When psychologists began to define psychology as a natural science, they chose Newtonian Physics as the model. Correlations were useful for making predictions, but an experimental analysis was required to establish causality. In the prototypical experiment, all known relevant factors were held constant save one, the “independent variable,” and if there were systematic changes in behavior, the “dependent variable,” associated with changes in the independent variable, then unidirectional causality could be legitimately inferred. The behavioristic paradigm was simply S > > R exemplified by the reflex arc.
In physics metal balls could be rolled down inclined planes and the measured speed, the dependent variable, was found to depend on the angle of incline, the independent variable. It was easy to infer that Speed = f(angle). In psychology, rats could be run down straight-alley mazes and the measured speed was found to depend on the amount of reinforcement available in the goal box. It was easy to infer that Speed = f(reinforcement).
The critical feature of the above formulation is that it is unidirectional. The rat’s speed of running is a dependent variable that is determined by the values of independent variables. The automatic relationship implied by the S > > R paradigm did not reflect the role played by the organism in the determination of behavior. Specifically, for example, the rat’s speed of running for food reward depended importantly on the conditions of deprivation. Hence, the behavioristic paradigm became described as S > > O > > R.
Using the above terminology, it can be noted that all psychological research involves “S” and “O” and “R” operations. The “S” is actually the environmental context and is the focus of those whose primary interest is in sensory, perceptual, and social processes. The “O” is actually any variable involving the organism and is the focus of those whose primary interest is in developmental, clinical, and physiological processes.
The “R” is actually any behavior and is the focus of those whose primary interest is in learning and performance processes. But regardless of focus, psychologists of all ilks observe the behavior of interest by the organism of interest in the environmental context of interest.
It is my thesis that the fundamental paradigm of psychology is one of interdependence that can be symbolized S < > O < > R. Although research based on the independent-dependent variable paradigm has led to identification of many important facts, the conceptual principles must incorporate both independent and interdependent variables. In sum, behavior is not merely determined by stimulus and organism factors but helps to determine those factors. This note illustrates this thesis in several contexts that were the focus of my research.
First, however, consider an issue that preoccupied theoretical analyses of learning for many years. In its most general formulation, learning is the result of exposing an organism to some environmental contingency. In the Pavlovian classical contingency, the occurrence of the reinforcer (food) is an independent variable and seemed to imply the acquisition of an S-S association. In contrast, the occurrence of the reinforcer (food) in the Thorndikian instrumental contingency is an interdependent variable because it can be performed only if the organism emits the designated response. This seemed to imply the acquisition of an S-R association. In sum, different learning processes could be inferred when the reinforcer is independent versus being interdependent of behavior.
My contention is that the basic nature of what-is-learned is the same without regard to the experimental paradigm employed. Although I do not presume to know the resolution of that issue, one possible approach requires only the assumption that the precursor of a response is anticipatory feedback; that is to say, learnable responses are the result of an antedating image of the sensory consequences of that response. Given that assumption, all learning can be conceptualized as S-S associations, with “S” being either exteroceptive or interoceptive. When the consequent stimulus involves the “idea,” of an external event (classical conditioning) the association is functionally S-S; when the consequent stimulus involves the “idea” of response feedback (instrumental conditioning), the association is functionally S-R. But both are neurologically S-S associations and one idea may overshadow the other depending on the situation.
The Interdependence Paradigm
I believe that many if not all psychological processes differ when controlled independently by the environment from when controlled interdependently by the organism. Among many examples: the effect of a placebo is different if one knows that one is taking placebo; the effect of alcohol is different if one’s drink is unknowingly spiked by someone else; and to add a bit of a paradox, one cannot tickle oneself.
The educational psychologist must contend with the fact that the distribution of practice is determined by the student; the clinical psychologist must contend with the fact that therapy is importantly determined by the patient; the developmental psychologist must contend with the role of individual differences in determining aging processes; and again to add a bit of a paradox, the social psychologist must contend with the fact that social sex is different from solitary sex.
The “interdependence paradigm” (S < > O < > R) is any conceptual analysis that concurrently encompasses independent and interdependent variables. One must first determine if the effect of a variable is different when the organism does or does not have control over that variable, and if so, one must incorporate interdependence in a single conceptual analysis. The interdependence paradigm applies to those situations in which each variable determines and is determined by the other variable.
In order to test the basic premise of the historical approach, I ran some rats in a straight alley maze under conditions of negatively correlated reinforcement. Under those conditions, the amount of reinforcement depends on the rat’s speed; the faster it runs, the smaller the reinforcer. Now, if speed is truly determined by the amount of reinforcement, and the conditions vary the amount of reinforcement with speed, then there is only one possible outcome. The rat must learn to run at that speed that results in an amount of reinforcement that, in turn, determines that same speed.
