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Different subgroups of high-scorers on the TAS-20 based on the big five personality traits
Personality and Individual Differences 68 (2014) 71–76
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Different subgroups of high-scorers on the TAS-20 based on the big five personality traits Mayumi Ueno a, Motonari Maeda b, Gen Komaki c,⇑ a
Department of Psychosomatic Research, National Institute of Mental Health, National Center of Neurology & Psychiatry, Tokyo 187-8553, Japan College of Art and Design, Joshibi University of Art and Design, Kanagawa 228-8538, Japan c School of Health Sciences Fukuoka, International University of Health and Welfare, Fukuoka 831-8501, Japan b
a r t i c l e
i n f o
Article history: Received 15 December 2013 Received in revised form 5 April 2014 Accepted 11 April 2014
Keywords: Alexithymia TAS-20 NEO-FFI Neuroticism Personality
a b s t r a c t We investigated whether it was possible to obtain a consistent representation of the alexithymia trait by using the twenty-item Toronto Alexithymia Scale (TAS-20). TAS-20 and the NEO-Five Factor Inventory were administered to nonclinical participants (N = 2188). The results of hierarchical cluster analysis and a two-way analysis of variance indicated two subgroups with high scores on the TAS-20. One group had difficulty identifying feelings and high neuroticism; the other had a high externally oriented cognitive style and low openness to experience. These results suggest that the total score on the TAS-20 should not be considered a uni-dimensional measure of alexithymia. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Alexithymia, literally ‘no words for feelings’ in Greek, is a term first introduced by Sifneos to describe a marked difficulty in verbalizing feelings, impaired recognition of emotion and a diminution of fantasy of psychosomatic patients (Sifneos, 1973). The most widely used method to measure alexithymia is the twentyitem Toronto Alexithymia Scale (TAS-20; Bagby, Parker, & Taylor, 1994). It is a self-report questionnaire (Bagby, Parker et al., 1994) that excludes items assessing constricted imagination in daydreaming activity from the original twenty-three-item measure (Taylor, Ryan, & Bagby, 1985) to form the twenty-item version of the TAS (Taylor, Bagby, & Parker, 1992). The three-factor structure of alexithymia was used in TAS-20: (a) difficulty identifying feelings (DIF); (b) difficulty describing feelings to others (DDF); and (c) externally-oriented thinking (EOT: Bagby, Parker et al., 1994). Alexithymia is a dimensional personality trait that is distinct from DSM-based personality disorders (Taylor & Bagby, 2012). Several studies have explored the relationship between alexithymia and the big five factor model of personality. The five major domains of personality are as follows: Neuroticism (N), Extraversion (E), Openness to Experience (O), Agreeableness (A), and Conscientiousness (C: Costa & McCrae, 1992). N is characterized by
⇑ Corresponding author. Tel.: +81 944 89 2156; fax: +81 944 89 2001. E-mail address: [email protected] (G. Komaki). http://dx.doi.org/10.1016/j.paid.2014.04.012 0191-8869/Ó 2014 Elsevier Ltd. All rights reserved.
likeliness to experience such feelings as anxiety, anger, envy, guilt, and depressed mood. Individuals high in N are often self-conscious and shy, and they may have trouble controlling urges and delaying gratification. E is a trait to show positive emotions and the act, state, or habit of being predominantly concerned with and obtaining gratification from what is outside the self. Individuals high in E are gregarious, vibrant, and dominant. O involves active imagination, aesthetic sensitivity, attentiveness to inner feelings, preference for variety, and intellectual curiosity. A is a personality trait manifesting itself in individual behavioral characteristics that are perceived as kind, sympathetic, cooperative, warm and considerate. C is characterized as being efficient, organized, neat, and systematic, also including such elements as self-discipline, carefulness, thoroughness, self-organization, deliberation (the tendency to think carefully before acting), and need for achievement. Conscientious individuals are generally hard working and reliable. A moderately strong negative relation between alexithymia assessed by TAS-20 and the O dimension has consistently been found (Bagby, Taylor, & Parker, 1994; Taylor & Bagby, 2012), as well as a positive relation with the N dimension (Bagby, Taylor et al., 1994; Messina, Fogliani, & Paradiso, 2010). The negative relationship between O and TAS-20 conceptually supports the alexithymia construct. On the other hand, individuals high in N are characterized as ‘‘more likely to experience such feelings as anxiety, anger, envy, guilt, and depressed mood’’ (Costa & McCrae, 1992). Because N measures emotional instability, a positive
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correlation between TAS-20 and N contradicts the relative and absolute stability of alexithymia (Luminet, Bagby, & Taylor, 2001; Taylor & Bagby, 2012). Based on these prior findings with the TAS-20, it was considered worthwhile to clarify the correlation of between the alexithymia construct and certain dimensions of the big five personality model in patients with high TAS-20 scores. In the present study, we examined whether individuals with high scores on the TAS-20 fell into subgroups that followed these patterns of scores on the NEO. In addition, relations between the subscales of the TAS-20 and the NEO were examined. The aim of the present study, therefore, is as follows: (1) to identify subgroups of individuals with high scores on the TAS-20, and (2) to explore the characteristics of those subgroups based on the big five personality traits.
2. Methods 2.1. Participants The community sample in this study was recruited for a previous study (Moriguchi et al., 2007). Participants resided in cities and towns in 16 prefectures throughout Japan. Of the 2718 participants who completed the TAS-20 and NEO-FFI, 530 participants were eliminated because of missing values. Hence, the final sample consisted of 2188 participants (1114 men and 1074 women; age range of 14–84 years, mean age = 39.44, SD = 12.76). The number of participants in each age bracket was as follows: 10–19 year olds (n = 95), 20–29 years olds (n = 471), 30–39 years olds (n = 488), 40–49 years olds (n = 599), 50–59 years olds (n = 437), for 60– 69 years olds (n = 76) and 70 years or older (n = 22). No participant had any history of psychiatric disorder. All worked in business companies, agricultural cooperatives, fitness clubs, schools (as teachers), residents’ associations, universities and colleges, and the civil service. Almost all of the participants had graduated from college and were white-collar works. Written informed consent was obtained from all individuals. The study design was approved by the local ethics committee of the National Center of Neurology and Psychiatry.
2.3. Procedure The process of data collection for the TAS and NEO-FFI questionnaires have been described in detail elsewhere (Moriguchi et al., 2007). We used SPSS for Windows, version 18, for all statistical analyses. Initially we conducted sets of analyses (correlation and multiple regression) that assessed the association between scores on the TAS-20 and NEO-FFI. We empirically described the degree of the correlation (r) based on the following criteria: |r| > 0.7 (strong); 0.4 < |r| < 0.7 (moderate); 0.2 < |r| < 0.4 (weak); and |r| < 0.2 (very weak or almost nonexistent), when p value was significant. In the first step, in order to identify any possible subgroups of alexithymia, the Ward’s method of hierarchical cluster analysis was performed with all subscale scores of the TAS-20. Cluster analysis is a method to group entities on the basis of their similarity with respect to selected variables, so that the members of the resulting groups are as similar as possible to others within their group and as different as possible to those in other groups (Clatworthy, Buick, Hankins, Weinman, & Horne, 2005). Ward’s method, which is based on squared Euclidean distances implemented to split the group of cases into homogeneous subgroups, tends to create clusters of relatively equal sizes and has been widely used in the social sciences. Subsequently, in order to establish the internal validity of the clusters, a one-way analysis of variance (ANOVA) was conducted with the clusters as independent variables and the TAS-20 total score as the dependent variable. In order to explore the clusters’ relationship to other variables, two individual two-way analyses of variance (MANOVAs) were conducted with (1) the clusters as independent variables and the three subscales of TAS-20 score as dependent variables, and (2) the clusters as independent variables and the five dimensions of the NEO-FFI as dependent variables. Where significant F-values occurred, Tukey post hoc comparisons were conducted to determine the simple effects between clusters. The number of clusters to retain was determined by examination of scree plots and the interpretability of the clusters. When determining the adequacy of selected cluster solutions, theoretical perspectives and clinical utility also were taken into consideration.
