Brightness Induction and the Café Wall Illusion

Perception ◽  
1983 ◽  
Vol 12 (2) ◽  
pp. 131-142 ◽  
Author(s):  
Mark E McCourt
Keyword(s):  
Visual System ◽  
Present Experiment ◽  
Alternative Explanation ◽  
Visual Illusion ◽  
Perpendicular Line ◽  
Parallel Lines ◽  
Locking Mechanism ◽  
Line Elements

The Café Wall illusion is a distortion illusion in which the parallel lines of a chessboard-like figure consisting solely of parallel and perpendicular line elements appear to converge in alternating rows, creating a wedge distortion similar to that of the well-known Zöllner illusion. Gregory and Heard have formulated an explanation for the Café Wall illusion which relies upon the operation of a ‘border-locking mechanism’ in the visual system. The results of the present experiment suggest an alternative explanation in which the operation of brightness induction within the mortar regions of the Café Wall produces a series of ‘twisted cords' or slanted line elements akin to those of the Fraser or Zöllner figures. A series of such ‘twisted cords' is shown to be capable of itself to produce an illusory convergence like that of the Café Wall. Manipulations of the luminance of discrete regions in the mortar lines of the Café Wall, designed either to augment or cancel the effects of brightness induction in the production of these slanted line elements, are successful in enhancing or reducing, respectively, the wedge distortion of this visual illusion.

The Pong Effect as a Robust Visual Illusion: Evidence From Manipulating Instructions

Perception ◽  
2020 ◽  
Vol 49 (12) ◽  
pp. 1362-1370
Author(s):  
Emily L. Laitin ◽  
Jessica K. Witt
Keyword(s):  
Visual Perception ◽  
Alternative Explanation ◽  
Visual Illusion ◽  
Energetic Cost ◽  
Body Type ◽  
Systematic Testing ◽  
Action Capability ◽  
Specific Effects ◽  
Ability To Act

Visual perception is not always veridical but can be influenced by factors such as ease of acting, energetic cost, and even body type of the observer. This notion is called action-specific perception. Several effects of action capability on visual perception have been found, but there is much controversy as to whether these effects are truly perceptual. Because perception cannot be measured directly, resolving the controversy relies on ruling out alternative explanations through systematic testing. We combined one of the most robust action-specific effects (the Pong effect) with one of the primary suggestions for exploring an alternative explanation, namely whether the effect persists across instructions that emphasize different aspects of the task. The Pong effect was robust to the type of instructions. The results provide critical evidence that the Pong effect is truly perceptual, furthering the argument that a person’s ability to act can influence visual perception.

scholarly journals Visual Entrainment at 10 Hz causes periodic modulation of the Flash Lag Illusion

2019 ◽  
Author(s):  
Samson Chota ◽  
Rufin VanRullen
Keyword(s):  
Visual System ◽  
Visual Processing ◽  
Time Course ◽  
Visual Illusion ◽  
Sensory Information ◽  
Temporal Perception ◽  
Static Object ◽  
Lag Effect ◽  
Continuous Stream ◽  
And Behavior

AbstractIt has long been debated whether visual processing is, at least partially, a discrete process. Although vision appears to be a continuous stream of sensory information, sophisticated experiments reveal periodic modulations of perception and behavior. Previous work has demonstrated that the phase of endogenous neural oscillations in the 10 Hz range predicts the “lag” of the flash lag effect, a temporal visual illusion in which a static object is perceived to be lagging in time behind a moving object. Consequently, it has been proposed that the flash lag illusion could be a manifestation of a periodic, discrete sampling mechanism in the visual system. In this experiment we set out to causally test this hypothesis by entraining the visual system to a periodic 10 Hz stimulus and probing the flash lag effect (FLE) at different time points during entrainment. We hypothesized that the perceived FLE would be modulated over time, at the same frequency as the entrainer (10 Hz). A frequency analysis of the average FLE time-course indeed reveals a significant peak at 10 Hz as well as a strong phase consistency between subjects (N=26). Our findings provide evidence for a causal relationship between alpha oscillations and fluctuations in temporal perception.

