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Susceptibility to positive and negative mood states: test of Eysenck’s, Gray’s and Newman’s theories
Personality and Individual Dierences 29 (2000) 351±365
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Susceptibility to positive and negative mood states: test of Eysenck's, Gray's and Newman's theories R. Gomez*, A. Cooper, A. Gomez School of Behavioural and Social Sciences and Humanities, University of Ballarat, Victoria, Australia Received 25 February 1999; accepted 31 August 1999
Abstract The study examined the relationships of extraversion and neuroticism with trait anxiety and impulsivity, and how extraversion and neuroticism, and impulsivity and anxiety are related to negative and positive mood states. Subjects completed questionnaires covering extraversion, neuroticism, anxiety and impulsivity, and were divided randomly into two mood induction groups: positive (N = 50) and negative (N = 48). The positive mood induction group was provided with money, progressively, during performance of a go/no-go task, while for the negative mood induction group, money was progressively withdrawn during task performance. Results showed that negative mood induction was predicted by neuroticism and extraversion neuroticism, while positive mood induction was predicted by extraversion. Anxiety and impulsivity also predicted negative and positive mood induction, respectively. These ®ndings are discussed in the context of Eysenck's, Gray's and Newman's theories of personality and mood. 7 2000 Elsevier Science Ltd. All rights reserved. Keywords: Extraversion; Neuroticism; Impulsivity; Anxiety; Positive and negative moods
1. Introduction Two dimensions that appear consistently in factor-analytic studies of personality questionnaires are extraversion±introversion and neuroticism±stability (Costa & McCrae, 1985; Eysenck, 1967; Goldberg, 1990). However, these dimensions are thought to be associated with dierent responses in Eysenck's, Gray's, and Newman's theories of personality. Many studies * Corresponding author. Tel.: +61-3-53279760; fax: +61-3-53279754. E-mail address: [email protected] (R. Gomez). 0191-8869/00/$ - see front matter 7 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 1 9 1 - 8 8 6 9 ( 9 9 ) 0 0 1 9 8 - 1
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have compared the dierences by examining predictions arising from them. This study extends the research in this area, especially in relation to positive and negative mood states. According to Eysenck (1967), the extraversion dimension is orthogonally related to the neuroticism dimension. Individuals who score high on extraversion (or extraverts) are generally outgoing, sociable, active and optimistic, while those who score low on this dimension (or introverts) are quiet, unsociable, passive and careful. Eysenck (1967) has suggested that individual dierences in extraversion re¯ect dierences in cortical arousal, resulting from dierences in the reactivity of the ascending reticular activating system to environmental stimuli. They have argued that as introverts exhibit higher cortical arousal than extraverts, introverts are more easily conditioned. In Eysenck's theory, neuroticism is viewed as re¯ecting individual dierences in reactivity to negative environmental stimuli, with high scorers (i.e. neurotics) being more negatively reactive or prone to unpleasant experience than low scorers (stable individuals). The neural substrate of this dimension is thought to be the visceral brain, made up of the septum, hippocampus, cingulum, amygdala and hypothalamus (Eysenck & Eysenck, 1985). Although Gray (1970, 1981, 1987) has proposed that anxiety and impulsivity are the major dimensions of personality, he has mapped these dimensions on to Eysenck's personality space. According to Gray, the anxiety axis runs from the stable±extraversion quadrant (low anxiety) to the neuroticism±introversion quadrant (high anxiety), while the impulsivity axis runs from the stable±introversion quadrant (low impulsivity) to the neuroticism±extraversion quadrant (high impulsivity). However, the anxiety and impulsivity dimensions are thought to lie closer to 308 (rather than 458) of the neuroticism and extraversion dimensions, respectively (Gray, 1970; Pickering, Corr & Gray, 1999; Pickering et al., 1997). Gray's model implies that anxiety will be positively associated with neuroticism, and negatively with extraversion, while impulsivity will be positively associated with extraversion, and positively with neuroticism. Also, the ratio of neuroticism to extraversion will be 2:1 for anxiety, and 1:2 for impulsivity. Consistent with Gray's theory there are studies showing that anxiety correlates positively with neuroticism and negatively with extraversion (Corr, Pickering & Gray, 1997; Diaz & Pickering, 1993; Eysenck, 1967; MacAndrew & Steele, 1991; Torrubia & Tobena, 1984; see also Gray, 1970). Also, in most of these studies, the correlation of neuroticism and anxiety was about twice more than that between extraversion and anxiety (Diaz & Pickering, 1993; Eysenck, 1967; MacAndrew & Steele, 1991; Torrubia & Tobena, 1984). The existing data on impulsivity, however, appear to provide only partial support for Gray's theory. Although data indicate that both neuroticism and extraversion are positively associated with trait impulsivity, the correlation between extraversion and impulsivity has generally been found to be less than (rather than) two times the correlation between neuroticism and impulsivity (Corr et al., 1997; Corulla, 1987; Diaz & Pickering, 1993). These studies derived the extraversion scores using the extraversion scale of the Eysenck Personality Questionnaire (EPQ; Eysenck & Eysenck, 1975). Diaz and Pickering (1993) have raised doubts about the relevance of the EPQ extraversion to BAS-related personality and behaviour. This is because when there was the change from the EPI to the EPQ the extraversion scale lost several items to the new psychoticism scale. This left the extraversion scale of the new EPQ measuring primarily sociability and liveliness, rather than impulsivity (Eysenck & Eysenck, 1991). Thus, the lower than expected proportion of extraversion in this mixture in past studies may have arisen from how the extraversion scores
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were measured. This argument implies that if extraversion is measured by an extraversion scale that also incorporates elements of impulsivity, as in the Eysenck Personality Inventory (EPI; Eysenck & Eysenck, 1964), a higher proportion of extraversion in this mixture can be expected. In Gray's theory, anxiety is thought to re¯ect individual dierences in the behavioural inhibition system (BIS), while impulsivity is thought to re¯ect individual dierences in the behavioural approach system (BAS). According to Gray, the neural basis of the BIS are the noradrenergic and serotonergic pathways, and for the BAS it is the dopaminergic pathways. In addition to the BIS and the BAS, Gray's model also includes a third system, referred to as the nonspeci®c arousal system (NAS). The NAS is thought to receive excitatory outputs from both the BIS and the BAS (i.e. nonspeci®c), and thereby aects the responses mediated by both the behavioural activation systems. Such a view diers from Eysenck's theory, which (as mentioned earlier) links neuroticism to reactivity. In Gray's theory, currently referred to as the reinforcement sensitivity theory (Pickering et al., 1997, 1999), the BIS and BAS are linked to dierent types of reinforcements. The BIS is thought to be sensitive to signals of punishment, frustrative nonreward and novelty, and its activation is thought to decrease behaviours toward such stimuli, and is also associated with negative mood. The BAS is believed to be sensitive to signals of reward and nonpunishment, and its activation is thought to increase approach behaviours toward these stimuli, and is also associated with positive mood. Viewed in terms of Eysenck's neuroticism and extraversion dimensions, Gray's theory suggests that both neuroticism and extraversion will contribute to mood states, with neuroticism contributing more to negative mood, and extraversion contributing more to positive mood. This view diers from Eysenck's model of personality and mood. Although Eysenck's arousal/activation theory is not associated directly with positive and negative emotion in the daily lives of individuals, apart from the notion that there are optimal and suboptimal levels of cortical arousal for hedonic tone (pleasure vs displeasure), it has been proposed that neuroticism (but not extraversion) and extraversion (but not neuroticism) are associated with negative and positive mood states, respectively (Eysenck & Eysenck, 1985; see also Costa & McCrae, 1980; Tellegen, 1985; Watson & Clark, 1992). Consistent with Eysenck's model, many studies have shown a positive association between positive mood (both trait and state) and extraversion, and between negative mood (both trait and state) and neuroticism (e.g., Costa & McCrae, 1980; David, Green, Martin & Suls, 1997; Larsen & Ketelaar, 1989, 1991; Watson & Clark, 1992). For example, Larsen and Ketelaar (1989, 1991) found that during negative mood induction (via exposure to negative material), neuroticism correlated positively with negative mood, but there was no correlation between extraversion and negative mood. During positive mood induction (via exposure to positive material), extraversion, but not neuroticism, correlated with positive mood. Also, Carver and White (1994) found that extraversion was positively associated with happy mood during positive mood induction. Newman's theory of personality is a synthesis of Gray's and Eysenck's personality theories, in that the three systems of Gray's model are mapped onto Eysenck's personality dimensions of extraversion and neuroticism (Bachorowski & Newman, 1985; Nichols & Newman, 1986; Wallace & Newman, 1998; Wallace, Newman & Bachorowski, 1991). According to Newman, the BAS re¯ects high extraversion, while the BIS re¯ects low extraversion (or introversion). In his theory, the behavioural and mood states mediated by the BAS and the BIS are considered
