Lecturer's Précis - James (1890)

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First published online 11:58 GMT 7th March 2002, Copyright Derek J. Smith (Chartered Engineer). This version [HT.1 - transfer of copyright] dated 09:00 13th January 2010


James's (1890) "Hemispheric Loop-Line" Omega

William James (1842-1910) trained originally as a physician, but gradually specialised in philosophy and psychology. He founded the first North American experimental psychology laboratory at Harvard University in 1875, and between 1878 and 1890 wrote "The Principles of Psychology", soon to be recognised as one of the classical textbooks of psychological science. Here, from that textbook, is his attempt to provide what he called a "general notion" (p20) of the physiological layout of the nervous system. The resulting general notion is that "the lower centres act from present sensational stimuli alone; the hemispheres act from perceptions and considerations" (ibid.; italics original). Here is that notion, summarised graphically:

James (1890): Here is a nice metaphor for the three-layer omega. Circle C (green circle, central) represents the nervous system below the level of the cerebral hemispheres, and H (tan, top) represents the hemispheres themselves. There is a large and constant flow of information from the senses (bottom right) to C. This information is then analysed and used to support behaviour of the muscles (bottom left). James describes this basic biological layout as the "direct line". He then describes the hemispheres as adding a "long circuit" or "loop-line" "through which the [nervous] current may pass when for any reason the direct line is not used" (p21). We show the direct line as solid black lines, red arrowed, and the loop-line as dotted black lines, blue arrowed. James provided this diagram in an introductory context, so it does not pretend to be a precise engineering blueprint, merely an attempt to convey a complex principle as vividly as possible to newcomers to the subject. He therefore chose not to differentiate between higher (brainstem) and lower (spinal) reflex levels, which must both be seen as functions of Circle C.


Redrawn from a black and white original in James (1890:21, Figure 2). This version Copyright © 2002, Derek J. Smith.



James, W. (1890). The Principles of Psychology. New York: Holt.

Recommended Reading

"The Principles of Psychology"

James (1890/1995)

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