A behavioral method for efficient screening of visual acuity in young infants. I. Preliminary laboratory development.

A technique for rapid behavioral screening of grating acuity in infants 1 to 4 months of age is described. The approach, called forced-choice preferential looking (FPL), depends upon the fact that normal infants will stare fixedly at acuity gratings with stripe widths above a rather abrupt cutoff width. The present task is to find the minimum stripe width, termed the diagnostic stripe width, to which infants with normal visual acuity will readily respond. The expectation is that infants with below-normal acuity will not be able to respond to diagnostic stripes so defined. To assess the feasibility of such a test procedure and define preliminary diagnostic stripe widths for infants 4, 8, 12, and 16 weeks of age, 76 presumptively normal infants were tested in the laboratory with a 40-trial FPL procedure. Sixty-nine infants (91%) completed the test procedure. For each age group, a preliminary estimate of the diagnostic stripe width was found. The group performance was uniformly high for the stripe widths designated as diagnostic and fell off sharply for finer stripes, confirming the feasibility of the approach.