2.2. Measures
3. Results
2.2.1. TAS-20 The TAS-20 is a self-report questionnaire which consists of 20 items (Bagby, Parker et al., 1994). The reliability and validity of the Japanese version of TAS-20 was established (Komaki et al., 2003; Moriguchi et al., 2007) and used in a study that investigated (1) difficulty in identifying feelings (DIF), and (2) difficulty in describing feelings to others (DDF), as well as (3) externally oriented thinking (EOT) by Komaki et al. (2003).
3.1. Correlations between the scores on the TAS-20 and the NEO-FFI
2.2.2. NEO-FFI The NEO-FFI (the NEO-Five Factor Inventory) consisting of 60 items is an abridged version of the NEO-PI-R (the Revised NEO Personality Inventory). It is a widely used measure and is a self-report instrument designed to provide a general description of normal personality (Costa & McCrae, 1992). The NEO-FFI is one of the standard measures of the big five factor model and the Japanese version has been validated (Shimonaka, Nakazato, Gondo, & Takayama, 1999). The five major domains of personality are as follows: Neuroticism (N), Extraversion (E), Openness to Experience (O), Agreeableness (A), and Conscientiousness (C).
Table 1 summarizes the descriptive statistics for TAS-20 scores and NEO-FFI scores, and Pearson’s product-moment correlations among the total score and its three factors of TAS-20 and NEOFFI scores. The results show moderate positive correlations between the scores of DIF and the scores of DDF, whereas there were poor correlations between the scores of those two factors and the scores of EOT. Total score on the TAS-20 positively correlates with those three factors. Total score on the TAS-20 shows weak negative correlations with E, O, A, and C factors of the NEO-FFI, whereas moderately positive correlations are obtained with N. In Table 2, the multiple linear regression analyses (independent variables = each factor of the TAS-20; dependent variables = each factor score of the NEO-FFI) show that all models are statistically significant for regression. The standardized beta comparing each variable to the other factors show that DIF has a moderate positive correlation with N, DDF has a weak, but significant negative correlation with E, and EOT has a moderate negative correlation with O, respectively.
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M. Ueno et al. / Personality and Individual Differences 68 (2014) 71–76 Table 1 Descriptive statistics and Pearson’s product-moment correlations between the TAS-20 and NEO-FFI (N = 2188). Mean TAS-20 total DIF DDF EOT N E O A C
SD
48.28 14.41 14.38 19.49 25.62 25.30 29.44 30.62 27.11
8.87 5.16 3.68 3.90 7.26 6.06 5.01 5.21 4.93
DIF
DDF **
.81 –
EOT **
.74 .49 –
N **
.51 .05 .09 –
**
* **
.45 .53 .38 .05 –
E **
O .29 .17 .37 .09 .30
** ** *
–
** ** ** ** **
.20 .05 .04 .48 .08 .14 –
A ** * * ** ** **
.30 .28 .16 .16 .28 .27 .17 –
C ** ** ** ** ** ** **
.31 .25 .25 .15 .26 .31 .02 .21 –
** ** ** ** ** **
**
Note: TAS-20 = Toronto Alexithymia Scale-20; NEO-FFI = NEO-Five Factor Inventory, DIF = difficulty in identifying feelings, DDF = difficulty in describing feelings, EOT = externally oriented thinking, N = Neuroticism, E = Extraversion, O = Openness to Experience, A = Agreeableness, and C = Conscientiousness. * p < .05. ** p < .01.
Table 2 Multiple linear regression analyses between TAS-20 and NEO-FFI scores (N = 2188). N R2 .31⁄⁄ b DIF DDF EOT
.46 .17 .09
E R2 .14⁄⁄ b ** ** *
.02 .38 .05
O R2 .24⁄⁄ b n.s. ** **
.10 .05 .48
A R2 .10⁄⁄ b ** * **
.27 .02 .14
C R2 .10⁄⁄ b **
.16 .16 .13
n.s. **
** ** **
Note: TAS-20 = Toronto Alexithymia Scale-20; NEO-FFI = NEO-Five Factor Inventory, DIF = difficulty in identifying feelings, DDF = difficulty in describing feelings, EOT = externally oriented thinking, N = Neuroticism, E = Extraversion, O = Openness to Experience, A = Agreeableness, and C = Conscientiousness. * p < .05. ** p < .01.
3.2. Subgroups with high TAS-20 scores We conducted a hierarchical cluster analysis with each factor of the TAS-20 to examine whether any subgroups showed various characteristics. The analysis identified 2, 3, 4, 5, or 7 distinct clusters. We chose the 5-cluster solution in accordance with the interpretability of the clusters. A one-way ANOVA indicated that there was a statistically significant difference in the total TAS-20 score between the 5 clusters (F(4, 2183) = 1111.39, p = .000). Because significant F-values occurred, post hoc comparisons were conducted. In these comparisons all between-group differences were significant, except between cluster 2 and cluster 3 which had the highest TAS-20 scores (Fig. 1). Then, a MANOVA was conducted in order to verify the characteristics of each cluster. The MANOVA
included the 5 clusters as between-group factors and standardized scores for the 3 factors of the TAS-20 (DIF, DDF, EOT) as withingroup factors. A significant main effect of the 5 clusters (F(4, 2183) = 1043.69, p = .000), and the 3 factors of the TAS-20 (F(1.96, 4276.28) = 14.80, p = .000), was found. Furthermore, a significant interaction effect was found (F(7.84, 4276.28) = 413.06, p = .000). Post hoc comparison on that interaction indicated different types for each cluster (Table 3, Fig. 2). Focusing on cluster 2 and cluster 3, which had the highest TAS-20 scores, cluster 2 had higher DIF and lower EOT scores than DDF scores; by contrast, cluster 3 had higher EOT scores than DIF and DDF scores (Fig. 3). Thus, we found that there were 2 clusters with high scores on the TAS-20 that showed distinct characteristics. A Pearson’s Chi-squared test was performed to investigate gender differences between cluster 2 and cluster 3, which indicated significant differences (X2 = 22.936, df = 1, p = .000) as shown in Table 3. A one-way ANOVA was conducted to examine differences in the mean ages of the 5 clusters (Table 3). There was a significant difference (F(4, 2183) = 21.11, p = .000). Post hoc analysis, focused on cluster 2 and cluster 3, indicated that cluster 2 was significantly younger than cluster 3 (p = .000). We also conducted a two-way MANOVA with the 5 clusters as between-group factors and the 5 factors of the NEO-FFI (N, E, O, A, C) as within-group factors to verify the different personality characteristics of each cluster. The results are displayed in Fig. 4. There was a significant main effect of the 5 clusters (F(4, 2183) = 54.75, p = .000), and a significant interaction effect (F(14.75, 8050.01) = 64.15, p = .000). Post hoc analysis focused on cluster 2 and cluster 3 indicated that N was the highest of any of the NEO-FFI subscales in cluster 2, whereas cluster 3 showed the distinct feature of very low O (Fig. 5). 4. Discussion
Fig. 1. Total Toronto Alexithymia Scale (TAS-20) Score. ⁄p < .05,
⁄⁄
p < .01.
