This pilot research will test the feasibility of introducing an innovative approach to infant visual acuity assessment--the orienting response as indexed by cardiac deceleration to a novel stimulus. The purpose is to determine whether high spatial frequency information that elicits visual evoked potentials (VEPs) in the primary visual cortex may also be available to response systems outside this brain area. The issue is important because VEP methods indicate rapid acuity development at the level of the primary visual cortex by age six months, while behavioral techniques, based on the infant's actual looking, suggest that high spatial frequency information is not """"""""used"""""""" at this age to direct behavior. The visual acuity of infants less than one year of age will be assessed by presenting gratings of varying spatial frequencies on a video monitor and measuring the resulting evoked responses from the primary visual cortex using scalp electrodes. Heart rate will be measured simultaneously.
The aim i s to demonstrate the feasibility of the procedures as the first step in a research program intended to help clarify the interpretation of VEP estimates of visual acuity and to possibly develop a simple orienting-response-based assessment procedure for clinical use with nonverbal humans.
