Purpose: To provide immediate feedback as to whether both eyes are turned on, whether they are pointed to the same place in space, and whether perception of where a target is matches its real location. Also, to increase familiarity with the feeling of converging and diverging, aiding conscious control of the process.

Materials: Brock String Doorknob or other Fixture

Procedure: 1. Tie one end of string to doorknob, screw eye, etc. Hold the string taut and with the other end on the bridge of the nose, directly between the eyes.

2. The helper should space the beads out along the string with a greater distance between the beads at the far end of the string than the nearer beads.

3. Give the patient the color of a bead to which they are to “jump” their eyes. Before jumping, while looking at another bead, the patient should use peripheral vision to see where the bead is that they are jumping to, plan the move in their mind first, then make the jump on the command “GO”.

4. Select a series of beads to which to “jump” the eyes. For example, red to green to yellow. Think about the pattern and plan ahead to know exactly where and which way the eyes will be moving.

5. On the command of the helper to “GO,” make the planned jump. Try to notice if the strings cross directly at each bead and make their “X.” The helper should watch the patient’s eyes to see if they move together and go to the proper places. Repeat several times using different sequences of beads.