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February 1957


Author Affiliations

Human Engineering Branch Medical Research Laboratory U. S. Naval Submarine Base New London, Conn.

AMA Arch Ophthalmol. 1957;57(2):312-314. doi:10.1001/archopht.1957.00930050321027

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To the Editor:  —Replying to Drs. Shipley and Walker, I wish briefly to say:

  1. Shipley and Walker claim that work done in the darkroom alleys cannot be said to have been carried out under scotopic conditions.

    Reply: Unquestionably, points of light in a darkroom are perceived by the foveal cones, but a few points of light in a wholly dark surround do not prevent scotopic adaptation (the stars are seen at night with dark-adapted eyes). Therefore, experiments with darkroom alleys involve foveal (cone) perception by eyes which are in a state of scotopic adaptation—a complex which has not been sufficiently examined by darkroom experimenters. However, I have no objection to using the term darkroom alleys and have in general used this term in my article.

  2. Shipley and Walker claim I conclude that the white lighted and darkroom alleys give the same results.

    Reply: Nowhere do I conclude that

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