Memory is a fascinating subject to me; especially how it is stored in our brain and how we can measure it. I got a better understanding of memory when I found out that electrical impulses in the brain transmit it and store it, similar to a computer. It is also interesting that memory, which initially seems abstract, can be measured using recall, recognition and relearning.

Human memory stores information into our brain, like a computer, for later use. Both use electrical impulses. We and the computer need to use three processes which involve memory. These are:

1. Encoding which is used to transform information to be stored. In a computer that means transferring data into code. For us, it is transforming data into a meaningful association, image or sound.
2. Storage is where the information is stored. In order for this to happen, the computer must physically write 1’s and 0’s within the hard drive. We store memory through a physiological change.
3. Retrieval, which is taking the memory out of storage and returning information to a similar form that was originally stored.

The main difference between humans and computers is how memory is stored. Computers have only 2 types: permanent storage and permanent deletion.

Humans have 3 types: sensory, short term and long term memory.

Sensory memory is the sense that we receive information from. This memory lasts only a few seconds.

Short term memory (STM) is when our consciousness receives transferred information from sensory memory.

Long term memory (LTM) is similar to the computers permanent storage. It is information that goes through our short term memory and into the long term memory that typically has significance attached to it. LTM has 2 subcategories, declarative and non-declarative.

Declarative memory is where information of live events of facts of memories in our environment is stored. This includes semantic memory, which is the knowledge that gives us the ability to do math and understand the meaning of words and concepts, and episodic memory which is memory of events and situations.

Nondeclarative memory is internalized information from habits, practice or conditioning (such as brushing your teeth).

(Memory)

We can measure memory by three commonly used methods: recall, recognition, and relearning.

Recall can be things that happened a long time ago or a direct retrieval of recent facts or information.  Recall can be word for word memory, or ideas or events, not necessarily word for word, such as something you learned a long time ago or an event that occurred.

Recognition is normally superior to recall in terms of confirming details (for example, recognizing a face rather than describing it). Recognition is very accurate for pictures and photos. Investigators proved that between 85 to 95 percent of the time people can recognize pictures after seeing them a second time and differentiate them from new pictures.

Relearning is recalling previously learned or memorized information. The information can be relearned or memorized 25% faster than if it is new information. It is partially stored in memory and recalled through relearning.

These three methods are all related to each other, because they all encode, store and retrieve information, and they all involve the interplay of short term and declarative long term memory. Therefore these methods of measuring memory actually investigate the major processes the brain uses to store memories, which give these methods validity.