Manual anchoring biases in slant estimation affect matches even for near surfaces.
People verbally overestimate hill slant by ~15°-25°, whereas manual estimates (e.g., palm board measures) are thought to be more accurate. The relative accuracy of palm boards has contributed to the widely cited theoretical claim that they tap into an accurate, but unconscious, motor representation of locomotor space. Recently, it was shown that a bias that stems from anchoring the hand at horizontal prior to the estimate can quantitatively account for the difference between manual and verbal estimates of hill slant. The present work extends this observation to manual estimates of near-surface slant, to test whether the bias derives from manual or visual uncertainty. As with far surfaces, strong manual anchoring effects were obtained for a large range of near-surface slants, including 45°. Moreover, correlations between participants' manual and verbal estimates further support the conclusion that both measures are based on the same visual representation.
Department of Psychology, Ohio State University-Mansfield, 1760 University Drive, Mansfield, OH, 44906, USA. shaffer.247@osu.edu.
Dennis M
DM
Shaffer
Department of Psychology, Ohio State University-Mansfield, 1760 University Drive, Mansfield, OH, 44906, USA.
Eric
E
McManama
Department of Psychology, Swarthmore College, Swarthmore, PA, USA.
Frank H
FH
Durgin
D000328:Adult; D015982:Bias; D005260:Female; D006801:Humans; D008297:Male; D008369:Manual Communication; D011897:Random Allocation; D013028:Space Perception; D035501:Uncertainty; D014705:Verbal Behavior; D014796:Visual Perception
Action measures; Anchoring; Geographical slant; Two systems