The purpose of this study was to identify different subgroups of high scorers on the TAS-20 and to explore the characteristics of those obtained subgroups based on the big five personality traits. By conducting correlation analyses, multiple linear regression analysis and cluster analysis, we revealed that there are two distinct subgroups of individuals with high TAS-20 scores with the following characteristics: one showed very high scores on difficulty in identifying feelings (DIF) and also neuroticism (N) and the other showed very high scores on externally oriented thinking (EOT) and very low scores on openness (O) to experience. As alexithymia is a dimensional personality trait, several studies have examined the correlations between alexithymia and personality dimensions by using the TAS-20 or TAS and three- or five-factor models of personality (Bagby, Taylor et al., 1994;
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Table 3 Descriptive statistics for TAS-20 and NEO-FFI scores for each cluster. Cluster
n
M/F
1 2 3 4 5
801 463 191 225 508
358/343 198/265 121/70 102/123 235/273
N
Age
TAS-20
DIF
DDF
EOT
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
42.03 36.11 41.86 39.02 37.67
11.76 13.89 12.69 13.56 11.87
36.35 50.06 48.51 28.70 39.72
3.88 5.55 3.87 4.70 5.36
10.97 21.45 16.77 10.86 14.08
2.58 3.69 2.92 3.77 3.25
12.78 17.07 16.37 8.69 16.22
2.29 3.11 2.66 1.52 2.80
12.60 11.54 15.37 9.15 9.42
2.51 2.60 2.02 2.40 2.17
E
O
A
C
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
22.88 30.63 26.77 21.70 26.68
6.13 6.43 6.11 7.10 7.08
25.97 23.69 23.86 29.30 24.50
5.68 5.94 5.74 6.42 5.73
28.32 29.72 25.94 32.17 31.05
4.39 5.18 4.51 5.03 4.67
31.36 28.44 28.87 32.69 31.17
4.91 4.98 4.43 5.70 5.10
27.54 25.62 25.54 29.58 27.28
4.48 4.70 4.95 5.51 4.94
Note: TAS-20 = Toronto Alexithymia Scale-20; NEO-FFI = NEO-Five Factor Inventory, DIF = difficulty in identifying feelings, DDF = difficulty in describing feelings, EOT = externally oriented thinking, N = Neuroticism, E = Extraversion, O = Openness to Experience, A = Agreeableness, and C = Conscientiousness; M = male, F = female.
Fig. 2. Standard scores (z-scores) on the Toronto Alexithymia Scale (TAS-20) subscale for each cluster. TAS-20 = Toronto Alexithymia Scale-20, DIF = difficulty in identifying feelings, DDF = difficulty in describing feelings, EOT = externally oriented thinking.
Fig. 4. Standard scores (z-scores) on the NEO-FFI dimensions for each cluster. NEOFFI = NEO-Five Factor Inventory, N = Neuroticism, E = Extraversion, O = Openness to Experience, A = Agreeableness, and C = Conscientiousness.
Fig. 3. Standard scores (z-scores) on the Toronto Alexithymia Scale (TAS-20) for cluster 2 and cluster 3. DIF = difficulty in identifying feelings, DDF = difficulty in describing feelings, EOT = externally oriented thinking. ⁄p < .05, ⁄⁄p < .01.
Luminet, Bagby, Wagner, Taylor, & Parker, 1999; Wise & Mann, 1994; Wise, Mann, & Shay, 1992). The correlations between TAS20 and N and O in the present study confirmed previous findings. Moreover, the correlations found for other NEO-FFI scores such as E, A, and C conceptually, supported the findings of Wise et al. (1992).
Fig. 5. Standard scores (z-scores) on the NEO-FFI dimensions for each cluster. NEOFFI = NEO-Five Factor Inventory, N = Neuroticism, E = Extraversion, O = Openness to Experience, A = Agreeableness, and C = Conscientiousness. ⁄⁄p < .01.
M. Ueno et al. / Personality and Individual Differences 68 (2014) 71–76
However, there is a controversy concerning the relationship between the alexithymia construct and neuroticism (Lumley, 2000; Rubino, Grasso, Sonnino, & Pezzarossa, 1991; Taylor, Bagby, & Parker, 1993). Individuals high in neuroticism make fewer and less effective attempts at affect regulation (John & Gross, 2007). They could be, however, aware of their predisposition to experience negative affect, be concerned about negative affect-eliciting situations, and have a preference for avoiding such situations. These personality traits are seemingly different from personality traits reflecting a deficiency in affect experience (Wise, Jani, Kass, Sonnenschein, & Mann, 1988). The relationship between externally oriented cognitive style and openness, on the other hand, reflects the low empathy and reduced fantasy life of alexithymic individuals (Nemiah, Freyberger, & Sifneos, 1976). The salient negative correlation between openness and external oriented thinking style is consistent with the alexithymic trait (Komaki, 2013; Luminet et al., 1999). A hierarchical cluster analysis of the each factor of the TAS-20 score revealed that there were 5 clusters (subgroups) of individuals with different patterns of TAS-20 and NEO-FFI scores. Consistent with the findings of relationships between the facets of the TAS20 and the NEO-FFI scores, two groups (cluster 2 and cluster 3) were identified with similarly high TAS-20 scores, as ‘‘alexithymic,’’ but accompanied with different characteristics of the NEOFFI traits: cluster 2 was characterized by ‘difficulty in identifying feelings’ with high neuroticism, whereas cluster 3 was characterized by ‘externally oriented thinking’ with very low openness to experience. The clinical implications of these findings suggest the necessity to carefully examine individuals with high TAS-20 scores. Individuals in cluster 2, who are high in the facets of DIF and DDF might be aware of their predisposition to experience negative affect, might be concerned about negative affect-eliciting situations, and have a preference for avoiding such situations (John & Gross, 2007), in addition to having a subjective sense of vulnerability and distress (Wise et al., 1992). Therefore, it seems unlikely that cluster 2 individuals are truly alexithymic. In contrast individuals in cluster 3, EOT is less influenced by negative affects such as depression and anxiety (Monsen, Eilersten, Melgard, & Odegard, 1996) and it is congruent with the view that a maladaptive, low openness to experience is associated with ‘‘alexithymia’’ for feelings, and a normal low openness is associated with ‘‘constricted, blunted’’ feelings in the variants of each pole of the five-factor model of personality (Widiger, Samuel, Mullins-Sweatt, Gore, & Crego, 2012). No previous studies have suggested subgroups like this among highly ‘‘alexithymic’’ individuals, except one research group that proposed two different subtypes of alexithymia based on the self-reported Bermond–Vorst Alexithymia Questionnaire (BVAQ) scores (Vorst & Bermond, 2001). They proposed two types of alexithymia consist of Type I, which characterized by a low degree of conscious awareness of emotional arousal and a low degree of emotion accompanying cognitions; and Type II, which is characterized by a normal or high degree of conscious awareness of emotional arousal together with a low degree of emotions accompanying cognitions. Moreover, based on correlations with the TAS-20 scores, they suggested that the TAS-20 measures only ‘‘cognitive’’ aspects of alexithymia (Identifying, Analyzing and Verbalizing disability) and not the ‘‘affective’’ dimension (Emotionalizing and Fantasizing disability) because the affective composite is absent in the TAS-20 (Bermond, Vorst, & Moormann, 2006; Vorst & Bermond, 2001). Based on the present correlations and cluster analyses, however, their arguments were only partially supported. High TAS-20 scores do not support the selective deficit in the ‘‘cognitive’’ facets because these ‘‘cognitive’’ facets of the TAS-20 (‘DIF’ and ‘DDF’ subscales) were found to be rather more associated with neuroticism and/or negative affect. Regarding the ‘‘affective’’