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to be similar to Gray's theory. Thus, viewed in terms of Eysenck's theory, Newman's theory suggests that high extraversion is positively associated with sensitivity to rewards and positive mood, while low extraversion is positively associated with sensitivity to punishment and negative mood. Similar to Eysenck, Newman views neuroticism in terms of reactivity, with higher neuroticism re¯ecting higher reactivity. According to Newman, neuroticism re¯ects the reactivity of the NAS, and, therefore, neuroticism moderates both the BAS and BIS (Wallace et al., 1991). Recently, Pickering et al. (1999) have illustrated the relation between Eysenck's and Gray's models in terms of algebraic equations. According to them, in Eysenck's model, BAS A extraversion, and BIS A neuroticism. In Gray's model, BAS A (2 extraversion+neuroticism), and BIS A (2 neuroticism±extraversion), where the ``2'' re¯ects Gray's 308 rotation of Eysenck's dimensions. Extending these equations, Rusting and Larsen (1997, 1999) have proposed that in Newman's model BAS A [extraversion+neuroticism+(extraversion neuroticism)], and BIS A [neuroticism±extraversion+(extraversion neuroticism)]. However, as Newman's theory does not implicate a direct relation between neuroticism and the behavioural activation systems, the following equations would appear more appropriate: BAS A [extraversion+(extraversion neuroticism)], and BIS A [ÿextraversion+(extraversion neuroticism)]. The above equations indicate that for comparisons of the three models in terms of predictions relating to susceptibility to mood states, the mood has to be regressed on the appropriate Eysenckian dimensions. This approach was adopted by Rusting and Larsen (1997). Results indicated that for positive mood induction, post-exposure positive mood was predicted positively by extraversion, and neuroticism did not contribute to this prediction. For negative mood induction, post-exposure negative mood was predicted positively by neuroticism and negatively by extraversion, and the ratio of the beta weights of neuroticism to extraversion was about 2:1. The study found that when the neuroticism extraversion was entered in the regression equations (after entering neuroticism and extraversion), it did not make a signi®cant prediction to either the positive or negative mood induction. Overall, therefore, the ®ndings in this study for positive mood induction supported Eysenck's theory, while the ®ndings for negative mood induction supported Gray's theory (Pickering et al. 1999). Although Rusting and Larsen (1999) have interpreted their ®ndings as not supporting Newman's model, this conclusion must be viewed cautiously. As pointed out earlier, Newman's model does not implicate a direct relation between neuroticism and the mood states. Thus the entry of neuroticism in the regression equations in the Rusting and Larsen study may have confounded results. Indeed, the ®ndings that extraversion was related to both positive and negative mood states among individuals with high neuroticism (McFatter, 1994), and that extraversion neuroticism predicted positive mood during dieting (Williams, Surwit, Babyak & McCaskill, 1998) provides suggestive support for Newman's model. Clearly, more studies are needed in this area. There were three aims in this study. The ®rst aim was to examine the location of Gray's personality dimensions on Eysenck's personality space. However, unlike previous studies which measured extraversion using the EPQ, in this study, extraversion was measured by the EPI. Gray's model would predict that trait anxiety would be predicted negatively by extraversion and positively by neuroticism, with neuroticism contributing two times more than extraversion.
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The prediction for trait impulsivity would be that it would be predicted positively by both extraversion and neuroticism, with extraversion contributing two times more than neuroticism. The second aim of this study was to compare Eysenck's, Gray's and Newman's theories in relation to how extraversion and neuroticism are related to positive and negative mood states. Unlike the study by Larsen and his associates, positive and negative mood states in this study were directly induced by monetary reward and monetary withdrawal, respectively. As already noted, Eysenck's model would suggest that neuroticism would positively predict negative mood induction, while extraversion would positively predict positive mood induction. Gray's theory would suggest that negative mood induction would be predicted negatively by extraversion and positively by neuroticism, with neuroticism contributing two times more than extraversion. For positive mood induction, Gray's model would predict positive contributions by both extraversion and neuroticism, with extraversion contributing two times more than neuroticism. Newman's model would suggest that extraversion would predict negative mood induction negatively, and positive mood induction positively. In addition, extraversion neuroticism would also contribute positively to the predictions of both mood inductions. The third aim was to test Gray's theory of personality and mood using the dimensions of trait anxiety and impulsivity. Based on Gray's theory, it was predicted that trait anxiety and impulsivity would positively predict negative mood induction and positive mood induction, respectively. 2. Method 2.1. Participants Participants comprised 98 students from the University of Ballarat, who responded to a notice for volunteers for this study. For all participants, informed consent was obtained prior to the study. The subjects were divided randomly into two groups: positive mood induction group (N = 50) and negative mood induction group (N = 48). There were 22 males and 28 females in the positive mood induction group, and 21 males and 27 females in the negative mood induction group. All participants were between 18 and 25 years of age, and were screened for known psychological disorders. 2.2. Personality measures The following personality questionnaires were used: the Eysenck Personality Inventory (EPI; Eysenck & Eysenck, 1964), the Trait-Anxiety scale of the State-Trait Anxiety Inventory Form (STAI-T; Spielberger, Gorsuch, Lushene, Vagg & Jacobs, 1983), and the eleventh version of the Barratt Impulsiveness Scale (BIS-11; Patton, Stanford & Barratt, 1995). The EPI is a 57-item ``yes''/``no'' questionnaire, and provides scores for extraversion, neuroticism and lie. The EPI has been extensively validated and used in past personality research. The internal consistencies (Cronbach's as) of the extraversion and neuroticism subscales for the participants in this study were 0.74 and 0.83, respectively. The STAI-T is a 20-item questionnaire, measuring trait anxiety, and each item is rated on a Likert scale,
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ranging from 1 (``almost never'') to 4 (``almost always''). The scale had an internal consistency of 0.92 for the participants in this study. The BIS-11 has 30 items. The total score for these items provides a global measure of trait impulsivity. The full scale had an internal consistency of 0.82 for the participants in this study. 2.3. Mood measure Mood was measured using the Positive and Negative Aective Schedule (PANAS; Watson, Clark & Tellegen, 1988). The PANAS, used widely in mood research, provides scores for two orthogonally related dimensions of mood states: positive and negative. There are 10 adjectives covering positive aect, and 10 adjectives covering negative aect, and each aect is rated from 1 (``very slightly or not at all'') to 5 (``extremely''). The internal consistencies for positive mood and negative mood for the participants in this study were 0.90 and 0.83, respectively. 2.4. Mood induction procedure Positive and negative mood states were induced through reward and punishment, involving winning and losing money, respectively, while performing a go/no-go task. It is to be noted that when used in our previous study (Gomez & McLaren, 1997), the reward version of this task produced a higher level of happy mood than the punishment version, while the punishment version produced a higher level of nervous mood than the reward version. Both the reward and punishment versions of the go/no-go task were presented on a green monochrome IBM monitor. In both versions, there were 96 test trials, divided into 8 sets of 12 trials each. Each trial consisted of one of 12 two-digit numbers, presented randomly. In each trial, the stimulus was presented until the subject responded or for a maximum of 3 s if the subject did not respond. The inter-stimulus interval was 1.5 s. Of these 12 numbers, six were `good' numbers, and six were `bad' numbers. Subjects were instructed to learn which were `good' numbers and which were `bad' numbers by trial and error. Eighteen practice trials were presented before the 96 test trials. For the reward version of the go/no-go task, subjects were instructed that every time they responded to a `good' number or refrained from responding to a `bad' number they would gain 10 cents, and that there was no loss of money for failing to respond to a `good' number or for responding to a `bad' number. Correct responses (responding to a `good' number or not responding to a `bad' number) resulted in a 1-s visual feedback indicating that the subject had earned 10 cents. For the punishment version, all subjects started with a bonus of $9.60. They were instructed that every time they failed to respond to a `good' number or they responded to a `bad' number they would lose 10 cents, and that there was no gain of money for responding to a `good' number or not responding to a `bad' number. Incorrect responses (not responding to a `good' number or responding to a `bad' number) resulted in a 1-s visual feedback indicating that the subject had lost 10 cents. The directions for each condition were presented to subjects on the computer screen. For both the reward and punishment versions of the go/no-go task, the following scores were recorded: hits (i.e. responding to a `good' number), errors of commission (i.e. responding to `bad' numbers), total number of responses, and mean reaction time to all responses. Hits
