Concept availability in the causal inferences of children and adults.

What supplies the concepts in causal inferences in story comprehension? This question was examined in 5 experiments. Elementary school children and college students listened to stories containing a "premise" sentence describing a character's intent in initiating a series of actions, followed by an unexpected "outcome." After each story, the subjects were asked inference questions about the reason for the outcome (Experiments 1-4) or asked to explain the outcome (Experiment 5). In the various experiments, the availability of object concepts for an inference was manipulated by providing 0 or 2 clues preceding the outcome, additional filler information that diluted the clue information, a mention of an object in the premise or no mention, and an object title for each story or no title. The results suggested that the availability of an object concept in sentences prior to the outcome was a critical determinant of whether an object inference occurred, especially for children. Given availability, the thematic prominence of the object influences whether the object will be used in an inference.

Place and action in children's representations of stories.

The purpose of the four experiments was to examine the prominence of place and action information in the story representations of second (7-year-old), fifth (10-year-old), and sixth (11-year-old) grade children and college students. The subjects were read short stories in which the information in a premise and an outcome sentence were consistent or inconsistent in describing place or action information. Judgments about story adequacy and the conditional probability of an inadequacy judgment given inconsistency detection were measures of prominence in the story representation, and prominence was manipulated by providing place titles, action titles, or no titles. The results showed that place inconsistency is more important than action inconsistency in children's judgments of story adequacy, except when the action involves the story theme. Developmental differences in story judgments generally were larger for inconsistent actions than for inconsistent places, perhaps due to children's problems in abstracting an action theme early in story processing.

Stresses created by occlusal prematurities in a new photoelastic model system.

A new photoelastic model system incorporating a simulated periodontal ligament sleeve around an experimental first molar has been developed. The system was used to visualize internal compressive stresses created by various premature occlusal incline relationships in both buccolingual and mesiodistal dimensions. When prematurities were applied singly and observed buccolingually, both class 1 and and class 2 prematurities produced stresses along the lingual aspect of the root, whereas the class 3 prematurity produced stresses along the buccal aspect of the root. When viewed buccolingually, combinations of class 1 and class 2 prematurities resulted in stresses along the lingual aspect of the root. The stress pattern was similar to those created by the single class 1 or class 2 prematurities. A combination of class 2 and class 3 prematurities did not produce a well-defined indication of stress distribution. There was slightly more stress along the buccal aspect of the root. Comparison of this combination with individual class 2 and class 3 prematurities indicates that such a combination tended to diminish tipping of the tooth in any one direction. A combination of class 1 and class 3 prematurities showed slightly greater stress along the buccal aspect of the root surface. Again, the combination produced less tipping of the tooth in any one direction when compared with tipping caused by the individual prematurities. When all three prematurities were tested at the same time, the stress pattern was almost coincident with that achieved in the absence of prematurities. When prematurities were observed mesiodistally, the location of stresses was dependent on the mesial or distal placement of the prematurity, irrespective of its position buccolingually.