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dimension of alexithymia, on the other hand, our findings suggest that it rather relates to an ‘EOT’ subset of the TAS-20, a so-called operative thinking style (pensée opératoire; Nemiah et al., 1976), the reduced fantasy and imaginative thinking facet of the alexithymia construct. Thus, their two subtypes seem to partially fit the results of the cluster analysis of TAS-20 samples. Prior age-related differences in TAS-20 subscale scores (Moriguchi et al., 2007) support the present results. The subjects of cluster 2 are younger and those of cluster 3 are older in the present study. The evidence indicates developmental aspects of emotional regulation (Igarashi et al., 2011; Nishimura et al., 2009). In particular, the age-related difference in ‘DIF’ and ‘DDF’ might reflect age-related alteration of self-consciousness, such an aspect of neuroticism that is related to the discrete-emotion construct of shame declining with age (Magai, 2008). The gender differences between cluster 2 and cluster 3 are consistent with previous studies that have indicated significantly higher DIF scores in females and significantly higher EOT scores in males, without there being any significant differences in the total TAS-20 score (Moriguchi et al., 2007). This finding is also partly supported by a cross cultural study in which Asian males showed higher EOT scores than European American males (Le, Berenbaum, & Raghavan, 2002). Nevertheless, it is suggested that gender differences in alexithymia should be more precisely investigated in future studies. One potential limitation of the present study is that we used only self-report measures of alexithymia. The correlation between DIF and DDF on the one hand and EOT on the other hand was very low. It has been questioned if a self-report scale can adequately assess a construct that involves impairments in self-awareness of emotions (Erni, Lotscher, & Modestin, 1997; Lane, Ahern, Schwartz, & Kaszniak, 1997; Sifneos, 1996). However, the present findings are also corroborated by measures of alexithymia other than self-reports, such as the modified Beth Israel Hospital Psychosomatic Questionnaire (SIBIQ), which was significantly correlated with facets of EOT and TAS-20 total scores, but not with facets of DIF and DDF (Arimura, Komaki, & Tamagawa, 2002). Another limitation of this study is that we did not elaborate the facet level of the big five-personality traits, because we used the short version of NEO-PIR (Costa & McCrae, 1992). Therefore, how each factor of TAS-20 was associated with the facet level of each trait of the five-factor model remains to be clarified. Further limitations of this study are that we neither focused on clusters that were related to low TAS-20 scores, nor examined the influences of culture on the clusters. Therefore, the precise definition of alexithymia cluster(s) and the investigation of their stability remain important tasks for future studies. Nevertheless, alexithymia may correspond not to any single dimension of the five-factor model but is captured by a complex mixture of narrow personality traits (Taylor & Bagby, 2012). It is suggested that these issues should be investigated in the future. Taking into consideration the limits of the self-report measures of alexithymia, the present results suggest that the total score on the TAS-20 should not be used as a uni-dimensional measure of alexithymia, and instead it should only be used as a rough indication of alexithymia. For diagnostic purposes of individuals, the profiles of subscale scores are required to obtain a more finely grained assessment of alexithymia and we should further conduct the structured interview for alexithymia.
Competing interests The authors declare that they have no competing interests.
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Acknowledgement This study was funded by Grant-in-Aid for Scientific Research Nos. 14A-9 and 17A-3 from the Ministry of Health, Welfare, and Labour of Japan. References Arimura, T., Komaki, G., Murakami, S., Tamagawa, K., Nishikata, H., Kawai, K., et al. (2002). Development of the Japanese version of the structured interview by the modified Beth Israel Hospital Psychosomatic Questionnaire (SIBIQ) to assess alexithymia. Japanese Journal of Psychosomatic Medicine, 42(4), 259–269. Bagby, R. M., Parker, J. D., & Taylor, G. J. (1994). The twenty-item Toronto Alexithymia Scale – I. Item selection and cross-validation of the factor structure. Journal of Psychosomatic Research, 38(1), 23–32. Bagby, R. M., Taylor, G. J., & Parker, J. D. (1994). The Twenty-item Toronto Alexithymia Scale – II. Convergent, discriminant, and concurrent validity. Journal of Psychosomatic Research, 38(1), 33–40. Bermond, B., Vorst, H. C., & Moormann, P. P. (2006). Cognitive neuropsychology of alexithymia: Implications for personality typology. Cognitive Neuropsychiatry, 11, 332–360. Clatworthy, J., Buick, D., Hankins, M., Weinman, J., & Horne, R. (2005). The use and reporting of cluster analysis in health psychology: A review. British Journal of Health Psychology, 10, 329–358. Costa, P. T., Jr., & McCrae, R. R. (1992). Revised NEO Personality Inventory (NEO-PI-R) and NEO Five-Factor Inventory (NEO-FFI) professional manual. Odessa, FL: Psychological Assessment Resouces Inc.. Erni, T., Lotscher, K., & Modestin, J. (1997). Two-factor solution of the 20-item Toronto Alexithymia Scale confirmed. Psychopathology, 30(6), 335–340. Igarashi, T., Komaki, G., Lane, R. D., Moriguchi, Y., Nishimura, H., Arakawa, H., et al. (2011). The reliability and validity of the Japanese version of the Levels of Emotional Awareness Scale (LEAS-J). BioPsychoSocial Medicine, 5(2). John, O. P., & Gross, J. J. (2007). Individual differences in emotion regulation. In J. J. Gross (Ed.), Handbook of emotion regulation (pp. 351–372). New York: Guilford Press. Komaki, G. (2013). Alexithymia and somatic symptoms. In K. B. Koh (Ed.), Somatization and psychosomatic symptoms (pp. 41–49). New York: Springer. Komaki, G., Maeda, M., Arimura, T., Nakata, A., Shinoda, H., Ogata, I., et al. (2003). The reliability and factorial validity of the Japanese version of the 20-Item Toronto Alexithymia Scale (TAS-20). Japanese Journal of Psychosomatic Medicine, 43, 839–846. Lane, R. D., Ahern, G. L., Schwartz, G. E., & Kaszniak, A. W. (1997). Is alexithymia the emotional equivalent of blindsight? Biological Psychiatry, 42(9), 834–844. doi: S0006-3223(97)00050-4, [pii]. Le, H. N., Berenbaum, H., & Raghavan, C. (2002). Culture and alexithymia: Mean levels, correlates, and the role of parental socialization of emotions. Emotion, 341–360. http://dx.doi.org/10.1037/1528-3542.2.4.341. Luminet, O., Bagby, R. M., & Taylor, G. J. (2001). An evaluation of the absolute and relative stability of alexithymia in patients with major depression. Psychotherapy and Psychosomatics, 70(5), 254–260. doi: 56263, [pii] 56263. Luminet, O., Bagby, R. M., Wagner, H., Taylor, G. J., & Parker, J. D. (1999). Relation between alexithymia and the five-factor model of personality: A facet-level analysis. Journal of Personality Assessment, 73(3), 345–358. http://dx.doi.org/ 10.1207/S15327752JPA7303_4. Lumley, M. A. (2000). Alexithymia and negative emotional conditions. Journal of Psychosomatic Research, 49(1), 51–54.