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were obtained in order to examine if there was a dierence in the rate of learning across the two versions of the go/no-go task. The other measures were obtained to examine if the dierent versions were eective in activating the BAS (via the reward version) and the BIS (via the punishment version). 2.5. Procedure Following consent, appointments for the laboratory sessions were given to participants. For the laboratory session, participants were tested individually. The experimental session began with participants completing the set of personality questionnaires. This took about 15 min, and was done to equate the participants' experiences prior to testing. Following this, participants completed the PANAS in terms of how they were feeling at that point in time. Immediately after this, participants completed the appropriate go/no-go task. Participants in the positive mood induction group completed the reward version, while participants in the negative mood induction group completed the punishment version. On completion of this task, participants completed the PANAS once again, with instructions to rate the items in terms of how they felt while performing the go/no-go task. Participants were then informed of how much money they earned (positive mood induction group) or had remaining (negative mood induction group), and were paid this sum of money. 3. Results 3.1. Extraversion and neuroticism as predictors of trait anxiety and impulsivity Table 1 shows the results of the regression analyses, involving all the participants, in which trait anxiety and impulsivity were regressed (separately) on both extraversion and neuroticism. As will be noticed, extraversion contributed signi®cantly and negatively to the prediction of anxiety, while neuroticism contributed signi®cantly and positively to this prediction. The standardised b values indicated that neuroticism contributed about 2.7 times more than Table 1 Regression of trait anxiety and impulsivity on extraversion and neuroticism (P < 0.05; Variable Trait anxiety on extraversion and neuroticism Extraversion Neuroticism Trait impulsivity on extraversion and neuroticism Extraversion Neuroticism
b
SE
P < 0.01;
b
P < 0.001)
t
ÿ0.52 0.17 ÿ0.23 1.12 0.14 0.63 [R 2=0.48; F (df = 2, 95)=43.86]
3.12 8.56
0.89 0.18 0.44 0.39 0.16 0.22 [R 2=0.22; F (df = 2, 95)=13.57]
4.80 2.44
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extraversion to the prediction of anxiety. For impulsivity, both extraversion and neuroticism made signi®cant positive contributions, with extraversion contributing 2 times more than neuroticism. The ®ndings also showed that, together, extraversion and neuroticism contributed only 22% and 48% of the variance for trait impulsivity and anxiety, respectively. 3.2. Extraversion and neuroticism, and extraversion and extraversion neuroticism as predictors of negative and positive mood induction Prior to the examination of how Eysenck's personality dimensions predicted negative and positive mood induction, we examined the comparability of the subjects in the two groups for personality, and whether the reward and punishment used in the study were successful in activating the appropriate behavioural activation systems and mood states. Table 2 provides the mean and standard deviation scores for extraversion, neuroticism, anxiety, impulsivity, and go/no-go performance scores of the two groups. It also shows the results of the t test for dierences between the groups on these measures. As shown, there was no signi®cant dierence between the groups on any of the personality measures, indicating that the groups were comparable on personality. There was also no group dierence for hits, suggesting no dierence in learning across the two versions of the go/no-go task. The positive mood induction group made more commission errors and total responses, and responded faster than the negative mood induction group. These ®ndings imply that the reward used produced more BAS activation, while the punishment used produced more BIS activation. Table 3 shows the mean and standard deviation scores for negative mood and positive mood Table 2 Extraversion, neuroticism, trait anxiety and impulsivity, and go/no-go task scores: mean scores, standard deviations and group dierences (P = 0.05; P < 0.01) Variable
Induction group: mean (SD)
t statistics (df=96)
Positive
Negative
Eysenck Personality Inventory Extraversion Neuroticism
13.84 (3.98) 10.16 (5.36)
13.94 (5.09) 11.56 (5.11)
0.11 1.32
Spielberger's STAI-Trait Form Trait anxiety
37.46 (10.44)
40.48 (9.70)
1.48
Barratt Impulsiveness Scale Global impulsivity
65.74 (9.80)
65.50 (8.75)
0.13
Go/no-go task Hits Commission errors Total responses Reaction time (s)
38.14 22.98 61.12 1.27
38.42 18.00 56.42 1.43
0.17 2.75 1.95 3.33
(8.30) (9.31) (13.07) (0.23)
(7.39) (8.71) (10.51) (0.23)
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Table 3 Positive and negative moods: mean scores, standard deviations and group dierences (P < 0.01; for negative and positive mood induction groups are 47 and 49, respectively) Group/mood
P < 0.001; df
Test phase: mean (SD)
t statistics
Pre
During
Negative mood induction group Negative mood Positive mood
12.71 (3.75) 27.31(7.75)
14.97 (5.45) 28.83 (8.95)
3.21 1.80
Positive mood induction group Negative mood Positive mood
12.88 (4.06) 29.38 (9.61)
13.98 (5.21) 34.20 (8.08)
1.61 4.72
just before and during performance for the mood induction groups, and the results of the t tests for dierences in mood scores before and during performance. Results for the negative mood induction group indicated increase in negative mood from pre-performance to performance, but no change from pre-performance to performance for positive mood. Results Table 4 Regression analyses showing prediction of negative mood during performance from neuroticism and extraversion, extraversion and extraversion neuroticism, and anxiety (P < 0.05; P < 0.01) DR 2 Extraversion and neuroticism on negative mood during performance Step 1: Preperformance negative mood Step 2: Preperformance negative mood Extraversion Neuroticism
SE
0.65 0.19 0.15
Extraversion and extraversion neuroticism on negative mood during performance Step 1: Preperformance negative mood Step 2: Preperformance negative mood 0.12 Extraversion Extraversion neuroticism Anxiety on negative mood during performance Step 1: Preperformance negative mood Step 2: Preperformance negative mood Anxiety
b
0.11
b
t
0.45 3.41
0.49 0.19 0.33 2.48 ÿ0.11 0.14 ÿ0.10 0.81 0.39 0.15 0.37 2.67
0.65 0.19
0.45 3.41
0.54 0.19 0.38 2.86 ÿ0.40 0.15 ÿ0.38 2.64 0.02 0.11 0.33 2.23
0.65 0.19
0.45 3.41
0.19 0.19 0.20 0.07
0.35 2.71 0.35 2.71
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for the positive mood induction group showed higher positive mood during performance compared to just before performance. For this group, negative mood did not vary from before to during performance. Overall, as desired, the punishment and reward used were clearly successful in inducing negative mood and positive mood, respectively. Table 4 shows the results of the regression analyses involving the negative mood induction group, in which negative mood during performance of the go/no-go task was regressed on extraversion and neuroticism together, and on extraversion and extraversion neuroticism together. It also shows the results of the regression analysis involving trait anxiety as a predictor of performance negative mood. In these analyses, the score for negative mood just before task performance was partialed out. As non-centered cross-product terms are not interactions, centered scores (i.e., the actual score minus the mean score) were used in the regression analysis involving extraversion and extraversion neuroticism. Centered scores also reduce problems of multicolinearity of product terms (Cohen & Cohen, 1983). For the analysis involving extraversion and neuroticism, only neuroticism contributed signi®cantly (positively) to the prediction of negative mood. For the analysis involving extraversion and extraversion neuroticism, both predictors contributed signi®cantly (positively) to the prediction of negative mood. Trait anxiety also contributed positively to this prediction. Table 5 shows the results for the positive mood induction group. For these analyses, positive mood during performance of the go/no-go condition was regressed on extraversion and Table 5 Regression analyses showing prediction of positive mood during performance from neuroticism and extraversion, extraversion and extraversion neuroticism, and impulsivity (P < 0.05; P < 0.01; P < 0.001) DR 2 b Extraversion and neuroticism on positive mood during performance Step 1: Preperformance positive mood Step 2: Preperformance positive mood Extraversion Neuroticism
SE b b
0.57 0.09 0.07
0.07
0.68 6.40
0.55 0.09 0.65 6.33 0.53 0.21 0.27 2.28 ÿ0.10 0.16 ÿ0.07 0.66
Extraversion and extraversion neuroticism on positive mood during performance Step 1: Preperformance positive mood 0.57 Step 2: Preperformance positive mood 0.08 0.56 Extraversion 0.68 Extraversion neuroticism ÿ0.01 Step 1: Preperformance positive mood Step 2: Preperformance positive mood Impulsivity
t
0.09
0.68 6.40
0.08 0.67 6.51 0.24 0.33 2.86 0.01 ÿ0.16 1.30
0.57 0.09
0.68 6.40
0.58 0.08 0.21 0.08
0.70 6.94 0.26 2.53
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neuroticism together, extraversion and extraversion neuroticism together, and trait impulsivity by itself. The score for positive mood just before task performance was partialed out. Again, in the analysis involving extraversion and extraversion neuroticism, the scores for these variables were centered. In the analysis involving extraversion and neuroticism, only extraversion contributed signi®cantly (positively) to the prediction of positive mood. In the analysis involving extraversion and extraversion neuroticism, only extraversion made a signi®cant (positive) contribution to the prediction of positive mood. Trait impulsivity signi®cantly predicted performance positive mood.
