- Email: [email protected]
The role of active inhibitory control in psychological well-being and mindfulness
Personality and Individual Differences 53 (2012) 618–621
Contents lists available at SciVerse ScienceDirect
Personality and Individual Differences journal homepage: www.elsevier.com/locate/paid
The role of active inhibitory control in psychological well-being and mindfulness Yi-Chen Lee, Hsuan-Fu Chao ⇑ Chung Yuan Christian University, Chung Li, Taiwan
a r t i c l e
i n f o
Article history: Received 18 November 2011 Received in revised form 31 March 2012 Accepted 7 May 2012 Available online 3 June 2012 Keywords: Active inhibition Psychological well-being Peace of mind Satisfaction with life Depression Mindfulness
a b s t r a c t Inhibition is an essential cognitive ability. In this paper, we propose that the faculty of active inhibition is important for psychological well-being because people can use this capacity to reduce interference from unwanted emotional distractors. In order to examine this hypothesis, we investigate the relationship between the capacity for active inhibition and psychological well-being. Study 1 shows that people with higher capacities for active inhibition have more peace of mind and higher satisfaction with life. Study 2 indicates that people who exhibit higher capacities for active inhibition have more peace of mind and are less likely to be depressed. In addition, Study 2 also shows that people with higher capacities for active inhibition are more able to act with awareness. Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction The inhibition of unwanted information is essential for everyday human cognition. Inhibition is required while humans process external input. The environment contains many objects that distract people from their target objects. In order to locate an object that one seeks and ignore all other distracting objects, one must use distractor inhibition (Tipper, 1985, 2001). Inhibition is also a component of action control. Response inhibition is used to suppress prepotent responses; it is necessary in order to avoid the production of an inappropriate action (Logan & Cowan, 1984). In addition, inhibition is required in order to process internal thoughts and memories (Anderson & Green, 2001; Levy, McVeigh, Marful, & Anderson, 2007); without inhibition, irrelevant or disturbing thoughts or memories might overwhelm the individual. Inhibition is also crucial for emotional regulation. Consistent with this idea, it has been demonstrated that impaired cognitive inhibition is associated with depression (Frings, Wentura, & Holtz, 2007; Goeleven, De Raedt, Baert, & Koster, 2006; Joormann, 2004; Joormann & Gotlib, 2010). In these studies, negative priming, which is an automatic inhibition task (Nigg, 2000) was used to measure the performance of cognitive inhibition. However, the role of active inhibitory control in emotion regulation and psychological well-being has not yet been clarified.
⇑ Corresponding author. Address: Department of Psychology, Chung Yuan Christian University, No. 200 Chung Pei Rd., Chung Li 32023, Taiwan. Tel.: +886 3265 3410; fax: +886 3265 3499. E-mail address: [email protected] (H.-F. Chao). 0191-8869/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.paid.2012.05.001
It is important to make a distinction between automatic and active inhibition because the latter is also an important mechanism for emotion regulation in daily life. Automatic inhibition, such as negative priming (Tipper, 1985, 2001) or inhibition of return (Posner & Cohen, 1984; see Klein, 2000 for a review), can operate without a person’s awareness of the distracting information or an incentive to inhibit the non-predictive cues. In contrast, active or intentional inhibition operates via effortful control and involves executive functioning (Nigg, 2000). Consistent with this idea, active inhibition requires working memory resources in order to operate (Chao, 2010a, 2011). In addition, active inhibition is observed only when there is an incentive or an intention to actively inhibit the distractor (Chao, 2010a, 2011) and when there is sufficient time for active inhibition to take place (Chao, 2010a). The ability to exert active inhibitory control is important for emotional regulation. Active inhibitory control provides a method by which people can deliberately exclude emotional distractors (e.g., an angry face, a negative thought, or a negative event) that may affect their well-being. By excluding unwanted emotional information, people can focus on desired or goal-related information and thereby promote their own well-being. For instance, in a recent study on the role of attentional control of emotional distractors in times of life stress, Vanderhasselt, Koster, Goubert, and De Raedt (in press) suggested that the capacity to overcome distraction caused by emotional information may promote adaptive responses to stress. Considering their findings, active inhibition, a mechanism for actively excluding unwanted distractors, could be important for adaptive coping and well-being. In addition, Lee, Lin, Huang, and Fredrickson (in press) argued that the process of emotional control plays an important role in achieving peace of
