Associationism is the idea that mental processes operate by the association of one mental state with its successor states. It holds that all mental processes are made up of discrete psychological elements and their combinations, which are believed to be made up of sensations or simple feelings. In philosophy, this idea is viewed as the outcome of empiricism and sensationism. The concept encompasses a psychological theory as well as comprehensive philosophical foundation and scientific methodology. This view was then widely embraced until the emergence of British associationism, which began with Thomas Hobbes.
John Locke
The phrase "association of ideas" was first used by John Locke in 1689. 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. He writes, Although he believed that some associations were natural and justified, he believed that others were illogical, causing errors in judgment. He also explains that one can associate some ideas together based on their education and culture, saying, "there is another connection of ideas wholly owing to chance or custom".
David Hume
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. He argues that the mind uses these principles, rather than reason, to traverse from idea to idea. For a fuller explanation of the intellectual history of associationism and the "Associationist School", see Association of Ideas.
Applications
Associationism is often concerned with middle-level to higher-level mental processes such as learning.