4. Discussion Consistent with Gray's (1970) theory, and existing data (Corr et al., 1997; Diaz & Pickering, 1993; Eysenck, 1967; Gray, 1970; MacAndrew & Steele, 1991; Torrubia & Tobena, 1984), the results of this study showed that trait anxiety was predicted signi®cantly and positively by neuroticism, and signi®cantly and negatively by extraversion. The results also showed that both extraversion and neuroticism signi®cantly and positively predicted trait impulsivity. The ®ndings here showed that neuroticism contributed about 2.7 times the contribution made by extraversion in the prediction of trait anxiety, while extraversion contributed 2 times more than neuroticism in the prediction of trait impulsivity. These ®ndings dier somewhat from existing data, in that, existing data show that the correlation between neuroticism and trait anxiety is about twice more than that between extraversion and trait anxiety, while the correlation between extraversion and trait impulsivity is less than two times the correlation between neuroticism and trait impulsivity (Corr et al., 1997; Corulla, 1987; Diaz & Pickering, 1993; Eysenck, 1967; MacAndrew & Steele, 1991; Torrubia & Tobena, 1984). The dierences in ®ndings between this study and previous studies may have arisen because of dierences in the extraversion measure. Previous studies used the EPQ, while this study used the EPI. As noted earlier, EPQ extraversion does not have impulsivity items, while EPI extraversion has impulsivity items. As the EPI extraversion has impulsivity items, it is possible that this may have contributed to a higher proportion of extraversion in the prediction of impulsivity, and a lower proportion of extraversion in the prediction of anxiety in this study compared to past studies. Taken together, the ®ndings here are supportive of Gray's general locations of trait anxiety and impulsivity in terms of Eysenck's personality space. However the precise locations of trait anxiety and impulsivity in Eysenck's personality space appear to be governed by the way extraversion is de®ned or measured. When extraversion is measured by the EPQ (as in past studies), it appears that there is support for Gray's placement of the anxiety axis at 308 from the neuroticism axis, but not for the placement of the impulsivity axis at 308 from the extraversion axis. When extraversion is measured by the EPI (as in this study), the opposite appears to be the case: there is no support for the placement of the anxiety axis at 308 from the neuroticism axis, but support for the placement of the impulsivity axis at 308 from the extraversion axis. An important implication of these ®ndings is that the questionnaires used need to be considered when locating Gray's dimensions in Eysenck's personality space. This study found that the subjects who were provided reward during task performance (i.e. the positive mood induction group) responded faster, made more responses, including
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commission error responses, than the subjects who were provided punishment during task performance (i.e. the negative mood induction group). Also, the reward used increased positive mood (but had no eect on negative mood), while the punishment used increased negative mood (but had no eect on positive mood). Other studies have also reported similar ®ndings (Carver & White, 1994; Corr et al., 1997; Gomez & McLaren, 1997; Hagopian & Ollendick, 1994; Newman, Patterson & Kosson, 1987). Taken together, the ®ndings here suggest that the reward used produced more BAS activation, while the punishment used produced more BIS activation. The ®ndings are also consistent with Gray's (1970) view linking BAS activation to approach and positive mood, and BIS activation to avoidance and negative mood. It is to be noted that the absence of dierence between the groups for hits implies that the dierences noted are unlikely to have resulted from any dierence in diculty levels between the reward and punishment versions of the go/no-go task. The ®ndings for the positive mood induction group showed that when positive mood during task performance was regressed on extraversion and neuroticism together, extraversion contributed signi®cantly and positively to the prediction of positive mood induction. Neuroticism did not make a signi®cant contribution in this prediction. Also, when performance positive mood was regressed on extraversion and extraversion neuroticism together, extraversion made a signi®cant and positive contribution to positive mood induction. Extraversion neuroticism did not contribute signi®cantly in this prediction. Eysenck's theory links extraversion (but not neuroticism) positively to positive mood state (Eysenck & Eysenck, 1985), while Gray's (1981, 1987) has linked positive mood state positively to extraversion and neuroticism. Newman's theory suggests that extraversion and extraversion neuroticism will predict positive mood. Thus viewed in terms of Eysenck's dimensions, the ®ndings here for positive mood are clearly supportive of Eysenck's theory, but not Gray's or Newman's theory. Existing data are also supportive of Eysenck's theory in this respect. For example, Larsen and Ketelaar (1989, 1991) found that during positive mood induction, extraversion correlated with positive mood, but there was no correlation between neuroticism and negative mood. Carver and White (1994) also reported that extraversion was positively associated with happy mood during positive mood induction. More recently, Rusting and Larsen (1997) found that when post-exposure positive mood was regressed on both extraversion, neuroticism and extraversion neuroticism, post-exposure positive mood was predicted positively by extraversion, and neither neuroticism nor extraversion neuroticism contributed to the prediction. The ®ndings here for the negative mood induction group showed that when performance negative mood was regressed on extraversion and neuroticism, neuroticism made a signi®cant negative contribution, while extraversion made no contribution. When performance negative mood was regressed on extraversion and extraversion neuroticism, extraversion made a signi®cant negative contribution and extraversion neuroticism made a signi®cant positive contribution. Eysenck has linked neuroticism (but not extraversion) positively to negative mood state (Eysenck & Eysenck, 1985). Gray's (1970, 1981, 1987) theory links negative mood state positively to neuroticism and negatively to extraversion, while Newman's theory suggests that negative mood state will be linked negatively to extraversion and positively to extraversion neuroticism. Thus the ®ndings of this study for negative mood are consistent with Eysenck's and Newman's theories, but not Gray's theory. The support for Eysenck's theory in relation to negative mood is consistent with existing data
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showing that during negative mood induction, neuroticism correlated with negative mood, but there was no correlation between extraversion and negative mood (Larsen & Ketelaar, 1989, 1991). Unlike this study, the study by Rusting and Larsen (1997) found no support for Newman's theory, but found support for Gray's theory. Two important dierences between this study and the Rusting and Larsen (1997) study are in the extraversion measures used, and the methods used to induce negative mood. Unlike this study, which used EPI extraversion and induced negative mood through loss of money, Rusting and Larsen used the EPQ and induced negative mood by exposure to unpleasant stories. Thus it would appear that the way extraversion is measured and/or the speci®c cues related to mood would have to be considered in examining the relationships between Eysenck's, Gray's and Newman's theories in relation to negative mood. As already noted, viewed in terms of Eysenck's dimensions of extraversion and neuroticism, the ®ndings here for both positive mood and negative mood failed to support Gray's theory. However, viewed in terms of Gray's own dimensions of trait anxiety and impulsivity, there was support for his theory. As predicted from Gray's theory, the ®ndings here showed that performance positive mood was positively predicted by trait impulsivity, while performance negative mood was positively predicted by trait anxiety. Taken together these ®ndings raise the possibility that the dimensions of extraversion and neuroticism (or indeed extraversion neuroticism) may be inadequate markers of trait impulsivity and anxiety. Indeed this argument is supported by the ®ndings here that, together, extraversion and neuroticism contributed only 22% and 48% of the variance for trait impulsivity and anxiety, respectively. The implication is that there is need for caution in interpreting results of studies examining Gray's theory of personality and mood when using Eysenck's dimensions of extraversion and neuroticism. In summary, the ®ndings in this study highlight the need to consider the speci®c questionnaires used, especially how extraversion is measured, when locating Gray's dimensions in Eysenck's personality space. Also, the ®ndings showed that questionnaires used, the personality dimensions measured, as well as the actual nature of the cues involved in inducing dierent mood states have to be considered in examining the relationships between Eysenck's, Gray's and Newman's theories in relation to mood induction states. Bearing these cautions in mind, the ®ndings in the study were supportive of Gray's general location of trait anxiety and impulsivity in terms of Eysenck's personality space. In relation to positive and negative mood, there was strong support for Eysenck's theory. Prediction arising from Newman's theory for negative mood, but not positive mood, was also supported. No support was found for Gray's theory for either positive or negative mood states. Thus, in conclusion, the results of this study appear to suggest that, overall, in terms of Eysenck's dimensions of extraversion and neuroticism, the relation between mood susceptibility and personality is predicted relatively better by Eysenck's theory compared to Gray's or Newman's theory. Indeed other personality theorists have also supported Eysenck's theory of personality and mood (Tellegen, 1985; Costa & McCrae, 1980).
Acknowledgements The study was supported by a grant from the School of Behavioural and Social Sciences and Humanities, University of Ballarat.
