A laser-based technique for measuring accuracy and distortion in judgments of linear dimensions

A new technique is described that permits precise measurement of accuracy and distortion in judgments of linear dimensions based on either perception or memory. This technique involves the use of a single laser beam and a reference line placed on a projection surface. By rotating a laser device, the distance between the reference line and the point created by the beam may be continuously varied. This procedure avoids unintentional distortion from misjudgment of standard metrics, while the semicircular movement required by this technique eliminates body-referenced estimation and some other potential confounds. Potential applications to research in visual perception, spatial memory, and body image are discussed.