Even though the human brain may look unappealing, it is house to a complex network of 90 billion neurons that receive and transmit electrochemical signals to one another. Neuroscience is the scientific study of the nervous system. This chapter will introduce biopsychology, which is one of the neuroscientific disciplines. Jimmie G. is an exemplary case of a neuroscientific deficiency: He could not retain any memory anymore after the age of 20. This chapter aims to teach its reader to think creatively about biopsychology, to learn about the clinical implications of neuropsychology, to learn to perceive facts through the evolutionary perspective and to learn about neuroplasticity.
Biopsychology is the scientific study of the biology of behavior. The publication of 'The Organization of Behavior' by Hebb in 1949 marked the emergence of the biopsychological science. In this book, Hebb described how he thought perceptions, emotions, memories en thoughts might be produced by activity in the brain. Up until then, many scientists thought psychology was too complex and difficult to be a chemical process. Hebb performed experiments on both animals and humans. Neuroanatomy, neurochemistry, neuroendocrinology, neuropathology, neuropharmalogy and neuropsysiology are all important neuroscientific disciplines that are important to the field of biopsychology. They will be covered by other chapters in this book.
Biopsychology is a broad and diverse neuroscience.
- Firstly, it can either involve human or nonhuman subjects. When nonhumans are used in biopsychological experiments, it mostly concerns mice and rats. It is more advantageous to use humans in biopsychological experiments, as (1) they can follow instructions, (2) they can report subjective experiences, (3) it is often cheaper, but most importantly: (4) they give the best insight into the mechanisms of the human brain, which is often what the researchers are interested in. However, using nonhumans in biopsychological experiments is more advantageous because (1) their brains and behavior are simpler than those of humans, (2) the research can be used to compare different species (the comparative approach) and (3) it is often easier to conduct research because of fewer ethical objections. Human and nonhuman brains are more quantatively different than qualatively different; meaning that the principles of brain functions are very comparable.
- Secondly, biopsychology can take the form of either formal experiments or nonexperimental studies. An experiment can either have a between-subjects desing, in which a different group of subjects is tested under each condition, or it can have a within-subjects design, in which the same group of subjects is tested under each condition. The dependent variable is measured by the experimenter in order to assess the effect of the independent variable, the latter which can be manipulated. It is important to make sure that there are no other differences between the different conditions aside of the independent variable, because an unintended difference in the form of a confounded variable could be the result. Eliminating all possible confouded variables is very hard. An example of an experiment in which a confounded variable had a major effect is displayed by the Coolidge effect: It was the fact that a copulating male hamster who becomes incapable of continuing to copulate with one sex partner can often recommence compulating with a new sex partner. The researchers in this experiment, Lester and Gorzalka, devised a solution to the problem of this confounded variable. At the same time a female subject was copulating with one male (the familiair male), the other male to be used in the test (the unfamiliair male) was compulating with another female. Then both males were given a rest while the female was copulating with a third male. Finally, the female subject was tested with either the familiair or unfamiliair male. The dependent variable was the amount of time the female showed lordosis (the physical posture that marks sexual receptivity). This is an example of creative thinking in biopsychology. Physical or ehtical implications frequently make it impossible to do experiments on human subjects. In such cases, quasiexperimental studies are an outcome. Quasiexperimental studies makes use of groups of subjects who have been exposed to the conditions of interest in the real world. The name 'quasiexperimental' stems from the idea that these studies have the appearance of an experiment, but are in fact not controlled. An example of a quasiexperimental study compared 100 detoxified male alcoholics with 50 male nondrinkers. They compared the two groups and found that alcoholics were more poorly educated, more likely to use other drugs, more likely to have poor diets and more prone to accidental head injury. The case of Jimmie G. that was discussed at the beginning of this chapter was an example of the long-term effects of long-term alcohol consumption. Another type of nonexperiment is a case study, which is focused on a single case or subject. They provide a more in-depth picture, but there is a problem with their generaliziability; the degree to which their results can be applied to other cases.
- Lastly, biopsychology can be either pure or applied. Pure research is motivated by the curiosity of the researcher and is meant to acquire new knowledge. Applied research is intended to bring about a direct benefit to human kind. Pure research often becomes translational research, which is aimed to translate the findings of pure research into useful applications. Pure research is more vulnerable to the differences in funding resulting from political regulations. Many biopsychological studies have won Nobel prizes.
