Psychophysical measurements of illusion of the puffy circle (original) (raw)
Related papers
1 Imagining Circles – Empirical Data and a 1 Perceptual Model for the Arc-Size Illusion 2
2015
13 An essential part of visual object recognition is the evaluation of the curvature of 14 both an object’s outline as well as the contours on its surface. We studied a striking 15 illusion of visual curvature – the arc-size illusion (ASI) – to gain insight into the visual 16 coding of curvature. In the ASI, short circular arcs appear less curved than full circles. 17 We investigated if and how the ASI depends on (i) the physical size of the stimulus and 18 (ii) on the length of the arc. Our results show that perceived curvature monotonically 19 increases with arc length up to an arc angle of about 60 ̊, thereafter remaining constant 20 and equal to the perceived curvature of a full circle. We investigated if the misjudgment 21 of curvature in the ASI translates into predictable biases for three other perceptual tasks: 22 (i) judging the position of the centre of circular arcs; (ii) judging if two circular arcs fall 23 on the circumference of the same (invisible) circle and (iii) in...
Imagining circles – Empirical data and a perceptual model for the arc-size illusion
Vision Research, 2016
An essential part of visual object recognition is the evaluation of the curvature of both an object's outline as well as the contours on its surface. We studied a striking illusion of visual curvature-the arc-size illusion (ASI)-to gain insight into the visual coding of curvature. In the ASI, short arcs are perceived as flatter (less curved) compared to longer arcs of the same radius. We investigated if and how the ASI depends on (i) the physical size of the stimulus and (ii) on the length of the arc. Our results show that perceived curvature monotonically increases with arc length up to an arc angle of about 60°, thereafter remaining constant and equal to the perceived curvature of a full circle. We investigated if the misjudgment of curvature in the ASI translates into predictable biases for three other perceptual tasks: (i) judging the position of the centre of circular arcs; (ii) judging if two circular arcs fall on the circumference of the same (invisible) circle and (iii) interpolating the position of a point on the circumference of a circle defined by two circular arcs. We found that the biases in all the above tasks were reliably predicted by the same bias mediating the ASI. We present a simple model, based on the central angle subtended by an arc, that captures the data for all tasks. Importantly, we argue that the ASI and related biases are a consequence of the fact that an object's curvature is perceived as constant with viewing distance, in other words is perceptually scale invariant.
Going round in circles: shape effects in the Ebbinghaus illusion
The Ebbinghaus illusion has traditionally been considered as either a sensory or a cognitive illusion, or some combination of these two. Cognitive contrast explanations take support from the way the illusion varies with the degree of shape similarity between the test and inducing elements; we show, however, that contour interaction explanations may account for this result too. We therefore tested these alternative theories by measuring the illusion with different test shapes as well as different inducer shapes, in all combinations. We found that for angular or hexagonal test shapes there is no similarity effect, and for some shape combinations there is no significant illusion, in contradiction to both of the traditional hypotheses. Instead, we suggest that an integrated model of visual processing is needed to account for the illusion.
Are perception and action affected differently by the Titchener circles illusion?