Y.-C. Lee, H.-F. Chao / Personality and Individual Differences 53 (2012) 618–621
mind (i.e., the enjoyment of a peaceful and balanced life). Active inhibition, as one important mechanism for cognitive control, may help people to exclude undesired emotional information and thoughts and hence promote peace of mind. Considering the importance of active inhibition, we hypothesize that people with higher capacities for active inhibition are more capable of voluntarily reducing interference from unwanted emotional distractors, and hence, they have higher levels of psychological well-being. In the present paper, we report two studies investigating this prediction. 2. Study 1 The relationship between active inhibition and psychological well-being was examined in Study 1. We predicted that people with high capacities for active inhibition have better psychological wellbeing than those with low capacities for active inhibition. We used two scales to reveal the relationship between the capacity for active inhibition and psychological well-being. One was the Satisfaction with Life Scale (SWLS; Diener, Emmons, Larsen, & Griffin, 1985), which is commonly used to reveal people’s subjective well-being. In addition, we used the Peace of Mind Scale (PoM; Lee et al., in press) to provide convergent evidence. The PoM is a measure of affective well-being that focuses on the enjoyment of a peaceful and balanced life. A sample item from this scale is ‘‘I have peace and harmony in my mind’’. PoM results have been demonstrated to be positively correlated with indices of subjective well-being and negatively correlated with indices of depression, anxiety, and entrapment (Lee et al., in press). For instance, in a study by Lee et al. (in press), the correlation between the PoM and the SWLS among 137 undergraduate students was .54, and the correlation between the PoM and low-arousal positive affect (Tsai, Knutson, & Fung, 2006) was .60. In addition, the correlation between the PoM and the Center for Epidemiological Studies Depression Scale (CES-D; Radloff, 1977) was .58. The location precue task (Chao, 2010a; Munneke, Van der Stigchel, & Theeuwes, 2008) was used as a measure of people’s capacity for active inhibition. Before the presentation of a location selection display, a spatial cue was presented to indicate the likely location of the upcoming distractor. Participants were instructed to actively inhibit the precued location of the distractor. A distractor precue conferred an advantage on a subsequent location selection task when the participants successfully inhibited the precued distractor and thereby diminished its interference. As this advantage is observed only when the precue is predictive of the upcoming distractor and when working memory is not preoccupied with another task (Chao, 2010a, 2011), the distractor precue advantage should reflect the results of effortful inhibitory control. 2.1. Methods 2.1.1. Participants Sixty undergraduate students (46 female, 14 male; mean age = 21.1 years, SD = 1.9 years) participated in this experiment at Chung Yuan Christian University for a monetary reward of NT$200. Each participant was tested individually. 2.1.2. Stimuli The viewing distance was maintained at approximately 57 cm throughout the experimental session. In the active inhibition task, the target was a white ‘‘O’’ and the distractor was a white ‘‘X.’’ Each stimulus letter subtended a visual angle of 0.8° vertically and horizontally. The target and distractor appeared simultaneously at four possible locations arranged in a flat-bottom ‘‘V’’ shape at the center of the screen. The horizontal distance between the two locations at
