تفاوت های فردی در واکنش پذیری هسته عاطفی

Abstract At the basis of any emotional phenomenon lies core affect, defined as a simple, volatile feeling that is a blend of hedonic and arousal values. The present study was intended to increase our understanding of core affect reactivity by investigating within-person relationships between two daily event characteristics and core affect, and individual differences in such relationships. For 7 days, 73 participants described their core affect nine times each day. Simultaneously, they rated the impact and valence of the most significant event that had occurred since the previous measurement occasion. Multilevel analyses found that the perceived event characteristics under study were significantly related to both core affect dimensions. Furthermore, individual differences in extraversion and neuroticism played a significant role in core affect reactivity. The different patterns of results for these traits suggest that omnibus models explaining how traits per se interact with situational forces to influence behaviour may need to be revised.

. Introduction At the basis of any emotional phenomenon lies core affect, defined by Russell as “a neurophysiologic state that is consciously accessible as a simple, non-reflective feeling that is an integral blend of hedonic (pleasure–displeasure) and arousal (sleepy–activated) values” (Russell, 2003, p. 147). As such, the term core affect refers to the most elementary consciously accessible affective feelings that need not be directed at anything. At each moment in time, an individual’s core affect can be depicted as a single point in a two-dimensional grid. The hedonic dimension of this grid ranges from pleasure through a neutral point to displeasure, and represents how well one is doing; the arousal dimension ranges from sleep through a neutral point to extreme excitement, and represents how energized an individual feels. Core affect is not assumed to be stable but volatile: It moves through its constituting two-dimensional space, reflecting how one feels throughout everyday life. Moreover, core affect is subject to various influences (Russell & Feldman-Barrett, 1999). A full understanding of core affect therefore requires understanding its dynamics, including the different sources of core affect variability and their respective influences. An important focus of studies on within-person variability of emotions has been the within-person relationship between daily events and emotions, or emotional reactivity. The majority of these studies have concerned changes in daily affect as a function of positive and negative daily events (e.g., David et al., 1997 and van Eck et al., 1998). More importantly, several studies have found individual differences in the within-person relationships between daily events and daily affect in terms of neuroticism or extraversion (e.g., Lucas and Baird, 2004 and Suls and Martin, 2005) and measures of well-being such as depression (e.g., Nezlek & Plesko, 2003). For example, Lucas and Baird (2004) found reliable evidence that extraverts were happier than introverts in both neutral and positive mood conditions, whereas Suls and Martin (2005) showed that persons who scored high (versus low) in neuroticism tended to experience more severe emotions in response to daily stressors. These results suggested that it would be useful to examine individual differences in the relationships between core affect and characteristics of the events people experience in their everyday lives. Such within-person relationships might vary straightforwardly as a function of dispositional measures, but individual differences might also show up in more complex ways. For example, as suggested by Marshall and Brown (2006), individual differences in emotional reactivity might vary as a joint function of dispositional factors and the strength of situational characteristics. In their presentation of the TASS model (traits as situational sensitivities), Marshall and Brown (2006) found support for the hypothesis that dispositional factors would be more influential when situational characteristics are moderate in strength compared to when situational characteristics are either strong or weak. In this article we focus on two different types of event characteristics reflecting the hedonic and arousal dimensions of core affect, the perceived valence and impact of an event. Consider, for example, an individual meeting with a friend Y and this friend starts talking about his new job. If we ask individual X to rate this event, he would probably rate it as a positive event with a low impact. Now, consider the situation where an employer accuses X of having made a mistake. X would probably rate this as a negative event with more impact than the previous example because of its greater importance and relevance. It is important to note that the perceived valence and impact of an event are conceptualized as independent. In general, we hypothesize that event valence is positively related to the hedonic dimension of core affect, in line with previous findings of Marco, Neale, Schwartz, Shiffman, and Stone (1999), and van Eck et al. (1998). We further hypothesize that more impactful events result in higher arousal levels of core affect, similar to the relationships between emotions and the primary appraisals of event importance and motivational relevance, as described by