Necker cube and autokinetic illusions after awakening from REM and NONREM sleep: lack of effect.

Earlier studies demonstrated differential perceptions of the visual illusions, beta movements and spiral aftereffect, following awakening from REM and NONREM sleep. The present study tested the effects of awakening from the two phases of sleep on two additional visual illusions, the Necker cube and autokinetic illusions. 12 young adults were wakened from REM and NONREM sleep and tested on both illusions for three 1-min. trials, within 1 to 2 min. of the awakening. Comparison of the post-REM and post-NONREM illusions indicated a nonsignificant difference between the two waking conditions in the passive spontaneous reversal rates of the Necker cube. Data for the autokinetic illusion were not reported as they were unreliable.     

Geometrical haptic illusions revisited: Haptic illusions compared with visual illusions

Révész (1934) reported that haptic illusions were observed in almost all of the geometrical optical illusion figures. The present study reexamined seven geometrical illusions in both haptic and visual modes. In the Müller-Lyer, Ponzo, and vertical-horizontal figures, haptic illusions equivalent to the visual illusions were observed. In the Oppel-Kundt figure, a haptic illusion similar to the visual one was obtained. In the haptic Delboeuf stimuli, the size illusion of the outer circle occurred, whereas that of the inner circle did not. No haptic illusion was obtained in the Poggendorff figure. In the Zöllner figure, a haptic illusion directionally opposite to the visual one was obtained. These results show that haptic illusions do not occur in all of the geometrical illusion figures. They also suggest that haptic illusions are not necessarily mediated by visualization and that haptic processing of the figures often occurs in a manner different from vision.     

Configurational coincidence among six phenomena: a comment on van Lier and Csathó (2006)

This study focuses on a configurational coincidence among six different illusions, two being motion illusions (reversed phi movement and phi movement), two being binocular stereo effects (Anstis-Rogers type and Gregory-Heard type), one being a position illusion (Gregory-Heard illusion), and one being an orientation illusion (Café-Wall-like tilt illusion). The stimuli of these six illusions or effects share the same configuration, in which a thin region is flanked by thick regions of different luminances. A phenomenological comparison is conducted with the use of dynamic demonstrations as well as static ones. In particular, the reversed phi movement is extensively discussed.     

Geometrical haptic illusions revisited: haptic illusions compared with visual illusions.

Révész (1934) reported that haptic illusions were observed in almost all of the geometrical optical illusion figures. The present study reexamined seven geometrical illusions in both haptic and visual modes. In the Müller-Lyer, Ponzo, and vertical-horizontal figures, haptic illusions equivalent to the visual illusions were observed. In the Oppel-Kundt figure, a haptic illusion similar to the visual one was obtained. In the haptic Delboeuf stimuli, the size illusion of the outer circle occurred, whereas that of the inner circle did not. No haptic illusion was obtained in the Poggendorff figure. In the Z?llner figure, a haptic illusion directionally opposite to the visual one was obtained. These results show that haptic illusions do not occur in all of the geometrical illusion figures. They also suggest that haptic illusions are not necessarily mediated by visualization and that haptic processing of the figures often occurs in a manner different from vision.     

Illusion reversal rate as a function of subjective depth

Undergraduate students (N = 48) served as subjects in a test of Gregory's theory of illusions. Twenty-four students made judgments about the subjective depth of three reversible illusions--Necker cube, Book, and Pyramid--under the conditions of complete versus incomplete illusions and illusions without depth cues versus with depth cues. An additional 24 subjects recorded the three illusion reversal rates under slightly altered conditions. Differences were found among the various illusions with respect to complete versus incomplete illusions, reversal rate, subjective judgments of depth, and certain correlation values. Support for Gregory's theory of illusion as displaced or misleading depth perception is offered by these results.     

Visual illusions affect planning but not control

Much debate has arisen over how to account for the pattern of effects of visual illusions on action - that is, the findings that illusions affect actions in some circumstances but not others. I propose that this pattern can best be explained by postulating that visual illusions affect the planning of actions but do not affect the on-line control of actions. Strong evidence for this viewpoint comes from recent studies that show 'dynamic illusion effects': a large illusion effect early in a movement, but a decreasing effect as the hand approaches the target. These findings pose difficulties for other models of illusion effects on action.     

