Lesson 3: The Concept of Cause in Psychology: Multifactorial Causation
The study of personality is an area in psychology that has a long history of 'dueling theories. To understand this statement, we first need to know what a "theory" is. A theory may be defined as a tentative explanation of a phenomenon. The explanation typically points to a cause or causes of the phenomenon. For example, a theory about "course grades" might state that the grade one gets in a course is caused by one or more of the following factors:
· amount of motivation to do well in a course
· level of reading ability
· level of writing ability
· amount of general intelligence
· how much and how well one studies
Although these factors may seem to you to be important ones, the theory is not yet a "scientific theory." In order to be a scientific theory, the explanation must be based on adequate observations (see Lesson 5). That is, scientific theories must be based on more than just speculation: there must be good empirically based reasons for proposing a particular explanation. For example, one theory of the development of phobias (pervasive and irrational fears) states that one learns to fear a relatively harmless event (such as flying in airplanes) because it has been paired in the past with another event that immediately elicited intense fear (such as seeing an airplane crash on a television news story). This theory, which makes use of the concept of classical conditioning, was first investigated in 1920 in a paper by John Watson and Rosalie Rayner. Since then, many others have examined this theory; and there are a number of observations in support of it.
You now should be able to see that the quotation above about "dueling theories" must be referring to a long history of competing causal explanations of personality. Some researchers, such as Sigmund Freud, have focused on conflicts among opposing motives as the primary cause of personality (a motive refers to an internal force that impels a person to accomplish a goal). Other researchers, such as Albert Bandura, have focused on the influence of beliefs, expectations, and other cognitive structures as the primary cause of personality (a cognition is a product of the process of knowing, such as a belief, a perception, an expectation, or a judgment). Still other researchers have focused on other kinds of cause.
We have two questions we need to answer if we are to think critically about the discussion of personality. First, what do psychologists mean when they refer to a "cause" of personality? Second, why do different personality psychologists tend to focus on very different causes of personality? We will examine the first question in this lesson and the second question in the next lesson.
What is a Cause?
You learned in Lesson 1 that psychologists generally do not think about causes in terms of necessary or sufficient conditions. Instead, they usually think about causes in terms of factors that increase or decrease the likelihood that a particular event will occur. For example, what does it mean to say that "smoking causes lung cancer"? Does it mean that, if you smoke, you will develop lung cancer? No, smoking is not a sufficient condition for developing lung cancer. Does it mean that, if you don't smoke, you will not develop lung cancer? No, smoking is not a necessary condition for developing lung cancer. When we use the term "cause" in this example, we mean that, if you smoke, you will increase your chances of developing lung cancer.
Why does smoking only increase a person's chances of developing lung cancer? Why does smoking not guarantee that a person will develop lung cancer? It probably occurred to you that there are other factors that increase or decrease the harmful effects of smoking. For example, genes, diet, amount of exercise, stress levels, amount of alcohol consumed, and so on, are factors that may interact with smoking in determining who will and who will not develop lung cancer.
Why can people develop lung cancer even though they don't smoke? Again, other factors, such as genes, diet, stress levels, etc., are thought to influence the development of lung cancer. Each factor, when looked at individually, increases the chance of developing lung cancer, but probably none alone is sufficient to cause lung cancer. It seems very likely that the causes of lung cancer are many and that their interactions are complex.
The behaviors and mental events studied by psychologists also tend to be caused by a large number of interacting factors. We need to perform investigations of a number of these factors and their interactions before we can develop a comprehensive theory of a psychological phenomenon. For example, our present understanding of schizophrenia suggests that the disease is caused by many interacting factors, such as mutant genes, viral infections, abnormal biochemical activity in the brain, psychosocial stress, and environmental toxins. Brown and Ghiselli (1955) stated that such theories are the norm in psychology:
The most consistent characteristic of human behavior is the complexity of its determinants. We must think of every behavior sequence as stemming from many determinants. Some of these initiate their influence at the time of the conception of the individual, others come into play just prior to the occurrence of the observed behavior, while numerous others arise in between these two extremes on the time axis. Behavioral processes do not function independently but interact with each other in many intricate and complex ways. Combinations of determinants act over various intervals: sometimes forming genetic series occupying hours, days, months, or years; at other times acting for merely a second or as a simultaneous flash occurrence."
