Creation of the horizontal-vertical illusion through imagery

Abstract

Perception of the horizontal-vertical illusion was examined as a function of imaging ability. Subjects who scored either high or low on this attribute (as assessed by the Vividness of Visual Imagery Questionnaire, or VVIQ) were asked to image an inducing line or lines of the illusory stimulus. High imagers reported perceiving the illusion whether the inducing line(s) were imaged or were physically present. Also, the magnitude of the illusion as created by imagery-induced lines was equivalent to that produced for physically present lines. Low imagers reported perceiving the illusion only when inducing lines were physically present. METHOD Subjects Forty volunteers from introductory psychology classes served as the subjects. All individuals previously had completed the Vividness of Visual Imagery Questionnaire, or VVlQ (Marks, 1973). This has been shown to be a good predictor of who is most capable of utilizing imagery in a perceptual task (Gur & Hilgard, 1975). Half of the subjects were selected for scoring in the top one-third of those who had participated in a mass-testing session of 482 individuals. The remaining subjects were chosen for scoring in the lowest one-third of the respondents.

Images contain what the imager put there: A nonreplication of illusions in imagery

“…In our procedure , subjects who imagined the configuration of a standard geometric illusion did not yield a reliable illusory effect. This was true for both subjects with vivid visual imagery and subjects without vivid imagery, results that are in clear contrast to data reported by Wallace (1984aWallace ( , 1984b.…”

“…The flaw in this argument lies in its premise : the suggestion that these extraneous factors were equivalent for high-and low-vividness subjects . In all of Wallace's (1984aWallace's ( , 1984b) studies, subjects were asked whether they were " able to see" the line(s) specified by the experimenter, whether they were able to "produce" or "conjure up" the relevant line. If the subject responded "yes" to this question, he/she was asked about the relative lengths of the figure's lines; if the subject responded "no" to the question, the procedure ended.…”

Is the Horizontal-Vertical Illusion Mainly a By-Product of Petter’s Rule?

“…However, amodal completion in a perceptual process occurs automatically in a very limited amount of time. Above all, it was demonstrated that the HV illusion also occurs when participants are simply required to imagine the two lines [16,22], showing that it is the mental representation of the stimuli, rather than the physical stimulation per se, that seems to count more for the emergence of this size illusion. Provided that it is hard to simultaneously represent two objects in the same portion of space and at the same distance from the observer, there is a concrete possibility that participants represent the two lines at different distances, with Petter's rule guiding them in establishing which line is behind the other.…”

Subjective Experience: Its Conceptual Status, Method of Investigation, and Psychological Significance

“…No such improvements occur among weak imagers or among those who cannot control their images. Again, Wallace (1984) found that those with vivid visual imagery, but not those with weak visual imagery, experience the horizontal-vertical illusion when physically presented with one of the lines (either horizontal or vertical) and when they are asked to project a visual image of whichever line is missing.…”