The psychometric function of single-letter identification is typically described as a function of stimulus intensity. However, the effect of stimulus exposure duration on letter identification remains poorly described. This is surprising because the effect of exposure duration has played a central role in modeling performance in whole and partial…

Visual spatial attention can be exogenously captured by a salient stimulus or can be endogenously allocated by voluntary effort. Whether these two attention modes serve distinctive functions is debated, but for processing of single targets the literature suggests superiority of exogenous attention (it is faster acting and serves more functions).…

Secondary task performance was used to evaluate the attentional demands of encoding the first letter in a sequential letter-match task. Unlike earlier studies, comparing secondary task performance between two primary task conditions indicated that letter encoding involves attention. Performance during the intertrial interval varied with subjects'…

In two experiments, a probe technique required subjects to respond when the digit 7 appeared in one of five-letter positions in words or nonwords, inserted at the onset and 500 msec after letter and word processing. The focus of attention given to a letter has a smaller spatial extent. (Author/CM)

In four experiments, college students were presented with lists of either Armenian or English letters on a tachistoscope. The data indicate that extensive practice may be a necessary condition for capacity-free processing but may not be a necessary condition for involuntary processing. (Author/RD)