James R. Deni

Ebbinghaus Illusion: Effect of Figural Similarity upon Magnitude of Illusion When Context Elements are Equal in Perceived Size

The magnitude of the Ebbinghaus illusion has been reported to be greater when test element and context elements are figurally similar as opposed to figurally dissimilar. In the current investigation with 16 observers, illusion magnitude was greater for a figurally similar configuration even though the context elements of the figurally similar configuration were perceived as smaller than the context elements of a figurally dissimilar configuration. Hence, figural similarity appears to have a prepotent effect in the Ebbinghaus illusion.

Is the Benussi Effect a Kinetic Depth Effect

Rapid, successive presentations of an eccentric circle pattern and its mirror-image elicited apparent depth and, as has been previously demonstrated for the Benussi effect, there was an increase in apparent depth with an increase in circle eccentricity. Taken together, these data were interpreted as contravening Wallach, Adams, and Weiszs account of the Benussi effect as an instance of the kinetic depth effect.

MOTION PARALLAX, RELATIVE SIZE, AND BENUSSI EFFECT '

Many observers perceive depth when a configuration of nonconcentric circles is rotated on a disc. While it has been suggested by a number of investigators that motion parallax has a role in generating this phenomenon, the supporting data are equivocal. The current study proposed that the ambiguity regarding the role of motion parallax may have arisen because there are contradictions between relative size cues and motion parallax cues in the configuration of rotating circles. However, with 17 undergraduate observers, apparent depth was no more reliably reported with consistent cues of motion parallax and relative size than when these cues were contradictory.

The Benussi Effect with Rectangles

The perceived depth of the Benussi effect is usually demonstrated by presenting a configuration of nonconcentric circles on a rotating disc. However, in the current investigation with 21 undergraduates the Benussi effect was elicited by presenting an eccentric configuration of rectangles. Depth was reported when the configuration of eccentric rectangles was alternated rapidly and successively with its mirror image. As is characteristic of the Benussi effect, there was an increase in apparent depth with an increase in the eccentricity of the rectangles.

A Size Illusion from Simultaneous Changes in Length and Direction of a Line Pattern

A circle was attached to one of three lines which were changing in length and direction simultaneously. This configuration of moving lines had been found previously to induce the perception of depth. Of 26 observers 20 reported that the moving circle appeared smaller in size than a physically equal stationary circle which was located outside the changing, depth-inducing configuration.

ATTENUATING NECKER CUBE DEPTH REVERSALS

Rapid, apparent, to-and-fro (tight-left) rotation of the Necker cube sharply reduced reversals in depth for 10 undergraduates. This finding was considered consistent with the satiation theory of Necker cube reversals.

Benussi Effect as an Integration of Disparity by Motion

It was hypothesized that the apparent depth of the Benussi effect could be elicited using stimuli corresponding to retinally disparate images. When such stimuli were presented rapidly and successively in a manner approximating apparent motion, 21 of 22 observers reported apparent depth.

APPARENT DEPTH THRESHOLD FOR THE BENUSSI EFFECT

Using the single staircase psychophysical method, the apparent depth threshold for the Benussi effect was determined for 5 observers. The threshold occurred at an eccentricity of 2r/3, where r equals the radius of the larger circle expressed in millimeters.

Learning from Prose in Grade School Children: Similarity Versus Identity of Context Clue

Summary The purpose of the present investigation was to examine specific transfer of learning effects as a function of context clue similarity from study to test lists. Two treatments were used. In treatment I, the clues on the study and test lists were identical. On treatment II, the clues on the study list were similar to those on the test list. Sixty boys and girls (20 each from the second, fourth, and sixth grades) were randomly assigned to the treatment conditions and were administered four trials of the task. Results showed that the sixth graders outperformed the second graders (p < .001), but no other between groups differences were found. Although no treatment effects were found for the second grade, the clue identical treatment was superior to the clue similar condition for the fourth and sixth graders. The predicted differences in transfer of learning from study to test lists as a function of degree of context clue similarity between lists was not supported by the results of the present investig...