October 2003
Volume 3, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   October 2003
Greater immaturity in sensitivity to second-order gratings than to first-order gratings during infancy
Author Affiliations
  • Terri L. Lewis
    Department of Psychology, McMaster University, Hamilton, Canada
  • Vikas C. Bhagirath
    Department of Psychology, McMaster University, Hamilton, Canada
  • Dave Ellemberg
    McGill Vision Research, McGill University, Montreal, Canada
  • Daphne Maurer
    Department of Psychology, McMaster University, Hamilton, Canada
Journal of Vision October 2003, Vol.3, 530. doi:10.1167/3.9.530
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      Terri L. Lewis, Vikas C. Bhagirath, Dave Ellemberg, Daphne Maurer; Greater immaturity in sensitivity to second-order gratings than to first-order gratings during infancy. Journal of Vision 2003;3(9):530. doi: 10.1167/3.9.530.

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Abstract

PURPOSE. To study the development of sensitivity to first- and second-order gratings by measuring thresholds for the detection of motion in 3-month-olds, 5-year-olds, and adults. METHODS. Subjects (n = 24/age) saw two 15 × 15° vertical 0.5 c/deg sine-wave gratings that were separated horizontally by a 5 gap. The gratings were added to (first-order condition) or multiplied with (second-order condition) binary noise. Randomly, on each trial one of the gratings was stationary and the other moved outward at 6 deg/sec. Amplitude modulation was varied over trials. For babies, we used the method-of-constant stimuli and data from 16 trials per baby to calculate two group thresholds, one for first-order gratings and one for second-order gratings. On each trial, a trained tester who was unaware of the side of motion decided whether the moving grating was on the left or right based on any reliable cues provided by a baby (direction of first look, of longest look, etc.). The group thresholds from babies were compared to the mean individual thresholds from 5-year-olds and adults who, on each trial, indicated which side had the moving stripes. RESULTS. Thresholds for infants were far more immature for second-order gratings (2.5 times worse than adults) than for first-order gratings (1.09 times worse than adults). However, by 5 years of age, thresholds were close to adult levels (1.03 and 1.09 times worse than adults for first-order and second-order gratings, respectively) and were no more immature for second-order than for first-order gratings (p > 0.05). CONCLUSIONS. During early infancy, the neural mechanisms that detect second-order gratings are especially immature compared to those that detect first-order gratings. By 5 years of age, at least under the present testing conditions, mechanisms detecting second-order gratings are almost adult-like and are no less mature than those detecting first-order gratings.

Lewis, T. L., Bhagirath, V. C., Ellemberg, D., Maurer, D.(2003). Greater immaturity in sensitivity to second-order gratings than to first-order gratings during infancy [Abstract]. Journal of Vision, 3( 9): 530, 530a, http://journalofvision.org/3/9/530/, doi:10.1167/3.9.530. [CrossRef]
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