Experimental Brain Research, 1999
In the present study, we investigated the effects of the Titchener circles illusion in perception and action. In this illusion, two identical discs can be perceived as being different in size when one is surrounded by an annulus of smaller circles and the other is surrounded by an annulus of larger circles. This classic sizecontrast illusion, known as Ebbinghaus or Titchener Circles Illusion, has a strong perceptual effect. By contrast, it has recently been demonstrated that when subjects are required to pick up one of the discs, their grip aperture during reaching is largely appropriate to the size of the target. This result has been considered as evidence of a clear dissociation between visual perception and visuomotor behaviour in the intact human brain. In this study, we suggest and investigate an alternative explanation for these results. We argue that, in a previous study, while perception was subjected to the simultaneous influence of the large and small circles displays, in the grasping task only the annulus of circles surrounding the target object was influential. We tested this hypothesis by requiring 18 subjects to perceptually estimate and grasp a disc centred in a single annulus of Titchener circles. The results showed that both the perceptual estimation and the hand shaping while grasping the disc were similarly influenced by the illusion. Moreover, the stronger the perceptual illusion, the greater the effect on the grip scaling. We discuss the results as evidence of an interaction between the functional pathways for perception and action in the intact human brain. Illustration of the effect of the small-and large-circles array on perceptual estimation and maximum grip aperture. The illusion effect represents the average difference between each illusory Titchener circles array and the neutral array. Error bars indicate the standard error of the mean. * P<0.01, by Newman-Keuls posthoc test
Geometrical illusions: study and modelling
Biological Cybernetics, 1997
The phenomena of geometrical illusions of extent suggest that the metric of a perceived field is different from the metric of a physical stimulus. The present study investigated the Müller-Lyer and Oppel-Kundt illusions as functions of spatial parameters of the figures, and constructed a neurophysiological model. The main idea of the modelling is based on the uncertainty principle, according to which distortions of size relations of certain parts of the stimulus, socalled geometrical illusions, are determined by processes of spatial filtering in the visual system. Qualitative and quantitative agreement was obtained between psychophysical measurement of the strength value of the illusions and the predictions of our model.
Scientific American, 1980
NINE GEOMETRICAL ILLUSIONS are presented on tbe opposite page. In tbe upside. down-T figure tbe vertical line and tbe borizontal line are tbe same lengtb. In the Lipps fig• ure tbe oblique lines in tbe middle are parallel. In both tbe Ponzo figure and the Miiller.Lyer figure the horizontal lines are equal in length. In the Judd figure tbe dot is at tbe midpoint of tbe borizontal line. In the Poggendorff figure tbe oblique lines are collinear. In tbe Zollner fig ure the oblique lines are paralleL In the Titchener figure the two inner circles are the same size. In tbe Delboeuf figure the outer circle on the left is tbe same size as the inner circle on the right.
Blindness to Curvature and Blindness to Illusory Curvature
i-Perception, 2018
We compare two versions of two known phenomena, the Curvature blindness and the Kite mesh illusions, to highlight how similar manipulations lead to blindness to curvature and blindness to illusory curvature, respectively. The critical factor is a change in luminance polarity; this factor interferes with the computation of curvature along the contour, for both real and illusory curvature.
Zimehr Abbasi, 2019
Physics has solved many thought-to-be unsolvable problems in fantastic ways. Most of the times these results are not possible to achieve experimentally, but in theory, succeed in presenting themselves to be suitable solutions. Einstein was a fan of these ideal solutions and was able to display extremely plausible ones as well such as the theory of special relativity. In theory, it works perfectly. However, there is no way of manifesting it experimentally. Any experiment can theoretically give a likely result, but the certainty of this result can only be verified by experimentation. However, in various theories, when testing is not possible due to lack of required technology, we go ahead and apply them based on how convincing the postulates and proofs are on paper. This theoretical proof is known as the Circle Illusion. Imagine there being 3 equidistant collinear bodies. It is evident that if all the 3 entities are of the same size, shape, and opaque, then the extreme bodies will not be in each other’s line of sight. However, this experiment showcases a solution which allows them to be in each other’s line of sight without moving them from their extreme positions and keeping them collinear.
Geometric-optical illusions have been the subjects of research interest in a number of disciplines in science. Moreover, investigation of the patients' reactions to illusory configurations has been somewhat instrumental in the understanding of impaired neuro-cognitive processes underlying some of the neurological and/or psychiatric disorders. Recently, neuroscientists have made some progress in understanding the neural underpinning of the geometric-optical illusions. However, a closer collaboration between psychology and neuroscience may lead to a better understanding of not only the neural basis of the illusions but the function of the brain in general. The purpose of the present analysis is to outline a sound epistemological ground for such a relationship and to demonstrate how psychological theories may potentially play a guiding role in the context of scientific discoveries in the neuro-science of illusory phenomena. In order to do so, two concepts of the " many-one " relationship between the mental and the neural states and " context-sensitivity " will be described with regard to the possible relationships between perception and brain in the context of research on illusions. In addition, the implications of the top-down strategy for research in Psychiatry will be explained and the strategy will be discussed as a path towards the unification of scientific explanations.