A test of constancy scaling theory in a modified Mueller-Lyer illusion

The center line of each of the two Mueller-Lyer figures was replaced by a rectangle whose length and width were both judged. The rectangle, bounded by wings positioned outward, was judged both longer and narrower than a standard rectangle of equal size, while the rectangle bounded by wings oriented inward was judged to be both shorter and wider than the standard rectangle. These results were considered to provide evidence against a constancy scaling explanation of geometric illusions. Other theories to account for the results were considered and found inadequate.     

A test of color constancy in 4-month-old human infants

Forty-five 4-month-old infants were tested for color constancy using a familiarization, paired-comparison paradigm. Infants were familiarized and tested with colored stimuli under two conditions: (1) no change in the illuminant between familiarization and test and (2) a change in the illuminant between familiarization and test. Infants correctly recognized the familiarization color when tested with no change in the illuminant. Infants tested with a change in the illuminant correctly recognized the familiar color under some conditions yet failed to do so under others. Several explanations are considered for these results and it is concluded that color constancy operates immaturely at 4 months of age.     

A test of independence of dimensions in multidimensional scaling

Models for multidimensional scaling use metric spaces with additive difference metrics. Two important properties of additive difference metrics are decomposability and intradimensional subtractivity. A prediction was derived from these properties and tested experimentally. Rectangles varying in area and shape served as stimuli. Dissimilarity judgments were obtained by both rating and pair comparison procedures. The assumptions of the model were violated by most of the Ss. Apparently this violation was due to an interaction between the two dimensions.     

The case for misapplied constancy scaling: depth associations elicited by illusion configurations

It has been suggested that many visual-geometric illusions arise from inappropriate evocation of size-constancy by depth cues implicit in illusion configurations. Observers gave free association responses while viewing illusion figures. Analysis of these responses provides weak but consistent evidence for the elicitation of depth in the Sander parallelogram, Mueller-Lyer, Zoellner, and Ehrenfels variant of the Ponzo illusion. No evidence for depth is found in the normal form of the Ponzo, Poggendorff, and horizontal-vertical illusions, and the evidence is ambiguous in the Orbison configurations. These results indicate that depth processing may be evoked by some, but not all, classical illusion forms.     

Lightness constancy: a direct test of the illumination-estimation hypothesis

Many models of color constancy assume that the visual system estimates the scene illuminant and uses this estimate to determine an object's color appearance. A version of this illumination-estimation hypothesis, in which the illuminant estimate is associated with the explicitly perceived illuminant, was tested. Observers made appearance matches between two experimental chambers. Observers adjusted the illumination in one chamber to match that in the other and then adjusted a test patch in one chamber to match the surface lightness of a patch in the other. The illumination-estimation hypothesis, as formulated here, predicted that after both matches the luminances of the light reflected from the test patches would be identical. The data contradict this prediction. A second experiment showed that manipulating the immediate surround of a test patch can affect perceived lightness without affecting perceived illumination. This finding also falsifies the illumination-estimation hypothesis.     

A demonstration of shape constancy

In order to compare the recognition of objective (defined in three dimensions) and projective (on the frontal-parallel plane) shapes, subjects were asked to identify angles (either objective or projective) on random polygons that were displayed in complex and meaningful photographic slides in the frontal-parallel plane. The subjects’ judgments corresponded much more closely to the objective than to the projective shapes, almost independently of which of the two shapes they were asked to judge and of whether the slides were presented in a normal upright orientation or were rotated 180 deg. The results are incompatible with the strong form of the shape-slant hypothesis, which assumes that the primary perceptual information concerns the properties of the projective retinal image. The results indicate, instead, that a tacit conception of three-dimensional space is primary in the perceptual process.     

A meta-analytic test of intergroup contact theory

The present article presents a meta-analytic test of intergroup contact theory. With 713 independent samples from 515 studies, the meta-analysis finds that intergroup contact typically reduces intergroup prejudice. Multiple tests indicate that this finding appears not to result from either participant selection or publication biases, and the more rigorous studies yield larger mean effects. These contact effects typically generalize to the entire outgroup, and they emerge across a broad range of outgroup targets and contact settings. Similar patterns also emerge for samples with racial or ethnic targets and samples with other targets. This result suggests that contact theory, devised originally for racial and ethnic encounters, can be extended to other groups. A global indicator of Allport's optimal contact conditions demonstrates that contact under these conditions typically leads to even greater reduction in prejudice. Closer examination demonstrates that these conditions are best conceptualized as an interrelated bundle rather than as independent factors. Further, the meta-analytic findings indicate that these conditions are not essential for prejudice reduction. Hence, future work should focus on negative factors that prevent intergroup contact from diminishing prejudice as well as the development of a more comprehensive theory of intergroup contact.     

A test of the neo-behaviouristic theory of extinction

A test between Moltz's and Deutsch's theory of extinction was devised. Animals were trained to go to the same goal-box via two different paths. Then they were divided into two groups. The first found the goal-box empty, the second found the entrance into the goal-box blocked. The choices of the animals on the next trial were observed. The results are those predicted by Deutsch.     

A simple duality principle in test theory

It is demonstrated that theorems in test theory have corresponding dual theorems which are obtained by exchanging true scores and error scores, as well as reliability coefficients and their complements, in both the hypothesis and the conclusion. A formula that does not conform to the principle cannot be an identity in the test-theory model, but must be based on additional assumptions in the hypothesis tht perhaps are not immediately apparent. The usefulness of this principle is indicated, and its origin in the mathematical formalism underlying the theory is discussed.     

A test of the melioration theory of matching

Melioration theory entails that matching in concurrent schedules occurs because the subjects equalize the local reinforcement rates (reinforcers received for each alternative divided by the time allocated to each alternative). The role of local reinforcement rates was tested by using multiple schedules in which one component involved an alternative with a high absolute rate of reinforcement and a low local reinforcement rate while the second component involved an alternative with a low absolute rate and a high local rate. These alternatives were then presented simultaneously in probe trials to determine preference between them. Contrary to melioration, the absolute rate of reinforcement, not the local rate, was the controlling variable.     

A brief introduction to unified test theory

This article introduces McDonald's unified treatment of test theory, which merges the major contributions of Spearman (True Score Theory and Common Factor Theory) with aspects of Item Response Theory. The fundamentals are first presented. followed by elaboration of selected aspects of the treatment. An SAS program is given that estimates relevant parameters.