Assimilation and contrast illusions: Differences in plasticity

Three experiments show differences in the plasticity of the contrast and assimilation portions of the Delboeuf, Ebbinghaus, and Ponzo illusions. Contrast illusions show decrement in illusion magnitude with free inspection, whereas assimilation illusions do not. A model to explain both the original distortion and the differential susceptibility of the two classes of illusion to decrement is offered.     

Further studies of the Café Wall and Hollow Squares illusions

The effect of varying the contrast on the apparent convergence is measured for both the Café Wall and the Hollow Squares (Taylor-Woodhouse) illusions. The apparent convergence is dependent on the contrast, and also on the size of the stimulus, and varies in the same way for both illusions. This strengthens the argument that the illusions are not independent, as Taylor and Woodhouse originally claimed. McCourt has discussed brightness induction as a basis of the Café Wall illusion. Consideration of this theory leads to some interesting examples of interactions of the two illusions, and to a further, very strong, variation of the illusion in a real-life situation.     

Perception: A HyperCard stack for demonstrating visual perceptual phenomena

Perception is a HyperCard stack that allows users to explore visual illusions and other perceptual phenomena on the Apple Macintosh. The stack contains over 20 demonstrations of intersecting line illusions, size and shape illusions, subjective contours, color assimilation, and so forth. As a presentation tool for classroom or laboratory demonstrations, Perception offers three unique features for displaying visual phenomena: (1) the capability to “dissolve” the inducing elements of an illusion in order to show the objective state of affairs, (2) the ability to quickly reverse the inducing elements of an illusion and therefore the effects of the distortion, and (3) animation of the various components of an illusion to produce continuous distortions in-real time. These features are illustrated with use of the Orbison, Titchener, Hering, and Wundt illusions. Use of the stack reveals two interesting and unanticipated findings: (1) an apparent size distortion in the central square of the Orbison illusion as it moves back and forth across the background of concentric rings, and (2) perceptual aftereffects that arise when the inducing elements of the Titchener, Hering, or Wundt illusion is dissolved.     

Halt and recovery of illusory motion perception from peripherally viewed static images

We quantitatively investigated the halt and recovery of illusory motion perception in static images. With steady fixation, participants viewed images causing four different motion illusions. The results showed that the time courses of the Fraser-Wilcox illusion and the modified Fraser-Wilcox illusion (i.e., "Rotating Snakes") were very similar, while the Ouchi and Enigma illusions showed quite a different trend. When participants viewed images causing the Fraser-Wilcox illusion and the modified Fraser-Wilcox illusion, they typically experienced disappearance of the illusory motion within several seconds. After a variable interstimulus interval (ISI), the images were presented again in the same retinal position. The magnitude of the illusory motion from the second image presentation increased as the ISI became longer. This suggests that the same adaptation process either directly causes or attenuates both the Fraser-Wilcox illusion and the modified Fraser-Wilcox illusion.     

Trading on illusions: Unrealistic perceptions of control and trading performance

This paper examines the impact of illusory control beliefs on the performance of traders in financial instruments. The authors argue that the task and environment faced by traders are conducive to the development of illusions of control and that individual propensity to illusion of control will be (inversely) related to trader performance. Using an innovative computer task, designed to assess illusion of control in the field, data from 107 traders in four organizations showed individual differences in this bias to have a significant, inverse, association with performance, as measured by managers' ratings of trader performance and by total remuneration. The authors conclude that, at least in this context, illusion of control is maladaptive and that it is productive to take an individual difference approach to the study of such illusions. Implications for debates about the costs and benefits of positive illusions are discussed.     

Visual-geometric illusions: unisex phenomena

The possibility of sex differences in responses to visual-geometric illusions was investigated with the use of forty-five illusion variants and a sample of 221 observers. No difference in illusion magnitude as a function of sex was found. A second experiment measured illusion decrement and transfer of decrement to other illusion configurations. Again there were no significant differences between male and female observers.     

The Mystery Spot Illusion and its Relation to Other Visual Illusions

Observations at The Mystery Spot, a roadside attraction near Santa Cruz, California, suggest intriguing visual illusions based on tilt-induced effects. Specifically, a tilted spatial background at The Mystery Spot induced misperceptions of the orientation of the cardinal axes (i.e., true horizontal and vertical), which then led to illusions in the perceived height of twoindividuals. This illusion was assessed at The Mystery Spot and replicated in the laboratory using pictorial and lined displays rotated in the picture plane. These findings are described in terms of the orientation framing theory, which suggests that these and other tilt-induced illusions (e.g., Ponzo illusion, Zöllner illusion) can be attributed to distorted frames of reference.     