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the top of the V subtended a visual angle of 4.7° and that between the two locations at the bottom of the V subtended a visual angle of 3.3°. The vertical distance between the two pairs of locations subtended a visual angle of 3.0°. Each of these four locations was marked by a white placeholder line of width 2.0°. The cue was a white arrow with length 1.7° and thickness 0.1° presented at the center of the four locations. 2.1.3. Procedure Each participant performed the active inhibition task and completed the PoM (Lee et al., in press) and the SWLS (Diener et al., 1985). The students took the Chinese version of the SWLS (Wu & Yao, 2006). Participants rated each statement on a 7-point scale (1 = strongly disagree; 7 = strongly agree). On the PoM, the participants rated the frequency of each statement on a 5-point scale (1 = never; 5 = always). The participants were unaware of the relationship between these tasks. The active inhibition task was conducted using the DMDX software package (Forster & Forster, 2003). There were 12 practice trials followed by 120 test trials. Of the test trials, 96 were valid trials and 24 were control trials. In the valid trials, the distractor was displayed at a location indicated by the arrow cue. In the control condition, neither the target nor the distractor was shown at the cued location. These test trials were conducted in a random order. When each trial began, four placeholders were displayed. These placeholders were presented on the screen throughout the entire trial. After approximately 200 ms, an arrow cue was displayed. Simultaneously, a ‘‘ding’’ sound was played as a warning signal. After approximately 1500 ms, the arrow cue disappeared and there was a blank interval for approximately 620 ms. Following this, the target was presented at one of the four locations and the distractor was presented at another. The participants were instructed to indicate the location of the target by pressing F, V, J, or N on the keyboard, which were spatially mapped to the four locations. This stimulus display was presented on the screen until the participant pressed one of the buttons or until 3000 ms had elapsed, whichever occurred first. Participants were instructed to inhibit the precued distractor locations in order to reduce their interference with the follow-up location selection task. 2.2. Results The capacity for active inhibition was measured as the difference in reaction times (RTs) for correct responses between the valid condition and the control condition (i.e., RTcontrol RTvalid). The participants who scored in the top 25% of the group were classified as the high-capacity group; those who scored in the bottom 25% were classified as the low-capacity group. There were 15 participants in each of these groups. Table 1 shows the characteristics of these two groups. The performance of the high-capacity group during the active inhibition task was significantly better than that of the low-capacity group [t(28) = 11.14, p < .01]. These two groups did not differ in terms of age or gender [t(28) = 0.46, p > .10 and chi-squared (1) = 0.00, p > .10]. The relationships between the capacity for active inhibition and PoM and SWLS scores were evaluated via a one-tailed independent t-test (Table 1). The high-capacity group scored higher on the SWLS and the PoM than did the low-capacity group [t(28) = 2.32, p < .025 and t(28) = 1.74, p < .05, respectively]. 2.3. Discussion Both measures of psychological well-being supported the prediction that people with higher cognitive capacity for active inhibition have greater well-being. In other words, the capacity for active inhibition is related to individual differences in psychological
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Y.-C. Lee, H.-F. Chao / Personality and Individual Differences 53 (2012) 618–621
Table 1 Characteristics, psychological well-being, and mindfulness of college students of high and low capacity of active inhibition in Studies 1 and 2 (standard errors of the means are in parentheses). Ability of active inhibition
Study 1 Active inhibition Age
High
Low
26.4 (2.9) ms
13.9 (2.2) ms 21.2 (0.7) years 12 females, 3 males 17.2 (1.6) 3.0 (0.2)
Satisfaction with life scale (SWLS) Peace of mind scale (PoM)
21.5 (0.3) years 12 females, 3 males 21.9 (1.3) 3.4 (0.2)
Study 2 Active inhibition
35.3 (4.4) ms
Gender
Age Gender Peace of mind scale (PoM) Center for epidemiological studies depression scale (CES-D) Five facet mindfulness questionnaire (FFMQ) Observing Describing Acting with awareness Nonjudging of inner experiences Nonreactivity to inner experiences
20.9 (0.4) years 13 females, 5 males 3.5 (0.1) 11.8 (1.4)
3.3 3.0 3.6 2.6 3.1
(0.2) (0.1) (0.1) (0.1) (0.1)
14.8 (1.9) ms 20.8 (0.3) years 12 females, 6 males 3.2 (0.1) 17.5 (1.9)
3.3 2.9 3.0 2.3 2.8
(0.2) (0.2) (0.1) (0.1) (0.2)
Note: Active inhibition = reaction time (RT) in the invalid condition – RT in the valid condition.
