Purpose. A challenging objective in the field of developmental psychophysics is to produce tests that are rigorous scientifically, but for practical application, are also simple, time-efficient, and portable. Based on the Teller visual acuity cards, we have developed a non-verbal test of contrast sensitivity (CS) for infants and young children. Although successful methodologically, the sine waves in our prototype test were difficult to reproduce and were susceptible to light damage and chemical leaching. Here, we report on a new, more precise version of the test.
Methods.Using new custom software and an advanced photo quality printer, sine wave gratings were printed on high resolution photographic paper. To produce a stimulus “card”, each test grating (16 deg at 60 cm) was mounted on acid-free foam core, adjacent to a second “control” grating with 0% contrast. There were 5 sets of 56 × 28 cm cards, each with gratings of either 0.75, 1.5, 3, 6, & 12 c/deg, and contrast ranging from 57% to 3.6%. FPL thresholds were obtained at each spatial frequency for 30 infants(M = 12 mo) and preschoolers(M = 3.5 yr).
Results. All preschoolers and most infants completed the test in less than 10 min, and all generated a CSF with the typical inverted U-shape. Mean CSFs for both groups were well within the range of previous FPL studies. Moreover, we produced two other new sets of cards which continue to replicate contrast levels to almost exact specifications. There has been no evidence of light damage or chemical leaching.
Conclusions. We have been able to develop a new set of CS cards with sine-wave gratings reproducible with greater reliability and durability. Moreover, these cards yield interpretable data from young children in a relatively short period of time. These are important steps in the goal of developing a universal, time-efficient psychophysical tool for assessing this critical aspect of vision in the pre-verbal child.
Natural Sciences & Engineering Research Council of Canada