Memory

This is Unit Six of Psychology, Part One: getting information in, and keeping it. Memory is three operations, not one. Encoding gets information into a form the system can hold. Storage keeps it. Retrieval brings it back. And that division is the most practically useful thing in the unit, because any memory failure is a failure at exactly one of the three — and they need different fixes. This part covers the first two. How information gets in, in what form, and where it sits once it is there. There is a famous number in here, and the unit does something honest with it. Miller's seven plus or minus two is the best-known figure in cognitive psychology. More recent work, controlling for the techniques people use to inflate it, puts the real capacity nearer four. Then the divisions of long-term memory — which split first on whether a memory can be stated at all, and only then on what kind of thing it is. And the part closes on three brain structures, each required for a different kind of memory — which is why damage produces such specific losses. By the end you will be able to do five things. One: name the three operations and locate a failure at one. Two: say what Miller reported and what the revision changed. Three: name the three components of working memory. Four: place a memory in the right long-term division. Five: say what each of the three structures contributes.

Four entries, and the division they set up is what makes the rest of the unit usable. If somebody says they have a bad memory, that sentence has three possible meanings — and the fixes for the three have nothing in common.

The system.

Psych 0621 Memory

The system by which information is encoded, stored, and later retrieved. Three operations named in the definition, which is the whole structure of the unit.

The first.

Psych 0623 Encoding

Converting incoming information into a form the memory system can hold. If this fails, there is nothing to store and nothing to retrieve.

The second.

Psych 0625 Storage

The retention of encoded information over time. The operation that sounds most like what people mean by memory, and it is only one of three.

The third.

Psych 0627 Retrieval

Bringing stored information back into conscious awareness or into use. A failure here means the information is present and unreachable — which feels identical to not having it.

Two entries. Some things get encoded with no effort and no intention at all — where you sat, roughly what time it was, how often something happened. Everything else takes work.

Without effort.

Psych 0629 Automatic Processing

Encoding information such as time, space and frequency without conscious effort or intention. It happens whether or not anybody meant it to.

With effort.

Psych 0630 Effortful Processing

Encoding through deliberate attention and rehearsal. Everything anybody has ever studied for is this one, and it is the only kind that can be improved on purpose.

Four entries. Three ways information can be encoded — and one of them is stated outright as the most durable, which makes the ranking useful rather than descriptive. Then a way of getting anything into that best form.

The first, and best.

Psych 0632 Semantic Encoding

Storing information by its meaning, producing the most durable memory of the three types. Which means the practical instruction is to encode for meaning whenever the material permits it.

The second.

Psych 0634 Visual Encoding

Storing information as images. Powerful for material that has a picture in it, and it does not create meaning where there was none.

The third.

Psych 0636 Acoustic Encoding

Storing information by its sound. The shallowest of the three, and the one rote repetition produces.

And one effect.

Psych 0638 The Self-Reference Effect

Improved recall of information encoded in relation to oneself. A way of forcing meaning onto material that had none — which is why it works.

Two entries on the first two places information sits. The first holds a great deal and lasts a fraction of a second. The second holds very little and lasts under half a minute — and almost everything is lost at that handoff.

The first.

Psych 0640 Sensory Memory

A brief, high-capacity trace of incoming sensory information held for a fraction of a second. Large and very short — which means selection has to happen immediately.

The second.

Psych 0642 Short-Term Memory

A small amount of information held in conscious awareness for roughly fifteen to thirty seconds. Small and short, and everything that reaches long-term memory passed through here.

Four entries, and the first two are worth pausing on together. A famous figure, and then a later result that lowers it — because the original number included the effect of techniques people use without noticing.

The famous number.

Psych 0644 Miller's Seven Plus or Minus Two

Miller reported that short-term memory holds between five and nine items — the magic number seven plus or minus two. The best-known figure in the field.

And the revision.

Psych 0645 Cowan's Revision

More recent work places working memory capacity nearer four items, plus or minus one, when rehearsal and chunking are controlled for. The original figure measured capacity plus technique.

The first technique.

Psych 0647 Chunking

Grouping individual items into larger meaningful units, increasing how much can be held. The number of slots does not change — what fits in a slot does.

The second.

Psych 0649 Rehearsal

Conscious repetition to keep information available in short-term memory. It maintains rather than deepens, which is why it produces the shallowest encoding.

Four entries, and this is a different model rather than a different store. It describes what happens when information is not only held but used — with two separate holding components and something directing them.

The system.

Psych 0651 Working Memory

The system holding and manipulating information currently in use. Manipulating is the addition — short-term memory holds, this one also operates.

The first component.

Psych 0653 The Phonological Loop

Holding and rehearsing verbal and acoustic information. It is why reading and listening to speech interfere with each other and reading and looking do not.

The second.

Psych 0655 The Visuospatial Sketchpad

Holding and manipulating visual and spatial information. A separate component, which is why two tasks of different types can run at once.

And the third.

Psych 0657 The Central Executive

Directing attention and coordinating the other components. It holds nothing itself — it decides what the holders do, which makes it the bottleneck.

Six entries. The third store, and then a division worth getting in the right order — the first split is not about content at all. It is about whether a memory can be brought to mind and stated. Only after that does content matter.

The third store.

Psych 0659 Long-Term Memory

Holding information over extended periods with no known capacity limit. Unlike the previous two stores, size is not the constraint here.

The first branch.

Psych 0661 Explicit Memory

Information that can be consciously brought to mind and stated. If you can say it, it is on this side.

The second.

Psych 0662 Implicit Memory

Information influencing behavior without being consciously recalled. Present, effective, and unavailable to report.

Inside the first.

Psych 0664 Episodic Memory

Personally experienced events, including where and when they happened. The occasion is part of the memory.

Also inside the first.

Psych 0666 Semantic Memory

General knowledge and facts, detached from the occasion of learning them. You know the fact and not where you got it — which becomes a problem the second part of this unit returns to.

And inside the second.

Psych 0668 Procedural Memory

Learned skills and actions performed without conscious recall of the steps. Which is why explaining how you do something you can do is often impossible.

Three entries connecting this unit to Unit Two. Each structure is required for a different kind of memory — and the first one's wording is precise in a way that explains an entire pattern of amnesia.

The first.

Psych 0670 The Hippocampus in Memory

Required to form new explicit memories, and not required to retain older ones. Which is exactly why damage takes the future and leaves the past — the two jobs are separable and only one needs this structure.

The second.

Psych 0672 The Amygdala in Emotional Memory

Strengthening the storage of emotionally arousing events. Unit Two's significance detector, doing a memory job — and the source of the vividness Part Two will warn about.

The third.

Psych 0674 The Cerebellum in Procedural Memory

Required for forming procedural memories and classically conditioned responses. Which places Unit Five's conditioning inside this unit's architecture.

Five things you can now do, and Part Two takes up getting it back out. You can name the three operations — encoding, storage, retrieval — and locate any memory failure at exactly one of them, which is what decides the fix. You can say what Miller reported and what the revision changed: five to nine items, revised nearer four once rehearsal and chunking are controlled for. You can name the three components of working memory — a verbal holder, a visual and spatial holder, and an executive that holds nothing and directs both. You can place a memory in the right long-term division, splitting first on whether it can be stated at all and only then on what kind of content it is. And you can say what each structure contributes: forming new explicit memories, strengthening emotional ones, and forming procedural ones.