Subjective contours 1900–1990: Research trends and bibliography

Abibliography on subjective contours and a brief summary of trends in research-on-thin problem are presented. The bibliography covers the years 1900–1990 and contains 445 entries, each briefly annotated with a code that indicates the general content and theoretical orientation of the item.     

Left sidedness and sleep difficulty: the alinormal syndrome

Four indexes of laterality: handedness, footedness, eyedness, and earedness, were assessed in a sample of 1274 subjects. Left- and right-sided groups were compared on two aspects of self-reported sleep difficulty: trouble falling asleep and frequent night wakenings. The incidence of sleep difficulty was found to be elevated in the left-sided groups. The results are discussed in terms of a possible complex of behavioral deviations from the statistical norm, called the alinormal syndrome.     

The effects of perceptual set on the shape and apparent depth of subjective contours

Two experiments showed the influence of perceptual set on the perception of subjective contours. In the first, the perceived shape of a subjective-contour figure (a minimal version of the Ehrenstein configuration) was varied by altering the observer’s viewing set. The second experiment showed that apparent depth emerged in subjective-contour figures when observers were set to perceive the illusory contours.     

A comparison of five methods of illusion measurement

The relative efficiency of five techniques of illusion measurement were tested on parametric variations of the Mueller-Lyer and Ebbinghaus figures. The methods of average error, reproduction, and selection from a graded series all showed significant effects of configurational variations. The subjective scaling techniques each failed to measure adequately changes in illusion magnitude for one illusion configuration. The suitability of the tested measures for group administration is also discussed.     

A Power Test of Conceptual Complexity: Textual Correlates1

Conceptual complexity is a personality characteristic that involves the individual's ability to differentiate and integrate aspects of information. It is usu ally measured with the Paragraph Completion Test (PCT), which requires the completion of six paragraphs, in response to standard stems, often with a time limit of 100-120 sec each. In order to eliminate time pressure, which may reduce complexity, the current study evaluated a revised format that used only two stems but allowed 8 minutes per response. As expected, this procedure resulted in higher scores and produced enough written output to allow analysis of particular test components. Complexity scores from 277 university students were related to total number of words written, sentence length, and number of words with more than three syllables, but not to standard formulae designed to measure readability, such as the Flesch, SMOG and FOG indices. The modest size of the obtained correlations suggests that the scoring of conceptual complexity on the basis of semantic content cannot be replaced by indices based on linguistic and textual components.     

Moon illusion in pictures: a multimechanism approach

The existence of the moon illusion in pictorial representations was demonstrated in 6 experiments. Ss either judged the size of the moon in pictures, depicted as on the horizon or high in the sky, or drew horizon and elevated moons. The horizon moon was consistently judged to be larger than the elevated moon, independent of the angle at which the pictures are viewed. The distance paradox usually observed with the moon illusion (horizon moon apparently closer than the elevated moon) also exists in pictures. The magnitude of both size and distance effects depends on the salience of depicted depth cues. The pattern of results suggests that the moon illusion is caused by several interacting mechanisms and that use of pictorial stimuli may allow the separation of various cognitive from physiological contributions to the illusion.