Comments on “selective attention: Perception or response?“ reply

We cannot understand why Treisman and Geffen (1967) think their experiment argues against our theory (Deutsch and Deutsch, 1963). Briefly, Treisman and Geffen ask subjects to repeat and tap to certain words in one message, played to one ear, and only tap to such words when they occur in another message played to the other ear. They find that subjects neglect the words to which they only have to tap. According to our theory, stimuli with a greater weighting of importance inhibit certain outputs (such as storage, motor response) of the structures processing stimuli with a lesser weighting of importance. Now it seems to be clear that Treisman and Geffen have by their instructions (to tap and repeat one set of words and only to tap to another set of words) produced a situation in which one set of stimuli is given a larger weighting of importance than the other. It is therefore not surprising on our theory that the less important set is almost disregarded. It is instructive here to consider Lawson’s (1966) very similar experiment. In this experiment the signals to which the subject has to tap do not also have to be repeated if they occur in the message which is being shadowed. (These signals are non-verbal.) Lawson’s results are almost the opposite of Treisman and Geffen’s, as would be expected from our theory. “I t seems that analysis of simple physical signals precedes both the selective filter and the analysis of verbal content in the perceptual sequence, that the bottle-neck in attention arises chiefly in speech recognition where of course the information load is usually much higher. To confirm the belief that the verbal content of the secondary message was not being analysed, we find no evidence whatever of interference from secondary target words when these received no tapping response.” (We quote the last sentence as just one example of the fact that Treisman and Geffen have failed to understand our theory. It is one of the major points of this theory to explain why “secondary” messages do not cause interference with the “primary” message while they are being analysed.) To return now to the subject of Lawson’s experiments, we would suggest that the outcome of such experiments would be the same if instead of signals, words were used in Lawson’s paradigm. These words should occur on both channels and should be distinguishable by another speaking voice. To make sure the subject is not simply responding to differences in timbre, pitch, etc., the target words should be interspersed with other words. Treisman and Geffen could not then postulate differences in information load to explain an unfavourable result. Treisman and Geffen have some difficulty in explaining the discrepancy.