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Peripheral and central components in variants of the Mueller-Lyer illusion
Abstract
Illusion decrement with prolonged inspection was used as a technique to assess the relative amount of central component in
seven variants of the Mueller-Lyer illusion. Results indicate that all of the variant forms share a common, central component,
while the peripheral components, such as lateral inhibition, vary as a function of the presence of converging lines in the
illusion configurations.
... In 1896, Heymans reported that the magnitude of the Mueller-Lyer illusion decreased with prolonged exposure to the figure. 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. ...
... 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. ...
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.
... 3 Experiment 2 As early as 1902, Judd observed that the magnitude of the perceptual distortion found in the Muller-Lyer illusion diminished with free inspection. This illusion decrement has been repeatedly confirmed for the Muller-Lyer Girgus 1972b, 1974;Day 1962;Dewar 1968;Festinger et al 1968;Girgus et al 1973) and has also been shown to occur in other illusory configurations including the Poggendorff, the Zollner, the Wundt-Hering, and the Oppel-Kundt (Coren and Girgus 1972b;Coren and Hoenig 1972). A great deal of evidence seems to suggest that this decrement in illusion strength involves some form of perceptual learning. ...
... Settings to apparent equality were taken at 1 min intervals. Other investigators have shown that this procedure leads to sizeable reductions in illusion magnitude (Coren and Girgus 1972b;Girgus et al 1973). Following the inspection period, all observers made two additional settings to apparent equality on the initially tested illusion variant (either the Piaget or the exploded form). ...
The possibility of sex differences in responses to visual-geometric illusions was investigated with the use of forty-five illusion variants and a sample of 221 observers. No difference in illusion magnitude as a function of sex was found. A second experiment measured illusion decrement and transfer of decrement to other illusion configurations. Again there were no significant differences between male and female observers.
... For example, decrement responds to traditional learning variables, such as the spacing of trials (Dewar, 1968;Mountjoy, 1961), cumulates over extended time periods (Judd, 1902), and generalizes as a function of perceived rather than physical similarity between practice and test figures (Coren & Girgus, 1974). In addition, the cognitive nature of illusion decrement has been tested directly using a variety of MiHler-Lyer configurations which contain different amounts of converging or intersecting line elements (Girgus, Coren, & Horowitz, 1973;Girgus & Coren, Note 1). These studies indicate that an increase in converging contours results in a greater initial illusion but does not affect the rate of decrement. ...
Used illusion decrement to explore the relative contributions of structural factors and cognitive processing factors to the commonly found age differences in the magnitude of the Muller-Lyer illusion. A total of 160 7-, 9-, 11-, and 21-yr-olds judged the standard Brentano form and a dot form of the illusion for 5 trials at 30-sec intervals. The initial illusion magnitudes for the Brentano form showed the usual decrease with age; however, the age trend for the dot form was considerably weaker. For both configurations, the initial age trends completely disappeared over the 2.5-min testing session. (34 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
... illusion. The remaining 78 % is then. presumably. due to other factors. Bekesy (1967) and Ganz (1966) also utilize a structural source of illusory distortion when they propose that lateral inhibitory interactions operating on converging or intersecting line elements cause some of the obtained contour displacements and distortions. Coren (1970) and Girgus, Coren. and Horowitz (1973) have shown that removal of the converging line elements necessary for the operation of this mechanism does. in fact. reduce the magnitude of several classical illusions. However. even when all opportunities for such contour interactions have been removed. significant visual distortions in the classically observed directions still remain ...
Available evidence seems to indicate that illusion decrement represents reorganization of cognitive components involved in
visual-geometric illusions. Observers viewed one of the two forms of the Mueller-Lyer illusion, containing differential opportunities
for peripheral structural interactions, for a 10-min test session on each of 5 successive days. The magnitude of the distortion
decreased to a different asymptotic level in each of the two configurations with the form, with more opportunity for structural
interactions showing the higher asymptote. Thus, this asymptote probably represents the structural or physiological contribution
to the illusory distortion.
