Testing the Ocular Dominance of Infants
- Author:
Norma V. Scheidemann
University College, University of Southern California and Gladys E. Robinette Director and Teacher of Child Development, John Muir Pre-School, Pasadena, California
The normal individual by nature is either right or left-sided. One side of the body seems to be used in preference to the other so that the individual is dextro-expert in regard to hand, eye, foot, ear, nose, and so on, or he is sinistro-expert.1 The native dominance of one of these factors may, then, be considered an index to the native sidedness of an individual. Of these various factors, native eyedness is the one most readily discoverable and the most reliable, since it is not affected by training. Handedness often is influenced by extraneous conditions and is subject to training hence cannot be taken as an index of native sidedness. The discovery of the dominance of other factors entails too much labor to be practical. Clinical diagnosis often requires the determination of an individual’s native sidedness, and at present the simplest way of determining this is to determine ocular dominance. Several commercial tests for ocular dominance are on the market, but the paperhole test is much simpler and is wholly satisfactory since it comprises the principles underlying the commercial tests. This test is no more than a sheet of paper in which a small hole (about onehalf inch in diameter) is cut. The paper is held about fifteen or twenty inches from the eyes of the subject, and the subject is required to look through the hole at a small object about twelve inches on the opposite side of the hole. When the subject has fixated the small object the subject’s head and the paper are held steady while the subject’s right eye is covered. If the subject then fails to see the small object, he is right-eyed; if he still sees the object, he is left-eyed. With a little practice the experimenter will be able to observe which eye the subject uses in fixating the object. When the writers found this test wholly satisfactory in testing 1 Gould, G. M., Right-Handedness and Left-Handedness, J. B. Lippincott Company, 1908, pp. 18-20.
kindergarten and pre-school children, they wondered whether it would be possible to discover the eyedness of infants. After some experimentation a satisfactory method of procedure was developed that seemed to be satisfactory for infant testing. A large cardboard with a small hole in it was first placed in the child s hands. Usually he proceeded to stick a finger through the hole. The experimenter then took the cardboard and tried to induce the child to play “peek-a-boo” through the hole or asked Where s the block ?’’ while holding a brightly colored block at some distance in back of the hole. In some cases the child’s attention was attracted to the hole and cooperation was initiated by projecting a pencil through the hole and then withdrawing it slowly while the child watched it. A small pocket flashlight proved to be the best stimulus and was especially satisfactory in a dimly lighted room. A rattle was used for variety when there was difficulty in obtaining the child’s attention. When the child succeeded in fixating the object behind the hole it was possible to observe which eye he used from the position in which he held his head. This general procedure first was carried out with a child twentynine months of age. Attempts on two days were unsuccessful, but on the third day the child’s fixed attention and prolonged gaze through the hole that permitted the use of only one eye was taken to indicate that the light was fixated. In this case the child used his right eye. At varying intervals nine more trials were made; in each the child used his right eye.
Work with a twenty-seven months old child proved successful after the attempts on two preceding days were unsuccessful. In this case the child used her left eye. Repeated trials on three succeeding days found this child always used her left eye. She also reached for the light with her left hand, and tried to brush the card away with her left hand. When the mother was informed of this, she said that the child eats with her left hand and shows preference for it in many ways.
Efforts with infants twenty-four, twenty-three, and twenty-one months of age respectively proved to be successful, but no results were obtained with infants sixteen, twelve, and six months of age. At what particular age it is possible to obtain a child s attention so that this experiment may be successful is not known, but undoubtedly the age would vary with individual children. The work in this study shows that ocular dominance can be tested at a much earlier age than commonly is supposed to be possible. This fact may be found to have practical implications.
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