Held et al. (1979) Vision Res. 19, 1377-1379, have recently provided evidence for the existence of non-monotonic psychometric functions in infant acuity testing. We argue that these non-monotonicities are statistically significant in the original report, but are not robust across small variations of stimuli and testing techniques. The existence of such non-monotonicities in some laboratories does not imply that infant acuity has been universally underestimated by all PL techniques, nor does it argue against the general sensitivity of PL techniques as measures of other visual capacities in infants. © 1982.