Terrestrial passage theory of the moon illusion.

Reviews theories of the celestial, or moon, illusion and asserts that they have neglected geometric characteristics of movement along and above the surface of the earth. It is suggested that the illusion occurs because the characteristics of terrestrial passage are attributed to celestial passage. In terrestrial passage, the visual angle subtended by an object changes discriminably as an essentially invariant function of elevation above the horizon. In celestial passage, by contrast, change in visual angle is indiscriminable at all elevations. If a terrestrial object gains altitude, its angular subtense fails to follow the expansion projected for an orbital course: Angular diminution or constancy is equivalent to distancing. On the basis of terrestrial projections, a similar failure of celestial objects in successive elevations is also equivalent to distancing. It is argued that the illusion occurs because of retinal image constancy, not—as traditionally stated—despite it. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A simple but powerful theory of the moon illusion.

Modification of F. Restle's (1970) theory explains the moon illusion and related phenomena on the basis of three principles: (1) The apparent sizes of objects are their perceived visual angles. (2) The apparent size of the moon is determined by the ratio of the angular extent of the moon relative to the extents subtended by objects composing the surrounding context, such as the sky and things on the ground. (3) The visual extents subtended by common objects of a constant physical size decrease systematically with increasing distance from the observer. Further development of this theory requires specification of both the components of the surrounding context and their relative importance in determining the apparent size and distance of the moon. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The cyclopean (stereoscopic) barber pole illusion

Across two experiments, this study found that the barber pole illusion (i.e. grating pattern appearing to move in the direction of the long axis of a rectangular aperture) is perceived with stereoscopic (cyclopean) motion. The grating and aperture comprising the barber pole display were created from binocular disparity differences embedded in a dynamic random-dot stereogram or from luminance differences. In Experiment 1, observers viewed a square-wave grating moving through a rectangular aperture of 2:1 or 4:1 aspect ratio and indicated whether the grating appeared to move in a direction perpendicular to its orientation or in the direction of the long axis of the aperture. For both stereoscopic and luminance stimuli equally, the grating appeared to move in the direction of the aperture (i.e. the barber pole illusion) more often with the larger aspect ratio than with the smaller aspect ratio. The condition for which a stereoscopic grating moved through a luminance rectangular aperture was also examined: the grating appeared to move in the direction of the aperture (inter-attribute barber pole illusion). In Experiment 2, observers viewed a square-wave grating moving through a rectangular aperture of 3:1 aspect ratio whose sides were indented in order to change the local direction of motion of the line terminators. For both stereoscopic and luminance stimuli, the grating appeared to move more frequently in a direction perpendicular to its orientation with the indented aperture (i.e. the illusion was diminished). Thus, local velocity signals from moving stereoscopic line terminators play a role in the production of the barber pole illusion similar to that of luminance motion signals. This suggests that the generation and propagation of motion signals at cyclopean levels of vision play a part in the representation of coherently-moving rigid surfaces.     

The tactile continuity illusion.

We can perceive the continuity of an object or event by integrating spatially/temporally discrete sensory inputs. The mechanism underlying this perception of continuity has intrigued many researchers and has been well documented in both the visual and auditory modalities. The present study shows for the first time to our knowledge that an illusion of continuity also occurs with vibrotactile stimulation. We found that when the brief temporal gaps inserted into a vibrotactile target were filled with vibrotactile noise, the target vibration was perceived to continue through the noise if the target vibration was sufficiently weak relative to the noise. It is important that the illusory continuity of the vibration cannot be distinguished from the physically continuous vibration. These results therefore suggest that the continuity illusion is common to multiple sensory modalities and that it reflects a fundamental principle of perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hallucinantion and illusion (author''s transl)

The value of an anaesthetic attachment during the first two postgraduate years is considered under three major headings, the value to the recent graduate, the value to the specialty, and the value to the community. The anaesthetic attachment offers all recent graduates an opportunity to perfect practical skills which should from part of the armamentarium of all doctors, and for some there is the option to acquire the ability to administer a safe anaesthetic. Exposure to the specialty at this time is important for recruitment to the specialist ranks.     

Lunacy and the moon.

Reviews empirical literature concerning the belief in a relationship between phases of the moon and human behavior. Studies are examined relating lunar phase to psychiatric hospital admissions, suicides, and homicides. It is concluded that lunar phase is not related to human behavior and that the few positive findings are examples of a Type I error. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The illusion of external agency.

