1. 1.

    The movements of both distal eye stalks in the horizontal plane, elicited by optokinetic stimuli, have been recorded simultaneously.

  2. 2.

    A panorama was split into two separate halves and was either oscillated around the animal in a sinusoidal fashion or displaced in a stepwise manner. Both eyes could be stimulated independently.

  3. 3.

    The stimuli on both sides differed either (a) in the illumination, or (b) in the total amount of light impinging upon the eyes or (c) in the relative phase of the sinusoidal stimuli to either eye.

  4. 4.

    As the illumination decreases the optokinetic response weakens.

  5. 5.

    If one eye has no or only weak optokinetic input, it will be driven by the other eye. The response mediated by the contralateral optokinetic stimulus diminishes if the amount of light impinging upon the driven eye is increased.

  6. 6.

    There is a logarithmic relationship between the response of the driving eye and that of the driven eye.

  7. 7.

    The possible biological significance of these relationships is seen in the enhanced coupling at low light intensities.

  8. 8.

    The variable strength of coupling and possible roles of movable eyes are discussed.

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