Modification of the infant contrast sensitivity card procedure

Drover, James R. (2000) Modification of the infant contrast sensitivity card procedure. Masters thesis, Memorial University of Newfoundland.

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Abstract

Recent attempts to measure spatial vision in infants have encountered serious drawbacks, such as the expense and sophistication of the equipment required, or the time necessary to complete the test. Adams, Mercer, Courage, and van Hof-van Duin (1992) have developed a prototype contrast sensitivity (CS) card procedure which sidesteps these problems, most notably test time. Despite its success, the prototype possesses several limitations which affect the accuracy and the efficiency of the procedure. -- In the present thesis, custom software and printing techniques were developed to construct a new set of CS cards which, compared to the prototype, contain four improvements: (1) Larger, more salient test gratings; (2) higher contrast "warm-up" cards in each spatial frequency set; (3) smaller contrast step size between adjacent cards; (4-) gratings mounted onto more durable backgrounds. The success of the new cards was evaluated by testing 3- and 12-month-old human infants and comparing the results to those obtained with the prototype cards. -- Results indicate that the new CS cards were very successful. Compared to the prototype, which required 10 to 15 minutes, the new card procedure was completed by most subjects within 5 to 8 minutes. Also, compared to the prototype, individual contrast sensitivity functions (CSFs) of 12-month-olds tested with the new cards are more typical of healthy infants as measured by more rigorous behavioral procedures. Surprisingly, however, group CSFs obtained with the new cards were lower than those obtained with the prototype, a discrepancy that may be due to differences in space average luminance between the two sets of cards. In all, the new CS card procedure possesses several merits which give it potential as a technique for widespread adoption by both researchers and clinicians.

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