We refer to this as multifactorial causation, which means that a phenomenon is determined by many interacting factors. As Brown and Ghiselli suggested, the many factors that determine a phenomenon are thought to occur over the lifetimes of individuals. In the case of schizophrenia, there are distal factors (those that occurred some time ago)--such as viral infections during fetal development--and proximal factors (those that occurred recently)--such as stressful events. The distal and proximal factors tend to interact in complex ways that can be difficult to investigate.
When we are talking about mental disorders (such as schizophrenia), we often refer to distal factors for the disorder as predisposing factors: they set the stage for the development of the disorder but they are not sufficient to cause it. For example, the genes one inherits at conception are important distal factors for personality. If some of these genes are abnormal ones associated with schizophrenia, the person is predisposed to develop the disorder. But these "schizophrenia genes" are not sufficient for causing schizophrenia. To see that this is true, we can look at the results of twin studies of schizophrenia. It was stated in the textbook that identical twin share 100% of their genes. When one member of an identical-twin pair develops schizophrenia, the other twin has only about a 50% chance of developing the disease. This means that genes alone are not sufficient for causing schizophrenia. Instead, genes are predisposing factors: when present, they make it more likely that other (more proximal) factors will lead to the development of schizophrenia.
When we are talking about mental disorders, we often refer to proximal factors for the disorder as precipitating factors: they trigger the development of the disorder whenever a person has been exposed to predisposing factors in the past. For example, "psychosocial stressors" (mental or interpersonal events--such as a divorce or job loss--that cause difficulties in coping) are proximal factors that may precipitate the development of schizophrenic symptoms. The stress by itself is not sufficient to cause schizophrenia, however: the person must have experienced one or more of the predisposing factors in the past.
Critical Thinking Questions
Question 3-1
There are a number of people who claim that many diseases are caused by too little or too much of a particular food ingredient or ingredients. The cure, they say, involves adding or subtracting these ingredients to the diets of affected people. Based on what you have learned in this lesson, critique the claim that most diseases could be cured by changing the diet alone. (In answering this question, it may help you to read an on-line article on this topic).
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Question 3-2
Although a change in a person's diet typically is not sufficient to treat or prevent most diseases, there is at least one example in which such a treatment is effective. Ingesting too much phenylalanine (an amino acid) can cause disturbances in the development of the nervous system, which often results in severe mental retardation (among other problems). Putting people on a low-phenylalanine diet when they are very young, however, will prevent the build-up of phenylalanine, thereby allowing them to develop normal intellectual abilities. Given this information, would you tell parents of a newborn to put their baby on a low-phenylalanine diet in order to prevent mental retardation? Why or why not?
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Question 3-3
In your textbook, it was stated that comparing identical twins (who share 100% of their genes) with fraternal twins (who share, on average, only 50% of their genes) allows us to test the idea that aspects of personality are influenced by genes. The thinking behind the "twin method" is this:
Both types of twins usually grow up in the same home, at the same time, exposed to the same relatives, neighbors, peers, teachers, events, and so forth. Thus, both kinds of twins normally develop under similar environmental conditions, but identical twins share more genetic kinship. Hence, if sets of identical twins exhibit more personality resemblance than sets of fraternal twins, this greater similarity is probably attributable to heredity rather than environment.
Given what you know about twins, what are some possible problems with this line of reasoning? That is, how might environmental factors important for personality development be more similar for the two members of an identical-twin pair than for the two members of a fraternal-twin pair?
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Question 3-4
Each of the approaches propose that both distal and proximal causes affect the development and expression of the adult personality.
(a) Which distal and proximal causes of the adult personality are proposed in the psychoanalytic approach of Sigmund Freud?
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(b) Which distal and proximal causes of the adult personality are proposed in the behavioral approach of B. F. Skinner?
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(c) Which distal and proximal causes of personality are proposed in the humanistic approach of Carl Rogers?
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Bibliography and References
Brown, C. W., & Ghiselli, E. E. (1955). Scientific method in psychology. New York: McGraw-Hill.
Hayden, G. (August, 1998). Seeing double. Profiles Magazine. Retrieved March 27, 2002, from http://www.yorku.ca/ycom/profiles/past/aug98/current/features/article1.htm
Kerr, G. R. (1997). Diet, Disease, and Definitions of 'Proof'. Priorities for Health, 9 (4). Retrieved February 24, 2002, from http://www.acsh.org/publications/priorities/0904/definitions.html
Watson, J. B., & Rayner, R. (1920).Conditioned emotional reactions. Journal of Experimental Psychology, 3, 1-14.