Allocation of attention in dichotic listening: Effects on the detection and localization of targets within lists

In each of two dichotic listening experiments, 48 normal right-handed adult s were instructed to attend selectively to the left and right ears and to d ivide attention equally between ears. Participants listened for specified t argets and reported the ear of entry when the target was heard. Stimuli con sisted of lists of digit names in Experiment 1 and lists of words in Experi ment 2. Shifts of attention altered ear asymmetry for localizing but not fo r detecting digit names. For words, attention shifts altered both detection asymmetry and localization asymmetry, but the effect of attention on detec tion seemed to reflect differential retrieval from short-term memory rather than differential perception. In both experiments, shifting attention towa rd either ear resulted in a reporting bias such that signals were attribute d to the attended ear more often than to the unattended ear. The results co nfirm our previous findings, for single pairs of stimuli, that volitional s hifts of attention alter response selection rather than perception.