Scratch density differentiates microsmic from normosmic and anosmic subjects on the University of Pennsylvania Smell Identification Test.

During assessment of smell function using the University of Pennsylvania Smell Identification Test, we observed that some persons with diminished smell perception seemed to perserverate in their attempts to release the odorant from the microencapsulated odorant strips. In this study we quantified the marked area of 1680 such strips from tests administered to 42 anosmics, normosmics, and microsmics. The density of pixels on the microencapsulated labels from the microsmic patients was greater than that from the other two groups, which did not differ significantly from one another. These data suggest (i) that persons with diminished olfactory ability attempt to increase the perceived intensity of the stimulus by marking the test's scent strips more vigorously and (ii) that the density of such marking may prove useful in detecting malingerers attempting to feign microsmia.