Behaviorism modeled after Newtonian physics
The neurobehaviorist Clark Hull, in an effort to gain more respect and prestige for his field, aspired to make behaviorism a quantitatively exact science modeled after the physical sciences and specifically, Newtonian physics. Originally an engineer, he theorized that, “all the complex behavior of single individuals will ultimately be derivable as secondary law from (1) primary laws expressible quantitatively by means of a moderate number of ordinary equations, together with (2) the conditions under which behavior occurs; and that all behavior of groups as a whole may similarly be derived as quantitative laws from the same primary equations” (Hull, 1943, p. 43). In keeping with the tenets of behaviorism, he reiterated Thorndike’s (1932) Law of Effect, arguing that behavior consists of sets or chains of linked habits, each of which represents a Stimulus-Response connection that developed as a result of reinforcement. He extrapolated on this foundation, postulating that a number of factors work to enhance, limit or inhibit the formation of such habits, and deriving equations to calculate the exact effect of each of these factors (Hunt, 1993).
As indicated, Hull’s formulas represented a mathematical deductive theory of instrumental conditioning that attempted to define, with absolute specificity, the systematic set of conditions and responses that led to the formation of habits (Hergenhahn, & Olson, 2003; Ormrod, 2004). According to Hull (1934) there are two basic types of habitual behavior: the divergent mechanism and the convergent mechanism. The divergent mechanism refers to a situation where one stimulus elicits many similar responses. An example of this is an infant’s movements in response to a bottle. Among the many possible responses to this stimulus, a baby may grasp for the bottle instantly, stick its feet in the air in the direction of the bottle, smile, laugh or babble while engaging the holder of the bottle, or lift its entire body in the direction of the bottle. All the responses elicited by the baby are similar in that each is a movement in the direction of a single stimulus.
Conversely, Hull (1934) postulated that the convergent mechanism occurs when a single response is elicited from multiple stimuli. Using the example of the baby above, several similar stimuli, such as a bottle, pacifier, or a toy, may all elicit a single final response, to grasp the object, pull it toward the mouth and suck on the object. The two groups together constitute what Hull referred to as the habit family. The habit-family hierarchy refers to situation whereby the various S-R habits have differing levels of preference or habit strength that render them more or less likely to be evoked (Hergenhahn, & Olson, 2003; Ormrod, 2004). The key point in Hull’s research was that while each response may be elicited from either a single stimulus or multiple stimuli only one reaction can emerge forcing a type of competition in which the environment evokes the single response that is seen (Hull, 1934).
Hull (1934) illustrates the concept with the example of encountering a trail with there is a pool of water in the middle, blocking progress. In this situation, there is the choice to walk to on a path either to the right or to the left of the pool. Like rats learning a maze, one will eventually choose the path that is shorter (i.e. more beneficial) after having experienced both path choices. “The fact that both of the action sequences begin with the same stimulus and terminate in the same reaction constitutes them a habit family; the fact that one sequence is preferred about the other constitutes them a hierarchy,” (p. 40). This concept of habit families and hierarchy facilitates an understanding of how habits form in each individual. It is theorized to be operative in all situations where there is more than one distinct action sequence which will lead to the attainment of a particular goal or sub-goal.
A modern example of the hierarchy in action could occur when faced with choices for a snack while watching one’s favorite television program. Upon perusing the options available in the kitchen, one might find the choices to be brussel sprouts or an ice cream sundae. In the minds and taste buds of most people, the ice cream would be the preferred choice to satisfy the snack cravings. Clearly, these hierarchies are more complex in daily life as they typically involve many more competing choices, each with their own set of attracting and detracting properties. However, the basic structure of hierarchy remains the same, with the habit strength being predicted by a set of equations involving the various situational factors.
Although Hull’s theory was an elaborate conceptual presentation that was initially greatly admired and significantly influential in achieving the intellectual respectability of the scientific community, its unwieldiness, lack of empirical support and the subsequent decline of behaviorism has rendered it less influential than originally expected. While intuitively the field of psychology has accepted the general notion that certain responses are preferred over others that will lead to the same result, Hull’s set of equations seem to lack the human element and clash with our sense of control, individual freedom and will power. Perhaps it is that aspect of unpredictability within the context of the seemingly predictable that defines us uniquely as human beings.
References
Hergenhahn, B. R. & Olson, M. H. (2003). An introduction to theories of personality, 6e. Upper Saddle River, NJ: Prentice Hall
Hull. C. L. (1934). The concept of the habit family hierarchy and maze learning. Psychological Review, 41, 33-54.
Hull. C. L. (1943). Principles of behavior: An introduction to behavior theory. New York, NY: Appleton-Century-Crofts.
Hunt, M. (1993). The story of psychology. New York, NY: Anchor Books.
Ormrod, J. E. (2004). Human learning (4th ed.). Upper Saddle River, NJ: Merrill Prentice Hall.
Thorndike, E. L. (1932). The fundamentals of learning. New York, NY: Teachers College Press.