Abstract
When with six widely different figures subjects adjusted one 45° oblique bar or edge so that it appeared to be collinear with another, large misalignment errors of about the same size occurred in all figures, including one figure that consisted of two bars only (Experiment 1). When the ends of these bars were angled at 45° to their axes and vertical in the figure, the errors were consistently greater than when the ends were square and oblique in the figure (Experiment 2). As well as calling into question some recent explanations of Poggendorff-type misalignment effects, these results suggest an alternative, more general explanation in terms of physical misalignment relative to a figure axis. This axis can be defined by elongated bars or lines, the ends of oblique bars, the direction of movement of the adjustable bar, or a combination of these.
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This research was supported by a grant to R. H. Day from the Australian Research Council. The authors gratefully acknowledge the invaluable assistance given by Mike Durham, Rosemary Williams, and Vladimir Kohout in computer programming, illustration, and photography, respectively.
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Day, R.H., Stecher, E.J. Some variant forms of the Poggendorff illusion and their implications for an explanation. Bull. Psychon. Soc. 30, 26–28 (1992). https://doi.org/10.3758/BF03330387
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DOI: https://doi.org/10.3758/BF03330387