Efficiency of visual selection in duplex and conjunction conditions in partial report

Factors that determine the efficiency of visual selection were investigated in two precued partial-report experiments. There were four selection conditions: acolor condition (e.g., selecting purple letters among blue letters), aclass condition (e.g., selecting letters among digits), aduplex condition (e.g., selecting purple letters among blue digits; that is, the targets differed from the distractors both in color and in alphanumeric class), and aconjunction condition (e.g., selecting purple letters among blue letters and purple digits; that is, the targets differed from the distractors either in color or in alphanumeric class). The efficiency of visual selection was highest in the duplex condition and lowest in the conjunction condition. Thedifference in performance across the different selection conditions within subjects was accounted for by variation in the value of a single parameter of the fixed-capacity independent race model (FIRM) proposed by Shibuya and Bundesen (1988), which assumes independent parallel processing, limitations in both processing capacity and storage capacity, and time-invariant selectivity. By assuming that the factors that determine the efficiency of selection in the color and class conditions also underlie the efficiency of selection in the duplex and conjunction conditions, an extension of FIRM, FIRM+, accounted for therelationship with respect to efficiency of selection among the different conditions.