A failure to observe negative preference in infant acuity testing.

Held et al. (1979) Vision Res. 19, 1377-1379, reported that infants' psychometric functions in preferential looking experiments exhibit a region of below chance performance or "negative preference". They argued from this that previous preferential looking experiments may have systematically underestimated acuity because they ignored this negative preference. We present data from an experiment designed to reveal negative preference in the version of the preferential looking paradigm used in our laboratory. The results do not exhibit negative preference apart from random variations about 50%. Gwiazda et al. (1980) Am. J. Optom. physiol. Opt. 57, 420-427; 428-432, developed a psychophysical procedure for infant testing that is designed to yield accurate threshold estimates in a short period of time. We present the results of computer simulations of more conventional psychophysical procedures. The simulations demonstrate that an up-down staircase procedure is more efficient than the Gwiazda et al. procedure.