![[Image]](eysgray.jpg)
Jeffrey Gray BIS/BAS Theory & Others
© 2010
This eText is the property of Toru Sato. All rights reserved © 2010. This eText is not to be copied, distributed, or downloaded without permission of the author. Any violation of copyright found in this eText is unintentional. Please notify the author if copyrighted material is found and not appropriately referenced.
BAS & BIS
There have been many theorists who have examined how brain functioning may be related to our personality (e.g., Cloninger, 2000; Eysenck, 1990; Gray, 1981; Zuckerman, 1991). Jeffrey Gray is the originator of one of the most commonly discussed theories in this area. Gray was initially interested in the biological theories of Hans Eysenck (click here for an explanation of Eysenck's theory) and eventually developed his own theory. Gray used the findings of his earlier research on animals and applied it to the understanding of human personality. Similar to Eysenck (1990), Gray (1981) suggested that there are two systems in the brain that correspond to two major personality traits (Gray, 1981).
The first system is called Behavioral Approach system (BAS). It is sometimes also referred to as the Behavioral Activation System (Fowles,1988), or Behavioral Facilitation System (Depue & Iacono 1989). It is the considered to be the approach motivation system or the "GO" system. The BAS causes us to be sensitive to potential rewards. Because it is sensitive to potential rewards it is also related to motivations to seek out positive experiences (i.e., the ones that feel good). If you are craving for ice-cream, your BAS is most likely activated. The BAS is driven to experience positive emotion. These kinds of motivation are commonly referred to as approach motivation. The BAS is related to a personality trait called impulsivity (or impulsiveness). People who have a highly active BAS tend to be high in impulsivity. Gray believed that the parts of the brain most highly related to the functioning of the BAS were the septal area and the lateral hypothalamus. High activity in these areas of the brain may be one indication of high levels of impulsivity (Gray, 1987). In addition to higher levels of activity in this part of the brain, people with high levels of impulsivity seem to have higher levels of a neurotransmitter called dopamine in their synapses (Gray, 1987). Interestingly, recent research also suggests that extraversion is related to higher levels of dopamine (Depue & Collins, 1999). As we will see in the next section, there is a positive correlation between impulsivity and extraversion.
If the BAS is what motivates to you "GO", the Behavioral Inhibition System (BIS), the other system in Gray's theory, is the "STOP" system. The BIS is sensitive to signs of potential punishment, unfamiliar novel stimuli, and innately fear inducing stimuli. It often motivates us to stop doing things that may lead to punishment. The BIS is the system that causes us to be negatively aroused and highly alert. If you see a bear running towards you, your BIS would most likely be activated. The BIS drives us to avoid negative emotion. These kinds of motivation are commonly referred to as avoidance motivation. The BIS is related to an individual difference dimension called anxiety (or trait anxiety). People who have a highly active BIS tend to be high in anxiety. Gray believed that the part of the brain most highly associated with the functioning of the BIS was the septo-hippocampus. Information comes into the septo-hippocampus from the prefrontal cortex, and the septo-hippocampus sends messages out to the noradrenergic fibers of the locus coeruleus, and serotonergic fibers from the median raphe (Gray 1994). High activity in these areas of the brain may be one indication of high levels of anxiety (Gray, 1987). In addition to higher levels of activity in this part of the brain, people with high levels of anxiety seem to have higher levels of a neuropeptide called norepinephrine (Gray, 1987).
Relationship with Eysenck's theory
Gray (1981) claimed that his theory of impulsivity and anxiety accounts for all of the individual differences considered using the two main supertraits in Eysenck's theory, introversion-extraversion and neuroticism-emotional stability. To understand this, consider Eysenck's two main supertraits being on the horizontal and vertical dimension as in the figure on the left side below. You can see Gray's trait anxiety and impulsivity on the diagonal dimensions. If we rotate these two dimensions 45 degrees clockwise, we end up having the figure on the right side. Here we have anxiety and impulsivity on the vertical and horizontal dimensions and Eysenck's dimensions on the diagonals. This means that being emotionally unstable and extraverted in Eysenck's theory corresponds to being high in impulsivity in Gray's theory. Being emotionally unstable and introverted in Eysenck's theory corresponds to being high in anxiety in Gray's theory. Being high in impulsivity and low in anxiety in Gray's theory means we are high in extraversion Eysenck's theory and so on. I trust that you get the point by now. This configuration makes much sense if we consider Eysenck's theory of neuroticism. He suggested that people high in neuroticism tend to have a highly reactive limbic system (Eysenck, 1990). The septal area, lateral hypothalamus (related to impulsivity) and the septo-hippocampus (related to trait anxiety) are all parts of the limbic system and a person who is highly neurotic would be high in both impulsivity and trait anxiety.
Relationship with Psychological Disorders
Gray (1994) also tried to explain how there may be a biological basis for certain types of psychological disorders. He suggested that anxiety disorders may be related to an unusually active BIS. Of course, since the BIS is related to trait anxiety, this would naturally make sense. He also suggested that depression may be associated with a combination of an extremely active BIS and an extremely underactive BAS. When people are depressed, they are highly anxious and lose motivation for pleasurable activities. Lastly, he suggested the anti-social personality disorders may be related to an overly active BAS and an extremely inactive BIS. People with anti-social personality disorder tend to be impulsive and lack inhibitions and therefore are motivated to do things that are considered to be morally unacceptable for most people. Overall Gray's work, has received much attention due to it's relative simplicity as well as his convincing arguments relating his work to biological findings in animals. Gray's theory, however, is largely based on animal research. Because of this, some researchers argue that it may be premature to make generalization to the human population.
