Peripheral processing, as defined by Turvey (1973), was investigated in a study of binocular backward masking involving random visual noise. For young (mean age 20.3 years) and old (mean age 55.4 years) adults, processing time (represented by stimulus onset asynchrony, SOA) was characterized as a power function of target energy (TE) (i.e., TEb x SOA = K). Over a wide range of target energy levels, processing time showed a similar rate of decline (similar exponent, b) for both age groups with increasing target energy. However, old subjects processed targets more slowly at all target energy levels (different constant, K), and this age difference was constant across all target energy levels. Results were independent of variables such as sex, education, response criterion, unmasked threshold, and method of determining stimulus onset asynchrony.