A capacity theory of comprehension: individual differences in working memory.

A theory of the way working memory capacity constrains comprehension is proposed. The theory proposes that both processing and storage are mediated by activation and that the total amount of activation available in working memory varies among individuals. Individual differences in working memory capacity for language can account for qualitative and quantitative differences among college-age adults in several aspects of language comprehension. One aspect is syntactic modularity: The larger capacity of some individuals permits interaction among syntactic and pragmatic information, so that their syntactic processes are not informationally encapsulated. Another aspect is syntactic ambiguity: The larger capacity of some individuals permits them to maintain multiple interpretations. The theory is instantiated as a production system model in which the amount of activation available to the model affects how it adapts to the transient computational and storage demands that occur in comprehension.     

Mental rotation of objects retrieved from memory: a functional MRI study of spatial processing

This functional MRI study examined how people mentally rotate a 3-dimensional object (an alarm clock) that is retrieved from memory and rotated according to a sequence of auditory instructions. We manipulated the geometric properties of the rotation, such as having successive rotation steps around a single axis versus alternating between 2 axes. The latter condition produced much more activation in several areas. Also, the activation in several areas increased with the number of rotation steps. During successive rotations around a single axis, the activation was similar for rotations in the picture plane and rotations in depth. The parietal (but not extrastriate) activation was similar to mental rotation of a visually presented object. The findings indicate that a large-scale cortical network computes different types of spatial information by dynamically drawing on each of its components to a differential, situation-specific degree.     

A chronometric analysis of strategy preparation in choice reactions

In this research, we investigated the process of preparing strategies for performing choice-reaction tasks. Before each choice-reaction trial, subjects were shown a cue that indicated features of the stimulus-response mapping to be used on the upcoming trial. Subjects used this cue to specify their strategy for responding to the stimulus. The time needed for specifying the strategy was measured by allowing subjects to control the cue presentation and surreptitiously recording how long they spent looking at the cue. The experiments demonstrated that the time to prepare a strategy was a function of the number and nature of the strategy features that had to be specified; simple uncertainty about the possible strategies had little direct effect. The results discon-firmed a serial model in which the time to prepare a strategy is the sum of the times to specify the individual strategy features. A mixed serial-parallel model was proposed as an alternative.     

Changes in activation levels with negation

Three experiments investigated the effects of negation during on-line language processing. It was hypothesized that negation of a noun (e.g., no bread) would affect the activation level of the mental representation of that noun. Experiment 1 manipulated the location of the negation in sentences that were followed by a probe recognition task. Subjects were slower to indicate that a probe had been in the sentence when the probe corresponded to a negated noun. Experiment 2 replicated these results with a probe naming task. Experiment 3 replicated the result that reading the phrase no bread inhibits responses to bread in the probe task but found no evidence of inhibition of the response to an associate probe, such as butter. The results of these three studies suggest that negation affects the discourse focus of a noun phrase, and hence the activation level of its representation.     

Working memory constraints on the processing of syntactic ambiguity.

We propose a model that explains how the working-memory capacity of a comprehender can constrain syntactic parsing and thereby affect the processing of syntactic ambiguities. The model's predictions are examined in four experiments that measure the reading times for two constructions that contain a temporary syntactic ambiguity. An example of the syntactic ambiguity is The soldiers warned about the dangers . . . ; the verb warned may either be the main verb, in which case soldiers is the agent; or the verb warned may introduce a relative clause, in which case soldiers is the patient of warned rather than the agent, as in The soldiers warned about the dangers conducted the midnight raid. The model proposes that both alternative interpretations of warned are initially activated. However, the duration for which both interpretations are maintained depends, in part, on the reader's working-memory capacity, which can be assessed by the Reading Span task (Daneman & Carpenter, 1980). The word-by-word reading times indicate that all subjects do additional processing after encountering an ambiguity, suggesting that they generate both representations. Furthermore, readers with larger working-memory capacities maintain both representations for some period of time (several words), whereas readers with smaller working-memory capacities revert to maintaining only the more likely representation.     

Comprehending quantified sentences: The relation between sentence-picture and semantic memory verification

People were timed as they decided whether quantified sentences like All (some) of the round figures are red were true or false of an accompanying picture. The response latency was a function of the quantifier and the relation between the sets mentioned in the subject and predicate of the sentence. The pattern of latencies was similar to the pattern found for sentences that refer to concepts in semantic memory, e.g., All (some) dogs are animals (Meyer, 1970). This result suggests that the same process may be operating in both domains. Two alternative models of the process are considered. One model assumes that the common process consists of computing the relation between the two sets mentioned in the sentence. The other model assumes that the common process consists of comparing the representation of the sentence to the representation of information computed from the second source. Both models are integrated with broader theories of performance in various comprehension tasks.     

Paradigms and processes in reading comprehension

This article compares several methods of presenting text, including a new paradigm that produces reading-time data with many of the characteristics of naturally occurring eye-fixation data. In the new paradigm, called the moving window condition, a reader presses a button to see each successive work in a text, and the previous work is removed when a new work appears. The words appear in the same position that they would in normal test, and word-length information is available in peripheral vision. The results are qualitatively and quantitatively compared to the results obtained by monitoring the eye fixations of subjects reading normal text. The word-level effects are generally similar. Readers pause longer on longer words, on less frequent words, on words that introduce a new topic, and at ends of sentences. The results suggest that readers initiate thr processing of each word as soon as they encounter it rather than buffer words and delay processing. Also considered are two other reading-time paradigms, one in which words are cumulatively displayed on the screen and one in which each successive word is presented at the same location on the screen. Finally, we consider how the tendency to immediately process text might interact with other techniques for text presentation, such as the rapid serial visual presentation (RSVP) condition, and we generate predictions about the nature and limits of the method.     

3 cases of acute transverse syndrome caused by a dissecting aneurysm of the aorta

A relatively rare cause of the acuto transverse syndrome, aneurysma dissecans of the aorta followed by disturbance of the circulation in the spinal cord, is described on the basis of three cases. The special features of the blood supply of the spinal cord and the etiopathogenesis, symptomatology and prognosis of aneurysma dissecans are discussed. Attention is drawn to the necessity of unobtrusive methods for case taking and clinical examination to save the patient unnecessary stress and to improve the chances of survival.     

The computer and eye processing pictures: The implementation of a raster graphics device

The process of solving visual analogies was examined using a digital video display and video-based eye tracker. The results indicated that increasing the complexity of an analogy by increasing the number of relations involved in the problem resulted primarily in increasing the time it takes to discover the mapping between the two members of the first pair. The display of the picture and the analysis of the eye fixations are described.