DISTANCE AND AN ILLUSION OF LENGTH OF LINE

The apparent length of a line depends on the size of boxes placed at the ends of the line. This experiment showed that this dependence decreases as the boxes are separated from the ends of the line. As the boxes are separated farther from the ends of the line, the line is judged smaller. 9 undergraduates were Ss. The results fit a quantitative adaptation level formulation in which the height of the box and the distance from box to line are both factors in the adaptation level; and the weight of any factor, with respect to its effect on the test line, depends partly on how close that factor is to the test line. Thus, the adaptation level for a visual field is not a constant but a function of the field. (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.