Lecturer's Précis - Thorndike (1977)
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First published online 14:00 GMT 2nd December 2003, Copyright Derek J. Smith (Chartered Engineer). This version [HT.1 - transfer of copyright] dated 18:00 14th January 2010
This material previously appeared in Smith (1998; Chapter 5). It is repeated here with minor amendments and supported with hyperlinks.
Thorndike's (1977) "Story Memory" as a Form of Complex Propositional Knowledge
See firstly the several linked definitions pertaining to "propositional knowledge" in the Memory Glossary.
So what actually is it like, this pool of propositional knowledge from which our propositions flow and into which flow the propositions of others? Well although little is known about the mind's way of representing propositional knowledge, two approaches have been particularly influential over the years. The first of these is the very long-standing Associationist tradition, and the second is Head's (1926) concept of the schema. The former derives ultimately from ancient Greek philosophers such as Aristotle, regards knowledge as consisting of a massively interlinked network of individual ideas, and lives on as a tradition in modern network models of long term memory. Schema theory, on the other hand, emphasises the role of superordinate cognitive structures in understanding. It does not deny the existence of concepts as such, nor the importance of associations between them, but it looks up a level at how subsets of concepts are habitually organised by "an active organisation of past reactions, or of past experiences" (Bartlett, 1932, p201). Schemas predict what will happen to things in the future from how those things (or similar things) have behaved in the past, and the schema tradition has been brought up-to-date in a number of guises, including Thorndike's story structures (as introduced below). Thorndike's approach grew out of a series of experiments carried out in the mid-'seventies, and is worth a closer look .....
The Thorndike (1977) study looked at how the comprehensibility and recall of stories depends more on their plot complexity - the superordinate structure - than the amount of content per se. Thorndike's argument began with the theoretical assertion that a typical narrative relies on a small number of basic rules, as follows:
Rule 1 - a STORY is made up of a SETTING, a THEME, a PLOT, and a RESOLUTION
Rule 2 - a SETTING is made up of CHARACTER(S), A LOCATION, and a TIME
Rule 3 - a THEME is made up of EVENT(S) and a GOAL
Rule 4 - a PLOT is made up of one or more EPISODES
Rule 5 - each EPISODE is made up of a SUBGOAL, one or more ATTEMPTS, and an OUTCOME
Rule 6 - each ATTEMPT is made up of additional EVENTS and EPISODES
Rule 7 - each OUTCOME is made up of one or more EVENTS and a STATE
Rule 8 - each RESOLUTION will consist of an EVENT or a STATE
Rule 9 - SUBGOALS and GOAL both consist of DESIRED STATES
Rule 10 - a STATE must take account of CHARACTER(S), LOCATION(S), and TIME(S)
Now although there is only a finite set of elements available, several of them - eg. the number of CHARACTERS in a SETTING, or the number of EPISODES in a PLOT - can occur many times. The basic ten rules can therefore generate a theoretically infinite number of different "narrative structures", and what Thorndike did was to vary these structures independently of their content and see what effect this had on comprehension and recall. In one experiment, Thorndike arranged for there to be four variants of two core stories, each with roughly the same amount of content (35 individual propositions), but with increasing internal complexity. In decreasing order of complexity the variants were (1) the core story itself, (2) a narrative version with the unifying theme stated late, (3) a narrative version without an explicit theme, and (4) a simple descriptive version. Each variant could be presented in "natural" or "random" order. Here are variants #1 and #4 of the "Circle Island" story, both in their natural order. In variant #1, the SETTING is given first [propositions 1-10], followed by the THEME [11-16], and the PLOT consists of a series of EPISODES [17-31]. The (tags) allow cross reference to the corresponding structure diagram (Figure 1): they do not form part of the text. In variant #4, the present tense is used throughout, there is an indeterminate action sequence, and the propositions are presented as largely unlinked matters of fact, leaving no explicit THEME. The underlines show where changes to the core story have been made.
Variant #1 - Core Story: "(1) Circle Island is located in the middle of the Atlantic ocean, (2) north of Ronald Island. (3) The main occupations on the island are farming and ranching. (4) Circle Island has good soil, (5) but few rivers and (6) hence a shortage of water. (7) The island is run democratically. (8) All issues are decided by a majority vote of the islanders. (9) The governing body is a senate, (10) whose job is to carry out the will of the majority. (11) Recently, an island scientist discovered a cheap method (12) of converting salt water into fresh water. (13) As a result, the island farmers wanted (14) to build a canal across the island, (15) so that they could use the water from the canal (16) to cultivate the island's central region. (17) Therefore, the farmers formed a procanal association (18) and persuaded a few senators (19) to join. (20) The procanal association brought the construction idea to a vote. (21) All the islanders voted. (22) The majority voted in favour of construction. (23) The senate, however, decided that (24) the farmers' proposed canal was ecologically unsound. (25) The senators agreed (26) to build a smaller canal (27) that was 2 feet wide and 1 foot deep. (28) After starting construction on the smaller canal, (29) the islanders discovered that (30) no water would flow into it. (31) Thus the project was abandoned. (32) The farmers were angry (33) because of the failure of the canal project. (34) Civil war appeared inevitable."
Variant 4 - "Descriptive": "Circle Island is located in the middle of the Atlantic ocean, north of Ronald Island. The main occupations on the island are farming and ranching. Circle Island has good soil, but few rivers and hence a shortage of wildlife. The island is run democratically. All issues are decided by a majority vote of the islanders. The governing body is a senate, whose job is to carry out the will of the majority. Salt water is converted into fresh water by a cheap method discovered by an island scientist. The island farmers favour building canals across the island. Water from the rivers is used to cultivate the island's central region. A cooperative association formed by the farmers has persuaded a few senators to join. The cooperative association issues are periodically brought to a vote. All the islanders vote. The majority favour the association. The senate is responsible for the construction of a small canal that is 2 feet wide and 1 foot deep. The project was abandoned shortly after construction started on the small canal. The islanders discovered that no water would flow into it. Civil war appears inevitable. The farmers are angry because of the failure of the canal project. The senate believes that the farmers' proposed canal is ecologically unsound."
Thorndike delivered his material to 64 American undergraduates in a 4x2x2 between-subject design. Passages were presented visually or orally, and subjects immediately rated their comprehensibility on a ten-point scale. They then had either (a) to reproduce the story as accurately as possible, or (b) to summarise it. Results showed a progressive reduction in comprehensibility as the complexity decreased. The core "Circle Island" story scored 7 for complexity, the late theme variant scored 6, and the no theme and descriptive variants scored 5. The corresponding recall accuracies were 66%, 57%, 51%, and 45% respectively. Passage summaries did not differ in length across the four conditions, but showed a significant increase with decreasing structure (30%, 36%, 40%, and 58% respectively).
Figure 1 - Thorndike's (1977) Story Structures: Here is the narrative structure which corresponds to the core story shown above. The [number] tags cross reference back to individual propositions therein, and asterisks mark narrative elements where theoretically infinite repetition is possible.
Redrawn from a black-and-white original in Thorndike (1977, p81); asterisks added. This graphic Copyright © 2003, Derek J. Smith.