Abstract
Abstract: :
Purpose: To determine the feasibility of using two tablet computers for preferential looking studies of visual capabilities of infants. The computers have the advantage that they are compact (5 cm thick), have back–lighting, and use liquid crystal displays, which have perfect geometry and perfect focus. Methods: Two 210 mm by 158 mm Compaq tablet PC computers (TC1000) were mounted so that the computer screens were located at the right and left sides, respectively, of the window in a Teller Acuity Card stage. Separation between the inner edges of the two computers was 14 cm to permit an observer to position his/her head between the computers. A gray cardboard mask mounted behind the window in the Teller stage contained two 11.5–cm diameter circular apertures, one in front of each computer display, and a centrally–located 7 mm peephole. Pilot testing was conducted with infants between 2 and 11 months of age, using grating stimuli of various spatial frequencies paired with a gray stimulus (a checkerboard composed of adjacent 1–pixel–wide black–and–white checks). Results: Reliable preferential looking responses sufficient to allow measurement of visual acuity were observed in infants less then 6 months of age. Older infants, however, tended to look alternately between the two computer screens without showing a reliable preference for either screen. Conclusions: Although preferential looking responses can be obtained in young infants with this apparatus, additional strategies, such as increasing the salience of the target stimulus or decreasing the salience of the non–target stimulus, may be needed to permit testing of older infants.
Keywords: infant vision • clinical laboratory testing • visual acuity