The effects of framing ratio and oblique length on Ponzo illusion magnitude

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The orientation specificity of length assimilation and contrast was assessed using the parallellines array. The purpose was to determine the nature of the representation oflength both within and outside of the "attentive field." Experiments 1 and 2 demonstrated that when both contextual and test lines are within an attentive field and do not intersect, the resulting simultaneous length assimilation is independent of orientation. In Experiment 3, simultaneous length contrast was produced by placing the contextual line outside of the attentive field; it also was independent of orientation. Finally, Experiment 4 demonstrated that the sequential length contrast (length aftereffect) produced by a 5-sec prior inspection of a contextual line was independent of orientation, whereas the contrast produced by 60 sec of contextual-line inspection showed some degree of orientation specificity. These results, combined with those obtained with orientation illusions (Tyler & Nakayama, 1984;Wenderoth & Johnson, 1984;Wenderoth, O'Connor, & Johnson, 1986), suggest a qualitative relationship of length and orientation coding that is characterized by partial and mutual overlap of length and orientation information.The parallel-lines array is a minimal configuration for producing an illusion of perceived length. The direction of this distortion of perceived length depends on the spatial and temporal relationship of the test line and a parallel contextual line. In the usual parallel-lines array, the contextual and test lines are presented simultaneously and spatially proximal, and length assimilation is observed. For example, at a viewing distance of 40 em, a 9-cm horizontal contextual line will produce overestimation of a parallel 6-cm test line located 5 mm below it. However, length contrast has been demonstrated in the array under conditions of simultaneous viewing with a much larger spatial separation (100 mm) of the same contextual and test lines (Jordan & Schiano, 1986) and under conditions of sequential presentation of contextual and test lines within the aftereffect paradigm (Brigell & Uhlarik, 1979;Jordan & Uhlarik, 1985). Jordan and Schiano (1986) proposed revisions of descriptive models of length distortion that account for the reversals from length assimilation to length contrast outlined above. Their model is essentially a hybrid of Girgus and Coren's (1982) "pool and store" model of perceptual distortion and the most recent revision of Pressey's assimilation theory (Pressey & Wilson, 1980). According to Girgus and Coren's model, the visual information-processing system imposes constraints on the amount or the area of an array that an observer can sample simultaneously. The lengths of spatially proximal ele-. ments in an array are perceptually "pooled," resulting Preparation of this report was supported by NASA Grant NCC-2-327 to San Jose State University, Kevin Jordan, Project Director. Jerayr Haleblian is now at the University of Southern California. The authors are pleased to acknowledge the helpful comments of two anon...

Section: Resultsmentioning

confidence: 65%

Orientation specificity of length assimilation and contrast

Jordan

Haleblian

1988

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“…This factor would suggest a possible dissociation between the Ponzo illusion and size framing. Whereas the Ponzo is greatest when the gap between the apex line and the context lines is small (see, e.g., Fisher, 1969;Jordan & Randall, 1987), the opposite might be true of size framing. A second possibility is that in the typical size-framing experiment, the large and small frames form different objects, whereas in our figure, they form a single object (cf.…”

Section: Resultsmentioning

confidence: 99%

The Ponzo illusion and the perception of orientation

Prinzmetal

Shimamura

Mikolinski

2001

A new theory, called the tilt constancy theory, claims that the Ponzo illusion is caused by the misperception of orientation induced by local visual cues. The theory relates the Ponzo illusion-along with the Zöllner, Poggendorff, Wündt-Hering, and cafe wall illusions-to the mechanisms that enable us to perceive stable orientations despite changes in retinal orientation or body orientation. In Experiment 1, the magnitude of the misperception of orientation was compared with the magnitude of the Ponzo illusion. In Experiment 2, predictions of the tilt constancy theory were compared with accounts based on (1) low spatial frequencies in the image, (2) memory comparisons (pool-and-store model), and (3) relative size judgments. In Experiment 3, predictions of the tilt constancy theory were tested against predictions of the assimilation theory of Pressey and his colleagues. In the final experiment, the orientation account was compared with theories based on linear perspective and inappropriate size constancy. The results support the tilt constancy theory.

“…This tactic has been applied to Ponzo , Muller-Lyer (Pressey, Di Lollo, & Tait, 1977), and Baldwin (Pressey & Wilson, 1980) configurations. The qualitative and quantitative evidence appears to confirm the idea that spatial deployment of attention is essential in explaining diverse perceptual effects, and several groups of investigators have recognized the utility of the idea (Jaeger, 1985;Jordan & English, 1989;Jordan & Randall, 1987;McLellan, Bernstein, & Garbin, 1984;Restle & Decker, 1977).…”

Section: Integrative Field Theory: the Descriptive Versionmentioning

confidence: 77%

“…Gregory's (1963) point of view represents a fundamental shift in our approach to perception, but the specific theory suffers from what seems to be an insurmountable problem. It is difficult to generate unambiguous predictions, and those that are generated often are not verified (Jordan & Randall, 1987;Reardon & Parks, 1983;Waite & Massaro, 1970). One fact that is especially difficult to rationalize is that reversals in direction of distortion can occur.…”

mentioning

confidence: 99%

Spatial attention in Ponzo-like patterns

Pressey

Epp

1992

A variant of Ponzo's pattern was devised by drawing converging oblique lines at the ends of each of two horizontal lines that were located directly one above the other. Pairs of converging or diverging fins (either between or outside the horizontal shafts) were systematically removed. The results showed that, as predicted by integrative field theory, oblique lines between the shafts produced more distortion than did oblique lines outside the shafts. Also, it was shown that the attentive field construct in integrative field theory was crucial for predicting patterns of means and variances in this experiment. The modified Ponzo effect was shown to have much in common with the classical Muller-Lyer illusion. The subtle differences between the two were explained by proposing that the size of the optimum attentive field was larger in the Ponzo tasks than in the Muller-Lyer tasks because expansion fins are found on both shafts in the Ponzo-like figure.