History

     Donald Broadbent was born on May 6, 1926 in Birmingham, England to a wealthy stable family. This would later change when Broadbent reached the age of thirteen. His parents decided to get a divorce, moving Broadbent to Wales. After winning a scholarship he completed his schooling at a prestigious English independent school.

     In his teens, Broadbent was intrigued by flying and volunteered to join the Royal Air Force. During that time, he watched and noticed problems between the communication lines that often came from psychological causes. The main issue was not the equipment, but the processes of attention, perception, and memory of the individuals using the equipment. One example that Broadbent used to show the importance of the psychological processes in practices was stated by Dianne Berry, a long time colleague:

“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).”

     After noticing this problem happening often, Broadbent changed his focus away from physical sciences and moved towards psychology.

     Broadbent finished his time in the service and then began his studies at Cambridge’s psychology department. He found his calling in the Applied Psychology Unit. He would become the director in 1958 and stay for sixteen years. Most of Broadbent work was directed at the practical issues with the military, however, Broadbent quickly became well known for his theoretical work. Two of his theories, selective attention and short term memory, were developed just as digital computers were becoming available. These studies were among the first to use computer analogies to make a dramatic contribution for analysis of human cognition. Broadbent would also write a book, Perception and Communication, in 1958 which would become a text used in cognitive psychology for many years to come.

     By 1974, Broadbent would move further up in his career field by becoming a fellow at Wolfsan College, Oxford University where he would return to applied problems. Along with his colleague Dianne Berry, Broadbent would develop multiple new ideas about implicit learning from consideration of human performance in complex industrial processes (Berry,2002). He continued with this work until he retired from his position in 1991.

      Donald Broadbent died on April 10, 1993.

 

Work

     Best known for his contribution to the development of cognitive psychology, Broadbent wrote his book, Perception and Communication. His book has been rated "the single most influential book in the history of cognitive psychology" (Parasuraman,1996). Broadbent was the first to put together work on information processing with the problem of attention. This was a drastic move for psychology at the time because behaviorism was the dominant theory 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).

      During his entire career, Broadbent never abandoned practical problems. One example was that he studied problems that were caused by communication with gunnery and air control systems; there were too many communication channels at one time. Broadbent worked nonstop to fix the gap between the laboratory and the field. He constantly worked on topics like these or any that had significance for people and society.

 

Experiment: Dichotic Listening

     “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.”(New world encyclopedia,2011)

     Broadbent decided to extend this work by creating the “Dichotic Listening” experiment. The subjects in these studies were asked to listen to and separate different speech signals presented to each ear simultaneously (while wearing headphones). One example is there were three pairs of different digits that were present simultaneously, three digits in one ear and three in the other ear. It was stated that most participants in the study could recall the digits ear by ear, rather than pair by pair. Meaning if 496 were the digits presented in one ear and 852 in the other, the recall would be 496-852 rather than 48-95-62. After reviewing the results, Broadbent decided 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, for example the location.

      Multiple experiences were done with the subject’s ability to answer one of two questions asked at the same time. The subjects, with prior knowledge of which questions they should pay attention too, scored around 48 percent accuracy. Those subjects informed after the questions had been given had almost a zero percent accuracy rate. This case was an instance of selection in perception, also known as attention. The visual cue to the correct voice was useless when it arrived towards the end of the message. It became clear that the process of leaving out part of the information contained in the mixed voices had already taken place. It seemed possible that one of the two voices was selected for response without reference to its correctness and that the other was ignored. If one of the two voices was selected, or paid attention to, in the resulting mixture there was no guarantee that it would be the correct one. Also both call signs could not be perceived at once any more than both messages could be received and stored till a visual cue indicated that one to be answered. (Broadbent,1952)

 

Experiment: Filter Model of Attention

     The second experiment Broadbent is known for was developed by his theory of selective attention. This was based on his and other researchers’ experimental findings that used the information processing model. There are four main points to this experiment:

-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.

 

     “The point of this theory is 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. It explains both Cherry’s and Broadbent’s experimental findings of unattended messages that are rejected by the filter and thus receive very little processing. Dealing with the cocktail party, hearing one’s name spoken by anyone in the room leads to a switching of attention to that speaker. This theory 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).

     Broadbent’s 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). Typical of Broadbent’s approach to scientific research, he regarded all theories as temporary accounts of the current information that would likely need revision and improvement when new data emerged.

In conclusion, Donald Broadbent had a remarkable impact in cognitive psychology. He not only developed two of the main experiments to help develop the research in this area, but his book, Perception and Communication, is still used as the main educational guide to cognitive theories. There are numerous questions that remain unanswered in the psychology field, but because of Broadbent’s contributions we are one step closer to discovering the mysteries of cognitive psychology.

 

Resources

 

Broadbent, D. (1958). Perception and communication. New York: Pergamon Press.

 

Donald, B. (2011, October 31). Retrieved February 8, 2015, from             http://www.newworldencyclopedia.org/entry/Donald_Broadbent