What methods are used by psychologists to study the brain and its role in behavior How do these methods help to understand the effect of biology on human behavior?

Episode #5 of the course “Major Schools of Thought in Psychology”

Not surprisingly, biological psychology marries the two sciences of biology and psychology. Like other schools of thought, this is a perspective to the study of psychology rather than a science in and of itself. It is tied into the work of Charles Darwin and his observation of animals.

There are three methods that biological psychologists use to help learn about the human mind and human behavior. The first is the comparative method. This method implies that certain species of animals can be studied and compared, but it also works on humans—that is, studying various individuals and then comparing their responses can help psychologists understand more about human behavior. Second is physiology, which is the study of how the nervous system and hormone functions affect human behavior. Physiology also considers how the brain works and how altering these functions or the structure of the brain can affect behavior. Finally, biological psychologists consider how genetics or inheritance affects behavior or intelligence. Each of these methods is still used in studying human behavior and thinking today.

This school of thought focused on increasing the reliability and validity of psychological research by using these biologically-focused methods. Lab experiments were extremely common, and they were often geared toward finding correlations between two comparable subjects. Because of this, researchers held twin studies frequently. The work in this area helped develop comparative psychology as a field, and its basic methods were highly applicable in other areas of science.

Critics of the approach were concerned that too much reliance on humanism (development based on evolution as a human) meant that free will was virtually non-existent. The school does not recognize cognitive processes and simply focuses on “natural” adaptations. There was also some concern that this type of thought made very complex ideas (including physical systems) very simplistic, so much so that some had concerns about whether results generated by the method could be trusted.

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By Dr. Saul McLeod, updated 2015

Biological psychology, also called physiological psychology, is the study of the biology of behavior; it focuses on the nervous system, hormones and genetics. Biological psychology examines the relationship between mind and body, neural mechanisms, and the influence of heredity on behavior.

The biological approach believes behavior to be as a consequence of our genetics and physiology. It is the only approach in psychology that examines thoughts, feelings, and behaviors from a biological and thus physical point of view.

Therefore, all that is psychological is first physiological. All thoughts, feeling & behavior ultimately have a biological cause. A biological perspective is relevant to the study of psychology in three ways:

1. Comparative method: different species of animal can be studied and compared. This can help in the search to understand human behavior.

2. Physiology: how the nervous system and hormones work, how the brain functions, how changes in structure and/or function can affect behavior. For example, we could ask how prescribed drugs to treat depression affect behavior through their interaction with the nervous system.

3. Investigation of inheritance: what an animal inherits from its parents, mechanisms of inheritance (genetics). For example, we might want to know whether high intelligence is inherited from one generation to the next.

Each of these biological aspects, the comparative, the physiological (i.e., the brain) and the genetic, can help explain human behavior.

Investigation of Inheritance

Twin studies provide geneticists with a kind of natural experiment in which the behavioral likeness of identical twins (whose genetic relatedness is 1.0) can be compared with the resemblance of dizygotic twins (whose genetic relatedness is 0.5).

In other words, if heredity (i.e., genetics) affects a given trait or behavior, then identical twins should show a greater similarity for that trait compared to fraternal (non-identical) twins.

There are two types of twins:

• Monozygotic = identical twins (share 100% genetic information).
• Dizygotic = non-identical twins (share 50% genetic information, similar to siblings).

Research using twin studies looks for the degree of concordance (or similarity) between identical and fraternal (i.e., non-identical) twins. Twins are concordant for a trait if both or neither of the twins exhibits the trait. Twins are said to be disconcordant for a trait if one shows it, and the other does not.

Identical twins have the same genetic make-up, and fraternal twins have just 50 percent of genes in common. Thus, if concordance rates (which can range from 0 to 100) are significantly higher for identical twins than for fraternal twins, then this is evidence that genetics play an important role in the expression of that particular behavior.

Bouchard and McGue (1981) conducted a review of 111 worldwide studies which compared the IQ of family members. The correlation figures below represent the average degree of similarity between the two people (the higher the similarity, the more similar the IQ scores).

• Identical twins raised together = .86 (correlation).

• Identical twins raised apart = .72
• Non-identical twins reared together = .60
• Siblings reared together = .47
• Siblings reared apart = .24
• Cousins = .15

However, there are methodological flaws which reduce the validity of twin studies. For example, Bouchard and McGue included many poorly performed and biased studies in their meta-analysis.

Also, studies comparing the behavior of twin raised apart have been criticized as the twins often share similar environments and are sometimes raised by non-parental family member.

Methods of Studying the Brain

It is important to appreciate that the human brain is an extremely complicated piece of biological machinery. Scientists have only just “scratched the surface” of understanding the many functions of the workings of the human brain. The brain can influence many types of behavior.