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Nichols, S. L., & Newman, J. P. (1986). Eects of punishment on response latency in extraverts. Journal of Personality and Social Psychology, 50, 624±630. Patton, J. H., Stanford, M. S., & Barratt, E. S. (1995). Factor structure of the Barratt Impulsiveness Scale. Journal of Clinical Psychology, 51, 768±774. Pickering, A. D., Corr, P. J., & Gray, J. A. (1999). Interactions and reinforcement sensitivity theory: a theoretical analysis of Rusting and Larsen (1997). Personality and Individual Dierences, 26, 357±365. Pickering, A. D., Corr, P. J., Powell, J. H., Kumari, V., Thornton, J., & Gray, J. A. (1997). Individual dierences in reactions to reinforcing stimuli are neither black nor white: to what extent are they grey? In H. Nyborg, The scienti®c study of human nature: tribute to Hans J. Eysenck at eighty. London: Elsevier Sciences. Rusting, C. L., & Larsen, R. J. (1997). Extraversion, neuroticism, and susceptibility to positive and negative aect: a test of two theoretical models. Personality and Individual Dierences, 22, 607±612. Rusting, C. L., & Larsen, R. J. (1999). Clarifying Gray's theory of personality: a response to Pickering, Corr, and Gray. Personality and Individual Dierences, 26, 367±372. Spielberger, C. D., Gorsuch, R., Lushene, R., Vagg, P. R., & Jacobs, G. A. (1983). Manual for the State-Trait Anxiety Inventory (form Y). Palo Alto, CA: Consulting Psychologists Press. Tellegen, A. (1985). Structures of mood and personality and their relevance to assessing anxiety, with an emphasis on self-report. In A. H. Tuma, & J. Mason, Anxiety and the anxiety disorders (pp. 681±706). Hillsdale, NJ: Erlbaum. Torrubia, R., & Tobena, A. (1984). A scale for the assessment of ``susceptibility to punishment'' as a measure of anxiety: preliminary results. Personality and Individual Dierences, 5, 371±375. Wallace, J. F., & Newman, J. P. (1998). Neuroticism and the facilitation of the automatic orienting of attention. Personality and Individual Dierences, 24, 253±266. Wallace, J. F., Newman, J. P., & Bachorowski, J. (1991). Failures of response modulation: impulsive behaviour in anxious and impulsive individuals. Journal of Research in Personality, 25, 23±44. Watson, D., & Clark, L. A. (1992). On traits and temperament: general and speci®c factors of emotional experience and their relation to the ®ve factor model. Journal of Personality, 60, 441±476. Watson, D., Clark, L. A., & Tellegen, A. (1988). Development and validation of brief measures of positive and negative aect: the PANAS scales. Journal of Personality and Social Psychology, 54, 1063±1070. Williams, P. G., Surwit, R. S., Babyak, M. A., & McCaskill, C. C. (1998). Personality predictors of mood related to dieting. Journal of Consulting and Clinical Psychology, 66, 994±1004.
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Susceptibility to positive and negative mood states: test of Eysenck's, Gray's and Newman's theories R. Gomez*, A. Cooper, A. Gomez School of Behavioural and Social Sciences and Humanities, University of Ballarat, Victoria, Australia Received 25 February 1999; accepted 31 August 1999
Abstract The study examined the relationships of extraversion and neuroticism with trait anxiety and impulsivity, and how extraversion and neuroticism, and impulsivity and anxiety are related to negative and positive mood states. Subjects completed questionnaires covering extraversion, neuroticism, anxiety and impulsivity, and were divided randomly into two mood induction groups: positive (N = 50) and negative (N = 48). The positive mood induction group was provided with money, progressively, during performance of a go/no-go task, while for the negative mood induction group, money was progressively withdrawn during task performance. Results showed that negative mood induction was predicted by neuroticism and extraversion neuroticism, while positive mood induction was predicted by extraversion. Anxiety and impulsivity also predicted negative and positive mood induction, respectively. These ®ndings are discussed in the context of Eysenck's, Gray's and Newman's theories of personality and mood. 7 2000 Elsevier Science Ltd. All rights reserved. Keywords: Extraversion; Neuroticism; Impulsivity; Anxiety; Positive and negative moods
1. Introduction Two dimensions that appear consistently in factor-analytic studies of personality questionnaires are extraversion±introversion and neuroticism±stability (Costa & McCrae, 1985; Eysenck, 1967; Goldberg, 1990). However, these dimensions are thought to be associated with dierent responses in Eysenck's, Gray's, and Newman's theories of personality. Many studies * Corresponding author. Tel.: +61-3-53279760; fax: +61-3-53279754. E-mail address: [email protected] (R. Gomez). 0191-8869/00/$ - see front matter 7 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 1 9 1 - 8 8 6 9 ( 9 9 ) 0 0 1 9 8 - 1
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have compared the dierences by examining predictions arising from them. This study extends the research in this area, especially in relation to positive and negative mood states. According to Eysenck (1967), the extraversion dimension is orthogonally related to the neuroticism dimension. Individuals who score high on extraversion (or extraverts) are generally outgoing, sociable, active and optimistic, while those who score low on this dimension (or introverts) are quiet, unsociable, passive and careful. Eysenck (1967) has suggested that individual dierences in extraversion re¯ect dierences in cortical arousal, resulting from dierences in the reactivity of the ascending reticular activating system to environmental stimuli. They have argued that as introverts exhibit higher cortical arousal than extraverts, introverts are more easily conditioned. In Eysenck's theory, neuroticism is viewed as re¯ecting individual dierences in reactivity to negative environmental stimuli, with high scorers (i.e. neurotics) being more negatively reactive or prone to unpleasant experience than low scorers (stable individuals). The neural substrate of this dimension is thought to be the visceral brain, made up of the septum, hippocampus, cingulum, amygdala and hypothalamus (Eysenck & Eysenck, 1985). Although Gray (1970, 1981, 1987) has proposed that anxiety and impulsivity are the major dimensions of personality, he has mapped these dimensions on to Eysenck's personality space. According to Gray, the anxiety axis runs from the stable±extraversion quadrant (low anxiety) to the neuroticism±introversion quadrant (high anxiety), while the impulsivity axis runs from the stable±introversion quadrant (low impulsivity) to the neuroticism±extraversion quadrant (high impulsivity). However, the anxiety and impulsivity dimensions are thought to lie closer to 308 (rather than 458) of the neuroticism and extraversion dimensions, respectively (Gray, 1970; Pickering, Corr & Gray, 1999; Pickering et al., 1997). Gray's model implies that anxiety will be positively associated with neuroticism, and negatively with extraversion, while impulsivity will be positively associated with extraversion, and positively with neuroticism. Also, the ratio of neuroticism to extraversion will be 2:1 for anxiety, and 1:2 for impulsivity. Consistent with Gray's theory there are studies showing that anxiety correlates positively with neuroticism and negatively with extraversion (Corr, Pickering & Gray, 1997; Diaz & Pickering, 1993; Eysenck, 1967; MacAndrew & Steele, 1991; Torrubia & Tobena, 1984; see also Gray, 1970). Also, in most of these studies, the correlation of neuroticism and anxiety was about twice more than that between extraversion and anxiety (Diaz & Pickering, 1993; Eysenck, 1967; MacAndrew & Steele, 1991; Torrubia & Tobena, 1984). The existing data on impulsivity, however, appear to provide only partial support for Gray's theory. Although data indicate that both neuroticism and extraversion are positively associated with trait impulsivity, the correlation between extraversion and impulsivity has generally been found to be less than (rather than) two times the correlation between neuroticism and impulsivity (Corr et al., 1997; Corulla, 1987; Diaz & Pickering, 1993). These studies derived the extraversion scores using the extraversion scale of the Eysenck Personality Questionnaire (EPQ; Eysenck & Eysenck, 1975). Diaz and Pickering (1993) have raised doubts about the relevance of the EPQ extraversion to BAS-related personality and behaviour. This is because when there was the change from the EPI to the EPQ the extraversion scale lost several items to the new psychoticism scale. This left the extraversion scale of the new EPQ measuring primarily sociability and liveliness, rather than impulsivity (Eysenck & Eysenck, 1991). Thus, the lower than expected proportion of extraversion in this mixture in past studies may have arisen from how the extraversion scores
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were measured. This argument implies that if extraversion is measured by an extraversion scale that also incorporates elements of impulsivity, as in the Eysenck Personality Inventory (EPI; Eysenck & Eysenck, 1964), a higher proportion of extraversion in this mixture can be expected. In Gray's theory, anxiety is thought to re¯ect individual dierences in the behavioural inhibition system (BIS), while impulsivity is thought to re¯ect individual dierences in the behavioural approach system (BAS). According to Gray, the neural basis of the BIS are the noradrenergic and serotonergic pathways, and for the BAS it is the dopaminergic pathways. In addition to the BIS and the BAS, Gray's model also includes a third system, referred to as the nonspeci®c arousal system (NAS). The NAS is thought to receive excitatory outputs from both the BIS and the BAS (i.e. nonspeci®c), and thereby aects the responses mediated by both the behavioural activation systems. Such a view diers from Eysenck's theory, which (as mentioned earlier) links neuroticism to reactivity. In Gray's theory, currently referred to as the reinforcement sensitivity theory (Pickering et al., 1997, 1999), the BIS and BAS are linked to dierent types of reinforcements. The BIS is thought to be sensitive to signals of punishment, frustrative nonreward and novelty, and its activation is thought to decrease behaviours toward such stimuli, and is also associated with negative mood. The BAS is believed to be sensitive to signals of reward and nonpunishment, and its activation is thought to increase approach behaviours toward these stimuli, and is also associated with positive mood. Viewed in terms of Eysenck's neuroticism and extraversion dimensions, Gray's theory suggests that both neuroticism and extraversion will contribute to mood states, with neuroticism contributing more to negative mood, and extraversion contributing more to positive mood. This view diers from Eysenck's model of personality and mood. Although Eysenck's arousal/activation theory is not associated directly with positive and negative emotion in the daily