well-being: people who can better filter out unwanted information, thoughts, and emotions tend to have more satisfactory and peaceful lives. In Study 1, the relationship between the capacity for active inhibition and PoM did not reach the significance level of p = .025 after Bonferroni correction. Therefore, the PoM was included in Study 2 to determine whether the observed relationship could be replicated. 3. Study 2 Study 1 demonstrated the relationship between the capacity for active inhibition and psychological well-being using two positive measures. The present study aims to examine this relationship using a positive index, which had been used in Study 1 (PoM; Lee et al., in press), and a negative index (CES-D; Radloff, 1977). We hypothesized that people can use active inhibition to reduce interference from unwanted emotional distractors and to focus on their current target. In order to test this idea, Study 2 further investigated the relationship between the capacities for active inhibition and for mindfulness. Mindfulness captures the extent to which people pay attention to consciousness (Baer, Smith, Hopkins, Krietemeyer, & Toney, 2006) and has been shown to predict the enhancement of psychological well-being (Brown & Ryan, 2003). The Five Facet Mindfulness Questionnaire (FFMQ; Baer et al., 2006, 2008), was used in this study. The five facets of mindfulness include nonreactivity to inner experience, nonjudging of inner experience, observing, describing, and acting with awareness. The last facet is most relevant to the capacity for active inhibition, as it serves the purpose of focusing on a task without becoming distracted. A sample item of this facet is ‘‘I am easily distracted’’ (reverse coded; Baer et al., 2006). Hence, we predicted that people with high capacities for active inhibition should score better in the acting with awareness facet of the FFMQ.
3.1. Methods 3.1.1. Participants Seventy-two undergraduate students (43 female, 29 male; mean age = 20.9 years, SD = 1.3 years) participated in this experiment at Chung Yuan Christian University for a monetary reward of NT$200. Each participant was tested individually. 3.1.2. Stimuli and procedure The stimuli and procedure were similar to Study 1, with two exceptions. In Study 2, the CES-D (Radloff, 1977) was used rather than the SWLS. The students took the Chinese version of the CESD (Chien & Cheng, 1985). Participants rated each statement on a 4-point scale (0 = rarely or never; 3 = mostly or always). In addition, the students completed the FFMQ (Baer et al., 2006, 2008). The students took the Chinese version of the FFMQ (Chang, Lin, & Huang, 2010). Participants rated each statement on a 5-point scale (1 = never; 5 = always). 3.2. Results The criteria for selecting the high-capacity and low-capacity groups were identical to those in Study 1. There were 18 participants in each group. Table 1 shows the characteristics of these two groups. The performance of the high-capacity group during the active inhibition task was significantly better than that of the low-capacity group [t(34) = 10.39, p < .01]. These two groups did not differ in terms of age or gender [t(34) = 0.11, p > .10 and chi-squared (1) = 0.13, p > .10]. The relationships between the capacity for active inhibition and PoM and CES-D scores were evaluated via a one-tailed independent t-test (Table 1). The high-capacity group scored higher on the PoM than did the low-capacity group [t(34) = 1.90, p < .05]. In addition, the high-capacity group scored lower on the CES-D than did the low-capacity group [t(34) = 2.38, p < .025]. The relationship between the capacity for active inhibition and FFMQ scores was evaluated by a one-tailed independent t-test (Table 1). There was a significant difference between the highcapacity group and the low-capacity group in terms of the acting with awareness facet of the FFMQ [t(34) = 3.67, p < .001]. There were no significant differences between these two groups in terms of the other four FFMQ facets (ps > .09). 3.3. Discussion A positive measure and a negative measure of psychological well-being were used to examine the effects of capacity for active inhibition. The relationship between the capacity for active inhibition and peace of mind, which was tested in Study 1, was replicated in Study 2. High-capacity participants had more peace of mind than did low-capacity participants. Moreover, the present study indicates that high-capacity participants were less likely to be depressed than were low-capacity participants. The FFMQ results showed that people with higher capacities for active inhibition were more capable of focusing on the current task without becoming distracted. This finding is consistent with the idea that active inhibition is important for the cognitive operations of filtering irrelevant information and focusing on the current goal. 4. General discussion The present study investigates the role of active inhibition in psychological well-being and mindfulness. We hypothesized that active inhibitory control plays an important role in emotion regulation, and is especially crucial in inhibiting unwanted, irrelevant
Y.-C. Lee, H.-F. Chao / Personality and Individual Differences 53 (2012) 618–621