Perceptual Distinctiveness and Proactive Interference in the Primacy Effect

1975 ◽  
Vol 27 (2) ◽  
pp. 289-294 ◽  
Author(s):  
Geoffrey Underwood
Keyword(s):  
Proactive Interference ◽  
Present Experiment ◽  
Alternative Explanation ◽  
Critical Item ◽  
Semantic Category ◽  
Primacy Effect ◽  
Interference Theory

When subjects monitor a list of verbal items for one item which is to be selected and remembered, they are more likely to recall the critical item if it is the first member of the list than if it is presented towards the centre of the list. The present experiment examined the possibility that this primacy results from an accumulation of proactive interference from incidentally processed early members of the list which would cause a decrement in the recall of later members. By changing the semantic category of the list members before presentation of the critical item any accumulated interference would have been released, but this procedure produced no weakening of the primacy effect and so the interference theory of primacy was not supported. An alternative explanation of the effect was discussed in which it is assumed that the first member of a series is perceptually distinct from central members.

scholarly journals The Aftereffects of Müller-Lyer and Ponzo Illusions: Differences Revealed in Sensorimotor Domain

2017 ◽  
Vol 71 (5) ◽  
pp. 352-358
Author(s):  
Vsevolod Lyakhovetskii ◽  
Valeriia Karpinskaia
Keyword(s):  
Visual System ◽  
Visual Illusion ◽  
Ponzo Illusion ◽  
Touch Screen ◽  
Visual Illusions ◽  
Motor Tasks ◽  
Right Hand ◽  
Long Time ◽  
Visual Domain ◽  
Different Levels

Abstract Either effects or aftereffects of visual illusions are well studied at the visual domain while there are few studies of aftereffects at the motor tasks such as grasping or pointing at the illusory. The aftereffects of Müller-Lyer and Ponzo illusions in the sensorimotor domain were studied. We used four illusions: two versions of Müller-Lyer illusions (upper/bottom shafts appear longer) and two versions of Ponzo illusions (classical and inverted, upper/bottom shafts appear longer). They were presented to four experimental groups, each type to one of the groups. A fifth group was shown neutral stimuli (two horizontal lines, one under another). At first, one of the above described stimuli was presented ten times. Then, for testing the aftereffect, the neutral stimuli were presented thirty times. After the disappearance of each stimulus, the participant moved his/her right hand across the touch screen along its upper and lower shafts. The participants of all experimental groups experienced significant illusions, but only the classical Ponzo illusion caused significant long-time assimilative aftereffect. These results reveal the existence of an illusory aftereffect in the sensorimotor domain. Moreover, it depends on the type of visual illusion, thereby supporting the hypothesis of origin of the different visual illusions at different levels of the visual system.

scholarly journals An Alternative Explanation of the Orbital Expansion of Titan and Other Bodies in the Solar System

2022 ◽  
Author(s):  
Michal Křížek ◽  
Vesselin G. Gueorguiev ◽  
André Maeder
Keyword(s):  
Solar System ◽  
Quality Factor ◽  
Alternative Explanation ◽  
Q Factor ◽  
Hubble Expansion ◽  
Locking Mechanism ◽  
Standard Estimate ◽  
The Mean ◽  
Expansion Effect ◽  
Large Speed

Recently it was found from Cassini data that the mean recession speed of Titan from Saturn is v = 11.3 ± 2.0 cm/yr which corresponds to a tidal quality factor of Saturn Q ≈ 100 while the standard estimate yields Q ≥ 6 · 104 . It was assumed that such a large speed v is due to a resonance locking mechanism of five inner mid-sized moons of Saturn. In this paper, we show that an essential part of v may come from a local Hubble expansion, where the Hubble-Lemaˆıtre constant H0 recalculated to the Saturn-Titan distance D is 8.15 cm/(yrD). Our hypothesis is based on many other observations showing a slight expansion of the Solar system and also of our Galaxy at a rate comparable with H0. We demonstrate that the large disproportion in estimating the Q factor can be just caused by the local expansion effect. [Accepted for publication in "Gravitation and Cosmology". The paper is to appear in Vol. 28, Issue 2 (2022) of the journal Gravitation and Cosmology.]