The analysis is conceptually elegant but empirically false. Rats run slower than predicted, getting an amount of reinforcement that would normally result in a much faster speed. It is instructive to contrast those results with what would happen with a comparable experiment involving balls rolling down inclined planes. If one made the angle of incline depend inversely on speed, the balls would not learn to roll slowly down a steeply inclined plane; instead, over trials the angle would home in on the one value that would keep the angle and speed in equilibrium. Speed of inanimate objects in physics is not the same as speed of an animate organism in psychology.
One response to these findings is to contend that the conventional approach is appropriate when the experimenter controls the amount of reinforcement as an independent variable, but when the conditions involve correlated reinforcement, the analysis needs to be made at a different level. Specifically, different speeds are considered to be different responses and speed, rather than being used as a measure of response strength, becomes part of what is learned.
I contend that the true psychological principles do not change simply because an experimenter changes the conditions of reinforcement. If speed is part of what is learned in one situation, it must be part of what is learned in all situations. Accordingly, a single analysis treating quantitative dimensions of behavior as being learned can apply in all situations
A “free behavior situation” is where the organism “earns” all of some commodity (e.g., food or water) by emitting some freely available response. Here, the organism variable of deprivation is interdependent. In this situation, some functional relationships are different from those when deprivation is an independent variable. For example, whereas larger reinforcers typically lead to higher response rates, they lead to lower rates in the free behavior situation. But again, my contention is that the effect of motivation is the same whether it is controlled by the environment independently or whether it is an interdependent variable. In this example, larger reinforcers in the free behavior situation concurrently lead to a lower level of maintained deprivation and hence to lower “drive” motivation in spite of higher “incentive” motivation.
In my research on “decision making in rats” I gave them a choice between a large delayed reward and a smaller more immediate reward. As expected, I found that there was a basic tradeoff based on the differences in amount and delay. However, I also found that the solution depended on the length of the runways; with short runways they preferred the small-quick reward but with long runways, they preferred the large-delayed reward. Clearly, “chaining delay” (time to get to the goal box) is involved in the decision process. But chaining delay is in part an independent variable related to the length of the runway and in part an interdependent variable because it also depends on how fast the rat runs. If the rat runs faster in its preferred alternative, then there is another factor entering into the equation; rats prefer to spend more time running than the same amount of time waiting. This is because the effect of any delay depends on what the organism does during the delay.
In the research that I have just cited, I have illustrated how a single analysis can accommodate interdependence involving contingency factors by assuming that all learning consists of S-S associations including interoceptive events, a single analysis can accommodate interdependence involving S and R factors by assuming that all quantitative dimensions of a response are part of what is learned, and a single analysis can accommodate interdependence involving O and R factors by assuming the effect of different motivational factors. What remains is to suggest that the renewed interest in higher-mental cognitive processes can be conceptualized as an emphasis on the interdependent role of the organism between the S and the R of the S < > O < > R paradigm.
Interdependence does not resolve the fundamental issue of whether the human organism is active in the sense of agency but it does include the organism as being active in complex mediational processes. This means that one cannot understand the mind if one does not understand behavior and, conversely, one cannot understand behavior is one does not understand the mind. The human mind is surely more complex than the corresponding construct in other animals but the evidence to date favors an approach based on evolutionary development with the probability of emergent processes.
One way to accommodate cognition into a general formulation is to conceptualize higher-mental processes as interoceptive events that may occupy either or both sides of an S-S association. For example, rather than assuming that memory is a passive entity from which memories are “retrieved” by an executive function, one can take the classic view of memory as a reactive entity from which memories are “recalled” by associated recall cues. According to this approach to cognition, when one is thinking (at the speed at which one has learned,) both Ss are interoceptive and thoughts may or may not affect the external context or overt behavior. In sum, the organism is at the center of an interdependent system.
In 1935, Clark L. Hull chose the title “The conflicting psychologies of learning: A way out.” Although that was a dominant issue in mid-twentieth century, I believe that the issue now is conflicting psychologies more generally. I do not have Hull’s brilliance to venture a way out, but I do contend that greater recognition of interdependence in psychological processes can lead to a more cohesive discipline. It is not biological factors (e.g., nature) versus psychological factors (e.g., nurture) and it is not cognitive psychology versus behaviorism. After all, being “buried in thought” is a form of learned behavior requiring an adequate nervous system!