Some observations and measurements of the Pulfrich phenomenon

The Pulfrich pendulum was evaluated as a potential screening device for the detection of anomalies of binocular vision. For this purpose, a booth was set up at the Kentucky State Fair (1964) and the general public invited to observe the pendulum and record their responses with the equipment provided. The obtained results indicate that a dichotomy can be achieved between those who have binocular vision and those who do not. However, gradations of binocular vision from poor to good cannot be achieved with the pendulum as presently understood. Contrary to explanatory theory the characteristic shape of the seen pendulum path was asymmetrical following the rule that the path was displaced away from the observer on the side of the filtered eye.     

The effect of pattern and texture gradient on slant and shape judgments

The experiment reported was designed to explore the relationship between gradient of texture and monocular slantshape perception. The effects of instructional set and order of slant and shape judgments were studied in interaction with four patterns differing in regularity of texture. Judgments of slant and shape were made by the same Ss for all patterns at 20°, 45°, 60°slant for slant judgments and 0°, 20°, 45°, 60° for width judgments. There were three instructional groups. Within each group one half of the Ss made slant judgments first, the other half shape judgments first. For all patterns, accurate perception of the slant of patterned material resulted in increased compensation in width judgments. Apparent width was found to be a function of pattern and also subject to instructional manipulation.     

Observing responses and discrimination learning

An operant response in the pigeon, whose performance results in exposure to the discriminative stimuli, is described and suggested as an experimental analogue for “observing.” Such an operant response is then used to explore the relationship between observing responses and discrimination learning in a variety of discrimination situations, of progressively increasing complexity. In general, the results support the contention that the development and maintainence of observing responses is closely related to the degree of differential behaviour manifested toward the discriminative stimuli. Certain modifications are suggested in the theoretical formulation underlying the concept of “observing responses.”     

A note on the standard length of a test

This paper describes a relationship between the variance-covariance matrix of test items and Woodbury's concept of the standard length of a test. An index of item-test relationship is described in standard length terms. The sum of these indices for the items in a test is equal to the square of Jackson's coefficient of sensitivity.