emotional information. Hence, people with a higher capacity for active inhibition are more likely to enjoy better psychological well-being. Consistent with this hypothesis, Studies 1 and 2 show that in comparison to the low-capacity group, people with higher capacities for active inhibition had more peace of mind (measured using the PoM; Lee et al., in press), higher satisfaction with life (measured using the SWLS; Diener et al., 1985), and were less likely to be depressed (measured using the CES-D; Radloff, 1977). In addition, Study 2 shows that people with higher capacities for active inhibition were less likely to become distracted and were more capable of focusing on their current goals (measured using the FFMQ; Baer et al., 2006, 2008) than were people with low capacities for active inhibition. This finding is consistent with the hypothesis that people can use active inhibition to exclude unwanted, irrelevant information. Although the present study demonstrates the importance of active inhibitory control for psychological well-being and mindfulness, the hypothesized role of active inhibition in controlling interference from emotional distractors has not been directly examined. In order to test this hypothesis, we developed an emotional flanker task and examined the impact of active inhibition on performance (Chao & Lee, in preparation). The results supported our hypothesis that active inhibition can reduce interference from emotional distractors. When an emotional distractor was precued, participants benefited in that they responded to the target more promptly. In addition, we found that when participants did not actively inhibit the precued distractor, the distractor precue seemed to lose its benefit. In other words, the benefit was due to intentional, active inhibition rather than due to automatic inhibition, such as emotion-based inhibition of return (Chao, 2010b). These findings further support the idea that active inhibition can help to reduce interference from emotional distractors. The findings of the present study have important implications. First, we have shown that active inhibitory control is important for psychological well-being. In addition, we suggest that the process of active inhibition is important for achieving mindfulness, especially the acting with awareness facet thereof. The present study also suggests future research. First, the finding that active inhibition requires cognitive resources to operate (Chao, 2010a, 2011) implies that active inhibitory control may fail under cognitive load. This is consistent with the finding that thought suppression under load makes the to-be-inhibited information even more accessible (Wenzlaff & Wegner, 2000). A testable prediction is that under long-term cognitive load (for instance, due to anxiety or excessive worries), people cannot filter inappropriate thoughts and emotions. Consequently, psychological well-being may suffer. Second, Joormann and Tran (2009) have recently demonstrated that people with high self-reported rumination are less able to forget emotional information intentionally. The relationships among the capacity for active inhibition, intentional forgetting, rumination, and well-being deserve further investigation. Finally, although the present study shows a close correspondence between the capacity for active inhibitory control and psychological well-being, the causal relationship between these variables has not yet been elucidated. Further studies on active inhibitory control training will provide important information regarding this causal relationship. Acknowledgements This work was supported by grants from the National Science Council of Taiwan to Y.-C. Lee (NSC 99-2410-H033-056) and H.-F. Chao (NSC 96-2629-S-033-002 & NSC 97-2511-S-033-006-MY2).
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Contents lists available at SciVerse ScienceDirect
Personality and Individual Differences journal homepage: www.elsevier.com/locate/paid
The role of active inhibitory control in psychological well-being and mindfulness Yi-Chen Lee, Hsuan-Fu Chao ⇑ Chung Yuan Christian University, Chung Li, Taiwan
a r t i c l e
i n f o
Article history: Received 18 November 2011 Received in revised form 31 March 2012 Accepted 7 May 2012 Available online 3 June 2012 Keywords: Active inhibition Psychological well-being Peace of mind Satisfaction with life Depression Mindfulness
a b s t r a c t Inhibition is an essential cognitive ability. In this paper, we propose that the faculty of active inhibition is important for psychological well-being because people can use this capacity to reduce interference from unwanted emotional distractors. In order to examine this hypothesis, we investigate the relationship between the capacity for active inhibition and psychological well-being. Study 1 shows that people with higher capacities for active inhibition have more peace of mind and higher satisfaction with life. Study 2 indicates that people who exhibit higher capacities for active inhibition have more peace of mind and are less likely to be depressed. In addition, Study 2 also shows that people with higher capacities for active inhibition are more able to act with awareness. Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction The inhibition of unwanted information is essential for everyday human cognition. Inhibition is required while humans process external input. The environment contains many objects that distract people from their target objects. In order to locate an object that one seeks and ignore all other distracting objects, one must use distractor inhibition (Tipper, 1985, 2001). Inhibition is also a component of action control. Response inhibition is used to suppress prepotent responses; it is necessary in order to avoid the production of an inappropriate action (Logan & Cowan, 1984). In addition, inhibition is required in order to process internal thoughts and memories (Anderson & Green, 2001; Levy, McVeigh, Marful, & Anderson, 2007); without inhibition, irrelevant or disturbing thoughts or memories might overwhelm the individual. Inhibition is also crucial for emotional regulation. Consistent with this idea, it has been demonstrated that impaired cognitive inhibition is associated with depression (Frings, Wentura, & Holtz, 2007; Goeleven, De Raedt, Baert, & Koster, 2006; Joormann, 2004; Joormann & Gotlib, 2010). In these studies, negative priming, which is an automatic inhibition task (Nigg, 2000) was used to measure the performance of cognitive inhibition. However, the role of active inhibitory control in emotion regulation and psychological well-being has not yet been clarified.
