Retest variability of human infant contrast sensitivity: how many tests are sufficient?
Retest variability of a new infant contrast sensitivity (CS) card procedure was assessed by binocular measurement of a group of 20 6-month-olds twice within a 1-week period. Coefficient of reliability analyses showed that within-subject variability between tests was only slightly less than variation across subjects, which suggests that results from a single test are a poor predictor of an infant's "true" visual functioning. To determine how many tests are needed to estimate when infant CS stabilizes to within an acceptable (0.15 log unit) criterion, a second experiment was conducted in which a small group of subjects was tested repeatedly over a 2-week period. The results showed that averaging performance on 2 to 3 tests was required before an accurate estimate of the subject's performance could be obtained. Our results suggest that caution should be taken in the interpretation of a single measurement of infant visual functioning.
Adams
R J
RJ
Department of Psychology, Memorial University of Newfoundland, St. John's, Canada. michelem@morgan.ucs.mun.ca
Courage
M L
ML
Drover
J R
JR
D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D014787:Vision Tests / Q000592:standards*; D015348:Vision, Binocular / Q000502:physiology