Nature of schema

Of the three researchers influencing schema theory in 1975 -Minsky, Schank, and Rumelhart - David Rumelhart has probably contributed the most to our current understanding of schemas. He has written a number of important articles about the nature of schemas, beginning with the one in 1975 and culminating with his work on parallel distributed processing (PDP) in 1986. Whereas Minsky introduced the frame and Schank the script, Rumelhart retained the word schema in his research. However, it takes on a substantially different meaning from that in earlier schema studies. 

Almost certainly, the philosophical debate about the nature of schemas belongs at the most abstract level. In general, philosophers have not been concerned with a particular context in which schemas are used but rather with whether such knowledge structures exist at all. The method of study is largely reflection or introspection. 

Temporal XML Schema (Currim et al. 2009) - also referred to as xXSchema -is a way to formalize the temporal nature of schema and document versioning. The framework is assembled by the same research group that helped develop the temporal extensions to SQL. In all other frameworks discussed to date, the relationship between versions of schemas and documents are informal if they exist at all two versions of the same schema version are considered to be two separate schemas, related to each other only by whatever point-in-time script was used to perform the migration. xXSchcma makes evolution over time a first-class concept, modeling different versions of the same conventional XML schema in the same document. 

Figure 5 Sample database schema. A database schema shows the types and nature of links between different types of data. Each box represents a table within the database. The rows within that box correspond to the fields of the table. The lines connecting the boxes identify the required relationships amongst the different types of data stored in the different tables.

VAX LIMS DMDB. The key to good database design is the definition of records and the set relationships between them. The VAX DMDB schema (Bachman diagram) is shown in Figure 4. The diagram shows the major records (boxes) in the database and the relationship (arrows) between the records (sets). The records and their fields are determined by the nature of the data encountered in an analytical laboratory... 

To begin, however, we must first have an idea of how space could be used in abstract cognition. The first part of this introduction seeks to illustrate what is meant by spatial schemas, what is meant by abstract cognition, and how the latter may benefit from the former. In the second part, the aim is to identify two important points in formulating accounts of spatial schemas. First, our account of spatial schemas explores the idea that space can be a mechanism for cognition, not merely a metaphor for cognition. Second, our account of spatial schemas aims to identify the nature of the correspondences between space and other domains, and how those correspondences, or mappings, are established. The third part of this introduction proceeds to provide an overview of the contents of the book. 

Ample evidence in the literature and reviewed in this volume indicates that people use spatial representations to deal with problems in other cognitive domains. This section discusses the possibility that animals also might use spatial schemas to deal with problems in other cognitive domains. The fundamental nature of spatial representations for the survival of organisms suggests that such representations might be found in both humans and nonhumans. Two speculative examples will be discussed here. 

Two central meanings predominate in Plato s dialogues. First, schema (translated variously as form, shape, figure, or fashion ) often occurs, along with color, sound, or music, 3 in discussions about the intrinsic nature of objects for example, in the case of letters, we both see and know the form [schema] and color. 4 A second use occurs with abstract concepts, as in the form [schema] of a law, 5 the shapes [schemas] of lives, 6 or the fashion [schema] of a legend. 7 In both contexts, schema indicates the essential commonality of a broad category. 

It is worthwhile noting that Aristotle, Plato, and Kant were all concerned primarily with concepts (e.g., both Aristotle and Kant devoted many pages to the nature of number and to describing what makes a triangle a triangle).18 Modern psychological usage moves beyond this scope and looks at events, experiences, and situations as well. However, much of what these philosophers observed about schemas for concepts is equally valid for our topics as well. 

Together, Bartlett s and Piaget s ideas provide the skeleton of schema theory. It begins to be understandable but does not yet have sufficient substance. Several recent researchers have sought that substance by performing more-detailed empirical investigations about the nature of a schema and by developing sophisticated computer models that simulate schema instantiation. 

