Dynamic illusion effects in a reaching task: Evidence for separate visual representations in the planning and control of reaching.

The effects of an orientation illusion on perception and 2 different actions were investigated. An 8-cm?×?2-cm cylindrical bar was placed in front of participants at various orientations. A background grating was used to induce an orientation illusion. In a perception task, the illusion affected participants' ability to align the bar with their sagittal planes. In one reaching task, a similar effect of the illusion was found on the choice between 2 possible grasping postures. In a second reaching task involving a single grasping posture, the orientation illusion affected the orientation of the hand at the beginning of the reach but not near its end. The authors argue that reaching trajectories are planned and initiated through a context-dependent representation but are corrected on-line through a context-independent representation. The relation of this model to a more general dichotomy between perception and action is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assimilation theory and the Ponzo illusion: Quantitative predictions.

[Correction Notice: An erratum for this article was reported in Vol 26(2) of Canadian Journal of Psychology Revue Canadienne de Psychologie (see record 2007-04524-001). A corrected formula is provided.] Predicted that the ponzo illusion would increase, and then decrease as angle of the oblique arms increased, on the basis of assimilation theory. A reversed illusion was predicted when the angle was very obtuse. 4 orientations of the ponzo illusion were employed. In these the apex pointed to the top, bottom, left, and right. A different orientation was used on each of 4 sessions separated by a minimum of 1 day. The order was randomized for each of 9 men and 6 women ss. Both predictions were verified. Data suggest a change in the attentive field postulate of assimilation theory, and a general formula was derived to obtain a numerical estimate of illusion. (french summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

L'influence d'indices subliminaux perceptifs et symboliques sur la formation d'un concept.

Examined the learning of a simple concept represented by geometric figures as a function of subliminal stimuli of either a perceptual or a symbolic nature. Ss were 75 male students. Preceding each instance of a concept, a subliminal stimulus, indicating either the correct or incorrect solution, was presented by the technique of backward masking. Results show that only symbolic subliminal stimuli were effective in influencing the learning of a concept, and this particularly in the case where the correct solution was indicated. It is concluded that the effect of a subliminal stimulus depends on the degree of correspondence between the level of complexity of the stimulus and that of the task. (23 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sensibilité et diagnosticité de la mesure de la charge mentale par la tache secondaire de frappe cadencée.

Studied the sensitivity of finger tapping performance as a measure of the mental workload produced by a concurrent memory task. Ss were 8 normal male and female adults (aged 22–39 yrs). Over 4 experimental sessions, Ss were asked to complete 240 series of 13 finger taps at a rate of 1 tap every 2 sec. The concurrent primary task required Ss to search for a target item (presented after each tap) in a 3-digit set memorized before each series of taps. Processing load was varied by including letter targets among positive and negative digit targets. Intertap intervals for letter targets, positive digit targets, and negative digit targets were compared. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Assimilation Theory and the Ponzo Illusion: Quantitative Predictions": Erratum.

Reports an error in "Assimilation theory and the Ponzo illusion: Quantitative predictions" by A. W. Pressey, N. Butchard and L. Scrivner (Canadian Journal of Psychology Revue Canadienne de Psychologie, 1971[Dec], Vol 25[6], 486-497). A corrected formula is provided. (The following abstract of the original article appeared in record 1972-10045-001.) Predicted that the ponzo illusion would increase, and then decrease as angle of the oblique arms increased, on the basis of assimilation theory. A reversed illusion was predicted when the angle was very obtuse. 4 orientations of the ponzo illusion were employed. In these the apex pointed to the top, bottom, left, and right. A different orientation was used on each of 4 sessions separated by a minimum of 1 day. The order was randomized for each of 9 men and 6 women ss. Both predictions were verified. Data suggest a change in the attentive field postulate of assimilation theory, and a general formula was derived to obtain a numerical estimate of illusion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Type A behavior pattern and the judgment of noncontingency: Mediating roles of mood and perspective.

Tested past research findings that Type A's (coronary-prone) and Type B's (non-coronary-prone) differ in their behavioral responses to lack of control. 73 undergraduates, classified as Type A or B on the Jenkins Activity Survey, were used to examine perceptual judgments of noncontingency. Types A's and B's assumed the role of either an actor or an observer on a standard contingency-judgment task. Consistent with previous research, both Type A's and B's exhibited an illusion of control when in the role of actor. Only Type B's exhibited an illusion of control when observing another person perform the task. Additional analyses indicated that the absence of an illusion of control by Type A observers reflected accuracy rather than a motivational distortion. Mood was also found to mediate control judgments, but only for actors. The plausibility of a memory-based interpretation for the mood effects is discussed. (44 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concept comparisons, essay examinations, and conceptual knowledge.

Investigated the concept comparison task as a means of assessing knowledge of concept interrelationships. The task involves making a comparative judgment in the form of a rating on each pair of a set of concept labels. In the present study, the judgment involved the strength of relationship between members of pairs of concepts. The relationship between performance on the concept comparison task and essay test performance was examined. Exp I, with 64 undergraduates, considered the relationship between 3 types of essay questions (definition, application, and comparison) and measures derived from the concept comparison task. Materials used for the concept comparison task and essay tests were taken from the perception component of an introductory psychology course. A canonical correlation analysis indicated a fairly strong relationship between essay performance and performance on the concept comparison task. Regression analysis was used to investigate specific aspects of the relationship. Exp II used 67 different Ss and a different set of concepts (memory). It is concluded that the concept comparison task does assess conceptual knowledge in a nontrivial way. (19 ref) (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)     

A motion illusion from two-dimensional periodic patterns

The spatial properties of a motion illusion (the Ouchi illusion) that occurs in a stationary pattern were examined by means of a variety of two-dimensional periodic patterns (formed by multiplying pairs of various one-dimensional periodic functions). In two experiments, observers rated the magnitude of the illusion. The results showed that (1) patterns having large energy and steep saddle-shaped contrast gradients tended to generate stronger illusions, (2) the composite pattern made up of the sum of the fundamental and harmonic components exhibited a stronger illusion than either the fundamental or the harmonic pattern, (3) patterns possessing an element orientation and phase shift similar to those of a rectangular checkerboard, and with element sizes of 15-50 min in width and 4-8 min in height yielded a larger illusion, (4) equiluminant colors largely abolished the effect, and (5) blurring the boundary between the test and surround did not reduce the illusion. Interactions between spatially overlapping ON and OFF units was discussed as a possible underlying cause of this phenomenon.     

Apprentissage de la notion de nombre par une méthode fondée sur le modèle piagétien de la fusion des classes et des relations.

Constructed a series of "operational exercises" to train children on the concept of number. In an experiment with a total of 20 6-7 yr olds, classified as preoperational by a pretest that included 2 experiments on number, the series was given to 3 groups. In accordance with Piaget's theoretical model on the construction of number, the exercises were based on the generalization of class similarities (Group 1), the generalization of relational differences (Group 2), or on both alternately (Group 3). To measure the effect of the learning exercises, the 2 number experiments were readministered in 2 successive posttests with a 1-mo interval. It was found that (a) the performance of all 3 experimental groups was significantly higher than that of the control group; (b) the 2 groups that received only 1 type of exercise (just class or relation) did not differ from each other; and (c) the group subjected to the 2 kinds of exercises was significantly better on the 2nd posttest, although the same as the previous 2 groups on the 1st posttest. The discussion of results focuses on the differential progress of each group and on the child's construction of number. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Islands of health: Implications of academic psychology for psychotherapy technique and integration.

Recent research in academic psychology, particularly in areas pertaining to healthy illusion, has significant relevance to integrative psychotherapy, on both a technical and a conceptual level. The concept of healthy illusion can help us conceptually integrate--find common threads between--apparently disparate schools of psychotherapy. The cognitive-behavioral techniques of collaborative empiricism, manageable goal setting, and changes in self-talk; many of the dialectical-behavioral techniques used to balance acceptance and change, and to embrace paradox; the psychoanalytic concepts, and related techniques, of sublimation, self-object, internalization, transitional phenomena, and idealization have important links to the nourishing of positive illusion in therapy. The concept of healthy illusion also lends us some new integrative techniques, such as searching out, broadening, and even creating idealized figures and internalized objects, aside from the therapist. This research, in fact, challenges some of our most fixed and favorite beliefs about the process of therapy--particularly about the paramount importance of facing and accepting reality. Finally, the positive illusion research sheds some light on the difficulties of defining psychological health, hope, and resiliency. (PsycINFO Database Record (c) 2011 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)     

Geometrical illusions can affect time-to-contact estimation and mimed prehension.

Results indicate that under some conditions the Sander parallelogram illusion can affect time-to-contact (TTC) estimation in a prediction-motion (PM) task and in an interceptive action (IA). The illusion also affected mimed manual prehension. The implication is that the timing of responses in the PM and IA tasks may involve an estimate of TTC that is based on the perceived dimensions of the environment. Further research is warranted in the development of models of perceived collision and of visually guided actions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Understanding perceptual processes: Responses to a weight-illusion task.

In two studies, children and adults were presented with a weight illusion based on perceptual adaptation or contrast effects, in which one of two containers of equal weights felt heavier than the other. Of major concern were developmental trends in the extent to which Ss erroneously maintained that the perceived difference represented a real difference, versus one in appearance, and the extent to which cues alerting Ss to past adaptationlike experiences would affect their understanding of the illusion. Results showed improved performance, with increases in age and the effectiveness of cuing about previous adaptation experiences, but only after the task was altered to highlight the relevance of the condition that produced the illusion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Illusory tilt and Euclidean schemes as factors in performance on the water-level task.

Predictions made by models of water-level acquisition were tested to understand better the sensory factors, cognitive factors, or both, that differentiate people who fail the test (low scorers) from people who pass (high scorers). Experiments 1 and 2 showed that in a horizontal-edge detection task, low scorers were less likely than high scorers to "see" liquid edges in tilted containers as horizontal. Experiment 3 showed that water-level type displays belong to a class of tilt illusions that arise from early visual processes for both low and high scorers, but only high scorers spontaneously use cognitive schemes to minimize illusory tilt. In Experiment 4, high scorers, but not low scorers, overrode the orientation illusion in a production task. The findings suggest bottom-up processes cause embedded lines to be misperceived for both groups, but high scorers are more likely to use cognitive schemes spontaneously to overcome the orientation illusion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of an abstract order schema in conceptual judgment.

Ss performed same-different judgments for which order information was logically irrelevant. In Exps 1 and 2, the stimuli for the judgment task were derived from an ordered set of concepts from long-term memory (US presidents ordered on the dimension of historical time); in Exps 3 and 4 the stimuli were derived from 2 ordered sets of concepts. In the stimulus set for each experiment, there were several associate phrases for each concept and the task was to judge whether the phrases were paired with the same concept (Exps 1, 2, and 3) or the same ordering (Exp 4). The time to respond "different" decreased with the ordinal distance between the concepts even when the concepts belonged to different orderings. It is concluded that same-different judgments are based in part on amodal order information (i.e., not tied to any particular dimension). Two models of the implicated order schema are proposed and tested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual and decisional factors influencing the discrimination of inversion in the Thatcher illusion.

The Thatcher illusion (Thompson, 1980) is considered to be a prototypical illustration of the notion that face perception is dependent on configural processes and representations. We explored this idea by examining the relative contributions of perceptual and decisional processes to the ability of observers to identify the orientation of two classes of forms—faces and churches—and a set of their component features. Observers were presented with upright and inverted images of faces and churches in which the components (eyes, mouth, windows, doors) were presented either upright or inverted. Observers first rated the subjective grotesqueness of all of the images and then performed a complete identification task in which they had to identify the orientation of the overall form and the orientation of each of the interior features. Grotesqueness ratings for both classes of image showed the standard modulation of rated grotesqueness as a function of orientation. The complete identification results revealed violations of both perceptual and decisional separability but failed to reveal any violations of within-stimulus (perceptual) independence. In addition, exploration of a simple bivariate Gaussian signal detection model of the relationship between identification performance and judged grotesqueness suggests that within-stimulus violations of perceptual independence on their own are insufficient for producing the illusion. This lack of evidence for within-stimulus configurality suggests the need for a critical reevaluation of the role of configural processing in the Thatcher illusion. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Perception without attention: Evidence of grouping under conditions of inattention.

Many theories of visual perception assume that before attention is allocated within a scene, visual information is parsed according to the Gestalt principles of organization. This assumption has been challenged by experiments in which participants were unable to identify what Gestalt grouping patterns had occurred in the background of primary-task displays (A. Mack, B. Tang, R. Tuma, S. Kahn, & I. Rock, 1992). In the present study, participants reported which of 2 horizontal lines was longer. Dots in the background, if grouped, formed displays similar to the Ponzo illusion (Experiments 1 and 2) or the Müller-Lyer illusion (Experiment 3). Despite inaccurate reports of what the patterns were, participants' responses on the line-length discrimination task were clearly affected by the 2 illusions. These results suggest that Gestalt grouping does occur without attention but that the patterns thus formed may not be encoded in memory without attention. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Le développement de la notion de vitesse relative.

Administered a modified version of a Piagetian test on the concept of relative velocity (including questions on the duration of relative displacements) to 96 children placed in age groups of 7, 9, 11, and 13 yr. It was found that (a) the developmental stages of the concept were comparable to those observed by Piaget except for formal operations which seem to evolve later; (b) the combination of 2 movements of same direction but unequal velocity is more difficult to synthesize than any other; (c) success on the problem of durations is not a prerequisite of at least partial success on the problem of velocities; and (d) complete success on the problem of velocities is not necessarily verbalized in spatio-temporal terms. To explain the difficulty observed in synthesizing velocities, the importance of the instructions (e.g., specifying the speed of each mobile) and of changes in the spatial order of the mobiles was emphasized. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A jittered squares illusion and a proposed mechanism

A new visual illusion is reported in which randomly positioned squares that are perfectly aligned with the horizontal and vertical appear slightly rotated about their midpoints ('jittered') relative to each other. Possible mechanisms for the illusion have been explored in a series of three experiments. Experiment 1 showed that, unlike the Münsterberg illusion, the Jittered Squares illusion persists at isoluminance. Experiment 2 indicated that the degree of rotation from vertical and horizontal, of rows and columns of squares in which the edges of individual squares remain perfectly aligned with vertical and horizontal, changes the perceived strength of the illusion such that the strongest effect is found at rotations of +/- 10 degrees to +/- 15 degrees. Experiment 3 revealed that the illusion is dependent upon the spatial extent of the gaps between the squares, such that it becomes weaker as the separation increases. On the basis of the findings it is suggested that the jittering results from the extraction of obliquely oriented contours by an integrator mechanism when the difference in orientation, between the edges of the individual squares and the global orientation of a contour made up of a number of edges of individual squares, is not too dissimilar. It is proposed that a mechanism such as simultaneous orientation contrast between these global contours and the vertical and horizontal edges of the individual squares causes the squares to appear rotated away from the orientation of the extracted contours, leading to the perceived jittering.