lives of individuals, apart from the notion that there are optimal and suboptimal levels of cortical arousal for hedonic tone (pleasure vs displeasure), it has been proposed that neuroticism (but not extraversion) and extraversion (but not neuroticism) are associated with negative and positive mood states, respectively (Eysenck & Eysenck, 1985; see also Costa & McCrae, 1980; Tellegen, 1985; Watson & Clark, 1992). Consistent with Eysenck's model, many studies have shown a positive association between positive mood (both trait and state) and extraversion, and between negative mood (both trait and state) and neuroticism (e.g., Costa & McCrae, 1980; David, Green, Martin & Suls, 1997; Larsen & Ketelaar, 1989, 1991; Watson & Clark, 1992). For example, Larsen and Ketelaar (1989, 1991) found that during negative mood induction (via exposure to negative material), neuroticism correlated positively with negative mood, but there was no correlation between extraversion and negative mood. During positive mood induction (via exposure to positive material), extraversion, but not neuroticism, correlated with positive mood. Also, Carver and White (1994) found that extraversion was positively associated with happy mood during positive mood induction. Newman's theory of personality is a synthesis of Gray's and Eysenck's personality theories, in that the three systems of Gray's model are mapped onto Eysenck's personality dimensions of extraversion and neuroticism (Bachorowski & Newman, 1985; Nichols & Newman, 1986; Wallace & Newman, 1998; Wallace, Newman & Bachorowski, 1991). According to Newman, the BAS re¯ects high extraversion, while the BIS re¯ects low extraversion (or introversion). In his theory, the behavioural and mood states mediated by the BAS and the BIS are considered
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to be similar to Gray's theory. Thus, viewed in terms of Eysenck's theory, Newman's theory suggests that high extraversion is positively associated with sensitivity to rewards and positive mood, while low extraversion is positively associated with sensitivity to punishment and negative mood. Similar to Eysenck, Newman views neuroticism in terms of reactivity, with higher neuroticism re¯ecting higher reactivity. According to Newman, neuroticism re¯ects the reactivity of the NAS, and, therefore, neuroticism moderates both the BAS and BIS (Wallace et al., 1991). Recently, Pickering et al. (1999) have illustrated the relation between Eysenck's and Gray's models in terms of algebraic equations. According to them, in Eysenck's model, BAS A extraversion, and BIS A neuroticism. In Gray's model, BAS A (2 extraversion+neuroticism), and BIS A (2 neuroticism±extraversion), where the ``2'' re¯ects Gray's 308 rotation of Eysenck's dimensions. Extending these equations, Rusting and Larsen (1997, 1999) have proposed that in Newman's model BAS A [extraversion+neuroticism+(extraversion neuroticism)], and BIS A [neuroticism±extraversion+(extraversion neuroticism)]. However, as Newman's theory does not implicate a direct relation between neuroticism and the behavioural activation systems, the following equations would appear more appropriate: BAS A [extraversion+(extraversion neuroticism)], and BIS A [ÿextraversion+(extraversion neuroticism)]. The above equations indicate that for comparisons of the three models in terms of predictions relating to susceptibility to mood states, the mood has to be regressed on the appropriate Eysenckian dimensions. This approach was adopted by Rusting and Larsen (1997). Results indicated that for positive mood induction, post-exposure positive mood was predicted positively by extraversion, and neuroticism did not contribute to this prediction. For negative mood induction, post-exposure negative mood was predicted positively by neuroticism and negatively by extraversion, and the ratio of the beta weights of neuroticism to extraversion was about 2:1. The study found that when the neuroticism extraversion was entered in the regression equations (after entering neuroticism and extraversion), it did not make a signi®cant prediction to either the positive or negative mood induction. Overall, therefore, the ®ndings in this study for positive mood induction supported Eysenck's theory, while the ®ndings for negative mood induction supported Gray's theory (Pickering et al. 1999). Although Rusting and Larsen (1999) have interpreted their ®ndings as not supporting Newman's model, this conclusion must be viewed cautiously. As pointed out earlier, Newman's model does not implicate a direct relation between neuroticism and the mood states. Thus the entry of neuroticism in the regression equations in the Rusting and Larsen study may have confounded results. Indeed, the ®ndings that extraversion was related to both positive and negative mood states among individuals with high neuroticism (McFatter, 1994), and that extraversion neuroticism predicted positive mood during dieting (Williams, Surwit, Babyak & McCaskill, 1998) provides suggestive support for Newman's model. Clearly, more studies are needed in this area. There were three aims in this study. The ®rst aim was to examine the location of Gray's personality dimensions on Eysenck's personality space. However, unlike previous studies which measured extraversion using the EPQ, in this study, extraversion was measured by the EPI. Gray's model would predict that trait anxiety would be predicted negatively by extraversion and positively by neuroticism, with neuroticism contributing two times more than extraversion.
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The prediction for trait impulsivity would be that it would be predicted positively by both extraversion and neuroticism, with extraversion contributing two times more than neuroticism. The second aim of this study was to compare Eysenck's, Gray's and Newman's theories in relation to how extraversion and neuroticism are related to positive and negative mood states. Unlike the study by Larsen and his associates, positive and negative mood states in this study were directly induced by monetary reward and monetary withdrawal, respectively. As already noted, Eysenck's model would suggest that neuroticism would positively predict negative mood induction, while extraversion would positively predict positive mood induction. Gray's theory would suggest that negative mood induction would be predicted negatively by extraversion and positively by neuroticism, with neuroticism contributing two times more than extraversion. For positive mood induction, Gray's model would predict positive contributions by both extraversion and neuroticism, with extraversion contributing two times more than neuroticism. Newman's model would suggest that extraversion would predict negative mood induction negatively, and positive mood induction positively. In addition, extraversion neuroticism would also contribute positively to the predictions of both mood inductions. The third aim was to test Gray's theory of personality and mood using the dimensions of trait anxiety and impulsivity. Based on Gray's theory, it was predicted that trait anxiety and impulsivity would positively predict negative mood induction and positive mood induction, respectively. 2. Method 2.1. Participants Participants comprised 98 students from the University of Ballarat, who responded to a notice for volunteers for this study. For all participants, informed consent was obtained prior to the study. The subjects were divided randomly into two groups: positive mood induction group (N = 50) and negative mood induction group (N = 48). There were 22 males and 28 females in the positive mood induction group, and 21 males and 27 females in the negative mood induction group. All participants were between 18 and 25 years of age, and were screened for known psychological disorders. 2.2. Personality measures The following personality questionnaires were used: the Eysenck Personality Inventory (EPI; Eysenck & Eysenck, 1964), the Trait-Anxiety scale of the State-Trait Anxiety Inventory Form (STAI-T; Spielberger, Gorsuch, Lushene, Vagg & Jacobs, 1983), and the eleventh version of the Barratt Impulsiveness Scale (BIS-11; Patton, Stanford & Barratt, 1995). The EPI is a 57-item ``yes''/``no'' questionnaire, and provides scores for extraversion, neuroticism and lie. The EPI has been extensively validated and used in past personality research. The internal consistencies (Cronbach's as) of the extraversion and neuroticism subscales for the participants in this study were 0.74 and 0.83, respectively. The STAI-T is a 20-item questionnaire, measuring trait anxiety, and each item is rated on a Likert scale,
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ranging from 1 (``almost never'') to 4 (``almost always''). The scale had an internal consistency of 0.92 for the participants in this study. The BIS-11 has 30 items. The total score for these items provides a global measure of trait impulsivity. The full scale had an internal consistency of 0.82 for the participants in this study. 2.3. Mood measure Mood was measured using the Positive and Negative Aective Schedule (PANAS; Watson, Clark & Tellegen, 1988). The PANAS, used widely in mood research, provides scores for two orthogonally related dimensions of mood states: positive and negative. There are 10 adjectives covering positive aect, and 10 adjectives covering negative aect, and each aect is rated from 1 (``very slightly or not at all'') to 5 (``extremely''). The internal consistencies for positive mood and negative mood for the participants in this study were 0.90 and 0.83, respectively. 2.4. Mood induction procedure Positive and negative mood states were induced through reward and punishment, involving winning and losing money, respectively, while performing a go/no-go task. It is to be noted that when used in our previous study (Gomez & McLaren, 1997), the reward version of this task produced a higher level of happy mood than the punishment version, while the punishment version produced a higher level of nervous mood than the reward version. Both the reward and punishment versions of the go/no-go task were presented on a green monochrome IBM monitor. In both versions, there were 96 test trials, divided into 8 sets of 12 trials each. Each trial consisted of one of 12 two-digit numbers, presented randomly. In each trial, the stimulus was presented until the subject responded or for a maximum of 3 s if the subject did not respond. The inter-stimulus interval was 1.5 s. Of these 12 numbers, six were `good' numbers, and six were `bad' numbers. Subjects were instructed to learn which were `good' numbers and which were `bad' numbers by trial and error. Eighteen practice trials were presented before the 96 test trials. For the reward version of the go/no-go task, subjects were instructed that every time they responded to a `good' number or refrained from responding to a `bad' number they would gain 10 cents, and that there was no loss of money for failing to respond to a `good' number or for responding to a `bad' number. Correct responses (responding to a `good' number or not responding to a `bad' number) resulted in a 1-s visual feedback indicating that the subject had earned 10 cents. For the punishment version, all subjects started with a bonus of $9.60. They were instructed that every time they failed to respond to a `good' number or they responded to a `bad' number they would lose 10 cents, and that there was no gain of money for responding to a `good' number or not responding to a `bad' number. Incorrect responses (not responding to a `good' number or responding to a `bad' number) resulted in a 1-s visual feedback indicating that the subject had lost 10 cents. The directions for each condition were presented to subjects on the computer screen. For both the reward and punishment versions of the go/no-go task, the following scores were recorded: hits (i.e. responding to a `good' number), errors of commission (i.e. responding to `bad' numbers), total number of responses, and mean reaction time to all responses. Hits
