Memory Types: memory exists in at least two major forms called “explicit” (or ‘declarative’) and "implicit" (or ‘procedural’). These two very different memory systems involve different kinds of information, involve different kinds of brain structures, and have a different logic, conscious recall and unconscious recall. (Kandel Brain and Mind, 3)

In addition to “short-term” and “long-term memory,” memory types are also referred to by their sensory input, as in ‘auditory sensory memory,’  ‘visual sensory memory,’ etc. (Hockenbury) There is convincing neuropsychological evidence that linguistic memory can be separated from musical memory, memory for shapes, faces, bodily movements and the like. The notion of a single unitary memory falls apart under closer inspection. (Gardner2, FAQ)


Associative Memory: a vast network of ideas in which each idea is linked to many others. In the current view of how associative memory works a great deal happens at once. An “idea” that has been activated does not merely evoke one other idea. It activates many ideas, which in turn activate others. Only a few of the activated ideas will register in “consciousness.” Most of the work of 'associative thinking' is silent, hidden from our conscious selves. (Kahneman, 52)

Déjá Vu: a subjective feeling that an experience which is occurring for the first time has been experienced before. (MeSH) A brief but intense feeling of remembering a scene or an event that is actually being experienced for the first time. French for ‘already seen.’ The incidence of déjá vu steadily decreases over the lifespan. By the time people reach their early forties, they are averaging less than one déjá vu per year. (Hockenbury, 237) Occasional déjà vu experiences are normal, and they may reflect momentary glitches in memory. One explanation is that the neurons in the brain may get temporarily out of phase, and mislabel incoming new information as old. This may be particularly likely if some elements of the current situation are familiar, so that some aspects of the current situation match an old situation. Another explanation is a momentary lapse in attention: you see or hear something but aren’t paying attention and, a moment later, you process the scene more fully and think it’s familiar – and it really is, because you processed it a moment ago. The brain basis of déjà vu is not understood, but it may involve malfunction of the “temporal lobes,” a part of the brain that is important for new memory formation. Some patients, with damage to the temporal lobes or with “epilepsy” that originates in the temporal lobes,  experience persistent déjà vu. (MemoryLossOnline)

Explicit Memory: the conscious recall of people, places, objects, facts, and events. (Kandel, 132) Memories of names and facts. (Discover Aug 2007, 56) For example, knowledge that there are 7 days in a week, that Paris is the capital of France, etc. (Goldberg, 126) Things you know you remember, like the color of your car, or what happened yesterday afternoon. (Foer, 81) Without 'active rehearsal,' its content fades within a minute. (Koch, 197) What people normally think of as memory. Defining feature is that it requires conscious attention for recall. Involves a particular set of structures in the brain, the “medial” temporal lobes, and a region deep to it called the “hippocampus.” (Kandel Brain and Mind, 3) Also referred to as ‘declarative memory.’

Episodic Memory: a subpart of declarative memory that records personal experiences that are linked with specific times and places. (Coon, 305) Located in time and space. They have a ‘where’ and a ‘when’ attached to them. (Foer, 80) Memories of events that people have lived through. For example, JFK assassination in Dallas watched on TV by millions. Stored with memories of the context in which the fact occurred. (Goldberg, 127) The personal memories which represent our past experience, are encoded by the hippocampus and stored in the “cerebral cortex.” They end up scattered around the cortical areas of the brain. Retrieval, as with “semantic memory,” depends on the “frontal cortex.” (Carter, 162) Episodic memories are very dynamic. They change over time according to what else we experience. (CampbellVA, 202) Also referred to as ‘flashbulb memory.’

Semantic Memory: a subpart of declarative memory that records impersonal knowledge about the world. (Coon, 305) Facts registered by the cortex. They end up encoded in cortical areas in the temporal lobe. Retrieval of them is carried about by the frontal lobes. (Carter, 162) There can be semantic memory for specific facts and semantic memory for generic information. (Goldberg, 131) Stored independently of the context in which the memory occurred. (Goldberg, 127) Located outside of time and space, as free-floating pieces of knowledge. (Foer, 81)

Implicit Memory: unconscious memory for skills. For example playing tennis, knowing how to knot a tie. (Goldberg, 126) Things you know unconsciously, like how to ride a bike. (Foer, 81) It underlies "habituation," "sensitization," and "classical conditioning," as well as perceptual and motor skills. It is not a single memory system, but a collection of processes involving several different brain systems that lie deep within the cerebral cortex. It often has an automatic quality. It is recalled directly through performance, without any conscious effort or even awareness that we are drawing on memory. When we speak, we do not consider where in the sentence to place the noun or the verb. We do it automatically, unconsciously. This is the  type of ‘reflexive learning’ studied by Pavlov. (Kandel, 132) Once learned, these sensory-motor procedures last for a lifetime and are comparatively immune from the ravages that the passage of time visits upon declarative memory. (Koch, 194) Don’t seem to pass through the same short-term memory buffer as declarative memories, nor do they depend on the “hippocampal” region to be consolidated and stored. (Foer, 81) The ‘how to’ memory (is) stored in the “cerebellum” and “putamen.” Involves a set of deep “nuclei” in the brain, the “amygdala” (for learned fear) and the cerebellum (for motor learning). (Kandel Brain and Mind, 3) The vital learning that we do during the first years of life is virtually entirely of the implicit, non-declarative kind. (Foer, 84) Also referred to as ‘procedural memory.’

Phyletic Memory: genetically-encoded devices. For example, fear of snakes, fear of precipices, avoidance of fire, and feeling of joy at seeing the sun at dawn. (Goldberg, 87-96)