People typically underestimate their capacity to generate satisfaction with future outcomes. When people experience such self-generated satisfaction, they may mistakenly conclude that it was caused by an influential, insightful, and benevolent external agent. In three laboratory experiments, participants who were allowed to generate satisfaction with their outcomes were especially likely to conclude that an external agent had subliminally influenced their choice of partners (Study 1), had insight into their musical preferences (Study 2), and had benevolent intentions when giving them a stuffed animal (Study 3). These results suggest that belief in omniscient, omnipotent, and benevolent external agents, such as God, may derive in part from people's failure to recognize that they have generated their own satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of the false-memory illusion.

The counterintuitive developmental trend in the Deese-Roediger-McDermott (DRM) illusion (that false-memory responses increase with age) was investigated in learning-disabled and nondisabled children from the 6- to 14-year-old age range. Fuzzy-trace theory predicts that because there are qualitative differences in how younger versus older children and disabled versus nondisabled children connect meaning information across the words on DRM lists, certain key effects that are observed in adult studies will be absent in young children and in learning-disabled children. Data on 6 such adult effects (list strength, recall inflation, delayed inflation, delayed stability, thematic intrusion, and true-false dissociation) were used to investigate this hypothesis, and the resulting data were consistent with prediction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

False memory and the discrepancy-attribution hypothesis: The prototype-familiarity illusion.

According to the discrepancy-attribution hypothesis (B. W. A. Whittlesea & L. D. Williams, 1998), people experience a feeling of familiarity when they perceive their processing to be surprising, but for an indefinite reason. This hypothesis has been successful in explaining several illusions of familiarity. Here, it is applied to the prototype-familiarity effect, an illusion of remembering that occurs when people are shown prototype words after studying lists of associates. The experiments showed that studying associates enhances semantic, but not perceptual, processing of prototypes. They also showed that claims of recognizing prototypes can be modified by presenting them in predictive or incongruous contexts at test. The evidence suggests that the effect results from an evaluation process that monitors the coherence of processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of grouping abilities in humans (Homo sapiens) and baboons (Papio papio) with the Ebbinghaus illusion.

This research comparatively assessed grouping mechanisms of humans (n = 8) and baboons (n = 8) in an illusory task that employs configurations of target and surrounding circles arranged to induce the Ebbinghaus (Titchener) illusion. Analyses of response behaviors and points of subjective equality demonstrated that only humans misjudged the central target size under the influence of the Ebbinghaus illusion, whereas baboons expressed a more veridical perception of target sizes. It is argued that humans adopted a global mode of stimulus processing of the illusory figure in our task that has favored the illusion. By contrast, a strong local mode of stimulus processing with attention restricted to the target must have prevented illusory effects in baboons. These findings suggest that monkeys and humans have evolved modes of object recognition that do not similarly rely on the same gestalt principles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Object constancy: The illusion of being seen.

Recent theoretical advances in the concept of object constancy have placed it in the context of the child's establishing a separate identity. Although these advances were partly the result of examining the child's growing abilities to evoke a mental image of the absent mother, constancy cannot be well understood as a type of mental representation. It more resembles an illusion, specifically the illusion that the mother is constantly available in her mirroring function. The child's sense of his or her own reality is born in the mother's affectively attuned mirroring, as nothing about the child is real for the child until first seen by the mother. The illusion of the constant object allows the child to construct a sense of his or her own separate reality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional processing and the subjective contour illusion.

To distinguish between bottom–up and top–down (TD) accounts of subjective contour (SC) perception, the present investigation used a dual-task paradigm to test the relative attentional demands of real SC perception. In the primary task, 16 undergraduates made speeded same–different discriminations of either paired SC forms or their real contour analogs. Half the Ss performed this primary task in conjunction with a 6-digit short-term memory load secondary task. If subjective forms impose a greater limited-capacity processing load than real forms, then the need to share processing capacity with a secondary task was expected to produce a greater increment in RT for subjective relative to real forms. Results indicate that the expected enhanced RT increment for subjective relative to real forms with the addition of a concurrent memory load was limited to same trials. This result implies that the nature of response indicators must be considered in assessing capacity requirements with the sort of dual-task paradigm used in the present investigation. Nevertheless, the fact that the increment in same RT with the addition of a concurrent memory load was greater for subjective relative to real forms accords with expectations derived from the notion that the perception of SCs is more attention-demanding than that of real contours. A comprehensive theory of SC perception will most likely be formulated within the TD perspective of conceptually driven visual information processing. (90 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of vision in the on-line correction of illusion effects on action.

