Bartlett first introduced the notion of schema as early as 1932 in order to explain why people reconstructed a story when recalling it so as to make more sense of it in terms of their own knowledge and experience. According to Bartlett, the story is assimilated to pre-stored schemata based on previous experience. Rumelhart (1980) defined a schema as "a data structure for representing the generic concepts stored in memory. In other words, schema is an "organizing and orienting attitude that involves active organization of past experience" (Driscoll, 2000). Modern versions of schema theory incorporate many of Bartlett's ideas. For example, Shank and Abelson's concept of scripts (1977) proposed that such event schemata could be organized into a temporally ordered sequence of events. Alba and Hasher (1983) examined all schema theories and identified four major processes: selection, abstraction, interpretation, and integration. It explicitly illustrates how memory and comprehension operate.
One of the central issues that cognitive psychologists are interested in is mental structure. According to schema theory, the knowledge we have stored in memory is organized as a set of schemata or mental representations, each of which incorporates all the knowledge of a given type of object or event that we have acquired from past experience.
Schema theory provides an account to the knowledge structure and emphasizes the fact that what we remember is influenced by what we already know. Schemata facilitate both encoding and retrieval. Moreover, the mental structures are active. Memory can be reconstructed through the integration of current experience with prior knowledge. In other words, schemata represent an active process and can change over time as a result of new experiences and learning.
There are two information resources: the incoming from the outside world and information already stored in memory. The analysis of the sensory information coming in from the outside is known as bottom-up processing or data-driven processing because it relies on the data received via the senses. The information already stored in the memory in the form of prior knowledge influences our expectations and helps us to interpret the current input. This influence of prior knowledge is known as top-down or conceptual-driven processing. Schemata operate in a top-down direction to help us interpret the bottom-up flow of information from the world. Research on functions of the schema focused on the impact of prior knowledge on comprehension and memory (Driscoll, 2000).
Characteristics of schema
Rumelhart and Norman (1983) list five characteristics of schema:
- Schema represents knowledge of all kinds from simple to complex.
- Schema can be linked together into related systems.
- A schema has slots which may be filled with fixed, compulsory values or with variable, optional values.
- Schema incorporates all the different kinds of knowledge we have accumulated, including both generalizations derived from our personal experience and facts we have been taught.
- Various schemata at different levels may be activity engaged in reorganizing and interpreting new inputs.
Winn and Snyder (1996) also described the characteristics of a schema as follows:
- Schema as Memory Structure: schema contains the sum of knowledge of the world from different aspects of the environment
- Schema as Abstraction: Schema exists at a higher level of generality than our immediate experience with the world.
- Schema as Network: Schema consists of concepts that are linked together in a proposition.
- Schema as Dynamic Structure: Schema is dynamic, amenable to change by general experience or through instruction, assimilation, and accommodation.
- Schema as Context: Schema provides a context for interpreting new knowledge as well as a structure to hold it.
The processes of schema acquisition and modification
Three different processes have been proposed to account for changes in existing schemata and the acquisition of new schemata due to learning (Rumbelhart and Norman, 1978):
- Accretion: information is remembered that was instantiated within a schema as a result of text comprehension or understanding of some events.
- Tuning: Tuning occurs when existing schemata evolve to become more consistent with experience.
- Reconstructing: It involves the creation of entirely new schemata which replace or incorporate old ones.
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