An Age-decrement in the Ability to Ignore Irrelevant Information

• ESPONSES made by human beings typically concern circumscribed aspects of their en-vironments, and so are based upon a small frac-tion of the information simultaneously made available by their sense organs. This selectivity is a condition of survival, since urgent responses may be slowed by the consideration of irrele-vant information. Irrelevant perceptual input can be ignored by selecting between modalities. We may look or listen (Broadbent Gregory, 1961). Recent experiments have concerned selection between receptors in the same modality, particularly the ears (Broadbent, 1954; Treisman, 1961). Such selection is clearly central, and perhaps most interesting, when discriminations are made be-tween members of a set of complex stimuli which are all of the same kind. The example most frequently investigated has been the cocktail-party experiment (Cherry Taylor, 1953) in which Ss are required to discriminate between competing monologs, usually by re-peating one aloud and ignoring the other. Analogous situations occur in visual search, as when a crowd is scanned for a friend or when a particular word is sought in a diction-ary. Techniques for investigating performance in visual search allow the investigator to meas-ure the time taken to ignore irrelevant items