Third System
Although it has not received as much attention, there is a third system in Gray's theory. He calls it the fight-flight system and it relates to our experiences of extreme fear (Gray & McNaughton, 2000). As the term "fight-flight" suggests, the more active this system is, the more we tend to be either withdrawn or aggressive. Gray believes that this system is highly assocatied with a brain structure known as the amygdala.
Other Biological Research on Approach/Avoidance Motivation
Even though Gray's theory primarily focusing on finding the structures and processes of the brain that relate to approach and avoidance motivations (as well as positive & negative emotions) is very interesting and unique, there are other researchers examining this topic. For example, the work of Richard Davidson (1992) has suggested that approach motivations and positive feelings are highly related to activity in the left side of the frontal lobe of the cerebrum. When people are presented with a rewarding stimulus, they tend to have higher levels of activity in this area of the brain. In addition, research by Davidson and his colleagues have also suggests that activity in the right side of the frontal lobe is associated with feelings of anxiety, fear or disgust. When people are presented with disgusting images, they tend to have higher levels of activity in this area of the brain (e.g., Davidson, 1992; Davidson & Sutton, 1995). Although the left and right sides of the frontal lobes are not the parts of the brain that Gray directly related the BAS and BIS to, research in this area is examining how all of these different parts of the brain interact to influence our personality.
Another interesting biological theory related to approach/avoidance motivation is the work of Robert Cloninger (2000). He suggests that there may be three personality traits related to these two types of motivations. Two of them known as, novelty seeking and reward dependence, are related to approach motivations. Individuals high in novelty seeking are people who are highly motivated to experience stimulation that is either new or stronger than what they are used to. Cloninger suggests that these people may have higher levels of dopamine than individuals low on this personality trait. Since this personality trait seems similar to Eysenck's trait of extraversion and Gray's trait of impulsivity, it makes sense that it may also be related to high levels of dopamine. The other personality trait related to approach motivation is reward dependence. People high in reward dependence are highly motivated to experience positive types of human contact. They are more motivated to experience physical contact with others as well as develop caring and emotionally supportive relationships with others. Research suggests that individuals high in reward dependence tend to have lower levels of norepinephrine than people low on this personality trait. Earlier, we discussed how high levels of norepinephrine may be related to trait anxiety in Gray's theory. It might make some sense to think that people who are highly anxious may be less likely to feel comfortable and confident enough to seek out positive types of human contact. According to Cloninger's (2000) theory, the personality trait related to avoidance motivation is known as harm avoidance. Individuals with high levels of harm avoidance are highly concerned about negative things that might happen. They are highly motivated to avoid physically and psychologically dangerous situations. Research suggests that individuals high in harm avoidance tend to have higher levels of a neurotransmitter called serotonin than people low on this personality trait (Cloninger, 2000).
References
Cloninger, C. R. (2000). Biology of personality dimensions. Current Opinions in Psychiatry, 13, 611-616.
Davidson, R. J. (1992). Brain asymmetry, the emotions, and mood disorders. The Harvard Mental Health Letter, 9, 4-5.
Davidson, R. J., & Sutton, S. K. (1995). Affective neuroscience: The emergence of a discipline. Current Opinion in Neurobiology, 5, 217-224.
Depue, R. A. & Collins, P. F. (1999). Neuropsychology of the structure of personality: Dopamine, facilitation of incentive motivation, and extraversion. Behavioral and Brain Sciences, 22, 491-569.
Depue, R. A. & Iacono, W. G. (1989). Neurobehavioral aspects of affective disorders. Annual Review of Psychology, 40, 457-492.
Eysenck, H. J. (1990). Biological dimensions of personality. In L. A. Pervin (Ed.), Handbook of personality: Theory and research (pp. 244-276). New York: Guilford.
Fowles, D.C., 1988. Psychophysiology and psychopathology: a motivational approach. Psychophysiology 25, 373–391.
Gray, J. A. (1981). A critique of Eysenck's theory of personality. In H. J. Eysenck (Ed.), A model for personality (pp. 246–276). New York: Springer.
Gray, J. A. (1987). The neuropsychology of emotion and personality. In S. M. Stahl, S. D. Iverson, & E. C. Goodman (Eds), Cognitive neurochemistry. Oxford: Oxford University Press.
Gray, J. A. (1994). Framework for a taxonomy of psychiatric disorder. In S. H. M. van Goozen, & Van de Poll,Nanne E. (Eds.), Emotions: Essays on emotion theory. (pp. 29–59). Mahwah, NJ: Lawrence Erlbaum Associates, Inc.
Gray, J. A., & McNaughton, N. (2000). The Neuropsychology of Anxiety. Oxford: Oxford University Press.
Zuckerman, M. (1991). Psychobiology of Personality. Cambridge, UK: Cambridge University Press.