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Stimuli that intrude awareness

Neville Moray used Cherry's shadowed dichotic listening task in his 1959 research and was able to conclude that almost none of the rejected message is able to penetrate the block set up, except subjectively "important" messages. Personal names, taboo language, and backward language are the "subjectively" important messages that have been found to date.

Personal Names

Moray's 1959 well-known study of the "cocktail party phenomenon" found a 33% detection rate for personal names, which revealed that participants sometimes notice their name in an ignored auditory channel. This ability to selectively attend to one's own name has been found in infants as young as five months of age and appears to be fully developed by thirteen months of age. Rochelle S. Newman in a 2005 study found that five-month-old infants listened longer to their names when the target voice was 10dB, but not 5dB more intense than the background noise. Nine-month-olds also failed at 5dB, but thirteen-month-olds succeeded. This success in in recognizing one's own name in the unattended channel can be explained using Cherry's initial report on dichotic shadowing. Cherry found that the verbal content of the message in the unattended channel was completely blocked, so that the words were treated as merely sounds. This allows the subject to know that something has stimulated the ear whose message is rejected. It may be thought of as a general warning signal, that a sound has occurred to which the subject might need to respond.

Taboo Words

Sexually explicit information presented in the ignored channel has been found to exert influence on the processing of information in the attended channel. Taboo words presented in a shadowing task to newly admitted schizophrenics, neurotics, and healthy controls show that shadowing performances do not differ significantly between the different groups. All subject groups perform better when exposed to neutral irrelevant words in the unattended channel than to taboo words. When taboo words are presented in the ignored channel they seem to intrude upon awareness by triggering an attention alerting system that causes subjects to be certain the taboo words were present. If the taboo words did not intrude from the ignored channel, but were sometimes presented in the attended channel, subjects doubted they were present whether they had been present or not. These findings indicate sexually explicit material presented in the unattended channel reaches some level of semantic processing.

Backword Language

One of Cherry's conditions in the shadowed dichotic listening task was the change from ordinary English language to English played backward in the unattended channel. The change was generally not noticed, but a few subjects indicated the irrelevant channel had "something queer about it." Later studies done by Noelle L. Wood and Nelson Cowan showed that only subjects who shifted attention toward the unattended channel during the backward speech later recalled hearing it, causing dramatic shadowing errors. The change from normal speech to backward speech involves subtle physical changes and a dramatic semantic change, making it a borderline case. This fact has led Wood and Cowan believe that the backward speech condition may be of special interest because it may be near the threshold for detection of a change in the unattended channel.