On voluntary ocular accommodation

Young observers were challenged to induce a marked monocular accommodative response to a relatively weak accommodative stimulus by placing a-9 diopter contact lens on the eye. At first, observers could not produce the desired response, but with training, three of four subjects achieved criterion. Both a voluntary accommodative response and a response to an adequate accommodative stimulus were apparently involved. The voluntary component of the response could be demonstrated by having the observers repeat the task in total darkness.