MEMORY

‘’When I was younger, I could remember anything, whether it had happened or not’’

Mark Twain

Definition of Memory

The mental processes used to encode, store and retrieve information

Encoding

This takes many forms: visual, semantic, auditory, taste and smell. The information is transformed into codes, which create a memory trace, which is then stored in memory

Storage

Storage:Refers to the amount ofinformation that can bestored in memory Duration:How long information is

stored in memory

Retrieval

The process where information is dug out of memory, including recognition, recall and reconstruction.

The Multi-store Model of Memory

In 1968 Atkinson & Shiffrin propose the classic three stage memory model

The case of H.M. (Blakemore 1988)

H.M. underwent an operation for epilepsy and his hippocampus was removed on both sides of the brain

He had severe amnesia, in that he had difficulty laying down memories, even though he could remember things before the operation

This evidence supports the claim that there is a short-term and a long-term memory

two different memory stores

Information is maintained by continued attention and rehearsal

Duration of trace: up to 30 seconds

Capacity: Stores 7 +/- 2 items

Information is maintained by repetition, organisation

Duration of trace: from minutes to years

Capacity: limit not known

Short term memory Long term memory

Baddeley’s model of working memory

The contemporary model of working memory suggests an attentional control system, the central executive, that is supported by two subsystems, one visual, one verbal

Automatic or effortful processing?

Automatic processing: the processing of information that guides behaviour, but without conscious awareness, and without interfering with other conscious activity that may be going on at the same time:

for example, driving slowly down a street (automatic processing) while looking for a specific address (conscious processing)

Levels of processing

Craik and Lockhart (1972) challenged the idea of the dual store model (STM/LTM) and suggested that rehearsal is not enough to account for memory. Too simplistic.

Craik and Lockhart believe that memories occur as a by-product of the processing of information

Proposed that shallow processing of information results in a weak memory trace, compared to deep processing which results in a stronger, more durable memory trace.

Shallow…………..Deep

Information can be encoded at different levels, from shallow to deep:

Case (shallow level of processing): Is the word in capital letters? BOOK

Rhyme (intermediate level of processing):Does the work rhyme with fate?LATE

Sentence (deep level of processing): Does the word fit the sentence: He met a __________ in the pub? FRIEND

Levels of processing

Implicit/explicit memory

Explicit (declarative) memory: those things that you are aware of remembering and that you can describe in words, such as your birthday, or the meaning of the word "cradle"

There are two types of explicit memory:

Episodic memory the meal you ate last night, or the name of an old classmate, or the date of some important public event.

Semantic memory is the system that you use to store your knowledge of the world. It includes our memory of the meanings of words–the kind of memory that lets us recall not only the names of the world’s great capitals, but also social customs, the functions of things, and their colour and odour.

Implicit memory

Implicit (procedural) memory: expressed by means other than words. For example, when you ride a bike, juggle some balls or simply tie your shoelaces, you are expressing memories of motor skills that do not require the use of language. We form implicit memories without being aware that we are doing so.

How are memories stored?

Work with HM and other amnesiacs implicates the hippocampus as being crucial for memory formation explicit memories are laid down via the hippocampusImplicit memories are associated with the cerebellum Neuroscience explores the synaptic changes that affect memory

Synaptic changes and memory Hebb suggested in 1949 that memory is specific patterns of

activity across a network of neurons. Synapses (connections between neurons) become more extensive during the learning. This is a "mechanism" of long-term memory. 

Long Term Potentiation (LTP) an increase in a synapse’s firing potential after brief, rapid stimulation. Believed to be a neural basis for learning and memory

Fields (2005) with repeated neural firing a nerve cell’s genes produces synapse strengthening proteins, enabling long term memory to form

 

Retrieval

Retrieving a memory might involve recall, recognition or relearning

The encoding specificity principle states that memory is improved when information available at encoding is also available at retrieval.

Say "silk" five times. Now spell "silk." What do cows drink? 

If you said milk that is an example of phonetic priming

Retrieval….

...Is context dependent

Godden & Baddeley (1975)

Abernathy (1940)

and state dependent

Goodwin et al (1969)

Stress affects memory…