Rumelhart s later work turned explicitly to the nature of the schema. In 1977, he and Andrew Ortony published a speculative study about what constitutes a schema. Rumelhart, as noted, approached the study of schemas through his work on story grammars (1975). Ortony arrived by way of studying the metaphor (1975). In their joint endeavor, they outlined four essential characteristics of the schema, and most of their chapter addresses these issues. However, the essence of their position can be found in a brief paragraph that precedes the discussion of these four characteristics. In that small paragraph (Rumelhart Ortony, 1977, p. 101), they lay out a number of important points ... 

The first point of interest is that a schema is a structure for organizing data. The implication is that we should pay attention to its form. This is a key issue. Unless we can create exact hypotheses about the nature of the structure and how it serves memory, we will be unable to create viable models of the schema. Together with Minsky and Schank, Rumelhart and Ortony pushed the notion of schema away from a purely conceptual or interpreta-tional construct toward one whose form could be specified. This approach moves well beyond Kant s speculations and foreshadows the importance of formal models. 

Rumelhart and Ortony s third point is that there are a number of interrelations in a schema. A schema is not simply a list of features but rather is a collection whose parts are linked together. The nature of these linkages remains unspecified, but this notion is an... 

Minsky, Schank, Rumelhart and Ortony, and Winograd made important hypotheses about the nature of the schema. However, a limitation in their presentations is that they were confined to hypothesis or speculation. Brief hints appear of how models might be constructed or how individuals might use schemas, but they are not elaborated. We are left at this point with several good ideas but no evidence of whether schemas provide a viable means of describing human cognition. We must look elsewhere for such evidence. 

Stories of these kinds are used to demonstrate that individuals do use prior experience to comprehend stories. However, as evidence of schemas, they are somewhat weak. What we have is confirmation that prior experience is stored in memory and that it influences recall. Studies such as these cannot provide evidence about the structure of the memory storage. Why not We cannot make any such claims because the nature of the storage has not been specified nor have the specific contents. All that we can determine from these studies is that the prior knowledge does influence the subjects as they read and encode the story for later recall. However, these studies have made an important contribution to the overall understanding of schemas by expanding the focus of the research beyond the formal symbolism of the structural rule set to a more general conceptual framework. 

There are potentially three big areas in schema research the investigation of how schemas influence memory recall, the specification of models to simulate schema instantiation, and the study of how schemas develop and change. All require substantial theoretical and empirical study, but the nature of the theories differ. A considerable body of research exists for the first two areas, as is evident from the preceding discussion, but the third is largely untapped. For the most part, researchers have taken schemas as given, and few have dealt with issues having to do with schema creation or modification. 

In many domains, a person may develop a basis set of schemas quite naturally. In a number of educational domains, however, we have evidence that students are not developing powerful schemas... 

Adopting schema theory as the basis of instruction almost certainly necessitates a complete restructuring of the curriculum. It also raises questions about the nature of learning. In this part and the next, I address these two issues. 

Two characteristics of the schema have far-reaching effects on instruction. One is the componential nature of knowledge associated with it, and the other is its network structure. The impact of the four components of schema knowledge is that we may create sequences of instructional material to focus on each of them. The influence of the network structure is that we will tend to make many more explicit connections between topics of instruction than we might otherwise. Schema-based instruction looks very different from instruction based on other principles. 

A point to be highlighted is that students will develop schemas about the subject matter whether instruction takes a schema-based approach or not. Learners will search for structure and relationships. Thus, the questions to be asked about schema-based instruction do not center on whether or not students create schemas. They do. The questions focus instead on the nature of the schemas that are developed. We ask whether the instruction itself can promote more cohesive and better structured schemas than would instruction having another foundation. It is here that the basis set of schemas becomes important, because these lay the groundwork for the instructional design. 

The scope of schema theory embraces all three of the areas just described. Schemas have a natural place in each of them contexture, memory, and competency. Moreover, schema theory provides the relationships that tie all three together. The research in the following chapters illustrates this point. 

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