The assessment of components involved in illusion formation using a long-term decrement procedure

Girgus, Joan S.; Coren, Stanley; Durant, Mitchell J.; Porac, Clare

doi:10.3758/bf03204102

Cited by 45 publications

(24 citation statements)

References 32 publications

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“…However, Wenderoth and Wade (Note 1), using the dot form of the Poggendorff illusion, obtained a reduction in magnitude of 67% (noncognitive components). Taken together, Girgus et al (1975) and Wenderoth and Wade (Note 1), the reduction of 60% in the present experiments seems reasonable. The angle between the parallels and the obliques in the current study and Wenderoth et al 's experiments was 45 deg, whereas in Coren's (1970) experiment, it was 30 deg.…”

Section: Discussionsupporting

confidence: 56%

“…Using the data of Coren's (1970) dot form and Goldstein and Weintraub's (1972) subjective contour form, Coren et al (1978) reported a reduction in illusion magnitude of about 40% (noncognitive components) for the Poggendorff illusion. According to the interpretation of Coren et al (1978) and Girgus et al (1975), the reduction of 60% in the present experiments must be a reduction of noncognitive components. There exists a big difference between the current data and Coren's (1970) data andCoren et al's (1978) report.…”

Section: Discussionmentioning

confidence: 99%

“…Girgus, Coren, Durant, and Porac (1975) concluded that initial illusion reduction derives from a reduction of noncognitive components (peripheral components) because the reduction in magnitude by prolonged viewing was nearly the same size as an illusion magnitude of dot form (cognitive components). They obtained a reduction of 35% (cognitive components) using the full Mueller-Lyer illusion.…”

Section: Discussionmentioning

confidence: 99%

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Reduction of the Poggendorff effect by the motion of oblique lines

Mori¹

1981

Perception & Psychophysics

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The magnitude of the Poggendorff illusion was measured when the test lines were moved up or down and tracked by subjects. The difference between test lines and inducing lines caused by motion of the test lines significantly reduced the magnitude of illusion (60%). Supplementary experiments seemed to indicate that location of test lines. perceptual shrinkage of space in the vertical dimension. and effective display time were not the main factors contributing to the reduction in illusion magnitude. Instead. it seems that some reduction in interaction between test and inducing lines was the main cause of the reduction. The rising curve of the reduction was very steep with velocity, and the reduction magnitude was almost constant over most of the range of velocities studied. The current evidence seems to suggest that moving and stationary figures are processed by separate channels and that. therefore, the interaction between them is reduced.Visual-geometric illusions derive from some interaction between test and inducing figures. Illusion magnitude has usually been measured under conditions in which both test and inducing figures are stationary.The question addressed in the present study was whether or not the interactions that occur would be of the same size when some parts of the figure were in motion and other parts were stationary. Assuming that the interactions are affected by this differential motion, would the illusion become smaller or larger? How much would it change? Would the magnitude of change depend on velocity?The present experiments were planned to answer these questions. The Poggendorff illusion was selected as a stimulus. The illusion magnitude was measured under conditions in which the test figure (the transverse lines) was moved vertically while the subject tracked it. The vertical parallels remained stationary. Tracking of the test figure was introduced to avoid any perceptual distortion of the test figure, such as shrinkage in the vertical dimension, and to keep both test and inducing figures as clear as possible. A EXPERIMENT 1 MethodApparatus. A Megraphic 5000 display monitor (P40 phosphor) controlled by a NOV A-3 minicomputer was used in Experiment 1. The display was viewed in a darkened room. The subject was seated 62 cm from a screen, with his head upright and his chin in a chinrest. Figure I shows the figure used in Experiment I. Vertical line segments EF and GH were 31 em (28.1 deg) in length. ObliqueThe equipment used in Experiments 2 to 6 was provided in Sydney by ARGC Grant A 74/15177 to P. Wenderoth and H. Beh.Copyrigh t 1981 Psychonomic Society, Inc. line segments AB and CD were 4.13 ern (3.8 deg) in length. The width between EF and GH was .76 cm (.7 deg). All line widths were .3 mm (.03 deg). The angle between the obliques and parallels was 45 deg. The screen was 35.6 cm wide and 33.0 em high. All lines had a luminance of 1 mL. The luminance of the background screen was not measurable using a Tektronix J16 digital photometer, but was less than .01 rnl., the lower limit of the photom-

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Section: Discussionsupporting

confidence: 56%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Reduction of the Poggendorff effect by the motion of oblique lines

Mori¹

1981

Perception & Psychophysics

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“…Since that time, this finding has been replicated many times with the Mueller-Lyer illusion (Coren & Girgus, 1972a, b, 1974Dewar, 1968;Festinger, White, & Allyn, 1968;Girgus, Coren, Durant, & Porac, 1975;Girgus, Coren, & Horowitz, 1973;Judd, 1902;Mountjoy, 1958), and with other illusion figures as well (Coren & Girgus,I972b). A prerequisite for the diminution of illusion magnitude seems to be the opportunity to freely inspect the illusory configuration with saccadic eye movements.…”

mentioning

confidence: 51%

“…The decrement procedure was similar to one which has been used previously (Coren & Girgus, 1972a, b, 1974Girgus et al, 1973;Girgus et al, 1975). This method leads to sizable reductions in illusion magnitude.…”

Section: Methodsmentioning

confidence: 99%

The assessment of motor control in sighting dominance using an illusion decrement procedure

Porac

Coren

1977

Perception & Psychophysics

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Walls (1951) proposed that perceptual asymmetries between the sighting dominant and the nonsighting dominant eyes were based upon differences in the monitoring of eye movements. The present research explored this hypothesis in the context of an illusion decrement paradigm. Since illusion decrement seems to occur only under conditions of free eye-movement inspection, it was reasoned that any motoric asymmetries would manifest themselves through differences in the rate and extent of decrement. These predictions were partially confirmed. The sighting eye manifested greater illusion decrement, but the effect remained specific to conditions where both eyes were stimulated. In addition, asymmetries in the interocular transfer of illusion decrement were found to favor the sighting dominant eye.

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Visual Illusions

Coren¹

1978

Perception

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The assessment of components involved in illusion formation using a long-term decrement procedure

Cited by 45 publications

References 32 publications

Reduction of the Poggendorff effect by the motion of oblique lines

Reduction of the Poggendorff effect by the motion of oblique lines

The assessment of motor control in sighting dominance using an illusion decrement procedure

Visual Illusions

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