Activity in the brain determines whether you currently are in a normal or an altered state of consciousness. You will learn in Section 2-6 about the types of brain activity associated with several sleep states (e.g., dreaming-sleep versus nondreaming-sleep). The association between types of brain activity and states of consciousness is one piece of evidence supporting the brain-mind theory — the claim that activity in the nervous system is linked, in some unknown way, to mental activity (cognitions and emotions) and behavior. The brain-mind theory is more than a claim that brain activity and mental/behavioral activity are related in some way: it is the claim that brain activity and mental activity (and behavior) are fully integrated. In other words, it states that mental activity cannot exist (and behavioral responses cannot occur) without activity in the nervous system.
The brain-mind theory describes and explains very well how our cognitions, emotions, and behaviors occur: it is a “good scientific theory.” In Section 1-5, you learned that a good scientific theory has two characteristics:
- The theory is well-supported by empirical evidence.
- The theorydoes three things:
- it meaningfully organizes all observations;
- it accurately predicts future observations;
- it describes the primary causes of all observations.
In the rest of this section, we’ll begin to look at why the brain-mind theory is thought to be a good scientific theory in this sense.
Evidence for the Brain-Mind Theory
The best empirical evidence for the brain-mind theory begins with research performed during the second half of the nineteenth century. These studies were the first to show clearly that specific impairments in mental/behavioral functioning develop after damage to specific areas of the brain occurs. Perhaps the most-famous example involves a set of observations made by a French physician named Paul Broca (1861a; 1861b). Broca observed a patient with severe damage to the left side of his brain near the front who had completely lost the ability to communicate through speech. The hospital staff called him tan because tan was virtually the only sound he could make. His inability to speak was due neither to paralysis of his facial muscles nor any lack of intelligence. Instead, tan simply was unable to use language to express himself through speech or writing. Based on observations of tan and other patients with similar damage, Broca concluded that the left-front part of the brain was essential for the ability to produce language.
A more-recent example of evidence that supports the brain-mind theory was reported by the neurologist Oliver Sacks (1995). In 1977, Sacks met a patient who, two years earlier, had had a benign brain tumor surgically removed. The tumor was removed too late, however, to prevent the man’s brain from being severely damaged. This damage caused the man (to whom Sacks gave the pseudonym “Greg”) to develop severe mental, physical, and behavioral problems: Greg became blind and obese, lost all his hair, often made bizarre comments, and suffered from amnesia (memory loss), which was so severe that he didn’t know the year or even that he was in a hospital. In fact, he believed that he was still a teenager living in the late 1960s, a time during which he had been part of the “hippie culture” and had engaged in all the activities that went with that lifestyle, such as heavy drug-use. Greg eventually left all that behind after devoting himself to the practice of an Eastern religion. Not long after, he started to show the early signs of the developing tumor. But neither he nor the people in his religious sect knew what was happening, and so Greg did not get medical help until the tumor had damaged a large part of his brain.
Sacks (1995) described his first meeting with Greg:
Lacking facial hair, and childlike in manner, he seemed younger than his twenty-five years. He was fat, Buddha-like, with a vacant, bland face, his blind eyes roving at random in their orbits, while he sat motionless in his wheelchair. If he lacked spontaneity and initiated no exchanges, he responded promptly and appropriately when I spoke to him, though odd words would sometimes catch his fancy and give rise to associative tangents or snatches of song and rhyme. Between questions, if the time was not filled, there tended to be a deepening silence; though if this lasted for more than a minute, he might fall into Hare Krishna chants or a soft muttering of mantras. (p. 45)
Greg’s amnesia was so severe that he forgot almost everything that had happened in his life since 1968. In fact, he was unable to remember any life experiences for more than about 20 seconds after they had occurred. The damage to Greg’s brain, therefore, resulted in severe and permanent impairments physically, behaviorally, and psychologically — impairments that were linked directly to the specific areas damaged by the tumor.
Organizing, Predicting, & Explaining Observations
The brain-mind theory successfully achieves the three functions of a theory. First, it allows researchers to organize their observations of cognitions, emotions, and behaviors. Memory researchers, for example, are able to organize their observations of memory impairments in terms of which parts of the brain have been damaged. Greg’s type of amnesia is often seen when damage occurs deep in the middle part of the brain. The type of amnesia in which a person forgets events from long ago, but remembers recent events, often are observed when the surface of the brain is damaged.
Second, the brain-mind theory allows researchers to predict what they are likely to observe if something else happens first. For example, memory researchers can predict that, if they remove from an animal’s brain the same area that was damaged in Greg’s brain, it will show memory impairments similar to Greg’s (i.e., the animal should not remember certain things it learned recently).
Third, the brain-mind theory allows researchers to explain their observations in terms of causes. The identification of causes often follows from the first two functions: if a theory allows researchers to organize their observations and it also allows them to successfully predict what should be observed if something else happens first, it becomes much easier to identify likely causes. For example, if memory researchers observe over and over again that people with a particular type of amnesia have damage to a particular brain structure, and if they observe that animals develop a similar type of amnesia after that brain structure is surgically removed, they can conclude with some confidence that activity in that brain structure causes (in interaction with other causal factors) the development of the type of memories lost when the structure is damaged.
Testing the Brain-Mind Theory
As stated above, scientific theories must be supported by evidence. The best evidence for theories comes from research that includes the following two steps:
- Researchers predict what they should observe if the theory is true;
- They perform tests to see if the predicted observations occur.
An excellent example of this was the research described in Section 2-3 on N-rays and suggestion. You learned there that Robert Wood developed a theory that stated that observers’ judgments of an object’s brightness are strongly influenced by whether or not they believe that N-rays are present. In order to test his theory, Wood deceived observers into thinking that N-rays were present when they actually weren’t, and vice versa. His prediction: when observers believe that N-rays are present (regardless of whether they actually are), they will perceive objects as being brighter than when they believe that N-rays are absent (again, regardless of whether they actually are). He then performed the necessary tests and showed beyond any reasonable doubt that the evidence for the existence of N-rays was “contaminated” by suggestion.
Good theories are ones that generate many predictions that are found to be correct (i.e., confirmed predictions) and few predictions that are found to be incorrect (i.e., disconfirmed predictions). The brain-mind theory has been confirmed by a very large number of observations over the last 150 years. It is so well supported that we can consider it to be a fact that electrical activity in the nervous system is the most proximal cause of our cognitions, emotions, and behaviors. In the rest of this chapter, you will learn about some of this evidence with respect to altered states of consciousness.
Study Questions for Section 2-5
- What is the brain-mind theory?
- What is some scientific evidence supporting the brain-mind theory?
- What might be some evidence supporting the brain-mind theory from your own life?
- What are the three functions of scientific theories? How does the brain-mind theory accomplish these three functions?
- What are two steps involved in testing whether or not a theory is a good scientific theory?
- Is the brain-mind theory a “good scientific theory”? Why or why not?
Practice Quiz for Section 2-5
References
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