The effects of expectancy and variation in task demand on the rate of human information transmission were studied. Subjects performed an eight-choice key-pressing task, attempting to match characters presented singly under both increasing and decreasing demand. The results support previous research indicating that the relationship between the rate of information an individual is able to transmit and task demand depends, at least in part, upon the temporal history of demand. When a relatively high level of demand was imposed, performance failed to recover at the expected rate as demand was reduced. However, this 'hysteresis' effect occurred even when a cue was provided to indicate clearly that a reduction in task demand was imminent, suggesting that an overload of short-term memory, rather than an individual's erroneous expectations regarding demand, is primarily responsible for the effect.

The effects of verbal ability and sex on performance in a simultaneous matching task were studied. Subjects with high-verbal ability (high verbals) were much faster than subjects with low-verbal ability (low verbals) in making taxonomic category identity matches and homophone identity matches. These results suggest that verbal ability is related to the speed of retrieval from long-term memory. In addition, high verbals were faster in making physical identity word matches, suggesting that either lexicographically coded information stored in long-term memory is used in such a task or that verbal ability is also related to the speed of retrieval from short-term memory. As expected, males did not differ from females in the time they required to perform any of the matching tasks, although males made slightly more errors.

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For convenience in testing, the product axiom may be written in its logarithmic form:A special feature of these axioms is that they are applied before any scale is constructed, and a subset of the data is used to predict the residual data. Tests based on scales constructed from all the data are more likely to obscure possible violations ApparatusThe apparatus, described in detail elsewhere (Eskildsen, 1963), provided four luminous white circular targets 13 mm in diam, placed horizontally and separated by 90 mrn, center to center. The apparatus was located in a light-tight visual tunnel, and Ss were seated at a distance of 12 ft from the targets in an ordinary classroom desk seat. S reported his estimations orally. A brief dark-adaptation period of 15 min preceded each experimental session. METHOD SubjectsSubjects were two male and four female undergraduates at the University of Oregon, and were paid $1.50 per hour for their time. ProcedureThree of the Ss (randomly selected) did the difference estimation task first and the ratio task second, and the other three Ss performed the tasks in reverse order.Difference estimation task. Each trial began with the presentation of the standard pair, which consisted of two adjacent lights, one set at 30 (always on the left) and the other at 100 ft-L. By pushing a button S could then move a shutter to view the comparison pair which was always to the left of the standard pair. The S was told to call the difference in brightness for the standard pair 100, and to assign a number to the difference in brightness for the comparison pair in accord with usual magnitude estimation instructions. The S could move the shutter back and forth as many times as he wished to compare the two pairs. The trial ended when S responded and E turned out the lights. The following instructions were read for the difference estimation task: