Section 1: Perception and action.

Introduces the first section of this issue of the Canadian Journal of Experimental Psychology. A question often on the minds of Cognitive Neuroscientists these days concerns the relation between perception and action. Those who are outside the field of perception may be excused for thinking that this must have always been so. This section begins with a paper by Flanagan, King, Wolpert, and Johansson examining the role of long-term memories in participants' adaptation to a size-weight illusion. The paper by Glover and Dixon examines the online control of action using a visual illusion in which the orientation of a background grating influences the perceived orientation of a foreground bar that must be grasped by the hand. The paper by Fecteau, Chua, Franks, and Enns is also concerned with the on-line control of action, but this time using a finger pointing task made popular by Goodale and colleagues. The final paper in this section by James, Humphrey, and Goodale comes full circle in that it examines how perception is influenced by action, rather than the other way around. If the four papers included in this section are at all representative of the state of Canadian research on Perception and Action, then the next few years will be interesting and productive ones indeed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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)     

Comparing effects of the horizontal-vertical illusion on grip scaling and judgment: Relative versus absolute, not perception versus action.

The discovery that the prehension component of an open-loop, two-fingered reach is largely immune to certain salient pictorial illusions has been used to suggest that humans possess 2 distinct visual systems, 1 that subserves perceptual judgment and 1 that mediates visually controlled action. In this article, the authors present evidence that suggests that the critical distinction is not that of reaching and judgment but of relative and absolute perception. Experiment 1 extends the findings of S. Aglioti, J. F. X. DeSouza, and M. A. Goodale (1995) and suggests that the manual prehension component of open-loop reaching is affected by the horizontal-vertical illusion to a much smaller degree than perceptual size judgments. In Experiments 2 and 3, however, when perceptual size judgment is directed at a single element of the display, this difference vanishes. Experiment 4 demonstrates that grip scaling is strongly affected by the illusion when a single reach is scaled to both the horizontal and vertical components of a triangular figure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Ponzo illusion affects grip-force but not grip-aperture scaling during prehension movements.

Contextual cues such as linear perspective and relative size can exert a powerful effect on the perception of objects. This fact is demonstrated by the illusory effects that can be induced by such cues (e.g., the Ponzo railway track and Titchener circles illusions). Several recent studies have reported, however, that visual illusions based on such cues have little or no influence on the visuomotor mechanisms used to guide hand action. Furthermore, evidence of this sort has been cited in support of a distinction between visual perception and the visual control of action. In the current study, the authors investigated the effect of the Ponzo visual illusion on the control of hand action, specifically, the scaling of grip force and grip aperture during prehension movements. The results demonstrate that grip force scaling is significantly influenced by the Ponzo visual illusion, whereas the scaling of grip aperture is unaffected by the illusion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychophysical Test for the Independence of Perception and Action.

Research has suggested that perception and action are independent (see M. A. Goodale & A. Haffenden, 1998). The authors used the Ebbinghaus illusion to test this hypothesis in 2 experiments. Verbal reports of perceived size were compared with maximum grip aperture during grasping (Experiment 1) and manual reports of perceived size (Experiment 2). A multidimensional signal detection analysis was used to distinguish among the possible interactions between the two processes in each experiment (H. Kadlec & J. T. Townsend, 1992a, 1992b). In Experiment 1, the percepts were independent, and there were no interactions between processes for verbal and visuomotor responses. In Experiment 2, the percepts associated with verbal and manual reports were independent, but the processes interacted at the levels of the stimulus information and the decision rules used to transform each percept into a response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The use of visuomotor cues as a strategy for making perceptual judgments in a patient with visual form agnosia.

Accumulating evidence from human neuropsychological studies and from electrophysiological and behavioral work in the monkey is consistent with a recent proposal by M. A. Goodale and A. D. Milner (see record 1992-22553-001) that visual perception of the world is mediated by a ventral stream of visual processing projecting from striate to inferotemporal cortex whereas the visual control of skilled actions is mediated by a dorsal stream of visual processing projecting from striate to posterior parietal cortex. Compelling support for this view comes from work with a patient with visual form agnosia (DF), who cannot reliably report the size, orientation, and shape of different objects, yet can use this information to make accurate hand movements toward these same objects (for review see A. D. Milner & M. A. Goodale, 1995). Data demonstrate that DF is better able to discriminate between a square and a rectangle when she is required to reach out and pick up the designated target object than when she is required to verbally report the target's left/right position. (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)     

The tilt-consistency theory of visual illusions.

The authors argue that changes in the perception of vertical and horizontal caused by local visual cues can account for many classical visual illusions. Because the perception of orientation is influenced more by visual cues than gravity-based cues when the observer is tilted (e.g., S. E. Asch and H. A. Witkin, 1948), the authors predicted that the strength of many visual illusions would increase when observers were tilted 30°. The magnitude of Z?llner, Poggendorff, and Ponzo illusions and the tilt-induction effect substantially increased when observers were tilted. In contrast, the Müller-Lyer illusion and a size constancy illusion, which are not related to orientation perception, were not affected by body orientation. Other theoretical approaches do not predict the obtained pattern of results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

10 years of illusions.

A decade ago, S. Aglioti, J. F. X. DeSouza, and M. A. Goodale (1995) published an experiment that has had a big influence on the way that visual information is thought to control human behavior. Their findings have often been simplified as suggesting that action is immune to perceptual illusions. The current authors critically analyze the 4 steps involved in this simplification and argue that research during the last 10 years has shown that the validity of 3 of the 4 steps is doubtful. They conclude that this experiment cannot be regarded as firm support for the 2-visual-systems hypothesis (i.e., that the ventral stream is for perception and the dorsal stream is for visually guided actions). (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)     

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)     

The motion analogue of the Café Wall illusion

Detecting visual motion is computationally equivalent to detecting spatiotemporally oriented contours. The question addressed in this study is whether the illusory oriented contour in the space-space domain induces corresponding illusory motion perception. Two experiments were conducted. In experiment 1, the Café Wall pattern, which elicits a strong illusion of orientation (Café Wall illusion), was found to induce an illusion of motion when this pattern was converted to the space-time domain. The strength of the motion illusion depends on the mortar luminance and width, as for the Café Wall illusion. In experiment 2, the adaptation to this illusion of motion was found to induce a motion aftereffect in a static test, which indicates that a first-order-motion system contributes to the induction of the motion illusion. In fact, the motion-energy model was able to predict the strength of this motion aftereffect.     

Clinicians'' decision making about involuntary commitment

When we make a smooth eye movement to track a moving object, the visual system must take the eye's movement into account in order to estimate the object's velocity relative to the head. This can be done by using extra-retinal signals to estimate eye velocity and then subtracting expected from observed retinal motion. Two familiar illusions of perceived velocity--the Filehne illusion and Aubert-Fleischl phenomenon--are thought to be the consequence of the extra-retinal signal underestimating eye velocity. These explanations assume that retinal motion is encoded accurately, which is questionable because perceived retinal speed is strongly affected by several stimulus properties. We develop and test a model of head-centric velocity perception that incorporates errors in estimating eye velocity and in retinal-motion sensing. The model predicts that the magnitude and direction of the Filehne illusion and Aubert-Fleischl phenomenon depend on spatial frequency and this prediction is confirmed experimentally.     

Gravitoinertial force versus the direction of balance in the perception and control of orientation.

