From retina to response: contrast sensitivity and memory retrieval during visual word recognition.

Twenty-four young adults (M = 19.5 years) and 24 older adults (M = 68.4 years) performed a word/nonword classification task (i.e., lexical decision) in which a single letter-string was presented on each trial. Estimates were obtained of the time required to retrieve information regarding the orthography (pronounceability) and meaning of the letter-string. A measure of subjects' spatial resolution ability (contrast sensitivity) was also obtained. In the lexical decision task, the older adults' word recognition speed was slower than that of the young adults overall, but there was no age-related slowing associated specifically with the retrieval of either orthographic or semantic information. The similarity of the two age groups' retrieval estimates was independent of whether a manual or vocal response was required. An age-related change in the shape of the contrast sensitivity function was present. The age differences in the speed of word recognition, however, were not attributable to contrast sensitivity.