This theory relates ideas about learning, about motivation and about neuroscience.
Personality is a complex dimension that describes the behavioral, cognitive and emotional pattern of an individual; through which it expresses itself as an independent being within human multiplicity.
The scientific interest in knowing what personality is and how it manifests itself has led many researchers, over the years, to postulate different theoretical models for this purpose. One of them was Jeffrey Gray, who presented his theory of reinforcement sensitivity as an alternative to classical models (Eysenck’s, for example), but starting from a fundamentally neuropsychological basis.
In this article we will address the author’s theoretical postulates, which constitute a very important vision of the nature of acts and cognitions, from which we can better understand who we are and why.
Theory of reinforcement sensitivity
The theory of reinforcement sensitivity tries to explain what a human being is like based on his motivation to approach or move away from the environmental stimuli or situations that are available to him.
While it is true that there are a series of appetitive stimuli in the face of which an innate search unfolds in which learning has not mediated (such as foods with which to nourish ourselves), others have acquired their positive nuances through individual experience.
The theory considers both types of stimulus : those that provoke an unconditioned approach or rejection (learning shared by the entire species throughout evolution) and those that generate similar responses but as a result of personal experiences (avoidance of dogs because we had a unpleasant encounter with one of them or because we saw a third being the victim of an attack, for example).
The desire for approach and rejection / flight (maintained by motivational-type states), would depend on the activation / inhibition of a series of neural networks, which would rise as the organic substrate of the basic dimensions of the personality. According to this perspective, what we think, feel or do can be captured by a reduced group of attributes that have their roots in the brain (offering a parsimonious and clear explanation of behavior based on its multiple interactions).
After a meticulous study of neural structures, and equipped with a broad theoretical background on their functions, Gray proposed three brain systems that would be at the base of approaching and distancing behaviors: the behavioral approach system (SAC), the system of behavioral inhibition (SIC) and the fight or flight system (SLH). Every person would present a specific activity pattern for each of them, which would form the profile of how they act and feel in their natural environment.
Based on these observations, he additionally proposed two personality dimensions: anxiety and impulsivity, different from those usually considered. Each of them would be linked to one of the systems outlined and would also involve different emotional experiences.
As can be seen, Gray drew a direct relationship between brain and personality, understanding that both behavior and thought could be explained from the activity of the structures involved in their systems. Hereinafter we will connect these two phenomena, explaining in a simple way how neurology and psychology converge in this interesting integrated theoretical model.
1. The behavioral approach system (SAC)
The SAC is a neurological mechanism that encourages an approach behavior towards stimuli that have been conditioned in a positive way (that is, that are associated with desirable results or that allow avoiding adverse consequences), thereby motivating the active search for their proximity spatial and temporal. Thus, it would be responsible for promoting the availability of what is perceived as desirable or that increases the probability of survival.
All this would translate into a voluntary motor and emotional approach behavior, mediated by coordinated brain structures. Specifically, dopaminergic fibers that emerge from the midbrain (ventral tegmental area and nucleus accumbens) towards limbic regions such as the basal ganglia, as well as other neocortical type (sensorimotor, motor and prefrontal cortex). The activation of this system would manifest itself in positive affects associated with the impulsivity dimension.
The basal ganglia are responsible for the planning and integration of voluntary movement, as well as motivation and emotion, while the motor and sensorimotor areas are necessary to translate everything into explicit actions of approach.
What has been reviewed is complemented by the function of the frontal lobe (which includes intention and projection at an executive level) and the reward system (which contributes a positive tone to the life experience through the production of dopamine).
2. The behavioral inhibition system (SIC)
SIC is understood, in the context of reinforcement sensitivity theory, as a response that is opposed to that of SAC. In this case, it would be activated by stimuli that have been negatively conditioned (since they generate damage or prevent the achievement of something desirable), or that have been fixed throughout the development of the species as objects or situations that should be avoided. . This is why they promote behaviors whose purpose is active distancing.
Likewise, it also extends to novel or too ambiguous situations, in which it is necessary to act in a balanced way and paying special attention to the environment. Consequently, the action of approaching would be inhibited until a more precise knowledge of the nature of the events being faced was available, articulating from that moment on a series of proximity behaviors (mediated by the SAC) or avoidance ( mediated by the SIC and the SLH).
The brain structures that make up the SIC are the hippocampus and its projections towards the prefrontal cortex. The hippocampus would actively participate in memory and spatial orientation, while the prefrontal cortex would be in charge of attention and prospective reasoning. All of them would be coordinated to explore the immediate environment and predict what may happen at that very moment or as a consequence of it at a later time.
The system, therefore, is directly associated with anxiety and is in charge of continuously assessing (monitoring) the situation in which we are immersed and what could happen in the future, in order to anticipate the appearance of adverse events that we fear or that we believe should be avoided.
3. The fight or flight system (SLH)
SLH is related to the escape of adverse events in which one is a participant (which differentiates it from avoidance) and to fight or flight behaviors.
The brain structures involved are the amygdala (in which various emotional experiences are processed, but particularly fear) and the hypothalamus (which mediates stress responses and the activation of the autonomic nervous system). Anger and fear would depend on him, emotions that have the purpose of preparing the body to give an immediate response.
It is known that the simultaneous hyperactivation of this system and the SAC triggers an approach and escape behavior at the same time and towards the same object, a setback that would have to be resolved through the participation of the SIC. This dissonance between the appetitive and the aversive would be responsible for anxiety as a symptom within a disorder.
How would personality be understood from this model?
In order to explain personality according to the theory of sensitivity to reinforcement, the SAC and SIC systems are considered, very especially. Both work independently, so the high or low activation of one of them would not influence the other. Thus, there would be people with hyperactivation / hypoactivation of both systems, and others in which one would be hyperactivated and the other underactivated.
As previously stated, SAC would be related to impulsivity and SIC would be related to anxiety, these being the basic personality dimensions according to Gray’s model (thoughts or acts of approach and inhibition, respectively). In this sense, the subjects with hyperactive SAC would be the impulsive ones, and those with hyperactive SIC the anxious ones.
Some authors have drawn analogies to explain that the activation spectrum of the SAC would be associated with the continuous extraversion / introversion (tendency to sociability or preference for loneliness or individuality) while the SIC would do the same with that of neuroticism / stability (vulnerability to emotional distress or regularity in affective states).
At present the theory of reinforcement sensitivity is being the subject of numerous investigations, from which both favorable and contrary results emerge. Some of them suggest that the SAC and SIC systems could be related in some way (so they would not work independently) and the study of anxiety / depression is also being approached from this same prism. It still takes time, however, to know the true scope of Gray’s model.
- Bijttebier, P., Beck, I., Claes, L. and Vandereycken, W. (2009). Gray’s Reinforcement Sensitivity Theory as a framework for research on personality – psychopathology associations. Clinical Psychology Review, 29 (5), 421-430.
- Colder, CR, Trucco, EM, López, HI, Hawk, LW, Read, JP, Lengua, LJ… Eiden, RD (2011). Revised Reinforcement Sensitivity Theory and Laboratory Assessment of BIS and BAS in Children. Journal of Research on Personality, 45 (2), 198-207.