Assessment of vernier acuity development using the “Equivalent Intrinsic Blur” paradigm

Vernier acuity in human infants is more than two orders of magnitude poorer than in adults and does not appear to reach adult levels until well beyond the first postnatal year. One source of these developmental differences in vernier acuity may be the presence of levels of intrinsic blur that are higher in infants than in adults. We investigated this hypothesis by measuring vernier acuity in 3-month-olds, 5-month-olds, and adults using stimuli blurred by two-dimensional Gaussian filters. Experiment 1 showed that more stimulus blur is required to degrade vernier acuity in infants than in adults. From these data we estimated that the level of equivalent intrinsic blur for this vernier acuity task decreased by approx. 1.5 log units between 3 months of age and adulthood. These results also suggested that this reduction of equivalent intrinsic blur can account entirely for the improvement in vernier acuity between 3 and 5 months postnatal. However, the large further improvement which occurs between 5 months of age and adulthood cannot be explained solely by equivalent intrinsic blur. In Expt 2, we measured vernier acuity in 3-month-olds and adults using a non-blurred stimulus with the same luminance contrast as the most-blurred stimulus used in Expt 1. Infants' and adults' thresholds were degraded slightly, relative to the non-blurred stimulus from Expt 1, but still were significantly better than the most blurred condition of Expt 1. This suggests that the results from the first experiment were not due simply to the reduction in overall luminance contrast which occurs when stimuli are blurred.

[1]  D. Teller.  The forced-choice preferential looking procedure: A psychophysical technique for use with human infants. , 1979 .

[2]  K. W. Cattermole.  The Fourier Transform and its Applications , 1965 .

[3]  D. G. Green,et al.  Optical and retinal factors affecting visual resolution. , 1965, The Journal of physiology.

[4]  Bart Farell,et al.  Vernier acuity: Effects of chromatic content, blur and contrast , 1991, Vision Research.

[5]  Manfred Fahle,et al.  The development of vernier acuity in human infants , 1991, Vision Research.

[6]  Hugh R. Wilson,et al.  Responses of spatial mechanisms can explain hyperacuity , 1986, Vision Research.

[7]  H. Loos,et al.  Synaptogenesis in human visual cortex — evidence for synapse elimination during normal development , 1982, Neuroscience Letters.

[8]  Anthony M. Norcia,et al.  Development of contrast sensitivity in the human infant , 1990, Vision Research.

[9]  R. Watt,et al.  Spatial filters and the localization of luminance changes in human vision , 1984, Vision Research.

[10]  Colin Blakemore,et al.  Vision: Coding and Efficiency , 1991 .

[11]  Shinsuke Shimojo,et al.  Development of vernier acuity in infants , 1984, Vision Research.

[12]  B. Skottun,et al.  Effects of contrast and spatial frequency on vernier acuity , 1987, Vision Research.

[13]  A. Hendrickson,et al.  A qualitative and quantitative analysis of the human fovea during development , 1986, Vision Research.

[14]  J. A. Foley-Fisher,et al.  Contrast, Edge-gradient, and Target Line Width as Factors in Vernier Acuity , 1977 .

[15]  R. Bracewell.  The Fourier Transform and Its Applications , 1966 .

[16]  Shinsuke Shimojo,et al.  Vernier acuity is less than grating acuity in 2- and 3-month-olds , 1987, Vision Research.

[17]  Robert F. Hess,et al.  Is the increased spatial uncertainty in the normal periphery due to spatial undersampling or uncalibrated disarray? , 1993, Vision Research.

[18]  Hugh R. Wilson,et al.  Development of spatiotemporal mechanisms in infant vision , 1988, Vision Research.

[19]  M S Banks,et al.  Infant pattern vision: a new approach based on the contrast sensitivity function. , 1981, Journal of experimental child psychology.

[20]  H B BARLOW,et al.  Increment thresholds at low intensities considered as signal/noise discriminations , 1957, The Journal of physiology.

[21]  J. Lewis,et al.  Probit Analysis (3rd ed). , 1972 .

[22]  R E Manny,et al.  The development of vernier acuity in infants. , 1984, Current eye research.

[23]  Dennis M. Levi,et al.  Equivalent intrinsic blur in spatial vision , 1990, Vision Research.

[24]  R. J. Watt,et al.  Regional distribution of the mechanisms that underlie spatial localization , 1990, Vision Research.

[25]  Andrew D. Carkeet,et al.  Amblyopia: a consequence of abnormal visual development , 1993 .

[26]  D. Pelli.  The quantum efficiency of vision , 1990 .

[27]  Dennis M. Levi,et al.  Equivalent intrinsic blur in amblyopia , 1990, Vision Research.

[28]  H. Barlow.  Retinal noise and absolute threshold. , 1956, Journal of the Optical Society of America.

[29]  R. J. Watt,et al.  Spatial information and uncertainty in anisometropic amblyopia , 1987, Vision Research.

[30]  Richard N. Aslin,et al.  Spatiotemporal factors in infant position sensitivity: Single bar stimuli , 1992, Vision Research.

[31]  F. Campbell,et al.  Optical quality of the human eye , 1966, The Journal of physiology.

[32]  M. Banks,et al.  Optical and photoreceptor immaturities limit the spatial and chromatic vision of human neonates. , 1988, Journal of the Optical Society of America. A, Optics and image science.

[33]  M S Banks,et al.  Acuity and contrast sensitivity in 1-, 2-, and 3-month-old human infants. , 1978, Investigative ophthalmology & visual science.

[34]  S. Klein,et al.  Positional uncertainty in peripheral and amblyopic vision , 1987, Vision Research.