Date of Award

Summer 5-1977

Document Type


Degree Name

Master of Science (MS)


Most people when viewing horizontal-vertical lines of equal length, judge the vertical line as longer than the horizontal line. The relationship R = f(S) has been extensively studied in an attempt to explain the horizontal-vertical illusion (HVI). An adequate explanation has not been proposed, The present study approached the phenomenon of the illusion with the relationship R = f(0). The problem was to determine if aggressiveness was a significant factor in judgments of the HVI. The Edwards Personal Preference Schedule (EPPS) was used to define and measure aggression in forty students at Missouri Southern State College, Joplin, Missouri. The hypothesis was: There will be no significant difference between the horizontal-vertical illusion scores of aggressive and less aggressive persons. Eight students were randomly drawn from a sub-population of aggressive persons and were defined as the aggressive group. Eight more students were randomly drawn from a sub-population of less aggressive persons and defined as the less aggressive group. A students score was defined as the number of judgments made about the lengths of vertical and horizontal lines which did not conform to the actual physical lengths of the two lines. Judgments made about vertical and horizontal lines of equal length were not counted in scoring. The independent variable was the classification of students into aggressive and less aggressive groups. The dependent variable was judgments made about the lengths of two lines. It was found that the aggressive persons made significantly more wrong judgments on the illusion than did less aggressive persons, t(1.4) = 2.97, p


v, 45 leaves : ill. ; 28 cm. Bibliography: leaves 40-45


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