The Frisby Stereotest has three transparent plates. One of these is shown on each presentation to the subject. The box is for storing the plates. The box also has a fold-out flap for providing a clear background against which the plates are presented.
The three plates are of differing thickness, 6mm, 3mm and 1.5mm. Thus they present different sizes of disparity cues, thereby enabling the stereoacuity of the observer to be measured. The plates can be presented at differing distances to further vary the disparity cues.
A table in the box lid and in the Instructions Booklet shows disparities for each plate in the 40-80cm viewing distance range. A measuring tape is provided to assist in controlling eye-to-plate distance.
Ref Code: FRIS
The Frisby Screening Test is particularly useful where language barriers can create difficulties in communication. The test is just shown to the subject by opening the presentation box, and a spontaneous pointing or looking response can be sufficient to establish that stereopsis is present.
The Frisby Pocket Stereotest is used to screen for stereopsis.