In previous studies, subjects generally underestimated the number of elements present in a display. To eliminate the range and intertrial effects that arise when several displays are judged in succession and that might have produced the underestimation, subjects in the present study judged only a single display. The single judgments fitted a power function having an exponent of .83, which is consistent with previous data. Single judgments of loudness, area, and duration, by contrast, have produced abnormally low exponents apparently because the built-in scale unit, or modulus, available on numerosity is lacking for other modalities. The tendency to underestimate numerosity was much stronger for female than for male subjects.