Investigated the role of visual information during reaching by comparing conditions in which visual information was either available or unavailable during the movement. In this study, 24 participants reached out and picked up a bar placed on a background grating that induced an illusion in the perceived orientation of the bar. The illusion had a large effect on the orientation of the hand early in the reaches, but this effect decreased continuously as the hand approached the target. This pattern occurred whether or not participants were allowed vision of the hand and target while reaching. These results are consistent with a "planning/control" model of action, in which actions are planned using a context-dependent visual representation but monitored and corrected on-line using a context-independent visual representation. The hypothesized neural bases of these representations are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Depth cues and constancy scaling in the horizontal-vertical illusion: The bisection error.

Analysis of the horizontal-vertical illusion in terms of possible depth cues allows the prediction of a bisection illusion in which the length of the lower portion of the vertical is underestimated relative to the length of the upper segment. Significant variations in illusion magnitude as a function of line length and angle of inclination indicates that height in the plane is the depth cue which is evoking inappropriate size constancy scaling. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Induced mood and the illusion of control.

Examined the directionality of the relationship between realism in judging personal control and depression. Depressed and elated mood states were induced transiently in 40 naturally nondepressed and 40 depressed females (Beck Depression Inventory and the Multiple Affect Adjective Check List), and the impact of these transient mood states on susceptibility to the illusion of control was assessed. Naturally nondepressed Ss gave accurate judgments of control while naturally depressed Ss showed an illusion of control and overestimated their impact on an objectively uncontrollable outcome. Mood induction groups showed predicted changes in self-reported affect and a behavioral measure of depression. These results are in contrast to those of L. B. Alloy and L. Y. Abramson (1979). An implication of the present findings may be that therapeutic interventions for depression that successfully remediate depressive symptoms may also increase depressed individuals' susceptibility to the illusion of control. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuroticism and the illusion of mental health.

Comments on the argument by J. Schedler et al (see record 1994-09623-001) that standard mental health scales appear unable to distinguish between genuine mental health and the illusion of mental health created by psychological defenses. It is asserted that Schedler et al misstate the psychometric position and fail to demonstrate the superiority of clinical judgment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Internal clock processes and the filled-duration illusion.

In 3 experiments, the authors compared duration judgments of filled stimuli (tones) with unfilled ones (intervals defined by clicks or gaps in tones). Temporal generalization procedures (Experiment 1) and verbal estimation procedures (Experiments 2 and 3) all showed that subjective durations of the tones were considerably longer than those of unfilled intervals defined either by clicks or gaps, with the unfilled intervals being judged as approximately 55%-65% of the duration of the filled ones when real duration was the same. Analyses derived from the pacemaker-switch-accumulator clock model incorporated into scalar timing theory suggested that the filled/unfilled difference in mean estimates was due to higher pacemaker speed in the former case, although conclusively ruling out alternative interpretations in terms of attention remains difficult. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Constraints on the processing of rolling motion: The curtate cycloid illusion.

When a wheel rolls along a flat surface, a point on its perimeter traces a cycloid trajectory, forming a sequence of adjacent semicircle-like scallops. However, when mentally visualizing this point's trajectory, participants erroneously describe the point's path as looping back on itself between each scallop or phase of the cycloid, a phenomenon called the curtate cycloid illusion. The studies supported the hypothesis that the curtate cycloid illusion occurs because the cognitive system sometimes does not have sufficient resources for simultaneously processing 2 components of the motion: its translation and its rotation about its current instant center. Four experiments using computer-animated rolling wheels found that participants who were high in spatial ability were less susceptible to the curtate cycloid illusion than were low-spatial participants, that high-spatial participants were not susceptible to the illusion if they could control the animated wheel display, and that the illusion was substantially decreased if the opportunity to compute instant centers was reduced. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Duration illusion and auditory grouping in infancy.

Extended previous research on perceptual grouping in infancy (Thorpe, Trehub, Morrongiello, & Bull, 1988). Infants' detection of temporal increments to silent intervals between groups of tones was compared with their detection of comparable silent increments within groups of tones. Ss were presented with standard 6-tone sequences, with the first 3 tones differing from the last 3 in harmonic structure, frequency, or intensity, and contrasting sequences with increments of 80 or 100 ms to the silent interval between the 3rd and 4th tone (XXX OOO, between groups) or between the 4th and 5th tone (XXXO OO, within group). Infants discriminated temporally altered sequences from the standard only when the increments occurred within a group. The authors conclude that perceptual grouping processes are operative in infancy and that infants perceive the silent increments between groups of sounds as longer than identical intervals within a group, as do adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)