Eysenck has concluded from his factor analytic research that there are 3 primary dimensions in personality: NEUROTICISM, INTROVERSION-EXTRAVERSION (I-E), and PSYCHOTICISM. In the first version of Esyenck’s theory, he related I-E to the Hullian concept of Ir (reactive inhibition). In order to understand this, we must expand on the original formula

SER = [(SHR ) X (D)] - [IR + SIR]. SIR is known as conditioned inhibition.

Ir is the aversiveness of fatigue that comes from repeated responding. If an organism stops responding, Ir dissipates over time. Ir (also an intervening variable) is grounded on the response side by 1) the number of occurrences of a response, 2) the time between successive responses, and 3) the effort involved in making each response.

A hungry rat in a Skinner box will keep bar pressing for food. Bar pressing will stop because Drive will be reduced as the rat continues to eat and because Ir will keep increasing each time the rat makes a response. Whenever the inhibitory part [IR + SIR] of the Hull-Spence formula is greater in magnitude than the excitatory part [(SHR ) X (D)] of the formula, responding will stop (according to the theory). Think of a food deprived rat in extinction training. Drive will continue to increase because food deprivation will continue in extinction. The reason responding stops in extinction (theoretically), is because of the build-up in IR from continued responding.

When an organism stops responding there is “relief” from fatigue. The fatigue from IR is assumed to be an aversive drive. When there is reduction in this drive, there is learning in the form of SIR, conditioned inhibition--the learned response of not responding. IR and SIR account for phenomena such as extinction and spontaneous recovery from extinction.

In 1955 Eysenck wrote, “Individuals in whom IR is generated quickly, in whom strong IR are generated, and in whom IR is dissipated slowly are thereby predisposed to develop EXTRAVERTED patterns of behavior.

“Individuals in whom IR is generated slowly, in whom weak IR are generated, and in whom IR is dissipated quickly are thereby predisposed to develop INTROVERTED patterns of behavior.

Thus on conditioning tasks with massed practice (like pursuit rotor training), INTROVERTS (I) should show better performance than EXTRAVERTS (E) because of a more rapid buildup of IR in Es. On reminiscence tasks after massed practice (conducted after a rest interval of 8-10 min. in which IR is dissipated , the theory predicts E > I.

In 1955, Eysenck also linked Neuroticism with Hullian Drive, in much the same way Spence and Spence linked the MAS with D. Eysenck was probably assuming that the MAS was a less than perfect measure of the Neuroticism factor.

In the 1957 version of the theory Is were also postulated to develop stronger (and more rapid) SHR than Es.

In 1967 Eysenck choose to stop using Hull-Spence theory as a way of studying Neuroticism and I-E. Eysenck’s theory became physiological. Eysenck cites research showing 2 kinds of brain activity: 1) Cortical arousal ( located in the reticular formation--midbrain, cerebellum, pons, and medulla), which regulates attention and alertness, and 2)Autonomic activation (located in the limbic system--hypothalamus and amygdala), which regulates emotional patterns and primary drives.

INTROVERTS are theorized to have higher levels of cortical arousal than EXTRAVERTS.

NEUROTICS are theorized to have higher levels of autonomic activation than STABLES (folks low on Neuroticism). Thus I-E is related to learning; Neuroticism is related to emotionality.

Because Is should now learn and remember better than Es (ie., learning is dependent on the consolidation of memory traces, which is dependent on the level of cortical arousal), Eysenck appeared to have a problem with a lot of research showing E > I on reminiscence tasks after pursuit rotor training. Eysenck finds the concept of ACTION DECREMENT to solve his problem.

According to Walker, as memory is laid down in a permanent fashion, there is a temporary inhibition against immediate recall (i.e., the action decrement). This inhibition allows for the consolidation of traces in long term memory to go on without interruption. The greater the level of cortical arousal the greater the action decrement. Thus Is (with higher levels of cortical arousal) should have more action decrement than Es (with less cortical arousal). Thus high levels of cortical arousal should facilitate the ultimate retrieval of long term memory, while interfering with memory at shorter intervals because of high levels of action decrement. Thus after a learning task Es should have better memory in the short run (such as the 8-10 min. after a pursuit rotor task) than Is. However, ultimately, Is > Es in long term memory.

This was tested by Horvath & Eysenck (1968), Journal of Experimental Research in Personality, who gave a paired associate task of CVC nonsense syllables to 55 Is and 55 Es. The list was learned to a criterion of 1 correct trial of all 7 pairs. Then subjects were divided into 5 groups and tested at one of 5 intervals later (immediately, 1 min., 5 min., 30 min., and 24 hrs. Subjects were given 1 minute to print all pairs. 1 point was given for each correct stimulus reported, and 1 point for each correct response--if correctly paired. The results (of course) conformed to Eysenck’s theory (otherwise they never would have been published). There was a significant interaction of the two groups by trials. Recall scores for the Is went up over trials from about 7 at immediate recall to 13 at 24 hrs. Recall scores for the Es went down over trials from about 12 at immediate recall to 7 at 24 hrs.

SOMEDAY, I WILL LEARN TO DRAW ON THE COMPUTER AND PUT THIS IN THE FORM OF A GRAPH.