Donald Broadbent

Donald Eric Broadbent (May 6, 1926 - April 10, 1993) was an influential British experimental psychologist, most famous for his work on attention. Broadbent helped nurture what was then the infant field of psychology in England, becoming famous worldwide for his groundbreaking theories and experimental work. His 1958 publication Perception and Communication was radical in its approach, taking the new field of information processing to model unobservable mental processes in a time when Behaviorism was dominant. His career and research work bridged the gap between the pre-Second World War approach of Sir Frederic Bartlett and its wartime development into applied psychology, and what from the late 1960s became known as cognitive psychology.

Broadbent's influence continues not just through his theories, which as he expected have been modified greatly through further research, but through his influence on numerous students and colleagues. His philosophy, scientific rigor, and good character impressed and inspired many to work towards the solution to real human problems even when they appear intractable. Broadbent joins the ranks of those who have contributed to better understanding of human nature.

Life

Donald Broadbent was born on May 6, 1926 in Birmingham, England. His family was quite well off financially. However, this changed when he was 13 and his parents divorced and his home moved to Wales. He won a scholarship to the prestigious Winchester College, an English independent school and completed his schooling there.

As a boy he was fascinated by flying, and at age 17 he volunteered to join the Royal Air Force (RAF). During his time in the RAF, he observed communication difficulties often arose from psychological, not physical, causes. In particular, he noticed that inefficient processes of attention, perception, and memory led to problems, rather than failures of technical equipment. An anecdote he often told to illustrate the importance of psychological processes in practice was recounted by his long-time colleague, Dianne Berry:

The AT6 planes had two identical levers under the seat, one to pull up the flaps and one to pull up the wheels. Donald told of the monotonous regularity with which his colleagues would pull the wrong lever while taking off and crash land an expensive aeroplane in the middle of a field (Berry 2002).

Having made this observation, Broadbent's interests began to zero in on psychology, rather than his previous interest in the physical sciences. Psychology had the "concrete" quality of the physical sciences but it could also shed light on human problems.

Broadbent spent a short time after the war working in the personnel selection branch of the RAF before beginning his studies at Cambridge's psychology department. Due to its natural sciences orientation and emphasis on practical application, Broadbent found Cambridge ideal. The department was headed by Sir Frederick Bartlett and was eager to apply newfound cybernetic ideals towards understanding human behavior, especially in terms of control systems, practical problems, and psychological theory in general. Broadbent found his place in the Applied Psychology Unit (APU) which had been set up there in 1944, by the UK Medical Research Council (MRC) on Bartlett's persuasion.

In 1958, Broadbent became director of the Unit, a position he held for 16 years. Although much of the work of the APU was directed at practical issues of military or industrial significance, Broadbent rapidly became well known for his theoretical work. His theories of selective attention and short-term memory were developed as digital computers were beginning to become available to the academic community, and were among the first to use computer analogies to make a serious contribution to the analysis of human cognition. His 1958 book, Perception and Communication, became one of the classic texts of cognitive psychology.

In 1974, Broadbent became a fellow of Wolfson College, Oxford University and returned to applied problems. There, together with his colleague Dianne Berry, he developed new ideas about implicit learning from consideration of human performance in complex industrial processes (Berry 2002). He continued this work until his retirement in 1991.

Donald Broadbent died on April 10, 1993.

Work

Donald Broadbent is best known for his contribution to the development of cognitive psychology. His 1958 book, Perception and Communication, has been rated "the single most influential book in the history of cognitive psychology" (Parasuraman 1996). Broadbent was the first person to bring together the work on information processing with the problem of attention, a radical move at a time when Behaviorism was the dominant paradigm in psychology. Broadbent used data from behavioral experiments and inferred (unobservable) functional stages of processing and their order of occurrence from these data. In so doing, he invented the modern study of attention (Berry 2002).

In all his work, Broadbent never abandoned practical problems. For example, he studied problems caused by communication with gunnery and air control systems, in which many channels of communication were delivered at one time. His work effectively bridged the gap between the laboratory and the field, constantly working on topics that had significance for people and society.

