The Neurophysiological Basis of Conditioning
With the passage of time Pavlov's method has become more and more influential in the field of physiological psychology and his terminology has found even greater application. A survey of Pavlovian classical conditioning would be incomplete without mentioning the relevant neurophysiological observations that have arisen in recent research. The first stage of research in this area was to retest Pavlov's basic hypothesis on the role played by the cerebral cortex. This was followed by an attempt to determine the role of the various cerebral structures in conditional reflex formation and to establish the electroencephalographic correlates of conditional responses. Experimental studies since the 1930's have shown that, contrary to Pavlov's belief, the cerebral cortex is not essential for conditioning. However, as Hilgard and Marquis pointed out, its importance does increase throughout the phylogenetic scale. Pavlov thought of conditioning in terms of the spread of fields of cortical excitation and inhibition.