A note on a second stage in the formation of illusory contours

Day, R. H.; Jory, M. K.

doi:10.3758/bf03199910

Cited by 45 publications

(18 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is suggested that "classical" or simultaneous contrast from the corner elements and line-end contrast generated by the ends of the side elements (Day & Jory, 1978;Frisby & Clatworthy, 1975;Kennedy, 1979) spread to the partially delineated borders of the rectangle (or other shapes) in a manner described earlier by Day and Jory (1980). It is suggested also that apparent overlay serves primarily to enhance the delineation of the border with which the illusory contour is coincident, by apparent stratification of the rectangular figure and the corner elements.…”

Section: Discussionmentioning

confidence: 99%

“…Second, do the incomplete octagons and the parts of the incomplete cross impinging on the hypothetical edge of the rectangle contribute equally to the formation of the illusory contours? It is conceivable that, as Day and Jory (1980) suggested, the ends of the lines merely determine the location of the contours. The purpose of the first experiment was to answer these two questions.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Amodal completion as a basis for illusory contours

Day

Kasperczyk

1983

Perception & Psychophysics

Self Cite

View full text Add to dashboard Cite

Kanizsa's (1979) explanation of illusory contours in terms of amodal completion of perceptually incomplete elements was examined in five experiments by varying the elements partly delineating the corners and sides of a rectangle. The results from magnitude estimation of contour strength showed that (1) incomplete corner elements consistently resulted in stronger illusory contours than did complete elements, although contours nevertheless always occurred with the latter, (2) contours were always stronger with side elements than without but were not always reliably different in strength when the side elements were parts of an incomplete form, (3) incomplete octagons and slightly different but complete elements resulted in contours of the same strength, (4) the larger of two incomplete comer elements resulted in stronger contours, and (5) incomplete irregular elements resulted in stronger contours than did complete irregular ones, although weak contours again occurred with the latter. Together, the data do not strongly support the view that perceptual completion of incomplete figural elements is the basis of illusory contours. An alternative interpretation in terms of the spreading of induced contrast to partially delineated borders is proposed. It is suggested that apparent overlay occurring independently of perceptual completion enhances these borders and so strengthens the illusory contours.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Amodal completion as a basis for illusory contours

Day

Kasperczyk

1983

Perception & Psychophysics

Self Cite

View full text Add to dashboard Cite

show abstract

“…The illusory surface has no clearly defined boundaries. One may perceive a circle, a diamond, or a square in the center ofthe figure (see also Day & Jory, 1980). In the second stimulus, one perceives a sharp, illusory contour separating the two phase-shifted gratings.…”

Section: IIImentioning

confidence: 99%

Illusory form with inducers of opposite contrast polarity: Evidence for multistage integration

Dresp¹,

Salvano-Pardieu²,

Brunet³

1996

Perception & Psychophysics

View full text Add to dashboard Cite

The perception of brightness differences in Ehrenstein figures and of illusory contours in phaseshifted line gratings was investigated as a function of the contrast polarity of the inducing elements. Wepresented either continuous lines or line-like arrangements composed of aligned dashes or dots whose spacing was varied. A yes/no procedure was used in which naive observers had to decide whether or not they perceived a brightness difference in a given Ehrenstein figure or an illusory contour in a phase-shifted line grating. The results show that brightness differences are perceived to some extent in Ehrenstein figures with inducers of opposite polarity of contrast; however, the percentage of yes responses was systematically lower and response times were longer than for figures with inducers of the same polarity. Phase-shifted line gratings with lines of opposite polarity of contrast yielded stronger illusory contours and shorter response times than those with lines of the same polarity. When the sign of contrast was not the same within a given line of induction, neither differences in brightness nor illusory contours were perceived. The results suggest that the mechanisms that lead to apparent differences in brightness are more sensitive to input of the same contrast polarity, the mechanisms generating illusory contours more sensitive to input of opposite polarity. The data are discussed in the light of a multistage approach to illusory form perception and some implications for cortical models of illusory contour integration are discussed.

show abstract

“…Monash University, Clayton, Victoria, Australia Day and Jory (1980) and Kasperczyk (1983a, 1983b) have proposed that illusory contours, apparent edges in physically uniform regions (Ehrenstein, 1942;Gregory, 1972;Kanizsa, 1955;Schumann, 1904), are due primarily to the spread of induced contrast to partially delineated borders. Brightness (or darkness) is enhanced by simultaneous and line-end contrast and reduced by assimilation of brightness.…”

Section: R H Daymentioning

confidence: 99%

“…Earlier, Day and Jory (1980) showed that line-end contrast (Day & Jory, 1978;Frisby & Clatworthy, 1975;Kennedy, 1979)generated in a cross-like figure ( Figure 3A) devised by Koffka (1935) be expected to spread to the borders of the same figures. Neon spreading was generated in the Koffka figure by completing the black lines forming the arms of the cross with gray lines, as shown in Figure 3B.…”

mentioning

confidence: 99%

A note on a second stage in the formation of illusory contours

Abstract: Figure 1. The Koffka figure with an indefinitely shaped region of enhanced brightness at the center.

Cited by 45 publications

References 7 publications

Amodal completion as a basis for illusory contours

Amodal completion as a basis for illusory contours

Illusory form with inducers of opposite contrast polarity: Evidence for multistage integration

Neon color spreading, partially delineated borders, and the formation of illusory contours

Contact Info

Product

Resources

About