Smith and Lazarus (1990) and Sonnemans and Frijda (1995). Moreover, we examined individual differences in the relationships between event characteristics and core affect. Our specific research questions concerned individual differences in extraversion and neuroticism.1 With regard to extraversion, we based our expectations in part on research and theory concerning physiologically based personality theories (e.g., Beauducel et al., 2006, Eysenck, 1967 and Eysenck and Eysenck, 1985). Broadly speaking, these theories suggest that introverts have higher levels of brain activity in the ascending reticular activating system (ARAS) than extraverts, and as a consequence, introverts display more reactivity on the arousal dimension of the affective circumplex. Based on these theories, different predictions could be made for the present study. Base-line arousal models suggest a main effect: introverts should be more aroused than extraverts, regardless of the impact of an event. Taking into account individual differences in reactivity suggests one of two interactions. (1) Introverts and extraverts should be similarly aroused when events have no impact, but introverts should be more aroused when there is some impact. (2) Introverts should be more aroused than extraverts, and this difference should increase as event impact increases. With regard to neuroticism, our research questions concerned relationships between the hedonic dimension and neuroticism. Based on previous research different predictions could be made for the present study. Consistent with research that has found relationships between neuroticism and experienced negative emotions such as anxiety (e.g., Gomez & Francis, 2003) and negative emotionality ( Larsen & Ketelaar, 1991), we had reason to expect a main effect of neuroticism. Overall, we expected that more (as compared to fewer) neurotic individuals would be more likely to report feelings in the negative half of core affective space. Moreover, we expected this negative relationship between neuroticism and the hedonic dimension across all levels of event impact. In addition, as suggested by Marshall and Brown (2006), we examined the possibility of an interaction effect to occur between neuroticism and impact. Neuroticism might be negatively related to pleasure in the case of low or moderate impact events, whereas they might not be related for high impact events because the strength of the situation would override such individual differences. Individual differences might also be weak in situations without any impact. Such expectations are also suggested by Snyder and Ickes (1985) and Mischel (1977) who stated that traits have their greatest predictive ability when situations provide just enough provocation to evoke trait-relevant reactions in those who score high on a trait but not in those who score low. Taking all this together, we had reason to expect that relationships between neuroticism and pleasure would be strongest in situations of moderate impact. We examined these questions by conducting an experience sampling study in which participants described their experienced core affect and the valence and impact of events at random moments during their daily activities. They also completed various dispositional measures. There are numerous advantages of using experience sampling to examine the types of relationships in which we were interested. These include diminished reliance on memory and a consequent reduction of distortion (e.g., Stone et al., 1998) and the ability to sample variables in a broad range of every day circumstances, increasing ecological validity (Feldman-Barrett & Barrett, 2001).

Results 3.1. Descriptive statistics As a preliminary step, we performed a totally unconditional analysis of the arousal, pleasantness, and valence ratings to decompose the overall variance into the variances associated with the different levels. The results, including estimated means are presented in Table 1. The mean event is mildly positive (M = 0.31) (and greater than the scale midpoint of 0, t = 16.70, p < .001) but not very impactful (M = 0.99) (i.e., smaller than the scale midpoint of 3, t = 100.97, p < .001). Looking individually at events, the majority of the events was rated as positive for 60 out of the 73 participants, and had an impact rating of one or less for 38 participants. Table 1. Descriptive statistics for core affect and situational ratings. Mean Variance Occasion Day Person Arousal 5.28 3.20 0.38 0.28 Pleasure 5.90 2.49 0.52 0.36 Event valence 0.31 1.25 0.08 0.05 Table options 3.2. The relationship between the arousal dimension of core affect and event characteristics To examine the relationship between arousal and event impact and valence, a three level multilevel model was estimated as described above. The results of these analyses are presented in Table 2. Event impact as well as the valence of an event clearly had an effect on experienced arousal. Differences in arousal as a function of event impact were tested via a series of constraints on the model (e.g., Nezlek, 2001) that constrained pairs of coefficients to be equal. These analyses indicated that experienced arousal increased as a function of event impact. Arousal was greater in high impact events than in all other types of events (all ps < .01), moderate impact events were significantly more arousing than low or no impact events (all ps < .001), and