Abstract
A visual division characteristics of an interval between two scale lines (visual interpolation) is experimentally studied. Two scale lines are displayed on CRT and subjects are required to divide them into 10 equal intervals and to read the position of a pointer which appears between the scale lines randomly.
In the first experiment, the subjects answer if the pointer is on one of the 10 equally devided positions. After 2250 trials, it is found that at the positions of 3/10, 4/10, 6/10 and 7/10, the readings are less accurate than the others (i.e. 1/10, 2/10, 5/10, 8/10 and 9/10) and are closer to the center than the pointer positions. In the second experiment, the subjects are required to round off the positions of the pointer to the 10 equally devided positions (round off task). Each subject has 4000 trials. They seem to image the third scale line at the midpoint of the scale lines, and their readings deviate to the nearest scale line.
