to verbalize. Forming memory stored as implicit initially can be difficult and is done by completing many repetitive trials, but equally it is very difficult to unlearn. Another category of implicit memory are our conditioned emotional responses where a conditioned stimulus familiar to us elicits a conditioned emotional response. In this way fear conditioned responses are based on implicit memory. We react in the same way to a aversive stimulus we have encountered before without conscious awareness. 

Explicit memory involves conscious recollection of objects, events, figures and faces. Episodic/Autobiographical memory allows us to remember what has happened in our lives. We use this type of memory to recall what happened at a certain event such as who got married to who on a certain date. It also allows us to remember and contextualize the details associated with the event. An example would not only be who married who, but where, what did you eat, who did you sit next to, what colour tie did you wear and so on. The quality of memorization depends on our state of mind and emotions at the time of the event and how often we reaccess these memories. Without repetition we may lose the ability to recall the memories or begin to recall memories with less accuracy or out of context, so one wedding may get confused with another.

Semantic memory concerns our knowledge of the external world. Although conscious it involves effortless, rapid retrieval. It includes the meaning of language and facts and figures. Unlike episodic memory, semantic memory does not include spacial/temporal significance or when or where we learned the facts, figures or meanings, it simply encodes fact and its relevance.