Measures of RST have not been widely adapted to reflect the revised theory due to disagreement over related versus independent subsystems.
Eysenck's Extraversion-Arousal Hypothesis states that under low stimulation conditions, introverts (defined as low in Extraversion) will be more highly aroused than extraverts; however, under high stimulation, introverts may become over-aroused, which will feedback within the ascending reticular activating system and result in decreases in arousal.
[3] Eysenck's theory predicts that introverts are more likely to develop anxiety disorders because they show higher neuroticism and stronger emotional conditioning responses under high arousal.
His theory was criticized because introverts often show the opposite pattern, weaker classical conditioning under high arousal, and some supporting data confounded personality traits with time of day.
[26] Reinforcement sensitivity theory is one of the major biological models of individual differences in emotion, motivation, and learning.
[27] Furthermore, the possibility of anxiety's triggering panic and vice versa supports a model of the BIS and the FFFS in which the two are not causally independent.
[26][28] D.C. Blanchard and colleagues (2001) created vignettes with response options that modeled rodent reactions to anxiety (the BIS, used ambiguous/partially threatening stimuli) and fear (the FFFS, used pure threat situations) to study these constructs in humans.
[1] The SSH is proposed to operate in extreme circumstances, within individuals with highly reactive systems and/or experimental conditions that only present rewarding or punishing stimuli.
[30] The separable subsystems hypothesis has been applied successfully to study reinforcement learning and motivation in clinical populations.
[27] Alternatively, the joint subsystems hypothesis (JSH), in accordance with Gray's original animal models and the revised RST, states that reward and punishment exert combined effects in the BAS and the FFFS, while the BIS resolves conflict within and between the systems.
The joint subsystems hypothesis is most applicable in real-world contexts that contain mixed stimuli: strong, weak, punishment, and reward.
[25] The BAS, FFFS, and BIS are dependent systems, and current research attempts to define under what task situations and to what degree they interact.
[3] Pickering used regression and neural network models to show that patterns of inputs from the BAS and the BIS/FFFS generate a large range of outcomes that support the JSH (all three system activations were needed to determine best fit for behavioral output).
[1] As mentioned previously, these complex, dependent systems are not reflected in questionnaires, such as Carver's BIS/BAS,[22] that are oftentimes used to test RST predictions.
A variety of disparate experimental findings, originally viewed as inconsistent with Gray's Biopsychological theory, are more consistent with RST joint systems hypothesis.
[1] Smillie, Pickering, and Jackson (2006) advocated for renaming trait Impulsivity, which is associated with BAS in the revised RST, Extraversion.
[3][8] Regardless of the trait label, the authors point out that the RST did not develop as a theory to explain the personality constructs, Anxiety and Impulsivity.
[4][5] The proposed fear (FFFS) subscale is associated with avoidance behaviors (example item: 'If approached by a suspicious stranger, I run away') while the anxiety (BIS) subscale includes social situations wherein reward and punishment stimuli result in conflict between approach and avoidance motivations (example item: 'I prefer to work on projects where I can prove my abilities to others').
[4][5] Thus, current research aims to apply measures based on the revised RST to more accurately clarify relations between fear, anxiety, and job performance.
Researchers in fields ranging from cognitive science to self-regulation and attention are using the RST to investigate causal mechanisms that underlie the relationship between personality traits and psychopathology.
[1][3][27] A study by Masuyama et al. suggests that treatment interventions, which increase trait resilience, may be helpful in decreasing depressive symptoms.