⇑ Corresponding author. Address: Department of Psychology, Chung Yuan Christian University, No. 200 Chung Pei Rd., Chung Li 32023, Taiwan. Tel.: +886 3265 3410; fax: +886 3265 3499. E-mail address: [email protected] (H.-F. Chao). 0191-8869/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.paid.2012.05.001
It is important to make a distinction between automatic and active inhibition because the latter is also an important mechanism for emotion regulation in daily life. Automatic inhibition, such as negative priming (Tipper, 1985, 2001) or inhibition of return (Posner & Cohen, 1984; see Klein, 2000 for a review), can operate without a person’s awareness of the distracting information or an incentive to inhibit the non-predictive cues. In contrast, active or intentional inhibition operates via effortful control and involves executive functioning (Nigg, 2000). Consistent with this idea, active inhibition requires working memory resources in order to operate (Chao, 2010a, 2011). In addition, active inhibition is observed only when there is an incentive or an intention to actively inhibit the distractor (Chao, 2010a, 2011) and when there is sufficient time for active inhibition to take place (Chao, 2010a). The ability to exert active inhibitory control is important for emotional regulation. Active inhibitory control provides a method by which people can deliberately exclude emotional distractors (e.g., an angry face, a negative thought, or a negative event) that may affect their well-being. By excluding unwanted emotional information, people can focus on desired or goal-related information and thereby promote their own well-being. For instance, in a recent study on the role of attentional control of emotional distractors in times of life stress, Vanderhasselt, Koster, Goubert, and De Raedt (in press) suggested that the capacity to overcome distraction caused by emotional information may promote adaptive responses to stress. Considering their findings, active inhibition, a mechanism for actively excluding unwanted distractors, could be important for adaptive coping and well-being. In addition, Lee, Lin, Huang, and Fredrickson (in press) argued that the process of emotional control plays an important role in achieving peace of
Y.-C. Lee, H.-F. Chao / Personality and Individual Differences 53 (2012) 618–621
mind (i.e., the enjoyment of a peaceful and balanced life). Active inhibition, as one important mechanism for cognitive control, may help people to exclude undesired emotional information and thoughts and hence promote peace of mind. Considering the importance of active inhibition, we hypothesize that people with higher capacities for active inhibition are more capable of voluntarily reducing interference from unwanted emotional distractors, and hence, they have higher levels of psychological well-being. In the present paper, we report two studies investigating this prediction. 2. Study 1 The relationship between active inhibition and psychological well-being was examined in Study 1. We predicted that people with high capacities for active inhibition have better psychological wellbeing than those with low capacities for active inhibition. We used two scales to reveal the relationship between the capacity for active inhibition and psychological well-being. One was the Satisfaction with Life Scale (SWLS; Diener, Emmons, Larsen, & Griffin, 1985), which is commonly used to reveal people’s subjective well-being. In addition, we used the Peace of Mind Scale (PoM; Lee et al., in press) to provide convergent evidence. The PoM is a measure of affective well-being that focuses on the enjoyment of a peaceful and balanced life. A sample item from this scale is ‘‘I have peace and harmony in my mind’’. PoM results have been demonstrated to be positively correlated with indices of subjective well-being and negatively correlated with indices of depression, anxiety, and entrapment (Lee et al., in press). For instance, in a study by Lee et al. (in press), the correlation between the PoM and the SWLS among 137 undergraduate students was .54, and the correlation between the PoM and low-arousal positive affect (Tsai, Knutson, & Fung, 2006) was .60. In addition, the correlation between the PoM and the Center for Epidemiological Studies Depression Scale (CES-D; Radloff, 