... Because almost all previous information on illusion decrement has been based on the Miiller-Lyer illusion, it should be noted that the results of the present study are consistent with the results of a number of previous Milller- Lyer decrement studies. For example, Coren, Girgus, and their associates (Coren & Girgus, 1972a; Girgus et al., 1975; Girgus, Coren, & Horowitz, 1973) have evaluated decrement in a number of variants of the Miiller-Lyer illusion , and found similar decrement patterns for standard and modified figures. This finding is consistent with the similar decrement patterns found in real-and subjectivecontour figures in the present study. ...
The reduction in illusion magnitude with visual inspection and the transfer of such illusion decrement to a noninspected figure were examined in real- and subjective-contour Poggendorff figures. For both types of figures, illusion magnitude decreased significantly, and in a similar manner, during a 5-min inspection period. Postinspection tests showed that inspecting either a real- or subjective-contour figure resulted in a reduction in illusion magnitude for the other, noninspected figure. These findings suggest that real- and subjective-contour Poggendorff figures share a similar global organization and are thus probably processed in a similar manner. These characteristics make subjective-contour figures a useful tool for separating illusion-producing mechanisms into structural and strategy components.
In this volume, originally published in 1978, the authors survey the historical and contemporary research literature pertaining to two-dimensional visual-geometric illusions. They bring together much of the known data, summarising and evaluating theories that have been offered to explain these phenomena. Coren and Girgus provide a new conceptual framework that suggest that visual illusions are not unitary phenomena. Within this framework, illusions do not represent a breakdown in normal perceptual processing. Rather, it is proposed that each illusion is produced by a number of mechanisms operating at different levels in the visual information processing system. The book contains an extensive collection of illusion figures. It will be essential reading for all of those concerned with vision and visual perception, since it integrates the study of illusions into the main body of psychological and perceptual theories at the time.
Frequently, when an observer views a simple pattern and is asked to describe his conscious visual percept, his subjective assessment of stimulus relations, including the size, shape, or direction of pattern components, differs from what might be expected on the basis of direct physical measurements of the stimulus array. Configurations which reliably elicit such discrepant judgments are generally called visual-geometric illusions. Several hundred different illusion configurations have been catalogued since Oppel published the first formal investigations of these phenomena in 1854–1855.
It has often been suggested that many visual geometric illusions are caused by inappropriate constancy scaling triggered by depth cues implicit in the two dimensional array. A new size illusion based upon a minimal interposition cue is presented, which seems to support this contention. Asymmetries in the results suggest that the major component of the illusion is overestimation of apparently more distant targets rather than underestimation of apparently closer targets.
Illusion decrement with inspection was assessed separately for wings-in and wings-out Müller-Lyer figures. 150 undergraduates reproduced the central extent in Müller-Lyer figures under 3 conditions: the Ss in Exp 1 made responses at 1-min intervals during a 5-min inspection, the Ss in Exp 2 made responses at 1-min intervals without inspection between judgments, and Exp 3 provided the Ss with implicit feedback during inspection. Separate inspection of wings-in and wings-out figures produced similar decrement effects. Illusion decrement was observed in Exp 1, but the decrement was comparable to the control condition of repeated judgments without intervening inspection (Exp 2). When provided with implicit feedback during inspection (Exp 3), pronounced illusion decrement was obtained, but not for all Ss. The variability associated with responses in all experiments was high, and many Ss did not show illusion decrement after 5 min of inspection. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Noting the similarity between the illusion decrement and selective adaptation paradigms, Long has challenged the view that illusion decrement effects reflect a strategic--as opposed to a structural--underlying mechanism, and has called for further research on this issue. To investigate the confound between prolonged free inspection and repeated trials in the standard decrement procedure, the effects of three inspection conditions (continuous, intermittent, and immediate) on the magnitude of the overestimation Mueller-Lyer illusion have been assessed under two levels of trials (a total of two or six judgments). Significant illusion decline was found only under conditions of repeated trials, with either continuous or intermittent inspection. These findings do not support the predictions of purely structural theories (including neural adaptation and efferent readiness theories), according to which degree of decrement should be determined solely by viewing time. Instead, the data demonstrate that illusion decrement is a product of practice, providing converging evidence for the view of decrement as involving a cognitive 'recalibration' or learning process.
