Memory is the process of encoding, storing and retrieving information. Simplifying information occurs by converting information, especially stimuli, into useful forms that can be stored, and so, easily retrieved. It consists of three main steps:

1. encoding: the conversion of sensory information into a form that can be processed.

2. storage: the retention of information via a complex network of neural connections in the brain.

3. retrieval: the ability to recover information from the brain.

Multi-store Model of Memory

Richard Atkinson and Richard Shiffrin (1968) developed the staged model of memory that divides memory into three parts. In this, material can be transferred between the three memory stores via maintenance or elaborative rehearsal.

1. sensory memory - duration of 0.5-2 seconds, large capacity, and encoded via a sense.

2. short-term memory - duration of <30 seconds, capacity of 5-9 pieces, and consciously processed.

3. long-term memory - permanently stored, unlimited capacity, and encoded via changes to neurons.

There are various types of long-term memory. Procedural memory (or implicit memory) is the memory of the way you perform specific actions, whereas declarative (or explicit) memory allows you to remember what you perceived of an event or experience. Declarative memory can also be further divided into episodic and semantic memory. Episodic memory is the memory of past, specific events that are linked to feelings, whereas semantic memory is the knowledge of facts and information based on understanding.

Serial Position Effect

Proposed by Bennet Murdock in 1962, the ‘Serial Position Effect’ is described as the tendency for individuals to remember the first and last items presented in a list better than items in the middle of the list.

George A. Miller (1956)

Proposed that the amount of unrelated material that can be stored in short-term memory is between five and nine pieces of information. It can also be expressed as “seven, plus or minus two” (7+-2) pieces.

Working Memory Model

Alan Baddeley and Graham Hitch (1974) developed a model that emphasised memory’s active nature of processing. It focuses on the central executive that organises the information received and coordinates the ‘slave’ systems. In 2000, Baddeley updated the model to contain a third slave system, the episodic buffer, in addition to the two pre-existing slave systems.

The original model consists of three main components:

• the central executive acts as a supervisory system that controls the flow of information

• the first slave system, the phonological loop, stores verbal data

• the visuo-spatial sketchpad stores visual data as the second slave system

Long-term Potentiation

Refers to the physical changes in the structure of neurons to alter or strengthen neural networks and allow for greater memory retention. This increases efficiency and facilitates the passage of nerve impulses.

Measuring Memory

There are various methods that can be used to measure memory:

• recall - retrieving information without the use of prompts.

• recognition - identifying information from a number of alternatives, e.g. multiple choice.

• relearning - previously learned information is revised to become refamiliar.

Theories of Forgetting

Forgetting is seen as the failure to retrieve or use previously stored material.

There are four main types of forgetting:

• retrieval failure occurs when an individual fails to use memory cues to access information in LTM

• competing or similar information being stored and disrupting the retrieval of information is interference

  • retroactive interference is when new information blocks out old information

  • proactive interference is when old information blocks out new information

• motivated forgetting refers to a self-protection device where extreme cases are a defence mechanism and minor cases involve personal motivations, e.g. forgetting to clean the bathroom as it’s unpleasant

• information may be forgotten due to decay as a result of time progression, injury or drug use.