1977) was .58. The location precue task (Chao, 2010a; Munneke, Van der Stigchel, & Theeuwes, 2008) was used as a measure of people’s capacity for active inhibition. Before the presentation of a location selection display, a spatial cue was presented to indicate the likely location of the upcoming distractor. Participants were instructed to actively inhibit the precued location of the distractor. A distractor precue conferred an advantage on a subsequent location selection task when the participants successfully inhibited the precued distractor and thereby diminished its interference. As this advantage is observed only when the precue is predictive of the upcoming distractor and when working memory is not preoccupied with another task (Chao, 2010a, 2011), the distractor precue advantage should reflect the results of effortful inhibitory control. 2.1. Methods 2.1.1. Participants Sixty undergraduate students (46 female, 14 male; mean age = 21.1 years, SD = 1.9 years) participated in this experiment at Chung Yuan Christian University for a monetary reward of NT$200. Each participant was tested individually. 2.1.2. Stimuli The viewing distance was maintained at approximately 57 cm throughout the experimental session. In the active inhibition task, the target was a white ‘‘O’’ and the distractor was a white ‘‘X.’’ Each stimulus letter subtended a visual angle of 0.8° vertically and horizontally. The target and distractor appeared simultaneously at four possible locations arranged in a flat-bottom ‘‘V’’ shape at the center of the screen. The horizontal distance between the two locations at
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the top of the V subtended a visual angle of 4.7° and that between the two locations at the bottom of the V subtended a visual angle of 3.3°. The vertical distance between the two pairs of locations subtended a visual angle of 3.0°. Each of these four locations was marked by a white placeholder line of width 2.0°. The cue was a white arrow with length 1.7° and thickness 0.1° presented at the center of the four locations. 2.1.3. Procedure Each participant performed the active inhibition task and completed the PoM (Lee et al., in press) and the SWLS (Diener et al., 1985). The students took the Chinese version of the SWLS (Wu & Yao, 2006). Participants rated each statement on a 7-point scale (1 = strongly disagree; 7 = strongly agree). On the PoM, the participants rated the frequency of each statement on a 5-point scale (1 = never; 5 = always). The participants were unaware of the relationship between these tasks. The active inhibition task was conducted using the DMDX software package (Forster & Forster, 2003). There were 12 practice trials followed by 120 test trials. Of the test trials, 96 were valid trials and 24 were control trials. In the valid trials, the distractor was displayed at a location indicated by the arrow cue. In the control condition, neither the target nor the distractor was shown at the cued location. These test trials were conducted in a random order. When each trial began, four placeholders were displayed. These placeholders were presented on the screen throughout the entire trial. After approximately 200 ms, an arrow cue was displayed. Simultaneously, a ‘‘ding’’ sound was played as a warning signal. After approximately 1500 ms, the arrow cue disappeared and there was a blank interval for approximately 620 ms. Following this, the target was presented at one of the four locations and the distractor was presented at another. The participants were instructed to indicate the location of the target by pressing F, V, J, or N on the keyboard, which were spatially mapped to the four locations. This stimulus display was presented on the screen until the participant pressed one of the buttons or until 3000 ms had elapsed, whichever occurred first. Participants were instructed to inhibit the precued distractor locations in order to reduce their interference with the follow-up location selection task. 2.2. Results The capacity for active inhibition was measured as the difference in reaction times (RTs) for correct responses between the valid condition and the control condition (i.e., RTcontrol RTvalid). The participants who scored in the top 25% of the group were classified as the high-capacity group; those