Memory

A father had just arrived home from work, changed into comfortable clothes, and made himself a nice cup of coffee to unwind after a long day when he realised something. He had forgotten to pick up his son from nursery!! Oh, dear. A case of memory failure, or more precisely, prospective memory failure. Why can we recall memories from days, weeks, and years ago but at other times, our memory fails us? What types of memory are there? How do we store information using memories?

• First, we will define memory.
• Then, we will look at some different types of memory.
• After that, we will look at two models of memory; the multi-store memory model and the working memory model.
• Finally, we will look at issues with memory that may lead to forgetting information.

What is the definition of memory?

In psychology, memory is defined as when we absorb information from the world, process and store that information, and then retrieve that information at a later date. Thus, there are three major components to memory - encoding, storage, and retrieval.

Encoding is when the information we take in from our senses is encoded so that the brain can store that information. Different types of memory use various forms of encoding. For example, short-term memory mainly uses auditory to encode information, such as when you repeat aloud a phone number until you remember it.

Types of Memory

Here we will describe three basic types of memory: sensory memory, short-term memory (STM) and long-term memory (LTM).

Sensory Memory

The senses detect information from the world around us and first enter the sensory memory, which stores a brief impression of the detected stimuli. The sensory stores constantly receive information, but most of this information is not attended to and remains in memory very briefly. It is then replaced with new information. If you pay attention to one of this received information, it enters the STM. The duration of the sensory memory is concise, ¼ to ½ of a second. Sensory memory has different sensory stores for each of the senses to encode the incoming information, so a taste is stored as a taste, a touch is stored as a touch etc.

Short-Term Memory

Short-term memory is the storage of memory available for a short time only (around 30 seconds). Short-term memory can store seven items +/- 2 (so someone's STM might be able to store nine items while another person can store five items). The information to be remembered needs to be continually rehearsed, mainly through mentally repeating or repeating out loud, so that it is not lost from the STM. However, existing information in the STM can be forgotten due to new information coming in. This is known as displacement.

Long-Term Memory (LTM)

The duration and capacity (how much the LTM can store) are unlimited. There are three types of LTM -- episodic, semantic and procedural memory.

Episodic memory is the memory of events in your life. For example, what you did for your sweet 16th, everything you did on holiday in Italy. Episodic memory contains information on what, when and where an event happened.

Semantic memory is the collection of knowledge you have gained throughout your life. For example, the capital of France is Paris.

Procedural memory: procedural memory is your memory of how to do things, such as ride a bike or play the piano.

The Working Memory Model

Baddeley and Hitch's (1974) Working Memory Model sought to explain how short-term memory works. The multi-store model of memory suggested that short-term memory was just one single store; however, Baddeley and Hitch thought that short-term memory is more sophisticated, it contains multiple stores and is an actively working memory. The main components in this model are the 'central executive', 'visuospatial sketchpad', 'phonological loop' and 'episodic buffer'.

The central executive is the control centre that all the other components connect to and acts like a control centre. A visuospatial sketchpad is our ability temporarily to hold visual and spatial information. An example of our visuospatial sketchpad is remembering the location of where you left your school books.

A Phonological loop processes speech or verbal information. The phonological loop has two parts, a phonological store that holds verbal information and an articulatory loop which uses inner speech (mental rehearsal) to remember and retain the information in the phonological store.

The episodic buffer blends together information from the three other components (central executive, visuospatial sketchpad and phonological loop) and long-term memory.