low impact events were significantly more arousing than no impact events (p < .001). Table 2. Means and variance of core affect as a function of event. Event impact and valence Arousal Pleasantness Mean Random error Mean Random error No 4.81 .34⁎⁎⁎ 5.87 .52⁎⁎⁎ Low 5.34 41⁎⁎⁎ 5.41 .19⁎⁎⁎ Moderate 5.78 .36⁎⁎⁎ 5.34 .18⁎⁎⁎ High 6.14 .70⁎⁎⁎ 5.21 .12⁎⁎⁎ Valence 0.14 .04⁎⁎ 1.02 .03⁎⁎⁎ ⁎⁎ p < .01. ⁎⁎⁎ p < .001 Table options An important focus of our study was individual differences in reactions to events. Examination of the random error terms for the person levels indicated that there were statistically significant individual differences in how participants reacted to events differing in impact and valence, and these error terms are presented in Table 2. One of our primary research questions concerned relationships between extraversion and experienced arousal, and to test these hypotheses, we modeled individual differences in arousal as a function of extraversion. These analyses revealed that extraversion was positively related to experienced arousal for no and low impact events, and was negatively related for high impact events. These results are presented in Table 3. Table 3. Relationships between dispositional measures and core affect as a function of event impact. Event impact and valence Extraversion-arousal t-Ratio Neuroticism-pleasantness t-Ratio No 0.25 3.08⁎⁎ −0.35 3.73⁎⁎ Low 0.27 2.82⁎⁎ −0.16 2.03⁎ Moderate 0.15 −0.20 2.51⁎ High −0.29 2.32⁎ −0.20 2.95⁎⁎ Valence .05 .04 ⁎ p < .05. ⁎⁎ p < .01. Table options Analyses comparing the strength of the relationships between extraversion and arousal across the four levels of arousal (using the types of constraints discussed above) found that the relationship between extraversion and arousal for high impact events was significantly different from the relationship for all other types of event (all ps < .001). No other comparison produced a significant difference (all ps > .2). Extraversion did not moderate relationships between arousal and valence (t = 1.55, ns). Differences in the relationship between extraversion and experienced arousal as a function of event impact are depicted in Fig. 2. Graphical depiction of individual differences in the relationship between ... Fig. 2. Graphical depiction of individual differences in the relationship between arousal and event impact indicating the arousal level of (a) mean person, (b) a highly extraverted person (a score of one standard deviation above the mean) and (c) a low scoring extraverted person (a score of one standard deviation below the mean). Event valence is kept constant at the mean. Figure options 3.3. The relationship between the hedonic dimension of core affect and event characteristics To examine the relationship between the hedonic dimension of core affect and event impact and valence, a multilevel model with three equations that was structurally identical to that used to analyze arousal was estimated. The results of this analysis are presented in Table 2. Differences in pleasure as a function of event impact were tested via a series of constraints similar to those used to examine differences in arousal as a function of event impact. These analyses indicated that pleasantness was negatively related to impact. No impact events were significantly more pleasant than all other types of events (all ps < .001), low impact events were significantly more pleasant than high impact events (p < .01), and moderate impact events were more pleasant than high impact events (p = .05). We were also interested in how relationships between pleasantness and neuroticism might vary as a function of event impact. Examination of the random error terms for the models that included event impact at level 1 indicated that there were significant individual differences in experienced pleasantness in events of all level of impact. The corresponding person level variance estimates were all significant and are presented in Table 2. To examine relationships between neuroticism and experienced pleasantness, we modeled individual differences in pleasantness as a function of neuroticism (at the person level). The results are presented in Table 3. These analyses revealed that neuroticism was significantly and negatively related to experienced pleasantness for events at all levels of impact. Analyses comparing the strength of the relationships between neuroticism and pleasantness across the four levels of impact found that the relationship between neuroticism and pleasantness was stronger for no impact events than it was for all other types of events (versus low, p < .001; moderate, p < .05; and high, p = .11). No other comparison produced a significant difference (all ps > .5). Neuroticism did not moderate relationships between pleasantness and valence (t = 1.47, ns). Differences in the relationship between neuroticism and pleasantness as a function of event impact are depicted in Fig. 3. Graphical depiction of individual differences in the relationship between the ... Fig. 3. Graphical depiction of individual differences in the relationship between the hedonic dimension of core affect and event impact indicating the pleasantness level of (a) mean person, (b) a highly neurotic person (a score of one standard deviation above the mean), and (c) a low scoring neurotic person (a score of one standard deviation below the mean). Event valence is kept constant at the mean.