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This study examined relations between eye movements and accuracy scores in a delayed matching-to-sarnple procedure with multiple sample stimuli. Four adult humans responded with high accuracy when there were 2 samples per trial. When the number of samples was increased to 4 per trial, accuracy scores fell to intermediate levels for 2 of the subjects, and then recovered to high levels following practice. Eye-tracking analyses showed that subjects with high and low accuracy on the initial 4-sample trials made similar numbers of observations per trial , but high-accuracy subjects exhibited longer sample-stimulus observing durations. Practice and improvement to high accuracy was accompanied by relatively small changes in observing frequencies and large increases in sample-stimulus observing durations. The results are discussed in terms of independent stimulus control of different aspects of observing behavior topography.