Coactivation and Statistical Facilitation in the Detection of Lines

Perception ◽  
1994 ◽  
Vol 23 (2) ◽  
pp. 157-168 ◽  
Author(s):  
Wolfgang Schwarz ◽  
Anja Ischebeck
Keyword(s):  
Reaction Time ◽  
Alternative Explanation ◽  
Addition Reaction ◽  
Reaction Times ◽  
General Phenomenon ◽  
Probability Summation ◽  
Simple Reaction ◽  
Parallel Lines ◽  
Signal Onset ◽  
Specific Line

The redundant-signals effect describes the general phenomenon that simple reaction times to two simultaneously presented signals are typically faster than the corresponding reaction times to each of the signals presented alone. Recent studies (eg Miller 1982, 1986) indicate that models of probability summation in which an independent detection of both signals is assumed cannot completely account for the observed shortening of the reaction times. Therefore, models in which some kind of coactivation is assumed are often considered as an alternative explanation. In the present study simple reaction times to parallel lines are compared with those to orthogonal lines and single lines. Our first hypothesis is that because of the redundant-signals effect, the reaction time to configurations consisting of two lines (either parallel or orthogonal) will generally be faster than the reaction time to a single line. Furthermore, line detection can be related to orientation-specific line detectors. Therefore, parallel lines may be thought to activate similar line detectors and, by coactivation, facilitate detection. As our second hypothesis we thus expect that the reaction time to parallel lines will be shorter than the reaction time to orthogonal lines. To test these hypotheses, we conducted a simple reaction-time experiment in which signal onset asynchronies ranging from 0 to ±56 ms for the orthogonal lines were used. In addition, reaction times to parallel lines and single lines were measured. Both hypotheses are supported by our data. We formulate a stochastic model which is able to explain both statistical facilitation and coactivation in a physiologically plausible way.

Contextual Effects in the Parallel Lines Illusion: Some Implications for Assimilation Theory

1985 ◽  
Vol 61 (3_suppl) ◽  
pp. 1263-1273 ◽  
Author(s):  
Ted Jaeger
Keyword(s):  
Visual System ◽  
Cognitive Activity ◽  
Contextual Effects ◽  
Assimilation Theory ◽  
Illusion Figure ◽  
Parallel Lines ◽  
Apparent Length ◽  
Intermediate Distance ◽  
Assimilation Process ◽  
Size Contrast

32 undergraduates participated in each of two experiments designed to determine how structural manipulations of the parallel lines figure affect the resulting illusion. Collectively and for the range of figures studied, the data show (1) progressive elongations of the contextual lines of the illusion figure first increase, then decrease, the apparent length of the judged line; (2) the misestimation of the length of the judged line diminishes as the separation between it and shorter contextual lines increases; and (3) variations in contour lightness significantly affect the illusion when the contextual lines are shorter than and at any distance from the judged line or when the contextual lines are slightly longer than and at an intermediate distance from the judged line. These data indicate that size-assimilation, as well as size-contrast processes, contributes to the parallel lines illusion and that the assimilation process must be mediated by both sensory and cognitive activity in the visual system.

scholarly journals ‘Seeing’ proximal representations: Testing attitudes to the relationship between vision and images

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0256658
Author(s):  
Steven Samuel ◽  
Klara Hagspiel ◽  
Geoff G. Cole ◽  
Madeline J. Eacott
Keyword(s):  
Visual System ◽  
Perspective Taking ◽  
Present Experiment ◽  
Retinal Images ◽  
Visual Perspective ◽  
Size Constancy ◽  
Original Response ◽  
Adult Participants ◽  
The Relationship ◽  
As If

Corrections applied by the visual system, like size constancy, provide us with a coherent and stable perspective from ever-changing retinal images. In the present experiment we investigated how willing adults are to examine their own vision as if it were an uncorrected 2D image, much like a photograph. We showed adult participants two lines on a wall, both of which were the same length but one was closer to the participant and hence appeared visually longer. Despite the instruction to base their judgements on appearance specifically, approximately half of the participants judged the lines to appear the same. When they took a photo of the lines and were asked how long they appeared in the image their responses shifted; now the closer line appeared longer. However, when they were asked again about their own view they reverted to their original response. These results suggest that many adults are resistant to imagining their own vision as if it were a flat image. We also place these results within the context of recent views on visual perspective-taking.

Author response for "The brain of the African wild dog. IV . The visual system"

2020 ◽  
Author(s):  
Samson Chengetanai ◽  
Adhil Bhagwandin ◽  
Mads F. Bertelsen ◽  
Therese Hård ◽  
Patrick R. Hof ◽  
...  
Keyword(s):  
Visual System ◽  
Author Response ◽  
African Wild Dog ◽  
Wild Dog ◽  
The Brain
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