The Horizontal-Vertical Illusion and Knowledge of Results

Abstract

The Horizontal-Vertical (HV) Illusion was examined in two studies in which subjects adjusted the vertical line in L-shaped and inverted-T figures or produced lines in the vertical and horizontal planes. On the adjustment tasks, vertical lines were made significantly shorter than horizontal comparison lines, especially for the inverted-T figure. On the production tasks, lines drawn in the vertical plane were significantly shorter than lines drawn in the horizontal plane. The adjusted and created lines of subjects receiving intertrial feedback on illusion magnitude were significantly more accurate and less variable than the estimations of control subjects. Performance on either task or figure type did not differ as a function of sex of subject. The present results show that the HV illusion exists in the absence of line bisection or a comparison line and results from the overestimation of vertical lines. These findings further clarify the relative contributions of the structural and strategy mechanisms in the formation of the Horizontal-Vertical Illusion.

Analysis of individual variations in the classical horizontal-vertical illusion

“…We replicated the overestimation of the vertical in the classical HVI as reported previously with an upside-down T stimulus (Avery & Day, 1969;Brosvic & Cohen, 1988;Finger & Spelt, 1947;Künnapas, 1955; McBride, Risser, than if the horizontal line was adjusted. But this difference turned out to be insignificant.…”

“…In a similar way, Westheimer (2008Westheimer ( , p. 2134 argues that "there may even be simpler underlying principles, such as a vertical/horizontal anisotropy or one of oblique compared to cardinal orientation of contours." Brosvic and Cohen (1988) reported that the vertical illusion also exists in the absence of a horizontal comparison and can be accounted for by an overestimation in the vertical plane. Overestimation of vertical elements & Slotnick, 1987).…”

Provision of Feedback During Preparation For Academic Testing: Learning Is Enhanced by Immediate But Not Delayed Feedback

“…The superiority of immediate feedback has been robustly demonstrated for the acquisition of verbal materials (Ammons, 1956) and motor skills (Anderson, Magill, & Seklya, 2001;Brosvic & Cohen , 1988). The results observed when immediate feedback is delivered through the IF AT are similar to those observed in numerous studies despite considerable variation in the definition of immediate feedback (i.e., feedback provided immediately after a response to feedback provided by the end of the day), the use or nonuse of an answer-until-correct process, the provision of partial (e.g., 50% of test items) to complete feedback, and differing stimulus materials (fictional materials to classroom concepts).…”

Cultural and learning differences in the Judd illusion

“…The two groups differed, however, in their propensity to learn to perceive the midpoint of the line. First, although both the East Asians and Westerners clearly profited from feedback in order to reduce the illusory bias (see Brosvic & Cohen, 1988), the Westerners did so at a much faster rate. Even so, this difference between the two feedback groups had disappeared in the posttest.…”