Horizontal – Vertical Illusion Board (with stand) (Performance)

  This instrument is useful in studying the phenomenon of optical illusion. However, this instrument is used to study the effect of change in the method of presentation on the extent of illusion. This board will have a horizontal line and a vertical line exactly to the center of the horizontal line. However, the length of the vertical line can be adjusted by moving a slide provided. A metric scale is provided to measure the extent of estimation.