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were obtained in order to examine if there was a dierence in the rate of learning across the two versions of the go/no-go task. The other measures were obtained to examine if the dierent versions were eective in activating the BAS (via the reward version) and the BIS (via the punishment version). 2.5. Procedure Following consent, appointments for the laboratory sessions were given to participants. For the laboratory session, participants were tested individually. The experimental session began with participants completing the set of personality questionnaires. This took about 15 min, and was done to equate the participants' experiences prior to testing. Following this, participants completed the PANAS in terms of how they were feeling at that point in time. Immediately after this, participants completed the appropriate go/no-go task. Participants in the positive mood induction group completed the reward version, while participants in the negative mood induction group completed the punishment version. On completion of this task, participants completed the PANAS once again, with instructions to rate the items in terms of how they felt while performing the go/no-go task. Participants were then informed of how much money they earned (positive mood induction group) or had remaining (negative mood induction group), and were paid this sum of money. 3. Results 3.1. Extraversion and neuroticism as predictors of trait anxiety and impulsivity Table 1 shows the results of the regression analyses, involving all the participants, in which trait anxiety and impulsivity were regressed (separately) on both extraversion and neuroticism. As will be noticed, extraversion contributed signi®cantly and negatively to the prediction of anxiety, while neuroticism contributed signi®cantly and positively to this prediction. The standardised b values indicated that neuroticism contributed about 2.7 times more than Table 1 Regression of trait anxiety and impulsivity on extraversion and neuroticism (P < 0.05; Variable Trait anxiety on extraversion and neuroticism Extraversion Neuroticism Trait impulsivity on extraversion and neuroticism Extraversion Neuroticism
b
SE
P < 0.01;
b
P < 0.001)
t
ÿ0.52 0.17 ÿ0.23 1.12 0.14 0.63 [R 2=0.48; F (df = 2, 95)=43.86]
3.12 8.56
0.89 0.18 0.44 0.39 0.16 0.22 [R 2=0.22; F (df = 2, 95)=13.57]
4.80 2.44
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extraversion to the prediction of anxiety. For impulsivity, both extraversion and neuroticism made signi®cant positive contributions, with extraversion contributing 2 times more than neuroticism. The ®ndings also showed that, together, extraversion and neuroticism contributed only 22% and 48% of the variance for trait impulsivity and anxiety, respectively. 3.2. Extraversion and neuroticism, and extraversion and extraversion neuroticism as predictors of negative and positive mood induction Prior to the examination of how Eysenck's personality dimensions predicted negative and positive mood induction, we examined the comparability of the subjects in the two groups for personality, and whether the reward and punishment used in the study were successful in activating the appropriate behavioural activation systems and mood states. Table 2 provides the mean and standard deviation scores for extraversion, neuroticism, anxiety, impulsivity, and go/no-go performance scores of the two groups. It also shows the results of the t test for dierences between the groups on these measures. As shown, there was no signi®cant dierence between the groups on any of the personality measures, indicating that the groups were comparable on personality. There was also no group dierence for hits, suggesting no dierence in learning across the two versions of the go/no-go task. The positive mood induction group made more commission errors and total responses, and responded faster than the negative mood induction group. These ®ndings imply that the reward used produced more BAS activation, while the punishment used produced more BIS activation. Table 3 shows the mean and standard deviation scores for negative mood and positive mood Table 2 Extraversion, neuroticism, trait anxiety and impulsivity, and go/no-go task scores: mean scores, standard deviations and group dierences (P = 0.05; P < 0.01) Variable
Induction group: mean (SD)
t statistics (df=96)
Positive
Negative
Eysenck Personality Inventory Extraversion Neuroticism
13.84 (3.98) 10.16 (5.36)
13.94 (5.09) 11.56 (5.11)
0.11 1.32
Spielberger's STAI-Trait Form Trait anxiety
37.46 (10.44)
40.48 (9.70)
1.48
Barratt Impulsiveness Scale Global impulsivity
65.74 (9.80)
65.50 (8.75)
0.13
Go/no-go task Hits Commission errors Total responses Reaction time (s)
38.14 22.98 61.12 1.27
38.42 18.00 56.42 1.43
0.17 2.75 1.95 3.33
(8.30) (9.31) (13.07) (0.23)
(7.39) (8.71) (10.51) (0.23)
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Table 3 Positive and negative moods: mean scores, standard deviations and group dierences (P < 0.01; for negative and positive mood induction groups are 47 and 49, respectively) Group/mood
P < 0.001; df
Test phase: mean (SD)
t statistics
Pre
During
Negative mood induction group Negative mood Positive mood
12.71 (3.75) 27.31(7.75)
14.97 (5.45) 28.83 (8.95)
3.21 1.80
Positive mood induction group Negative mood Positive mood
12.88 (4.06) 29.38 (9.61)
13.98 (5.21) 34.20 (8.08)
1.61 4.72
just before and during performance for the mood induction groups, and the results of the t tests for dierences in mood scores before and during performance. Results for the negative mood induction group indicated increase in negative mood from pre-performance to performance, but no change from pre-performance to performance for positive mood. Results Table 4 Regression analyses showing prediction of negative mood during performance from neuroticism and extraversion, extraversion and extraversion neuroticism, and anxiety (P < 0.05; P < 0.01) DR 2 Extraversion and neuroticism on negative mood during performance Step 1: Preperformance negative mood Step 2: Preperformance negative mood Extraversion Neuroticism
SE
0.65 0.19 0.15
Extraversion and extraversion neuroticism on negative mood during performance Step 1: Preperformance negative mood Step 2: Preperformance negative mood 0.12 Extraversion Extraversion neuroticism Anxiety on negative mood during performance Step 1: Preperformance negative mood Step 2: Preperformance negative mood Anxiety
b
0.11
b
t
0.45 3.41
0.49 0.19 0.33 2.48 ÿ0.11 0.14 ÿ0.10 0.81 0.39 0.15 0.37 2.67
0.65 0.19
0.45 3.41
0.54 0.19 0.38 2.86 ÿ0.40 0.15 ÿ0.38 2.64 0.02 0.11 0.33 2.23
0.65 0.19
0.45 3.41
0.19 0.19 0.20 0.07
0.35 2.71 0.35 2.71
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for the positive mood induction group showed higher positive mood during performance compared to just before performance. For this group, negative mood did not vary from before to during performance. Overall, as desired, the punishment and reward used were clearly successful in inducing negative mood and positive mood, respectively. Table 4 shows the results of the regression analyses involving the negative mood induction group, in which negative mood during performance of the go/no-go task was regressed on extraversion and neuroticism together, and on extraversion and extraversion neuroticism together. It also shows the results of the regression analysis involving trait anxiety as a predictor of performance negative mood. In these analyses, the score for negative mood just before task performance was partialed out. As non-centered cross-product terms are not interactions, centered scores (i.e., the actual score minus the mean score) were used in the regression analysis involving extraversion and extraversion neuroticism. Centered scores also reduce problems of multicolinearity of product terms (Cohen & Cohen, 1983). For the analysis involving extraversion and neuroticism, only neuroticism contributed signi®cantly (positively) to the prediction of negative mood. For the analysis involving extraversion and extraversion neuroticism, both predictors contributed signi®cantly (positively) to the prediction of negative mood. Trait anxiety also contributed positively to this prediction. Table 5 shows the results for the positive mood induction group. For these analyses, positive mood during performance of the go/no-go condition was regressed on extraversion and Table 5 Regression analyses showing prediction of positive mood during performance from neuroticism and extraversion, extraversion and extraversion neuroticism, and impulsivity (P < 0.05; P < 0.01; P < 0.001) DR 2 b Extraversion and neuroticism on positive mood during performance Step 1: Preperformance positive mood Step 2: Preperformance positive mood Extraversion Neuroticism
SE b b
0.57 0.09 0.07
0.07
0.68 6.40
0.55 0.09 0.65 6.33 0.53 0.21 0.27 2.28 ÿ0.10 0.16 ÿ0.07 0.66
Extraversion and extraversion neuroticism on positive mood during performance Step 1: Preperformance positive mood 0.57 Step 2: Preperformance positive mood 0.08 0.56 Extraversion 0.68 Extraversion neuroticism ÿ0.01 Step 1: Preperformance positive mood Step 2: Preperformance positive mood Impulsivity
t
0.09
0.68 6.40
0.08 0.67 6.51 0.24 0.33 2.86 0.01 ÿ0.16 1.30
0.57 0.09
0.68 6.40
0.58 0.08 0.21 0.08
0.70 6.94 0.26 2.53
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neuroticism together, extraversion and extraversion neuroticism together, and trait impulsivity by itself. The score for positive mood just before task performance was partialed out. Again, in the analysis involving extraversion and extraversion neuroticism, the scores for these variables were centered. In the analysis involving extraversion and neuroticism, only extraversion contributed signi®cantly (positively) to the prediction of positive mood. In the analysis involving extraversion and extraversion neuroticism, only extraversion made a signi®cant (positive) contribution to the prediction of positive mood. Trait impulsivity signi®cantly predicted performance positive mood.