Magai, C. (2008). Long-lived emotions. A life course perspective on emotional development. In M. Lewis, J. M. Haviland-Jones, & L. F. Barrett (Eds.), Hand book of emotions (3 ed., pp. 376–392). New York: The Guilford Press. Messina, A., Fogliani, A. M., & Paradiso, S. (2010). Association between alexithymia, neuroticism, and social desirability scores among Italian graduate students. Psychological Reports, 107(1), 185–192. Monsen, J. T., Eilersten, D. E., Melgard, T., & Odegard, P. (1996). Affects and affect consciousness: Initial experience with the assessment of affect integration. Journal of Psychotherapy Practice and Research, 5, 238–249. Moriguchi, Y., Maeda, M., Igarashi, T., Ishikawa, T., Shoji, M., Kubo, C., et al. (2007). Age and gender effect on alexithymia in large, Japanese community and clinical samples: A cross-validation study of the Toronto Alexithymia Scale (TAS-20). BioPsychoSocial Medicine, 1, 7. http://dx.doi.org/10.1186/1751-0759-1-7. Nemiah, J. C., Freyberger, H., & Sifneos, P. E. (1976). Alexithymia: A view of the psychosomatic process. In O. W. Hill (Ed.), Modern trends in psychosomatic medicine (pp. 430–439). London: Butterworths. Nishimura, H., Komaki, G., Igarashi, T., Moriguchi, Y., Kajiwara, S., & Akasaka, T. (2009). Validity issues in the assessment of alexithymia related to the developmental stages of emotional cognition and language. BioPsychoSocial Medicine, 3, 12. doi: 1751-0759-3-12, [pii] 10.1186/1751-0759-3-12. Rubino, I. A., Grasso, S., Sonnino, A., & Pezzarossa, B. (1991). Is alexithymia a nonneurotic personality dimension? British Journal of Medical Psychology, 64(Pt 4), 385–391. Shimonaka, J., Nakazato, K., Gondo, K., & Takayama, M. (1999). NEO-PI-R, NEO-FFI common manual (for Adults and college students). Tokyo: Tokyo Psychology Co., Ltd.. Sifneos, P. E. (1973). The prevalence of ‘alexithymic’ characteristics in psychosomatic patients. Psychotherapy and Psychosomatics, 22(2), 255–262. Sifneos, P. E. (1996). Alexithymia: past and present. American Journal of Psychiatry, 153(7 Suppl.), 137–142. Taylor, G. J., Bagby, R. M., & Parker, J. D. (1992). The Revised Toronto Alexithymia Scale: Some reliability, validity, and normative data. Psychotherapy and Psychosomatics, 57(1–2), 34–41. Taylor, G. J., Bagby, R. M., & Parker, J. D. (1993). Is alexithymia a non-neurotic personality dimension? A response to Rubino, Grasso, Sonnino & Pezzarossa. British Journal of Medical Psychology, 66(Pt 3), 281–294. Taylor, G. J., & Bagby, R. M. (2012). The alexithymia personality dimension. In T. A. Widiger (Ed.), The oxford handbook of personality disorders (pp. 648–673). New York: Oxford University Press. Taylor, G. J., Ryan, D., & Bagby, R. M. (1985). Toward the development of a new selfreport alexithymia scale. Psychotherapy and Psychosomatics, 44(4), 191–199. Vorst, H. C. M., & Bermond, B. (2001). Validity and reliability of the Bermond–Vorst Alexithymia Questionnaire. Personality and Individual Differences, 30, 413–434. Widiger, T. A., Samuel, D. B., Mullins-Sweatt, S., Gore, W. L., & Crego, C. (2012). An integration of normal and abnormal personality structure: The five-factor model. In T. A. Widiger (Ed.), The oxford handbook of personality disorders (pp. 82–107). New York: Oxford University Press. Wise, T. N., Jani, N. N., Kass, E., Sonnenschein, K., & Mann, L. S. (1988). Alexithymia: Relationship to severity of medical illness and depression. Psychotherapy and Psychosomatics, 50(2), 68–71. Wise, T. N., & Mann, L. S. (1994). The relationship between somatosensory amplification, alexithymia, and neuroticism. Journal of Psychosomatic Research, 38(6), 515–521. Wise, T. N., Mann, L. S., & Shay, L. (1992). Alexithymia and the five-factor model of personality. Comprehensive Psychiatry, 33(3), 147–151. doi: 0010440X(92)90023-J.
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Different subgroups of high-scorers on the TAS-20 based on the big five personality traits Mayumi Ueno a, Motonari Maeda b, Gen Komaki c,⇑ a
Department of Psychosomatic Research, National Institute of Mental Health, National Center of Neurology & Psychiatry, Tokyo 187-8553, Japan College of Art and Design, Joshibi University of Art and Design, Kanagawa 228-8538, Japan c School of Health Sciences Fukuoka, International University of Health and Welfare, Fukuoka 831-8501, Japan b
a r t i c l e
i n f o
Article history: Received 15 December 2013 Received in revised form 5 April 2014 Accepted 11 April 2014
Keywords: Alexithymia TAS-20 NEO-FFI Neuroticism Personality
a b s t r a c t We investigated whether it was possible to obtain a consistent representation of the alexithymia trait by using the twenty-item Toronto Alexithymia Scale (TAS-20). TAS-20 and the NEO-Five Factor Inventory were administered to nonclinical participants (N = 2188). The results of hierarchical cluster analysis and a two-way analysis of variance indicated two subgroups with high scores on the TAS-20. One group had difficulty identifying feelings and high neuroticism; the other had a high externally oriented cognitive style and low openness to experience. These results suggest that the total score on the TAS-20 should not be considered a uni-dimensional measure of alexithymia. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Alexithymia, literally ‘no words for feelings’ in Greek, is a term first introduced by Sifneos to describe a marked difficulty in verbalizing feelings, impaired recognition of emotion and a diminution of fantasy of psychosomatic patients (Sifneos, 1973). The most widely used method to measure alexithymia is the twentyitem Toronto Alexithymia Scale (TAS-20; Bagby, Parker, & Taylor, 1994). It is a self-report questionnaire (Bagby, Parker et al., 1994) that excludes items assessing constricted imagination in daydreaming activity from the original twenty-three-item measure (Taylor, Ryan, & Bagby, 1985) to form the twenty-item version of the TAS (Taylor, Bagby, & Parker, 1992). The three-factor structure of alexithymia was used in TAS-20: (a) difficulty identifying feelings (DIF); (b) difficulty describing feelings to others (DDF); and (c) externally-oriented thinking (EOT: Bagby, Parker et al., 1994). Alexithymia is a dimensional personality trait that is distinct from DSM-based personality disorders (Taylor & Bagby, 2012). Several studies have explored the relationship between alexithymia and the big five factor model of personality. The five major domains of personality are as follows: Neuroticism (N), Extraversion (E), Openness to Experience (O), Agreeableness (A), and Conscientiousness (C: Costa & McCrae, 1992). N is characterized by
⇑ Corresponding author. Tel.: +81 944 89 2156; fax: +81 944 89 2001. E-mail address: [email protected] (G. Komaki). http://dx.doi.org/10.1016/j.paid.2014.04.012 0191-8869/Ó 2014 Elsevier Ltd. All rights reserved.
