Zllusory conjunctions. If focused attention to particular objects isprevented, either because time is too short or because attention is directedto other objects, the features of the unattended objects are “freefloating” with respect to one another. This allows the possibility of incorrectcombinations of features when more than one unattended object ispresented. Such “illusory conjunctions” have been reported. For example,the pitch and the loudness of dichotic tones are sometimes heard inthe wrong combinations (Efron & Yund, 1974), and so are the distinctivefeatures of dichotic syllables (Cutting, 1976). In vision, subjects sometimeswrongly recombine the case and the content of visual words presentedsuccessively in the same location (Lawrence, 1971). Treisman(1977) obtained a large number of false-positive errors in a successivesame-different matching task when the shapes and colors of two targetitems were interchanged in the two test stimuli. Each such interchangealso added a constant to the correct response times, suggesting that theconjunction of features was checked separately from the presence ofthose features.