Wednesday, April 18, 2012

Miller (1920 - ) Magic number 7 plus & minus 2 - chunking

George Miller is best known for his paper ‘The magic number 7 plus and minus 2’ (1956) which focused attention (literally) on a problem that plagues teaching and learning, the danger of ‘cognitive overload’. For this reason alone, he deserves mention. Short-term memory has a limited capacity and this capacity can be seen as being dependent on ‘attention’ i.e. our ability to attend to things in short-term memory. More than this Miller was one of the first to bring in cognitive information theory, famously saying the the mind had been brought back into psychology on the back of the machine.
Miller started by identifying relevant studies that show we remember ‘chunks’ of information. But what is a ‘chunk’? We can remember, on average, seven randomised numbers but only six letters and four or five words. Miller’s solution was to posit clusters of chunks e.g. a word is a cluster of letters, a phrase a cluster of words. But Miller’s definition proved inadequate. This problem, that we remember different types of content differently giving variable sizes of chunks, was to open up a whole field of experimental work that began to reveal how short-term memory works. The concept of a ‘chunk’ has proved enduring and useful in memory research.
Encoding methods
Research by Bower (1970, 1972) showed that meaning also played a role in chunking so that, for example, TVFBIJFKCIAIBM is far more difficult to remember than TV FBI JFK CIA IBM. Mnemonics, as chunks, can also be used to unpack larger amounts of information. Gardener (1988) then showed the power of the ‘generative effort’, where creating your own chunks, is even more effective.
Of course, chunking is just one form of encoding that increases retention, the organisation of material is another, chunking categories logically and with relatively few numbers of items in each category, increases recall, as do outlines. Imagery is another useful form of encoding, which is why loci and peg-word systems have been used for centuries to improve memory. In particular, movement and interaction between images so that they do things to each other, were shown by Wollen, Weber & Lowry (1972) to be particularly effective. Craig & Lockhart (1972) popularised the word ‘elaboration’ for techniques such as paraphrasing, summarising, highlighting and note taking, all of which improve recall.
Miller’s work also led to research on the time we are able to hold attention in short-term memory. Waugh and Norman (1965) found, in recall experiments, that this was around 18 seconds. However, if recognition, and not recall, is used this can stretch out to 90 seconds (Lutz & Wuencsch 1989).
E-learning and chunks
E-learning, with its learning objects, nuggets and page-based delivery has long sought to chunk material to make it more digestible and to increase encoding and retention. Chunked media objects such as short videos, animations, examples and so on, have also been part of the e-learning landscape. Attempts have even been made to determine standards around reusable learning objects that can be re-assembled in different orders and in different contexts and courses, like LEGO. The problem is the conflict between usability and the flow and context of the learning experience on one hand, and the fragmented nature of chunked learning objects on the other. This has also led to standards such as SCORM, that some believe traps designers in to producing learning objects and does not cope with more complex entities such as simulation and games pedagogy.
Miller, a pioneer in the information processing or computational model of memory, set us on the path of defining the limits of short-term memory, the gate through which attentive learning must pass. It proved to be limited in time, capacity and the way we encode information. This has opened up research on cognitive overload and a deeper exploration of what we now call ‘working’ memory and encoding through elaboration. The magic number ‘7’ may have proved misleading, as our short-term register often operates at a lower 3-4 register level, but the principle of cognitive overload remains a limit on learning.
Miller, G.A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63, 81-97.
Miller, G.A., Galanter, E., & Pribram, K.H. (1960) Plans and the Structure of Behavior. New York: Holt, Rinehart & Winston.
Miller G Psychology Penguin
Bower G. H. (1970) Organisational factors in memory Cognitive Psychology, 1, 18-46
Bower G. H. (1972) Mental imagery in associative learning in Gregg L,W. Cognition in learning and memory New York, Wiley
Gardener (1988) Generation and priming effects in word fragment completion Journal of Experimental Psychology: Learning, Memory and Cognition 14, 495-501
Wollen, Weber & Lowry (1972) Bizarreness versus interaction of mental images as determinants of learning Cognitive Psychology, 3, 518-523
Craig F. I. M. & Lockhart R.S. (1972) Levels of processing: A framework for memory research, Journal of Verbal learning and Behaviour, 11, 671-684.
Waugh N. C. and Norman D. A. (1965) Primary Memory, Psychological Review, 72, 89-104.(1965)
Lutz J. & Wuencsch K.L. (1989) Acoustic interference in a recognition task. The Journal of General Psychology, 116(4), 371-384

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