likeliness to experience such feelings as anxiety, anger, envy, guilt, and depressed mood. Individuals high in N are often self-conscious and shy, and they may have trouble controlling urges and delaying gratification. E is a trait to show positive emotions and the act, state, or habit of being predominantly concerned with and obtaining gratification from what is outside the self. Individuals high in E are gregarious, vibrant, and dominant. O involves active imagination, aesthetic sensitivity, attentiveness to inner feelings, preference for variety, and intellectual curiosity. A is a personality trait manifesting itself in individual behavioral characteristics that are perceived as kind, sympathetic, cooperative, warm and considerate. C is characterized as being efficient, organized, neat, and systematic, also including such elements as self-discipline, carefulness, thoroughness, self-organization, deliberation (the tendency to think carefully before acting), and need for achievement. Conscientious individuals are generally hard working and reliable. A moderately strong negative relation between alexithymia assessed by TAS-20 and the O dimension has consistently been found (Bagby, Taylor, & Parker, 1994; Taylor & Bagby, 2012), as well as a positive relation with the N dimension (Bagby, Taylor et al., 1994; Messina, Fogliani, & Paradiso, 2010). The negative relationship between O and TAS-20 conceptually supports the alexithymia construct. On the other hand, individuals high in N are characterized as ‘‘more likely to experience such feelings as anxiety, anger, envy, guilt, and depressed mood’’ (Costa & McCrae, 1992). Because N measures emotional instability, a positive
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correlation between TAS-20 and N contradicts the relative and absolute stability of alexithymia (Luminet, Bagby, & Taylor, 2001; Taylor & Bagby, 2012). Based on these prior findings with the TAS-20, it was considered worthwhile to clarify the correlation of between the alexithymia construct and certain dimensions of the big five personality model in patients with high TAS-20 scores. In the present study, we examined whether individuals with high scores on the TAS-20 fell into subgroups that followed these patterns of scores on the NEO. In addition, relations between the subscales of the TAS-20 and the NEO were examined. The aim of the present study, therefore, is as follows: (1) to identify subgroups of individuals with high scores on the TAS-20, and (2) to explore the characteristics of those subgroups based on the big five personality traits.
2. Methods 2.1. Participants The community sample in this study was recruited for a previous study (Moriguchi et al., 2007). Participants resided in cities and towns in 16 prefectures throughout Japan. Of the 2718 participants who completed the TAS-20 and NEO-FFI, 530 participants were eliminated because of missing values. Hence, the final sample consisted of 2188 participants (1114 men and 1074 women; age range of 14–84 years, mean age = 39.44, SD = 12.76). The number of participants in each age bracket was as follows: 10–19 year olds (n = 95), 20–29 years olds (n = 471), 30–39 years olds (n = 488), 40–49 years olds (n = 599), 50–59 years olds (n = 437), for 60– 69 years olds (n = 76) and 70 years or older (n = 22). No participant had any history of psychiatric disorder. All worked in business companies, agricultural cooperatives, fitness clubs, schools (as teachers), residents’ associations, universities and colleges, and the civil service. Almost all of the participants had graduated from college and were white-collar works. Written informed consent was obtained from all individuals. The study design was approved by the local ethics committee of the National Center of Neurology and Psychiatry.
2.3. Procedure The process of data collection for the TAS and NEO-FFI questionnaires have been described in detail elsewhere (Moriguchi et al., 2007). We used SPSS for Windows, version 18, for all statistical analyses. Initially we conducted sets of analyses (correlation and multiple regression) that assessed the association between scores on the TAS-20 and NEO-FFI. We empirically described the degree of the correlation (r) based on the following criteria: |r| > 0.7 (strong); 0.4 < |r| < 0.7 (moderate); 0.2 < |r| < 0.4 (weak); and |r| < 0.2 (very weak or almost nonexistent), when p value was significant. In the first step, in order to identify any possible subgroups of alexithymia, the Ward’s method of hierarchical cluster analysis was performed with all subscale scores of the TAS-20. Cluster analysis is a method to group entities on the basis of their similarity with respect to selected variables, so that the members of the resulting groups are as similar as possible to others within their group and as different as possible to those in other groups (Clatworthy, Buick, Hankins, Weinman, & Horne, 2005). Ward’s method, which is based on squared Euclidean distances implemented to split the group of cases into homogeneous subgroups, tends to create clusters of relatively equal sizes and has been widely used in the social sciences. Subsequently, in order to establish the internal validity of the clusters, a one-way analysis of variance (ANOVA) was conducted with the clusters as independent variables and the TAS-20 total score as the dependent variable. In order to explore the clusters’ relationship to other variables, two individual two-way analyses of variance (MANOVAs) were conducted with (1) the clusters as independent variables and the three subscales of TAS-20 score as dependent variables, and (2) the clusters as independent variables and the five dimensions of the NEO-FFI as dependent variables. Where significant F-values occurred, Tukey post hoc comparisons were conducted to determine the simple effects between clusters. The number of clusters to retain was determined by examination of scree plots and the interpretability of the clusters. When determining the adequacy of selected cluster solutions, theoretical perspectives and clinical utility also were taken into consideration.
2.2. Measures
3. Results
2.2.1. TAS-20 The TAS-20 is a self-report questionnaire which consists of 20 items (Bagby, Parker et al., 1994). The reliability and validity of the Japanese version of TAS-20 was established (Komaki et al., 2003; Moriguchi et al., 2007) and used in a study that investigated (1) difficulty in identifying feelings (DIF), and (2) difficulty in describing feelings to others (DDF), as well as (3) externally oriented thinking (EOT) by Komaki et al. (2003).
3.1. Correlations between the scores on the TAS-20 and the NEO-FFI
2.2.2. NEO-FFI The NEO-FFI (the NEO-Five Factor Inventory) consisting of 60 items is an abridged version of the NEO-PI-R (the Revised NEO Personality Inventory). It is a widely used measure and is a self-report instrument designed to provide a general description of normal personality (Costa & McCrae, 1992). The NEO-FFI is one of the standard measures of the big five factor model and the Japanese version has been validated (Shimonaka, Nakazato, Gondo, & Takayama, 1999). The five major domains of personality are as follows: Neuroticism (N), Extraversion (E), Openness to Experience (O), Agreeableness (A), and Conscientiousness (C).
Table 1 summarizes the descriptive statistics for TAS-20 scores and NEO-FFI scores, and Pearson’s product-moment correlations among the total score and its three factors of TAS-20 and NEOFFI scores. The results show moderate positive correlations between the scores of DIF and the scores of DDF, whereas there were poor correlations between the scores of those two factors and the scores of EOT. Total score on the TAS-20 positively correlates with those three factors. Total score on the TAS-20 shows weak negative correlations with E, O, A, and C factors of the NEO-FFI, whereas moderately positive correlations are obtained with N. In Table 2, the multiple linear regression analyses (independent variables = each factor of the TAS-20; dependent variables = each factor score of the NEO-FFI) show that all models are statistically significant for regression. The standardized beta comparing each variable to the other factors show that DIF has a moderate positive correlation with N, DDF has a weak, but significant negative correlation with E, and EOT has a moderate negative correlation with O, respectively.
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M. Ueno et al. / Personality and Individual Differences 68 (2014) 71–76 Table 1 Descriptive statistics and Pearson’s product-moment correlations between the TAS-20 and NEO-FFI (N = 2188). Mean TAS-20 total DIF DDF EOT N E O A C
SD
48.28 14.41 14.38 19.49 25.62 25.30 29.44 30.62 27.11
8.87 5.16 3.68 3.90 7.26 6.06 5.01 5.21 4.93
DIF
DDF **
.81 –
EOT **
.74 .49 –
N **
.51 .05 .09 –
**
* **
.45 .53 .38 .05 –
E **
O .29 .17 .37 .09 .30
** ** *
–
** ** ** ** **
.20 .05 .04 .48 .08 .14 –
A ** * * ** ** **
.30 .28 .16 .16 .28 .27 .17 –
C ** ** ** ** ** ** **
.31 .25 .25 .15 .26 .31 .02 .21 –
** ** ** ** ** **
**
Note: TAS-20 = Toronto Alexithymia Scale-20; NEO-FFI = NEO-Five Factor Inventory, DIF = difficulty in identifying feelings, DDF = difficulty in describing feelings, EOT = externally oriented thinking, N = Neuroticism, E = Extraversion, O = Openness to Experience, A = Agreeableness, and C = Conscientiousness. * p < .05. ** p < .01.
