A considerable amount of research has been

carried out on the nature and structure of

memory, its functions and processes but

recently, psychologists such as Schank

(1975) have started to conduct empirical

studies on the organisation of memory. This

essay will examine one of the more recent

developments in the organisation of memory,

the schema theory.

According to Gross (1999) the organisation of

memory involves two main concepts. These

are the format in which information is

arranged and how this information is

arranged. The earlier theories, such as the

matrix and hierarchical network models by

Collins and Quillians (1969, 1972) concerning

the organisation of memory adopted a logical,

sequential approach to the organisation of

memory. Later on, in the late 1970's

psychologists such as, Schank, Abelson and

Rumelhart realised that the organisation of

memory is not as logical as the earlier

models proposed. The schema theories

make an attempt at addressing the more

complex aspects of the organisation of

memory.

Semantic memory plays a fundamental role in

the earlier theories but according to Baddley

(1990) it became increasingly obvious during

the 1970's that the SM must contain structures

considerably larger than the simple concepts

discussed in the network models by Collins

and Loftus. Bartlett (1932) used the term

"˜schema' to refer to this larger unit of semantic

memory. According to Hayes (1999) a

schema is a "˜"¦.form of representation which

we use to guide our actions' Bartlett (1932)

described a schema as "˜ an active

organisation of past reactions, or of past

experiences which must always be supposed

to be operating in any well-adapted

organismic response'. Bartlett also realised

that our memory is often disorganised, vague

and incomplete and that any theoretical model

must attempt to explain such inaccuracies in

our representation of information or

knowledge. Bartlett also recognised that

memory is a reconstructive process in which

information already stored affects the

remembering of other events. According to

Cohen (1993), schema theory represents the

most influential approach to the fundamental

problem identified by Bartlett. At its core is the

belief that what we remember is influenced by

what we already know and that our use of past

experience to deal with new experience is a

fundamental feature of how the mind works.

Two major modern schema theories are

those of Rumelhart (1975) and Schank (1975)

and Schank and Abelson (1977). Their

theories greatly overlap and are, in many ways

inter-related. The main concepts and ideas in

these two theories were summarised by

Norman (183/85). First, that schema's have

variables or slots. Schemas are packets of

information, which comprise a fixed,

compulsory value plus a variable or optional

value. Rumelhart and Norman (1983)

described schemas as "˜varying considerably

in the amount of information they

contain-some are quite simple while others

are extremely complex'. Here, there is a

subtle reference to the variable slots. Second,

schemas can be related together to form

systems. That is, they are not mutually

exclusive packets of information but can be

overlapping. For example, a schema for a

picnic may be part of a larger system of

schemas including, meals, outings and

parties. Third, Schemas represent knowledge

of all levels of abstraction. Schemas can

relate to abstract ideologies, abstract

concepts or concrete objects. For example,

they may be used to describe justice or the

appearance of a face. Fourth, Schemas

represent knowledge rather than definition.

Schemas incorporate knowledge and

experience of the world rather than abstract

rules. Fifth, schemas are active recognition

devices. This is very similar to Bartlett's "˜ effort

after meaning' whereby we try to make sense

of ambiguous and unfamiliar information in

terms of our existing knowledge and

understanding.

According to Schank (1975) and Schank and

Abelson (1977) we develop schemas and

scripts which represent commonly

experienced social events such as catching a

bus or going to a restaurant. Baddley (1990)

says, " scripts can only be interpreted by

bringing in a great deal of additional

information" According to Schank et al, scripts

are essential ways of summarising common

cultural assumptions. Not only do they help us

to understand text and discourse but also

predict future events and behave appropriately

in given social situations. Furthermore,

scripts contain the sequences of actions one

goes through when carrying out stereotypical

events and would also include the sorts of

objects and actors we are likely to encounter.

Schank and Abelson (1977) built their scripts

into a computer program (SAM) which, they

claim is capable answers about restaurants

and accounts of restaurants. Their scripts

were supported by Bower et al (1979) where

he asked people to list 20 actions/events in

sequential order which commonly occur while

eating at a restaurant and found considerable

agreement. He found that 73% mentioned

sitting down, ordering, eating, paying the bill

and leaving. Also, at least 48% included

entering, giving the reservation name,

ordering drinks, eating dessert and leaving a

tip. Thus there were at least 15 events similar

to the majority of people. These findings

broadly agree with Schank and Abelson's

restaurant script. Interestingly, when such

events were embodied in a story people

tended to falsely recall the facts, which were

not explicitly recorded but were consistent with

the script.

The schema theories have strengths and

weaknesses. They were able to provide a

fundamental basis and further development in

theorising the organisation of memory. Not

only did they address the more complex

situations of social and cultural aspects of

everyday situations but were also to provide a

basis for the explanations of real life

situations. However, one of the main

problems of the schema theory is that it is

often very difficult to define what a schema is.

Rumelhart (1980) identified four different

analogies of what a schema is but was

unable to actually define a schema. The

schema theory is also very limited as Alber

and Hasher (1987) argue that memory

representation is much richer than the

schema theory suggests. The schema theory

adopted a rather limited model of the schema,

which said that schema first encoded only

relevant information and then extracted only

relevant meaning, so that none of the original

form of the information would be needed.

When Alber and Hasher identified aspects of

memory, which were richer than that, and also

included, irrelevant details they concluded that

schema were not adequate to explain how

organisation and memory representation

works.

Cohen (1993) points out that "˜ the whole idea

of a schema is too vague to be useful'. Also

that there is an overemphasis on the

inaccuracies of memory and overlooks the fact

that complex events are sometimes

remembered in great detail. Cohen further

argues that the schema theory does not

suggest the origin of schema or how they are

created in the beginning. Nonetheless, he

admits that without schemas we are unable to

interpret new experiences and also these new

experiences build up schemas. It seems that

schemas definitely form part of the

organisation of memory although the schema

theory itself had many limitations and needs

to be developed further.

In conclusion, the schema theory has

provided us with a fundamental basis on

which theorists may develop further and use it

as a solid grounding and basis for their

theories. However, the theory is too limited

and vague and does not address all aspects

of our complex memory system. Yet, it is

evident that schema play an important and

essential role in our social and cultural

environments and do explain some aspects of

the way our memory is organised.