Lecturer's Précis - Craik (1945)

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First published online 13:44 GMT 1st March 2002, Copyright Derek J. Smith (Chartered Engineer). This version [HT.1 - transfer of copyright] dated 12:00 13th January 2010


Craik's (1945/1966) "Neural Geography" Cognitive Hierarchy

Kenneth J.W. Craik (1914-1945) was one of the first scientists to realise that many of the principles of brain function are common to all information processing systems, including machines. During World War II, he worked at Cambridge University on a succession of War Department human performance projects, and soon came to see what he later called the "human operator" as an internally hierarchical part of an equally complex external command and control hierarchy. (He was therefore one of the first to attempt to put the human being "into the loop" of system control.) Here is how he saw that internal control hierarchy:

Craik (1945): Here is Kenneth Craik's version of the classical three-layer cognitive hierarchy. It consists of two distinct sensory-motor levels - a lower one handling spinal reflexes, and a higher one handling more complex learned associations - topped by an upper loop controlling willed action (just like James' "hemispheric loop line"). He used the diagram to help him address two "great problems" (p82), namely (a) identifying the biological mechanism of establishing new learned connections, and (b) identifying the neural pathway(s) in which (a) took place. He referred to the latter as searching for the "'geography' of the new connections" (ibid.). Craik's model deviates from the pattern of the earlier models in two important respects. Firstly, it makes explicit the localisation of the conditional and spinal reflexes (red and blue arrows respectively), and secondly it allows streams of both sensation and motor activity to bypass Level 1 and enter Level 2 directly. Craik does this to help explain the "arpeggio paradox", Humphrey's (1927) observation that a response conditioned to a single tone is no longer elicited when that tone is incorporated into a tone sequence. 


Redrawn from a black and white original in Sherwood (1966:84, Figure 4). This version Copyright © 2002, Derek J. Smith.

NB: These arrows are clearly shown ascending in the Sherwood edition, but this does match the accompanying text, which indicates that they should be descending. It is not clear whether this is Craik's own error, or a editorial one.



Humphrey, G. (1927). The effect of sequences of indifferent stimuli on a reaction of the conditioned response type. Journal of Abnormal and Social Psychology. 22:194-212.

Sherwood, S.L. (1966) The Nature of Psychology: A Selection of Papers, Essays and Other Writings by Kenneth J.W. Craik. Cambridge: Cambridge University Press. [The diagram in question is taken from Sherwood's collation of an incomplete and unpublished draft manuscript of Craik's, provisionally entitled "The Mechanism of Human Action". Craik began work on this book around October 1943, and it remained incomplete at the time of his death in a road traffic accident on 7th May 1945. We have therefore been mildly presumptive in referring to the diagram as his "1945 diagram".]