Table 2 Multiple linear regression analyses between TAS-20 and NEO-FFI scores (N = 2188). N R2 .31⁄⁄ b DIF DDF EOT
.46 .17 .09
E R2 .14⁄⁄ b ** ** *
.02 .38 .05
O R2 .24⁄⁄ b n.s. ** **
.10 .05 .48
A R2 .10⁄⁄ b ** * **
.27 .02 .14
C R2 .10⁄⁄ b **
.16 .16 .13
n.s. **
** ** **
Note: TAS-20 = Toronto Alexithymia Scale-20; NEO-FFI = NEO-Five Factor Inventory, DIF = difficulty in identifying feelings, DDF = difficulty in describing feelings, EOT = externally oriented thinking, N = Neuroticism, E = Extraversion, O = Openness to Experience, A = Agreeableness, and C = Conscientiousness. * p < .05. ** p < .01.
3.2. Subgroups with high TAS-20 scores We conducted a hierarchical cluster analysis with each factor of the TAS-20 to examine whether any subgroups showed various characteristics. The analysis identified 2, 3, 4, 5, or 7 distinct clusters. We chose the 5-cluster solution in accordance with the interpretability of the clusters. A one-way ANOVA indicated that there was a statistically significant difference in the total TAS-20 score between the 5 clusters (F(4, 2183) = 1111.39, p = .000). Because significant F-values occurred, post hoc comparisons were conducted. In these comparisons all between-group differences were significant, except between cluster 2 and cluster 3 which had the highest TAS-20 scores (Fig. 1). Then, a MANOVA was conducted in order to verify the characteristics of each cluster. The MANOVA
included the 5 clusters as between-group factors and standardized scores for the 3 factors of the TAS-20 (DIF, DDF, EOT) as withingroup factors. A significant main effect of the 5 clusters (F(4, 2183) = 1043.69, p = .000), and the 3 factors of the TAS-20 (F(1.96, 4276.28) = 14.80, p = .000), was found. Furthermore, a significant interaction effect was found (F(7.84, 4276.28) = 413.06, p = .000). Post hoc comparison on that interaction indicated different types for each cluster (Table 3, Fig. 2). Focusing on cluster 2 and cluster 3, which had the highest TAS-20 scores, cluster 2 had higher DIF and lower EOT scores than DDF scores; by contrast, cluster 3 had higher EOT scores than DIF and DDF scores (Fig. 3). Thus, we found that there were 2 clusters with high scores on the TAS-20 that showed distinct characteristics. A Pearson’s Chi-squared test was performed to investigate gender differences between cluster 2 and cluster 3, which indicated significant differences (X2 = 22.936, df = 1, p = .000) as shown in Table 3. A one-way ANOVA was conducted to examine differences in the mean ages of the 5 clusters (Table 3). There was a significant difference (F(4, 2183) = 21.11, p = .000). Post hoc analysis, focused on cluster 2 and cluster 3, indicated that cluster 2 was significantly younger than cluster 3 (p = .000). We also conducted a two-way MANOVA with the 5 clusters as between-group factors and the 5 factors of the NEO-FFI (N, E, O, A, C) as within-group factors to verify the different personality characteristics of each cluster. The results are displayed in Fig. 4. There was a significant main effect of the 5 clusters (F(4, 2183) = 54.75, p = .000), and a significant interaction effect (F(14.75, 8050.01) = 64.15, p = .000). Post hoc analysis focused on cluster 2 and cluster 3 indicated that N was the highest of any of the NEO-FFI subscales in cluster 2, whereas cluster 3 showed the distinct feature of very low O (Fig. 5). 4. Discussion
Fig. 1. Total Toronto Alexithymia Scale (TAS-20) Score. ⁄p < .05,
⁄⁄
p < .01.
The purpose of this study was to identify different subgroups of high scorers on the TAS-20 and to explore the characteristics of those obtained subgroups based on the big five personality traits. By conducting correlation analyses, multiple linear regression analysis and cluster analysis, we revealed that there are two distinct subgroups of individuals with high TAS-20 scores with the following characteristics: one showed very high scores on difficulty in identifying feelings (DIF) and also neuroticism (N) and the other showed very high scores on externally oriented thinking (EOT) and very low scores on openness (O) to experience. As alexithymia is a dimensional personality trait, several studies have examined the correlations between alexithymia and personality dimensions by using the TAS-20 or TAS and three- or five-factor models of personality (Bagby, Taylor et al., 1994;
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Table 3 Descriptive statistics for TAS-20 and NEO-FFI scores for each cluster. Cluster
n
M/F
1 2 3 4 5
801 463 191 225 508
358/343 198/265 121/70 102/123 235/273
N
Age
TAS-20
DIF
DDF
EOT
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
42.03 36.11 41.86 39.02 37.67
11.76 13.89 12.69 13.56 11.87
36.35 50.06 48.51 28.70 39.72
3.88 5.55 3.87 4.70 5.36
10.97 21.45 16.77 10.86 14.08
2.58 3.69 2.92 3.77 3.25
12.78 17.07 16.37 8.69 16.22
2.29 3.11 2.66 1.52 2.80
12.60 11.54 15.37 9.15 9.42
2.51 2.60 2.02 2.40 2.17
E
O
A
C
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
22.88 30.63 26.77 21.70 26.68
6.13 6.43 6.11 7.10 7.08
25.97 23.69 23.86 29.30 24.50
5.68 5.94 5.74 6.42 5.73
28.32 29.72 25.94 32.17 31.05
4.39 5.18 4.51 5.03 4.67
31.36 28.44 28.87 32.69 31.17
4.91 4.98 4.43 5.70 5.10
27.54 25.62 25.54 29.58 27.28
4.48 4.70 4.95 5.51 4.94
Note: TAS-20 = Toronto Alexithymia Scale-20; NEO-FFI = NEO-Five Factor Inventory, DIF = difficulty in identifying feelings, DDF = difficulty in describing feelings, EOT = externally oriented thinking, N = Neuroticism, E = Extraversion, O = Openness to Experience, A = Agreeableness, and C = Conscientiousness; M = male, F = female.
Fig. 2. Standard scores (z-scores) on the Toronto Alexithymia Scale (TAS-20) subscale for each cluster. TAS-20 = Toronto Alexithymia Scale-20, DIF = difficulty in identifying feelings, DDF = difficulty in describing feelings, EOT = externally oriented thinking.
Fig. 4. Standard scores (z-scores) on the NEO-FFI dimensions for each cluster. NEOFFI = NEO-Five Factor Inventory, N = Neuroticism, E = Extraversion, O = Openness to Experience, A = Agreeableness, and C = Conscientiousness.
Fig. 3. Standard scores (z-scores) on the Toronto Alexithymia Scale (TAS-20) for cluster 2 and cluster 3. DIF = difficulty in identifying feelings, DDF = difficulty in describing feelings, EOT = externally oriented thinking. ⁄p < .05, ⁄⁄p < .01.