Broadbent contributed both experimental methods and theory to the world of psychology. His best known, and still widely used, method is the dichotic listening experiment, and his filter model of attention is his best known theory. Both were developed during his time at the Applied Psychology Unit in Cambridge University.

Dichotic listening experiments

Although most people spend their lives surrounded by many different types of stimuli, they cannot respond to or describe the majority of them. A practical example of this is found in the "cocktail party effect," described by Colin Cherry (1953) as the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations. Cherry conducted experiments in which subjects were asked to listen to two different messages from a single loudspeaker at the same time and try to separate them, repeating one but not the other, known as a "shadowing" task. His work revealed that our ability to separate sounds from background noise is based on the characteristics of the sounds, such as the gender of the speaker, the direction from which the sound is coming, the pitch, or the speaking speed. When the messages were similar in these characteristics subjects were unable to complete the task successfully.

Broadbent extended this work by devising what is known as the "dichotic listening" experiment. In these studies, subjects were asked to listen to and separate different speech signals presented to each ear simultaneously (using headphones). For example, in one experimental setup, three pairs of different digits were presented simultaneously, three digits in one ear and three in the other. Most participants in the study recalled the digits ear by ear, rather than pair by pair. Thus, if 496 were presented to one ear and 852 to the other, the recall would be 496-852 rather than 48-95-62.

From the results of such experiments, Broadbent suggested that "our mind can be conceived as a radio receiving many channels at once." The brain separates incoming sound into channels based on physical characteristics (such as location).

Other experiments were concerned with the subject's ability to answer one of two questions posed at the same time. Subjects with advance knowledge of which question they should attend to scored around 48 percent accuracy. Those informed after the questions had been given had almost no success:

The present case is an instance of selection in perception (attention). Since the visual cue to the correct voice is useless when it arrives towards the ends of the message, it is clear that process of discarding part of the information contained in the mixed voices has already taken place…It seems possible that one of the two voices is selected for response without reference to its correctness, and that the other is ignored… If one of the two voices is selected (attended to) in the resulting mixture there is no guarantee that it will be the correct one, and both call signs cannot be perceived at once any more than both messages can be received and stored till a visual cue indicates the one to be answered (Broadbent 1952).

Filter model of attention

Broadbent developed his theory of selective attention based on his and other researchers' experimental findings using the information processing model. The major points of his filter theory can be summarized as follows:

• Stimuli presented at the same time are held in a short-term sensory buffer. Information can be retained there for a short period before being processed; after that it disappears from the processing system.
• A filter selects one of the inputs on the basis of its physical characteristics, passing it through a limited capacity channel for further processing.
• The input selected by the filter is analyzed for semantic content (meaning) and comes into conscious awareness.
• Any stimuli not selected by the filter do not receive this semantic analysis and never reach conscious awareness.

This theory provides an explanation of the "cocktail party" phenomenon, since the voice that a person is attending to has different physical characteristics from those of other people in the room. No semantic analysis is necessary to differentiate them. It also explains both Cherry's and Broadbent's experimental findings—unattended messages are rejected by the filter and thus receive very little processing.

Later findings, however, raised problems for this "all-or-nothing" filter model. In terms of the cocktail party, hearing one's name spoken by anyone in the room leads to a switching of attention to that speaker. This implies that the content of the message was analyzed prior to the filtering, which was supposed to occur before such analysis. This paradox did not deter Broadbent, and he accepted such data as reason to revise his theory (Craik and Baddeley 1995). His second book on the topic, Decision and Stress (1971) began with his filter model and was modified "to accommodate new findings that the model itself had stimulated" (Massaro 1996). This was typical of Broadbent's approach to scientific research—he regarded all theories as temporary accounts of the current information, likely to need revision and improvement when new data emerged.

Legacy

A lecture in Broadbent's honor is given every year at the annual conference of the British Psychological Society. Broadbent gave the inaugural lecture in 1991. After his death in 1993, tributes and biographical acknowledgments were written in his honor. A special issue of Applied Cognitive Psychology, edited by his long time colleague, Dianne Berry, was written to commemorate his contributions (Berry 1995).