4. Discussion Consistent with Gray's (1970) theory, and existing data (Corr et al., 1997; Diaz & Pickering, 1993; Eysenck, 1967; Gray, 1970; MacAndrew & Steele, 1991; Torrubia & Tobena, 1984), the results of this study showed that trait anxiety was predicted signi®cantly and positively by neuroticism, and signi®cantly and negatively by extraversion. The results also showed that both extraversion and neuroticism signi®cantly and positively predicted trait impulsivity. The ®ndings here showed that neuroticism contributed about 2.7 times the contribution made by extraversion in the prediction of trait anxiety, while extraversion contributed 2 times more than neuroticism in the prediction of trait impulsivity. These ®ndings dier somewhat from existing data, in that, existing data show that the correlation between neuroticism and trait anxiety is about twice more than that between extraversion and trait anxiety, while the correlation between extraversion and trait impulsivity is less than two times the correlation between neuroticism and trait impulsivity (Corr et al., 1997; Corulla, 1987; Diaz & Pickering, 1993; Eysenck, 1967; MacAndrew & Steele, 1991; Torrubia & Tobena, 1984). The dierences in ®ndings between this study and previous studies may have arisen because of dierences in the extraversion measure. Previous studies used the EPQ, while this study used the EPI. As noted earlier, EPQ extraversion does not have impulsivity items, while EPI extraversion has impulsivity items. As the EPI extraversion has impulsivity items, it is possible that this may have contributed to a higher proportion of extraversion in the prediction of impulsivity, and a lower proportion of extraversion in the prediction of anxiety in this study compared to past studies. Taken together, the ®ndings here are supportive of Gray's general locations of trait anxiety and impulsivity in terms of Eysenck's personality space. However the precise locations of trait anxiety and impulsivity in Eysenck's personality space appear to be governed by the way extraversion is de®ned or measured. When extraversion is measured by the EPQ (as in past studies), it appears that there is support for Gray's placement of the anxiety axis at 308 from the neuroticism axis, but not for the placement of the impulsivity axis at 308 from the extraversion axis. When extraversion is measured by the EPI (as in this study), the opposite appears to be the case: there is no support for the placement of the anxiety axis at 308 from the neuroticism axis, but support for the placement of the impulsivity axis at 308 from the extraversion axis. An important implication of these ®ndings is that the questionnaires used need to be considered when locating Gray's dimensions in Eysenck's personality space. This study found that the subjects who were provided reward during task performance (i.e. the positive mood induction group) responded faster, made more responses, including
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commission error responses, than the subjects who were provided punishment during task performance (i.e. the negative mood induction group). Also, the reward used increased positive mood (but had no eect on negative mood), while the punishment used increased negative mood (but had no eect on positive mood). Other studies have also reported similar ®ndings (Carver & White, 1994; Corr et al., 1997; Gomez & McLaren, 1997; Hagopian & Ollendick, 1994; Newman, Patterson & Kosson, 1987). Taken together, the ®ndings here suggest that the reward used produced more BAS activation, while the punishment used produced more BIS activation. The ®ndings are also consistent with Gray's (1970) view linking BAS activation to approach and positive mood, and BIS activation to avoidance and negative mood. It is to be noted that the absence of dierence between the groups for hits implies that the dierences noted are unlikely to have resulted from any dierence in diculty levels between the reward and punishment versions of the go/no-go task. The ®ndings for the positive mood induction group showed that when positive mood during task performance was regressed on extraversion and neuroticism together, extraversion contributed signi®cantly and positively to the prediction of positive mood induction. Neuroticism did not make a signi®cant contribution in this prediction. Also, when performance positive mood was regressed on extraversion and extraversion neuroticism together, extraversion made a signi®cant and positive contribution to positive mood induction. Extraversion neuroticism did not contribute signi®cantly in this prediction. Eysenck's theory links extraversion (but not neuroticism) positively to positive mood state (Eysenck & Eysenck, 1985), while Gray's (1981, 1987) has linked positive mood state positively to extraversion and neuroticism. Newman's theory suggests that extraversion and extraversion neuroticism will predict positive mood. Thus viewed in terms of Eysenck's dimensions, the ®ndings here for positive mood are clearly supportive of Eysenck's theory, but not Gray's or Newman's theory. Existing data are also supportive of Eysenck's theory in this respect. For example, Larsen and Ketelaar (1989, 1991) found that during positive mood induction, extraversion correlated with positive mood, but there was no correlation between neuroticism and negative mood. Carver and White (1994) also reported that extraversion was positively associated with happy mood during positive mood induction. More recently, Rusting and Larsen (1997) found that when post-exposure positive mood was regressed on both extraversion, neuroticism and extraversion neuroticism, post-exposure positive mood was predicted positively by extraversion, and neither neuroticism nor extraversion neuroticism contributed to the prediction. The ®ndings here for the negative mood induction group showed that when performance negative mood was regressed on extraversion and neuroticism, neuroticism made a signi®cant negative contribution, while extraversion made no contribution. When performance negative mood was regressed on extraversion and extraversion neuroticism, extraversion made a signi®cant negative contribution and extraversion neuroticism made a signi®cant positive contribution. Eysenck has linked neuroticism (but not extraversion) positively to negative mood state (Eysenck & Eysenck, 1985). Gray's (1970, 1981, 1987) theory links negative mood state positively to neuroticism and negatively to extraversion, while Newman's theory suggests that negative mood state will be linked negatively to extraversion and positively to extraversion neuroticism. Thus the ®ndings of this study for negative mood are consistent with Eysenck's and Newman's theories, but not Gray's theory. The support for Eysenck's theory in relation to negative mood is consistent with existing data
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showing that during negative mood induction, neuroticism correlated with negative mood, but there was no correlation between extraversion and negative mood (Larsen & Ketelaar, 1989, 1991). Unlike this study, the study by Rusting and Larsen (1997) found no support for Newman's theory, but found support for Gray's theory. Two important dierences between this study and the Rusting and Larsen (1997) study are in the extraversion measures used, and the methods used to induce negative mood. Unlike this study, which used EPI extraversion and induced negative mood through loss of money, Rusting and Larsen used the EPQ and induced negative mood by exposure to unpleasant stories. Thus it would appear that the way extraversion is measured and/or the speci®c cues related to mood would have to be considered in examining the relationships between Eysenck's, Gray's and Newman's theories in relation to negative mood. As already noted, viewed in terms of Eysenck's dimensions of extraversion and neuroticism, the ®ndings here for both positive mood and negative mood failed to support Gray's theory. However, viewed in terms of Gray's own dimensions of trait anxiety and impulsivity, there was support for his theory. As predicted from Gray's theory, the ®ndings here showed that performance positive mood was positively predicted by trait impulsivity, while performance negative mood was positively predicted by trait anxiety. Taken together these ®ndings raise the possibility that the dimensions of extraversion and neuroticism (or indeed extraversion neuroticism) may be inadequate markers of trait impulsivity and anxiety. Indeed this argument is supported by the ®ndings here that, together, extraversion and neuroticism contributed only 22% and 48% of the variance for trait impulsivity and anxiety, respectively. The implication is that there is need for caution in interpreting results of studies examining Gray's theory of personality and mood when using Eysenck's dimensions of extraversion and neuroticism. In summary, the ®ndings in this study highlight the need to consider the speci®c questionnaires used, especially how extraversion is measured, when locating Gray's dimensions in Eysenck's personality space. Also, the ®ndings showed that questionnaires used, the personality dimensions measured, as well as the actual nature of the cues involved in inducing dierent mood states have to be considered in examining the relationships between Eysenck's, Gray's and Newman's theories in relation to mood induction states. Bearing these cautions in mind, the ®ndings in the study were supportive of Gray's general location of trait anxiety and impulsivity in terms of Eysenck's personality space. In relation to positive and negative mood, there was strong support for Eysenck's theory. Prediction arising from Newman's theory for negative mood, but not positive mood, was also supported. No support was found for Gray's theory for either positive or negative mood states. Thus, in conclusion, the results of this study appear to suggest that, overall, in terms of Eysenck's dimensions of extraversion and neuroticism, the relation between mood susceptibility and personality is predicted relatively better by Eysenck's theory compared to Gray's or Newman's theory. Indeed other personality theorists have also supported Eysenck's theory of personality and mood (Tellegen, 1985; Costa & McCrae, 1980).
Acknowledgements The study was supported by a grant from the School of Behavioural and Social Sciences and Humanities, University of Ballarat.
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