Introduction to Memory Systems
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How We Remember & Why We Forget
There are various theories associated with human memory. A great deal of research has been conducted in pursuit of a definitive model and for cures of memory related diseases.

You do not need to have a scholarly understanding of these theories to benefit from them anymore than you need to know how an engine works to drive a car or how a computer works to use the Internet. However, a knowledge of some basic concepts will aid your overall progress and help you to understand why certain memory techniques work.

In your study of memory there are three things to consider:
  • How you form memories (encoding)
  • How you retain memories (storage)
  • How you recall memories (retrieval)
Encoding (getting your memories to stick)
Every waking moment you receive input from your senses and you are surrounded with information. There is more input and information than it is reasonable to process. It is not realistic or necessary to remember absolutely everything so you make choices. These choices are made both consciously and unconsciously.

The first stage of encoding new memories occurs when you select and focus your attention on something to be remembered. This may seem obvious but it is important to realize that the strength of your purpose and motivation for remembering something can have a significant affect on how successfully that information is encoded.

Did you know that tangible things are easier to encode than abstract concepts? This is because we use words to express our thoughts but we think in pictures. When you hear the word cat do you think of the three letters c-a-t or do you picture a cat. You see a cat, in fact you can probably call to mind many different cats of all shapes and sizes and breeds. When you hear the word Psychology what do you see? Probably not much because abstract concepts are difficult to visualize and therefore are harder to encode.

Encoding something that you wish to remember can be accomplished in a number of different ways:
  • Visual Encoding - placing emphasis on physical characteristics such as size, shape, and colour. Visual encoding plays a major role in many memory techniques.
  • Auditory Encoding - placing emphasis on the sound of words, names, or the sounds associated with things. Auditory encoding also occurs when you vocalize written material.
  • Other Primary Senses - Touch, Taste, and Smell also reinforce encoding of physical things.
  • Semantic Encoding - placing emphasis on the meaning of the information. This is generally accepted to be a deeper level of encoding.
  • Contextual Encoding - Some studies suggest that information pertaining to your physical locale and emotional state is added during the encoding process. The idea being that the same conditions will aid in the subsequent retrieval process (i.e. studying in the same area where you will write an exam). Evidence in this area is not conclusive.
  • Personal Relevance - Making information personally relevant can deepen its encoding. If your life depends on a certain piece of information the chances are greatly increased that you will remember it!
  • Repetition - We all know that if you read, write, or speak something repeatedly it can be committed to memory. Unfortunately this is one of the most ineffectual and time consuming methods.
  • Concentration - The ability to focus your attention on a specific task or thought can also improve the encoding process. Concentration requires practice but is within everyone’s capabilities.
The greater the number of encoding methods that you apply to a specific piece of information determines how effectively it is encoded into memory.

Mnemonic Memory Techniques discussed in later chapters utilize these encoding principles.

Storage (keeping your memories in)
A memory is formed by biochemical changes that occur at the synapses of our brain cells. We know that the human brain contains somewhere in the vicinity of 1015 synapses which creates almost limitless possibilities for connections. Rest assured that there has never been a case of someone running out of storage space!

Think of your memory as having three distinct components:

Sensory Memory
This is an automatic memory process that allows you to quickly form perceptions. It is very brief, lasting only a fraction of a second.

Short Term Memory
Consensus holds that your short-term memory lasts on average between 20 to 30 seconds and has a capacity of between 5 to 9 items. Note: if you continue to review the information in your short-term memory it will last as long as the review process continues. Short term memory is why you can dial a phone number and forget it moments later.

Long Term Memory
Your long-term memory is virtually unlimited in capacity and relatively permanent. To reach long term memory information must pass through both sensory and short-term memories and be effectively encoded.

Retrieval (getting your memories out when you need them)
Have you ever experienced a tip-of-the-tongue episode when you know you have the answer but are unable to retrieve it from memory? Or times when you can’t recall the answer to a question but can pick it from a multiple choice list. These common occurrences illustrate the difference between storage and retrieval. The information is in memory but you are having difficulty retrieving it.

The main reason why you will be unable to recall information from memory is because the information was never thoroughly encoded in the first place!

Retrieval also depends on ‘how’ the information was encoded. If something was encoded visually and you are trying to recall it by an alternate method it will be more difficult. If you were only shown pictures of a lion, a monkey, an elephant, and a dog you would have visually encoded them into memory. You would have no trouble recalling that you have seen the animal before but that is all you would know. Should you see the names of the animals (semantic) or hear the sounds made by these animals (auditory) you would be unable to match the name or the sound to the animal. You have encoded the information visually but have no semantic or auditory encoding to reference.

The advantage of encoding information in a variety of ways is that it increases the retrieval options. Other retrieval factors include:
  • Recency - It is easier to recall something, which has recently occurred.
  • Frequency - the more often we experience something or recall something from memory increases retrieval success.

Why We Forget
One of the interesting questions concerning memory is whether we forget because the information is gone from memory or whether we forget because the method of retrieval has been lost. There is good evidence to suggest that we retain more than what we can recall.

Dreams, hypnosis, electrical stimulation of the brain, near death experiences, and contextual stimulus have all been responsible for bringing forth memories long ‘forgotten’ by an individual.

Some things have been encoded so deeply into memory that you will never forget them. Your name and the names of family members, your face and those of the many people in your life, your birth date, the ABC’s, and the names of countless objects are just a few examples.

Then there are skills like talking, writing, tying your shoes, clapping your hands, and so forth. Literally thousands of pieces of information and skills that are permanently etched in your memory and that require no effort to instantly recall. So why are we unable to retrieve other things we have tried to commit to memory?

As stated earlier one of the main reasons why you forget is because of ineffective initial encoding. Other influences can include memory decay and memory interference.

It is generally accepted that memories fade over time. Whether information disappears completely is unknown. It could simply be that the means to recall the information is lost and that a very specific set of memory triggers based on the initial encoding are required to retrieve the information.

It is also believed that new information can sometimes compete and interfere with old information and vice versa.

The good news is that memories can be maintained. By recalling, reviewing, and if necessary re-learning information you will be reinforcing the material and slowing any decay process. If it is important to you, it can be retained for a lifetime with little effort.

Quick Review:
  • We form memories by encoding information
  • Encoding can occur through sensory input, the meanings we attach, the context in which it was learned, personal relevance, repetition, and concentration.
  • Memory storage is unlimited and consists of sensory memory - very brief perceptions, short-term memory - 20 to 30 seconds and 5 - 9 items, and long-term memory - generally permanent.
  • Most memory retrieval errors are the result of ineffectual initial encoding.
  • Retrieval is also influenced by recency - how long since something was last recalled, and frequency - how often something is recalled.
  • Memory loss can result from a number of factors including insufficient encoding and memory decay.
  • Memories can be permanently maintained through recall, review, and when necessary re-learning.
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