Broadbent is credited with being a major force in the development of cognitive psychology, particularly the study of attention. His 1958 book, Perception and Communication, is a classic that continues to inform the area today.

Broadbent’s contributions to experimental psychology were noteworthy not only for research on attention, but because they also contributed to belief in the need for societal relevance in research—that is, practical application. He believed wholeheartedly that research should not be driven solely by theory but should be guided by important practical problems, and conversely that experimental results should be used to modify theories (Parasuraman 1996). In addition, his informal speaking style and use of commonplace analogies to represent complicated ideas made him memorable to society as a whole, allowing people of all walks of life access to his theories. As noted by Craik and Baddeley (1995), Broadbent’s "psychology was intended for society and its problems, not merely for the dwellers in ivory towers."

His influence continues not just through his work but through the influence he had on numerous students and colleagues. He is remembered for the unmistakable image that he projected of himself, as “the man, the scholar, the scientist, the philosopher of science, and of his commitments to empirical psychology, to explicit models or theories, and to the application of psychological knowledge to real-word problems” (Massaro 1996). Unfailingly polite, helpful, and tolerant of the most naive questions posed by students, Broadbent was always approachable and generous with his time (Berry 2002). Yet he made a powerful impression on those who knew him, inspiring in them the conviction that good science would lead to solutions to real human problems.

Major works

• Broadbent, Donald E. 1952. Listening to one of two synchronous messages. Journal of Experimental Psychology 44: 51-55.
• Broadbent, Donald E. 1958. Perception and Communication. Elsevier Science Ltd. ISBN 0080090907.
• Broadbent, Donald E. 1961. Behavior. Basic Books. ISBN 0465005993.
• Broadbent, Donald E. 1962. Attention and the perception of speech Scientific American 206: 143-51.
• Broadbent, Donald E. 1971. Decision and Stress. Academic Press. ISBN 978-0121355500
• Broadbent, Donald E. 1973. In Defense of Empirical Psychology. Methuen young books. ISBN 041676780X.
• Broadbent, Donald E. 1993. The Simulation of Human Intelligence (Wolfson College Lectures). Blackwell. ISBN 0631185879.
• Broadbent, Donald E., and James T. Reason (eds.). 1990. Human Factors in Hazardous Situations. Oxford University Press. ISBN 019852191X.
• Pribram, Karl H., and Donald E. Broadbent (eds.). 1970. Biology of Memory. Academic Press, 1970. ISBN 0125643500.

References

ISBN links support NWE through referral fees

• Baddeley, Alan, and Lawrence Weiskrantz (eds.). 1995. Attention: Selection, Awareness and Control. A Tribute to Donald Broadbent. Oxford University Press. ISBN 0198523742.
• Berry, Dianne C. (ed.). 1995. Special Issue: Donald Broadbent and Applied Cognitive Psychology. Applied Cognitive Psychology 9(7): S1-S215.
• Berry, Dianne. 2002. Donald Broadbent. The Psychologist (15)(8) (August 2002): 402-405. Retrieved October 20, 2008.
• Cherry, Colin E. 1953. Some experiments on the recognition of speech with one and two ears. Journal of the Acoustical Society of America 25: 975-979.
• Craik, Fergus I. M. 2000. Broadbent, Donald E. Encyclopaedia of Psychology 1: 476-477.
• Craik, Fergus I. M., and Alan Baddeley. 1995. Donald E. Broadbent (1926-1993). American Psychologist 50(4): 302-303.
• Hothersall, David. 2003. History of Psychology. McGraw-Hill. ISBN 0072849657.
• Massaro, D. W. 1996. Attention: Yesterday, Today and Tomorrow. American Journal of Psychology 109(1): 139-150.
• Moray, N. 1995. Donald E. Broadbent: 1926-1993. American Journal of Psychology 108: 117-121.
• Parasuraman, Raja. 1996. Profiles in Psychology: Donald Broadbent. C S L Notes 20. Retrieved September 8, 2008.

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