Large Errors in the Perception of Verticality are Generated by Luminance Borders (Integrated across Space) Not by Subjective Borders

The rod-and-frame illusion shows large errors in the judgment of visual vertical in the dark if the frame is large and there are no other visible cues (Witkin and Asch, 1948 Journal of Experimental Psychology 38 762–782). Three experiments were performed to investigate other characteristics of the frame critical for generating these large errors. In the first experiment, the illusion produced by an 11° tilted frame made by luminance borders (standard condition) was considerably larger than that produced by a subjective-contour frame. In the second experiment, with a 33° frame tilt, the illusion was in the direction of frame tilt with a luminance-border frame but in the opposite direction in the subjective-contour condition. In the third experiment, to contrast the role of local and global orientation, the sides of the frame were made of short separate luminous segments. The segments could be oriented in the same direction as the frame sides, in the opposite direction, or could be vertical. The orientation of the global frame dominated the illusion while local orientation produced much smaller effects. Overall, to generate a large rod-and-frame illusion in the dark, the tilted frame must have luminance, not subjective, contours. Luminance borders do not need to be continuous: a frame made of sparse segments is also effective. The mechanism responsible for the large orientation illusion is driven by integrators of orientation across large areas, not by figural operators extracting shape orientation in the absence of oriented contours.

[1]  M. Morgan,et al.  How the human visual system encodes the orientation of a texture, and why it makes mistakes , 1997, Current Biology.

[2]  D. Spinelli,et al.  Modulation of the Rod-And-Frame Illusion by Additional External Stimuli , 1995, Perception.

[3]  U. Polat,et al.  The architecture of perceptual spatial interactions , 1994, Vision Research.

[4]  Guy Orban,et al.  Illusory, motion, and luminance-defined contours interact in the human visual system , 1994, Vision Research.

[5]  S. Ebenholtz,et al.  Inhibition of the rod-and-frame effect by circular contours. , 1982, Perception & psychophysics.

[6]  S. Ebenholtz,et al.  Absence of depth processing in the large-frame rod-and-frame effect , 1982, Perception & psychophysics.

[7]  S. Ebenholtz,et al.  Determinants of the rod-and-frame effect: Role of organization and subjective contour , 1980 .

[8]  D. Goodenough,et al.  Eye torsion in response to a tilted visual stimulus , 1979, Vision Research.

[9]  Eric Sigman,et al.  Instructions, Illusory Self-Tilt and the Rod-and-Frame Test , 1979 .

[10]  M Flannagan,et al.  Subjective Estimates of Body Tilt and the Rod-and-Frame Test , 1978, Perceptual and motor skills.

[11]  Sheldon M. Ebenholtz,et al.  Determinants of the rod and frame effect: The role of retinal size , 1977 .

[12]  Sheldon M. Ebenholtz,et al.  The rod and frame effect and induced head tilt as a function of observation distance , 1977 .

[13]  P Wenderoth,et al.  Component Analysis of Orientation Illusions , 1977, Perception.

[14]  P. Wenderoth.  The Distinction between the Rod-and-Frame Illusion and the Rod-and-Frame Test , 1974, Perception.

[15]  H. A. Witkin,et al.  Studies in space orientation; further experiments on perception of the upright with displaced visual fields. , 1948, Journal of experimental psychology.

[16]  D. Spinelli,et al.  Local and global visual mechanisms underlying individual differences in the rod-and-frame illusion , 1995, Perception & psychophysics.

[17]  Eric Sigman,et al.  A cognitive-style conception of the field-dependence dimension , 1985 .

[18]  Ken Nakayama,et al.  Size interactions in the perception of orientation , 1983 .

[19]  N. Wade,et al.  The influence of perceptual grouping on the tilt illusion , 1983, Psychological research.