The Study of Human Behavior in Psychology: Epistemological Context
For longtime, psychology has been considered as the science of mind and behavior. This definition is influenced by an essentialist perspective (Palmer & Donahoe, 1992; Donahoe, Burgos & Palmer, 1993; Donahoe, 2012).The word “Essentialism” was introduced by Karl Popper (1945). It assumes that observable objects are characterized by their essence, an underlying immutable cause of what makes an object what it is (Popper, 1945; Mayr, 1988).
“Essentialism is the view that certain categories have an underlying reality or true nature that one cannot observe directly but that gives an object its identity, and is responsible for other similarities that category members share. In the domain of biology, an essence would be whatever quality remains unchanging as an organism grows, reproduces, and undergoes morphological transformations (baby to man; caterpillar to butterfly). In the domain of chemistry, an essence would be whatever quality remains unchanging as a substance changes shape, size, or state (from solid to liquid to gas)”. (Gelman, 2004)
The essentialist perspective was predominant in most of human and natural sciences until the 19th century. In 1859, with the publication of The Origin of Species, Darwin proposed a theory which acted as a counterbalance to the dominant position of essentialism. He provided two ideas that revolutionized the scientific area. First, the principles of Evolution which can be defined as change in the characteristics of biological population over successive generation (Hall & Hallgrimsson, 2011). In Evolution Theory, changes, which were considered to be anecdotal in the essentialist perspective, because essence is immutable, became the variables under investigation. The second idea is that Evolution is made through a process labelled “natural selection” which is responsible for changes Animal just as Human characteristics.
Natural selection consists of three principles: variation, selection and retention. Variation refers to the different characteristics between organisms providing a basis upon which selection is possible. Applied to Human being, these variations refer to the different characteristics (color, length etc.) which are observable (or not) between two individuals of the Human species. Environment directly affects substrates of variation, making some characteristics essential to survive or on the contrary, making others useless. Considering our example, selection process has directly influenced the functional differences between individuals, for instance, we can observe structural and functional differences between an individual living in North Pole and one living in Amazonia. This second principle is defined as selection. Selection is not described as a goal-oriented process. Mutation of organisms are the result of many processes combined and do not serve a purpose. Changes in environment might favor or disfavor the features of some organisms. Finally, the last step of natural selection, named hereditary selection, or retention, consists in enabling the selected characteristics to be transmitted to the offspring. Natural selection as a process to explain evolution offered new perspectives to investigate human and natural sciences.
Behavioral Variability in Psychology
Behavioral variability commonly refers to the degrees of change that occur at different moments and spaces (Neuringer, 2002; Van Geert & Van Dijk, 2002). These variations can be investigated in a continuum between repetition, which implies prediction, and variation, which implies unpredictability. Commonly, experimental psychology is about description, prediction and control. One experimental question is: To what extent is a change in a dependent variable the result of the manipulation of independent variables? In classic textbooks on psychology, variability is described as an impediment to experimental conclusions. Indeed, it prevents the conclusion of the influence of the independent variable on the dependent variable when conditions are held constant. In an experiment, we study the influence of a variable A on a variable B in a repeated measured design. The basic and possibly the most common hypothesis is that B co-varies with A (see figure 2 for an illustration of variability in experimentation). If, when we verify this hypothesis, changes in A are independent of B, prediction is impossible. In this case, internal validity can be questioned. This situation has been an issue for many scientists independently of their theoretical backgrounds. In fact, the difference is in the way to handle variations in data. From a traditional perspective these variations are confounding variables which cannot be controlled. From a functional perspective, variability can also be a problem except that theoretically, it can be influenced by environmental contingencies. Moreover, this variability, from a selectionnist perspective can be a basis upon which selection is possible. In Thorndike’s experiments (1911) animals emitted different responses to get out of the puzzle box. We can imagine that, if they emitted no response, there is low probability in their success. In fact, one hypothesis is that, among the different responses emitted by the animal, some was selected by the opening of the door. The more the animal returned to the box, the more probable it emitted the correct response to get out. In that case, behavioral variability can also be a variable inherent to the trial and error learning. The next section aims at presenting the influence of the different conceptions on the way to consider variations.
Behavioral Variability and Animal Studies
Antonitis (1951) was the first to directly investigate the variability of operant response. Previous experiments (Skinner, 1938; Muenzinger, 1928) observed first that the variability of operant responses decreases in a Continuous Reinforcement Schedule (CRF). This schedule consists in systematically reinforcing each occurrence of a target behavior. For instance, distributing food systematically when a rat presses a lever may decrease the dimensions of variation related to this response (duration, location etc…). In other words, there are variable ways to press a lever and CRF schedule seems to reduce these variations. Second, it has been observed that these variations increased in extinction phase. In our example, when food is no longer distributed when rat presses the lever, it results in an increase of responses variations. The study of Antonitis aimed at assessing the relation between CRF – which seemed to reduce variability – and extinction – which induces variability. In his experiment, rats were reinforced when they poked their nose on a 50 cm horizontal slot without any constraint of location. The experiment alternated between CRF and extinction phases. During the CRF phase, the poked area, was high at the beginning of the experiment, which implies that rats tended to use the 50 cm surface of the horizontal slot. This area became restricted to a smaller region despite the absence of constraint, suggesting that CRF results in reducing variations. Repeating the same type of response over trials is categorized as stereotyped behavior. On the continuum of behavioral variability, it consists of repetitive pattern of behaviors. Although the CRF phase produced stereotyped pattern of behaviors, once under extinction, the poked area became more variable. Evidence of variability in this experiment was investigated by assessing the area of the poked location. The results of this experiment were replicated in several studies and across different operant responses (Tremont, 1984; Milenson, Hurwitz & Nixon, 1961). Overall, these experiments shown that CRF induces stereotyped behaviors but that extinction induces both a decrease of response rate and an increase in operant variability.
Table of contents :
1. Chapter 1: Theoretical Introduction
1.1 The Study of Human Behavior in Psychology: Epistemological Context
1.1.1 Behavioral Variability in Psychology
1.1.2 Behavioral Variability in Traditional Psychology: A Confounding Variable?
1.1.3 Behavioral Variability in Functional Perspectives
1.2 Experiments on Behavioral Variability
1.2.1 Behavioral Variability and Animal Studies
1.2.2 Is Variability an Operant Dimension of Behavior?
1.3 Investigating Operant Variability
1.3.1 Behavioral Variability is Controlled by Discriminative Stimulus
1.3.2 Behavioral Variability, Extinction and Selection by Consequences
1.3.3 Operant Variability and Selection by Consequences
1.4 Behavioral Variability and Human Studies
1.4.1 Operant Variability with Humans
1.4.2 Operant Variability and Selection by Consequences
1.4.3 Illustration of the Implication of Behavioral Variability in Behavioral Changes.
1.5 How to Investigate Operant Behavioral Variability?
1.5.1 Procedures to Condition Behavioral Variability
1.5.2 A Measure of Behavioral Variability: The U Value
1.7 Experimental Goals
2. Chapter 2: Variability and Resistance to Change
2.1 Repetition and Variability: the Case of Resistance to Change.
2.2 Experiment 1
2.2.4 Dependent variables
2.3.4 Dependent variables
3. Chapter 3: Repetition and Variability in the Acquisition of Rare Response
3.1 Experiment 3.1
3.1.4 Dependent variables
3.2 Experiment 3.2 (Pilot study)
3.2.4 Dependent variables
4. Chapter 4: General Discussion
4.1 Overall Aim of Thesis
4.2 Behavioral changes and Development
4.3 Behavioral variability: seeking for different perspectives