In addition to studying brain damaged patients, we can find out about the working of the brain in three other ways.

Children begin to plan activities, make up games, and initiate activities with others. If given this opportunity, children develop a sense of initiative and feel secure in their ability to lead others and make decisions.

1. Neuro Surgery

We know so little about the brain and its functions are so closely integrated that brain surgery is usually only attempted as a last resort. H.M. suffered such devastating epileptic fits that in the end a surgical technique that had never been used before was tried out.

This technique cured his epilepsy, but in the process the hippocampus had to be removed (this is part of the limbic system in the middle of the brain.) Afterwards, H.M. was left with severe anterograde amnesia. I.e., He could remember what happened to him in his life up to when he had the operation, but he couldn’t remember anything new. So now we know the hippocampus is involved in memory.

2. Electroencrphalograms (EEGs)

This is a way of recording the electrical activity of the brain (it doesn’t hurt, and it isn’t dangerous). Electrodes are attached to the scalp and brain waves can be traced.

EEGs have been used to study sleep, and it has been found that during a typical night’s sleep, we go through a series of stages marked by different patterns of brain wave.

One of these stages is known as REM sleep (Rapid Eye Movement sleep). During this, our brain waves begin to resemble those of our waking state (though we are still fast asleep) and it seems that this is when we dream (whether we remember it or not).

3. Brain Scans

More recently methods of studying the brain have been developed using various types of scanning equipment hooked up to powerful computers.

The CAT scan (Computerised Axial Tomography) is a moving X-ray beam which takes “pictures” from different angles around the head and can be used to build up a 3-dimensional image of which areas of the brain are damaged.

Even more sophisticated is the PET scan (Positron Emission Tomography) which uses a radioactive marker as a way of studying the brain at work.

The procedure is based on the principle that the brain requires energy to function and that the regions more involved in the performance of a task will use up more energy. What the scan, therefore, enables researchers to do is to provide ongoing pictures of the brain as it engages in mental activity.

These (and other) methods for producing images of brain structure and functioning have been extensively used to study language and PET scans, in particular, are producing evidence that suggests that the Wernicke-Gerschwind model may not after all be the answer to the question of how language is possible.

Timeline of the Biological Approach

Biological Approach Summary

Strengths

The biological approach provides clear predictions that can. This means that explanations can be scientifically tested and support with evidence.

Real life applications (e.g., therapy)

Emphasizes objective measurement

Many experiments to support theories

Highly application to other areas: Biology + Cog = Evolutionary Psy

Limitations

Ignores mediational processes (doesn’t recognize cognitive processes)

Bio psychological theories often over-simplify the huge complexity of physical systems and their interaction with the environment.

Too deterministic (little free-will)

Humanism – can’t compare animals to humans

Reductionist

Critical Evaluation

Theories within the biological approach support nature over nurture. However, it is limiting to describe behavior solely in terms of either nature or nurture, and attempts to do this underestimate the complexity of human behavior. It is more likely that behavior is due to an interaction between nature (biology) and nurture (environment).

For example, individuals may be predisposed to certain behaviors, but these behaviors may not be displayed unless they are triggered by factors in the environment. This is known as the diathesis-stress model of human behavior.

A strength of the biological approach is that it provides clear predictions, for example, about the effects of neurotransmitters, or the behaviors of people who are genetically related. This means the explanations can be scientifically tested and ‘proven.’

A limitation is that most biological explanations are reductionist, as it reduces behavior to the outcome of genes and other biological processes, neglecting the effects of childhood and our social and cultural environment. and don’t provide enough information to fully explain human behavior.

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How to reference this article:

McLeod, S. A. (2017, Febuary 05). Biological psychology. Simply Psychology. www.simplypsychology.org/biological-psychology.html

APA Style References

Bouchard, T. J., & McGue, M. (1981). Familial studies of intelligence: A review. Science, 212(4498), 1055-1059.

Darwin, C. (1859). On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (1st ed.). London: John Murray.

Harlow, J. M. (1848). Passage of an iron rod through the head. Boston Medical and Surgical Journal, 39, 389–393.

Tooby, J., & Cosmides, L. (1992). The psychological foundations of culture. In J. Barkow, L. Cosmides, & J. Tooby (Eds.), The adapted mind: Evolutionary psychology and the generation of culture. New York: Oxford University Press.

Wilson, E. (1975). Sociobiology: The New Synthesis. Harvard University Press

 Download this article as a PDF

How to reference this article:

McLeod, S. A. (2017, Febuary 05). Biological psychology. Simply Psychology. www.simplypsychology.org/biological-psychology.html

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