I. S. Curthoys and N. J. Wade (see record 1990-13799-001) appeal to land-based data in defending the traditional view that stimulation of the otolith organs leads to perception of the direction of gravitoinertial force. However, such data do not permit rejection of the hypothesis that the perception of orientation is based on the dynamically defined direction of balance, which is qualitatively different from the kinetically defined direction of gravitoinertial force. Furthermore, the approach of Curthoys and Wade is compromised by their failure to consider relations between the perception and control of orientation. Such relations must be considered in developing a general theory of orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A motor signal and "visual" size perception

Recent models of the visual system in primates suggest that the mechanisms underlying visual perception and visuomotor control are implemented in separate functional streams in the cerebral cortex. However, a little-studied perceptual illusion demonstrates that a motor-related signal representing arm position can contribute to the visual perception of size. The illusion consists of an illusory size change in an afterimage of the hand when the hand is moved towards or away from the subject. The motor signal necessary for the illusion could be specified by feedforward and/or feedback sources (i.e. efference copy and/or proprioception/kinesthesis). We investigated the nature of this signal by measuring the illusion's magnitude when subjects moved their own arm (active condition, feedforward and feedback information available), and when arm movement was under the control of the experimenter (passive condition, feedback information available). Active and passive movements produced equivalent illusory size changes in the afterimages. However, the illusion was not obtained when an after-image of subject's hand was obtained prior to movement of the other hand from a very similar location in space. This evidence shows that proprioceptive/kinesthetic feedback was sufficient to drive the illusion and suggests that a specific three-dimensional registration of proprioceptive input and the initial afterimage is necessary for the illusion to occur.     

Taking a long look at action and time perception.

Everyone has probably experienced chronostasis, an illusion of time that can cause a clock's second hand to appear to stand still during an eye movement. Though the illusion was initially thought to reflect a mechanism for preserving perceptual continuity during eye movements, an alternative hypothesis has been advanced that overestimation of time might be a general effect of any action. Contrary to both of these hypotheses, the experiments reported here suggest that distortions of time perception related to an eye movement are not distinct from temporal distortions for other kinds of responses. Moreover, voluntary action is neither necessary nor sufficient for overestimation effects. These results lead to a new interpretation of chronostasis based on the role of attention and memory in time estimation. (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)     

New perspectives on the effects of action on perceptual and cognitive development.

This special section was motivated by a resurgence in the view that it is impossible to investigate perceptual and cognitive development without considering how it is affected by, and intertwined with, infants' and children's action in the world. This view has long been foundational to the field, yet contemporary investigations of the effects of acting on cognition and perception have been limited. The research showcased in this section indicates that this trend is changing as researchers consider anew the ways in which cognition derives structure from action. The work presented here illustrates the breadth of these potential effects across ages and domains of development, and it highlights the breadth of methods that can be recruited to investigate them. This new research focus provides insight for the mechanisms by which action affects perception and cognition and at the same time reveals that much remains to be learned. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The bicycle illusion: Sidewalk science informs the integration of motion and shape perception.

The authors describe a new visual illusion first discovered in a natural setting. A cyclist riding beside a pair of sagging chains that connect fence posts appears to move up and down with the chains. In this illusion, a static shape (the chains) affects the perception of a moving shape (the bicycle), and this influence involves assimilation (averaging) rather than opposition (differentiation). These features distinguish the illusion from illusions of motion capture and induced motion. The authors take this bicycle illusion into the laboratory and report 4 findings: Na?ve viewers experience the illusion when discriminating horizontal from sinusoidal motion of a disc in the context of stationary curved lines; the illusion shifts from motion assimilation to motion opposition as the visual size of the display is increased; the assimilation and opposition illusions are dissociated by variations in luminance contrast of the stationary lines and the moving disc; and the illusion does not occur when simply comparing two stationary objects at different locations along the curved lines. The bicycle illusion provides a unique opportunity for studying the interactions between shape and motion perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

L'évaluation de l'orientation d'adresse en fonction de quatre types de jeux de hasard et d'argent.

Evaluated the validity of a questionnaire measuring the illusion of control and skill orientation of Ss using 4 types of games involving different levels of chance and skill. It was predicted that Ss playing Ring Toss would score higher on items related to skill orientation. This hypothesis was partially confirmed, suggesting that this questionnaire is relatively valid for studying psychological aspects of chance and money games. (English abstract) (5 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)