Visual and haptic perception of the horizontal-vertical illusion

The horizontal-vertical illusion consists of two lines of the same length (one horizontal and the other vertical) at a 90 degree angle from one another forming either an inverted-T or an L-shape. The illusion occurs when the length of a vertical line is perceived as longer than the horizontal line even though they are the same physical length. The illusion has been shown both visually and haptically. The present purpose was to assess differences between the visual or haptic perception of the illusions and also whether differences occur between the inverted-T and the L-shape illusions. The current study showed a greater effect in the haptic perception of the horizontal-vertical illusion than in visual perception. There is also greater illusory susceptibility of the inverted-T than the L-shape.     

The type I/type II perceptual dichotomy: a reanalysis for the illusions of extent

The categorization of geometrical illusions of extent as Type I or Type II phenomena based on variation in magnitude with age is critically examined. Methodological shortcomings and the failure of contemporary findings to show matching age trends for components of a single illusion are presented as factors undermining the usefulness of this perceptual dichotomy. Finally, it is shown that a new Type I/Type II dichotomy based on changes in perceived size rather than amount of illusion indicates a developmental commonality among most of the illusions of extent.     

Ebbinghaus illusions: Size contrast or contour interaction phenomena?

Forty-eight graduate and undergraduate students between 17 and 30 years of age judged the size of the central circle in Ebbinghaus figures presented under either simultaneous or successive viewing conditions. Successive presentation eliminated the illusion produced by the normally overestimated figure and diminished that produced by the underestimated figure. Under simultaneous viewing conditions, increasing the number of surrounding circles reduced the magnitude of the reversed illusion produced by the normally overestimated figure but had no effect on the illusion produced by the underestimated figure. Under successive viewing conditions, increasing the number of surrounding circles had no effect on the magnitude of illusion produced by the normally overestimated figure but increased the illusion produced by the underestimated figure. These data were interpreted as inconsistent with a size contrast explanation of the Ebbinghaus illusions and suggested that these illusions may be produced by a contour interaction process.     

错觉研究:从狭义到广义的演进

心理学家对错觉现象的关注由来已久,以往的错觉研究大部分关注与知觉过程相联系的错觉。近十几年来,当代错觉研究呈现出新的热点,并从狭义向广义演进。这一研究对象扩展的基础,是错觉现象的本质特征,即认知过程的一致性偏差。广义错觉研究的对象涉及知觉、记忆、思维、推理等各种心理过程。     

The material-weight illusion revisited

Experiment 1 documents modality effects on the material-weight illusion for a low-mass object set (58.5 g). These modality effects indicate that the material-weight illusion is principally a haptically derived phenomenon: Haptically accessed material cues were both sufficient and necessary for full-strength illusions, whereas visually accessed material cues were only sufficient to generate moderate-strength illusions. In contrast, when a high-mass object set (357 g) was presented under the same modality conditions, no illusions were generated. The mass-dependent characteristic of this illusion is considered to be a consequence of differing grip forces. Experiment 2 demonstrates that the enforcement of a firm grip abolishes the low-mass material-weight illusion. Experiment 3 documents that a firm grip also diminishes perceptual differentiation of actual mass differences. Several possible explanations of the consequences of increasing grip force are considered.     

Vicario's illusion of sloping steps reexamined

If a few parallel horizontal rows of dots are set diagonally, like steps, across the visual field, the inner rows appear not to be horizontal but sloping up to one side; the effect holds as long as the vertical distances between the rows do not exceed a given visual angle. This illusion, described by Vicario in 1978, was never explained. An experiment is reported in which the illusion was still visible at row separations well in excess of the spatial limits originally considered, provided the stimulus elements were enlarged. The maximum illusion was obtained for length ratios (interrow distance to size of dots) identical to those which have been shown to produce the largest effects in a number of illusions of area and length. This suggests that Vicario's illusion is similar to other illusions of extent, and that it can be explained by a neural extent-coding model.     

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.