Rectangular Stainless Steel Depth Perception Apparatus, Color : Black

The three needle apparatus has been widely used in studies of Depth Perception Apparatus. This consists of an elongated box which conceals inside three vertical rods or pins. These pins can be seen by a subject through a small window and the inside of the box is illuminated. Two of these rods are fixed and the one in the middle is movable,resting on a pulley bottom wheeled on a rod running completely across the length of the box. A meter -scale is fixed to the groove like opening on the top so that the exact position of the movable rod can be read.