Chunking in recall of symbolic drawings

Surface Information Loss in Comprehension

Shortly after a sentence has been comprehended, information about its exact surface form (e.g., its word order) becomes less available. The present research demonstrated this phenomenon during the comprehension of nonverbal stimuli (picture stories). In Experiment 1, significantly more surface (left/right orientation) information was lost after comprehending several picture stories than just one; in Experiment 2, more was lost after comprehending an entire picture story than half of one. In Experiment 3, subjects segmented the picture stories into their constituents; in Experiment 4, significantly more surface information was lost after crossing these constituents' boundaries than before. The present research also investigated why surface information is lost. Four explanations were considered: Surface information loss is the result of performing grammatical transformations (the linguistic hypothesis), exceeding short-term memory limitations (the memory limitations hypothesis), integrating information into gist (the integration hypothesis), shifting from building one substructure to initiating another (the processing shift hypothesis). The linguistic and memory limitations hypotheses were considered inadequate; the integration and the processing shift hypotheses were tested in the last set of experiments. In Experiment 5 (using nonverbal stimuli), the predictions made by the processing shift hypothesis were confirmed; in Experiment 6 (using verbal stimuli), these results were replicated. Other implications of the processing shift hypothesis concerning surface information loss are discussed.

Factors affecting developmental changes in the speed of processing

Although many studies have found developmental changes in the speed of various processes, they have potentially confounded the subject's age with his knowledge of the task domain and use of strategies. In this study, the strategies used by the subject and his domain knowledge were independently assessed by a number of tasks. Subsequently, processing rate measures were obtained for a task (the "same/different" judgment task of simultaneously presented stimuli) in which domain knowledge was manipulated independently of age while controlling for strategy usage. It was found that the usual adult superiority in speed of processing could be markedly reduced if children possessed equivalent amounts of domain knowledge and this effect was domain specific. Further, it was found that differences in knowledge affected processing rates in both knowledgeable adults and children and to about the same extent. It was concluded that some part of the typical adult superiority in processing rate was due to knowledge differences.