After Wundt’s change of status from being a physiologist of no particular note to professor of philosophy at Germany’s largest university, it was natural that he should make a more careful statement of his metaphysical position than the “Closing Remarks”with which he ended the Principles of Physiological Psychology (pp. 171–177). In the second edition, accordingly, that short chapter was expanded into two chapters, each twice as long as the original. Section 23 (“Metaphysical Hypotheses about the Nature of Mind”) is an expanded treatment of the topics included in paragraphs 3–7 of the earlier statement. Errors that had been committed in stating the views of Descartes and Leibniz were corrected by substituting for their names, at the appropriate places, “the Cartesians” and “followers of Leibniz.” Unguarded references to interaction (Wechselwirkung) of body and mind were not eliminated from this chapter.
Fifteen Ss (13 Negroes, two whites) rated as having dense or dark pigmentation at the Fundus oculi were compared with 20 Ss (one Negro, 19 whites) rated as lightly pigmented with respect to their sensitivity to a part of the Mueller-Lyer figure. The darkly pigmented Ss were significantly less sensitive than the lightly pigmented Ss. Biserial correlation of magnitude of illusion with pigmentation rating yielded a coefficient of −.745.
A horizontal line (L) looks shorter with large boxes (B) at the ends than with small Bs. This illusion was measured by having Ss judge the length of L on a 6-point scale. Six different lengths of L were combined factorially with six sizes of B to form 36 stimuli, and 51 Ss made four judgments each. Mean judgment increased smoothly with L and decreased with B. Data were fitted using Adaptation-Level formulas, and the weight of B was found to be approximately 14%. However, B had almost no effect on the judgment of very short Ls.
A series of observations are reported on the effects of repeated presentation of the Müller-Lyer illusion. A number of findings seem to support the thesis that the destruction of the Müller-Lyer illusion by repeated measurements is due to satiation rather than learning. Evidence includes: (1) destruction when Ss have no knowledge of results; (2) destruction when measurements are largely replaced by satiation periods; (3) failure of destruction with some Ss; (4) after effects to be expected if satiation had taken place; (5) failure of destruction in one position to be accompanied by destruction in other positions; (6) failure of destruction with tachistoscopic presentations.
A DECREMENT IN THE MAGNITUDE OF THE MULLER-LYER ILLUSION WAS FOUND IN 45 15-18 YR. OLD MALES IF FREE EYE MOVEMENTS WERE ALLOWED. LITTLE OR NO DECREMENT WAS OBTAINED IF SS FIXATED 1 POINT OF THE FIGURE DURING INSPECTION. WHEN EYE MOVEMENTS WERE RECORDED, SACCADES ACROSS THE PERCEPTUALLY SHORT SIDE OF THE MULLER-LYER FIGURE WERE FOUND TO BE SHORTER THAN ACROSS THE PERCEPTUALLY LONG SIDE. AFTER INSPECTION WITH FREE EYE MOVEMENTS, THE SACCADES BECAME MORE NEARLY EQUAL ON THE 2 SIDES. SUCH CHANGES IN EYE MOVEMENTS DID NOT OCCUR IF SS FIXATED 1 POINT DURING THE INSPECTION PERIOD. THE DATA ARE INTERPRETED IN TERMS OF PERCEPTION BEING DETERMINED BY THE EFFERENT READINESS ACTIVATED BY VISUAL INPUT, SO THAT THE DECREMENT IN THE MAGNITUDE OF THE ILLUSION RESULTS FROM RECALIBRATION OF THE EFFERENT PROGRAMS. (29 REF.) (PsycINFO Database Record (c) 2012 APA, all rights reserved)