Expanding the limits of the Teller Visual Acuity Cards.

A nomogram is presented that permits quick determination of Snellen visual acuity values for the Teller Visual Acuity Cards at distances up to 10 feet. With this nomogram, it is now possible to determine visual acuity in nonverbal populations, other than infants, while taking into account the effect of refractive error, especially myopia. The formula for constructing the nomogram is also included as generated by the Lotus 1-2-3 spreadsheet.

Spectral sensitivity in jumping spiders (Araneae, Salticidae).

1. We report here a psychophysical technique for studying the spectral sensitivity of jumping spiders (family Salticidae), based on a newly discovered oculomotor reflex. 2. Our results, obtained from Maevia inclemens (Salticidae), are compatible with electrophysiological findings of retinal cells maximally sensitive in the green and ultraviolet regions of the spectrum. 3. Sensitivity to longer wavelengths (greater than 650 nm) has been controversial. In our study jumping spiders are shown to have a broad spectral sensitivity function extending from the ultraviolet (330 nm) to the deep red (700 nm).