Associationism

[4] Members of the Associationist School, including John Locke, David Hume, David Hartley, Joseph Priestley, James Mill, John Stuart Mill, Alexander Bain, and Ivan Pavlov, asserted that the principle applied to all or most mental processes.

In chapter 33 of An Essay Concerning Human Understanding, which is entitled “Of the Association of Ideas″, he describes the ways that ideas can be connected to each other.

[6] Locke's view that the mind and body are two aspects of the same unified phenomenon can be traced back to Aristotle's ideas on the subject.

[8] In his 1740 book Treatise on Human Nature David Hume outlines three principles for ideas to be connected to each other: resemblance, continuity in time or place, and cause or effect.

[6] Later members of the school developed very specific principles elaborating how associations worked and even a physiological mechanism bearing no resemblance to modern neurophysiology.

He was considered the first experimenter to apply the associationist principles systematically, and used himself as subject to study and quantify the relationship between rehearsal and recollection of material.