Bias in spatial location due to categorization: Comment on Tversky and Schiano

B. Tversky and D. J. Schiano (1989) reported bias in reproducing the angle of a line in an ''ell'' frame. When no conceptual interpretation of the task was given, they argued that the bias was due to a perceptual process that produced an apparent tilt in the line (D. J. Schiano gr B. Tversky, 1992). We propose that J. Huttenlocher, L. V. Hedges, and S. Duncan's (1991) model of category effects on estimates of stimulus values provides a better explanation of this bias. Two experiments are presented that examine these alternative views. The results show effects of the orientation of the frame and of an interference task on bias that are more consistent with J. Huttenlocher et al.'s model than with the perceptual explanation adopted by D. J. Schiano and B. Tversky.