Biopsychology consists of six major divisions: (1) physiological psychology, (2) psychopharmacology, (3) neuropsychology, (4) psychophysiology, (5) cognitive neuroscience and (6) comparative psychology. There is a lot of overlap between these different divisions.
- Physiological psychology is the division of biopsychology that studies the neural mechanisms behind behavior by studying the direct manipulation and recording of the brain in controlled experiments. The subjects are most often laboratory animals. Physiological psychology is often pure research, as it is focused on the development of theories on the neural control of behavior.
- Psychopharmacology focuses on the manipulation of neural activity and behavior with the use of drugs. The purpose is often to develop therapeutic drugs or to reduce drug abuse. Psychopharmacologists study the effects of drugs on laboratory animals and sometimes on humans, in the case that this is ethical.
- Neuropsychology is the study of the psychological effects that brain damage causes in human subjects. Neuropsychology primarily uses case studies and quasiexperimental studies. The outer layer of the cerebral hemispheres, the cerebral cortex, is often the subject of a neuropsychological study, as it is the organ that is most often damaged. Neuropsychology facilitates diagnosis and in this way helps to find effective treatment. Mr. R., who suffered from deteriorated language skills, was found to have damage to his right temporal lobe as a result of a car accident he was in.
- Psychophisiology studies the relation between physiological activity and psychological processes in human subjects. The usual measure of brain activity that it uses is the electroencephalogram (EEG). Other psychophysiological measures are eye movement, muscle tension, heart rate, blood pressure, et cetera. The autonomic nervous system (ANS) regulates the body's inner environment. Most psychophysiological research focuses on processes such as attention, emotion and information processing, and sometimes this leads to practical applications.
- Cognitive neuroscience studies the neural bases of cognition; which refers to higher intellectual processes such as thought, memory, attention and complex perceptual processes. Most often, it uses human participants. Functional brain imaging is the method that is used most often by cognitive neuroscientists. Most cognitive neuroscientific research results from an interdisciplinary collaboration of psychologists, social psychologists, economists and mathematicians, as the theory and methods are very complex and applicable to many different fields.
- Comparative psychology studies comparisons between the behavior of different species in order to understand evolution, genetics and adaptiveness of behavior. Ethological research is the study of animal behavior in the natural environment. Laboratory studies are also common in the field of comparative psychology. Evolutionary psychology is a discipline within comparative psychology that focuses on understanding behavior through its likely evolutionary origins.
Major biopsychological issues are rarely solved by just one experiment or approach; so they require a combined approach, which is called converging operations. For example, the neuropsychological case study of Jimmie G. let to the discovery of Korsakoff's syndrome, which is the result of the toxic effects of alcohol on the brain. Subsequent research with laboratory rats showed that Korsakoff's syndrome is largely caused by the brain damage associated with thiamine (vitamin B1) deficiency. The strength of biopsychology lies in the diversity of its methods and approaches.
Scientific inference is the fundamental method of biopsychology and of most other sciences as well. It is the empirical method that is used to study the unobservable. Scientists carefully measure events they can observe and make logical inferences about the nature of events they cannot observe. An example is an experiment that you can do yourself which will make you able to discover the principle by which the brain translates the movement of images on your retinas into perceptions of movement. Hold your hand in front of your face, then move its image across your etinas by moving you eyes, by moving your hand, or by moving both at once. You will notice that only those movements of the retinal image produced by the movement of your hand are translated into the perception of motion. Hammond, Merton and Sutton (1956) did an important discovery and found that the eyes can be held stationary despite the brain's attempts to move them. If a visual object is focused on a part of your retina, and it stays focused there despite the fact that you have moved your eyes to the right, it too must have moved to the right. As a consequence, the brain assumes that an eye movement has been carried out, and it will perceive stationary objects as moving to the right. What this study teaches us is that biopsychologists can learn much about the activities of the brain through scientific inference without directly observing them.
The identification of weaknesses in existing beliefs we may have is one of the major stimuli for scientists to adopt creative new approaches. Critical thinking is the process by which these weaknesses of existing ideas and the evidence on which they are based are recognized. We can judge the validity of any scientific claim is to determine whether the claim and the research on which it is based were published in a reputable scientific journal. It is namely the case that in order to be published, an article has to be reviewed by experts in the field and judged for good quality.
