Abstract
Two psychophysical experiments were conducted on active tactual discrimination of line width using the method of constant stimuli with blind subjects. In Experiment I, 93 subjects made single judgments over each of five standards between 0.04 and 0.12 in. In Experiment II, 6 subjects were tested repeatedly over seven standards between 0.04 and 0.50 in. Over the range of standards common to both experiments, the Weber fractions decreased as the width of the standard increased. For two larger standards (0.25 and .50 in.), the Weber fractions approached asymptote and then increased respectively suggesting a U-shaped function. No differences in accuracy of discrimination were found between males vs. females, age groupings, or grade groupings.
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The authors extend their appreciation to Mr. George Whetstone. Superintendent of the W. Ross MacDonald School in Ontario. Canada, and to Mr. Will Evans. Superintendent of the Kentucky School for the Blind. We also extend our appreciation to Mr. John Siems. Assistant Data Processing Manager at the American Printing House for the Blind, for his aid in processing the data in this study, and Mr. Lawrence H. Butterfield. Jr., for drawing Figure I.
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Berla, E.P., Murr, M.J. Psychophysical functions for active tactual discrimination of line width by blind children. Perception & Psychophysics 17, 607–612 (1975). https://doi.org/10.3758/BF03203977
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DOI: https://doi.org/10.3758/BF03203977