Luminet, Bagby, Wagner, Taylor, & Parker, 1999; Wise & Mann, 1994; Wise, Mann, & Shay, 1992). The correlations between TAS20 and N and O in the present study confirmed previous findings. Moreover, the correlations found for other NEO-FFI scores such as E, A, and C conceptually, supported the findings of Wise et al. (1992).
Fig. 5. Standard scores (z-scores) on the NEO-FFI dimensions for each cluster. NEOFFI = NEO-Five Factor Inventory, N = Neuroticism, E = Extraversion, O = Openness to Experience, A = Agreeableness, and C = Conscientiousness. ⁄⁄p < .01.
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However, there is a controversy concerning the relationship between the alexithymia construct and neuroticism (Lumley, 2000; Rubino, Grasso, Sonnino, & Pezzarossa, 1991; Taylor, Bagby, & Parker, 1993). Individuals high in neuroticism make fewer and less effective attempts at affect regulation (John & Gross, 2007). They could be, however, aware of their predisposition to experience negative affect, be concerned about negative affect-eliciting situations, and have a preference for avoiding such situations. These personality traits are seemingly different from personality traits reflecting a deficiency in affect experience (Wise, Jani, Kass, Sonnenschein, & Mann, 1988). The relationship between externally oriented cognitive style and openness, on the other hand, reflects the low empathy and reduced fantasy life of alexithymic individuals (Nemiah, Freyberger, & Sifneos, 1976). The salient negative correlation between openness and external oriented thinking style is consistent with the alexithymic trait (Komaki, 2013; Luminet et al., 1999). A hierarchical cluster analysis of the each factor of the TAS-20 score revealed that there were 5 clusters (subgroups) of individuals with different patterns of TAS-20 and NEO-FFI scores. Consistent with the findings of relationships between the facets of the TAS20 and the NEO-FFI scores, two groups (cluster 2 and cluster 3) were identified with similarly high TAS-20 scores, as ‘‘alexithymic,’’ but accompanied with different characteristics of the NEOFFI traits: cluster 2 was characterized by ‘difficulty in identifying feelings’ with high neuroticism, whereas cluster 3 was characterized by ‘externally oriented thinking’ with very low openness to experience. The clinical implications of these findings suggest the necessity to carefully examine individuals with high TAS-20 scores. Individuals in cluster 2, who are high in the facets of DIF and DDF might be aware of their predisposition to experience negative affect, might be concerned about negative affect-eliciting situations, and have a preference for avoiding such situations (John & Gross, 2007), in addition to having a subjective sense of vulnerability and distress (Wise et al., 1992). Therefore, it seems unlikely that cluster 2 individuals are truly alexithymic. In contrast individuals in cluster 3, EOT is less influenced by negative affects such as depression and anxiety (Monsen, Eilersten, Melgard, & Odegard, 1996) and it is congruent with the view that a maladaptive, low openness to experience is associated with ‘‘alexithymia’’ for feelings, and a normal low openness is associated with ‘‘constricted, blunted’’ feelings in the variants of each pole of the five-factor model of personality (Widiger, Samuel, Mullins-Sweatt, Gore, & Crego, 2012). No previous studies have suggested subgroups like this among highly ‘‘alexithymic’’ individuals, except one research group that proposed two different subtypes of alexithymia based on the self-reported Bermond–Vorst Alexithymia Questionnaire (BVAQ) scores (Vorst & Bermond, 2001). They proposed two types of alexithymia consist of Type I, which characterized by a low degree of conscious awareness of emotional arousal and a low degree of emotion accompanying cognitions; and Type II, which is characterized by a normal or high degree of conscious awareness of emotional arousal together with a low degree of emotions accompanying cognitions. Moreover, based on correlations with the TAS-20 scores, they suggested that the TAS-20 measures only ‘‘cognitive’’ aspects of alexithymia (Identifying, Analyzing and Verbalizing disability) and not the ‘‘affective’’ dimension (Emotionalizing and Fantasizing disability) because the affective composite is absent in the TAS-20 (Bermond, Vorst, & Moormann, 2006; Vorst & Bermond, 2001). Based on the present correlations and cluster analyses, however, their arguments were only partially supported. High TAS-20 scores do not support the selective deficit in the ‘‘cognitive’’ facets because these ‘‘cognitive’’ facets of the TAS-20 (‘DIF’ and ‘DDF’ subscales) were found to be rather more associated with neuroticism and/or negative affect. Regarding the ‘‘affective’’
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dimension of alexithymia, on the other hand, our findings suggest that it rather relates to an ‘EOT’ subset of the TAS-20, a so-called operative thinking style (pensée opératoire; Nemiah et al., 1976), the reduced fantasy and imaginative thinking facet of the alexithymia construct. Thus, their two subtypes seem to partially fit the results of the cluster analysis of TAS-20 samples. Prior age-related differences in TAS-20 subscale scores (Moriguchi et al., 2007) support the present results. The subjects of cluster 2 are younger and those of cluster 3 are older in the present study. The evidence indicates developmental aspects of emotional regulation (Igarashi et al., 2011; Nishimura et al., 2009). In particular, the age-related difference in ‘DIF’ and ‘DDF’ might reflect age-related alteration of self-consciousness, such an aspect of neuroticism that is related to the discrete-emotion construct of shame declining with age (Magai, 2008). The gender differences between cluster 2 and cluster 3 are consistent with previous studies that have indicated significantly higher DIF scores in females and significantly higher EOT scores in males, without there being any significant differences in the total TAS-20 score (Moriguchi et al., 2007). This finding is also partly supported by a cross cultural study in which Asian males showed higher EOT scores than European American males (Le, Berenbaum, & Raghavan, 2002). Nevertheless, it is suggested that gender differences in alexithymia should be more precisely investigated in future studies. One potential limitation of the present study is that we used only self-report measures of alexithymia. The correlation between DIF and DDF on the one hand and EOT on the other hand was very low. It has been questioned if a self-report scale can adequately assess a construct that involves impairments in self-awareness of emotions (Erni, Lotscher, & Modestin, 1997; Lane, Ahern, Schwartz, & Kaszniak, 1997; Sifneos, 1996). However, the present findings are also corroborated by measures of alexithymia other than self-reports, such as the modified Beth Israel Hospital Psychosomatic Questionnaire (SIBIQ), which was significantly correlated with facets of EOT and TAS-20 total scores, but not with facets of DIF and DDF (Arimura, Komaki, & Tamagawa, 2002). Another limitation of this study is that we did not elaborate the facet level of the big five-personality traits, because we used the short version of NEO-PIR (Costa & McCrae, 1992). Therefore, how each factor of TAS-20 was associated with the facet level of each trait of the five-factor model remains to be clarified. Further limitations of this study are that we neither focused on clusters that were related to low TAS-20 scores, nor examined the influences of culture on the clusters. Therefore, the precise definition of alexithymia cluster(s) and the investigation of their stability remain important tasks for future studies. Nevertheless, alexithymia may correspond not to any single dimension of the five-factor model but is captured by a complex mixture of narrow personality traits (Taylor & Bagby, 2012). It is suggested that these issues should be investigated in the future. Taking into consideration the limits of the self-report measures of alexithymia, the present results suggest that the total score on the TAS-20 should not be used as a uni-dimensional measure of alexithymia, and instead it should only be used as a rough indication of alexithymia. For diagnostic purposes of individuals, the profiles of subscale scores are required to obtain a more finely grained assessment of alexithymia and we should further conduct the structured interview for alexithymia.
Competing interests The authors declare that they have no competing interests.
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