who scored in the bottom 25% were classified as the low-capacity group. There were 15 participants in each of these groups. Table 1 shows the characteristics of these two groups. The performance of the high-capacity group during the active inhibition task was significantly better than that of the low-capacity group [t(28) = 11.14, p < .01]. These two groups did not differ in terms of age or gender [t(28) = 0.46, p > .10 and chi-squared (1) = 0.00, p > .10]. The relationships between the capacity for active inhibition and PoM and SWLS scores were evaluated via a one-tailed independent t-test (Table 1). The high-capacity group scored higher on the SWLS and the PoM than did the low-capacity group [t(28) = 2.32, p < .025 and t(28) = 1.74, p < .05, respectively]. 2.3. Discussion Both measures of psychological well-being supported the prediction that people with higher cognitive capacity for active inhibition have greater well-being. In other words, the capacity for active inhibition is related to individual differences in psychological
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Table 1 Characteristics, psychological well-being, and mindfulness of college students of high and low capacity of active inhibition in Studies 1 and 2 (standard errors of the means are in parentheses). Ability of active inhibition
Study 1 Active inhibition Age
High
Low
26.4 (2.9) ms
13.9 (2.2) ms 21.2 (0.7) years 12 females, 3 males 17.2 (1.6) 3.0 (0.2)
Satisfaction with life scale (SWLS) Peace of mind scale (PoM)
21.5 (0.3) years 12 females, 3 males 21.9 (1.3) 3.4 (0.2)
Study 2 Active inhibition
35.3 (4.4) ms
Gender
Age Gender Peace of mind scale (PoM) Center for epidemiological studies depression scale (CES-D) Five facet mindfulness questionnaire (FFMQ) Observing Describing Acting with awareness Nonjudging of inner experiences Nonreactivity to inner experiences
20.9 (0.4) years 13 females, 5 males 3.5 (0.1) 11.8 (1.4)
3.3 3.0 3.6 2.6 3.1
(0.2) (0.1) (0.1) (0.1) (0.1)
14.8 (1.9) ms 20.8 (0.3) years 12 females, 6 males 3.2 (0.1) 17.5 (1.9)
3.3 2.9 3.0 2.3 2.8
(0.2) (0.2) (0.1) (0.1) (0.2)
Note: Active inhibition = reaction time (RT) in the invalid condition – RT in the valid condition.
well-being: people who can better filter out unwanted information, thoughts, and emotions tend to have more satisfactory and peaceful lives. In Study 1, the relationship between the capacity for active inhibition and PoM did not reach the significance level of p = .025 after Bonferroni correction. Therefore, the PoM was included in Study 2 to determine whether the observed relationship could be replicated. 3. Study 2 Study 1 demonstrated the relationship between the capacity for active inhibition and psychological well-being using two positive measures. The present study aims to examine this relationship using a positive index, which had been used in Study 1 (PoM; Lee et al., in press), and a negative index (CES-D; Radloff, 1977). We hypothesized that people can use active inhibition to reduce interference from unwanted emotional distractors and to focus on their current target. In order to test this idea, Study 2 further investigated the relationship between the capacities for active inhibition and for mindfulness. Mindfulness captures the extent to which people pay attention to consciousness (Baer, Smith, Hopkins, Krietemeyer, & Toney, 2006) and has been shown to predict the enhancement of psychological well-being (Brown & Ryan, 2003). The Five Facet Mindfulness Questionnaire (FFMQ; Baer et al., 2006, 2008), was used in this study. The five facets of mindfulness include nonreactivity to inner experience, nonjudging of inner experience, observing, describing, and acting with awareness. The last facet is most relevant to the capacity for active inhibition, as it serves the purpose of focusing on a task without becoming distracted. A sample item of this facet is ‘‘I am easily distracted’’ (reverse coded; Baer et al., 2006). Hence, we predicted that people with high capacities for active inhibition should score better in the acting with awareness facet of the FFMQ.
3.1. Methods 3.1.1. Participants Seventy-two undergraduate students (43 female, 29 male; mean age = 20.9 years, SD = 1.3 years) participated in this experiment at Chung Yuan Christian University for a monetary reward of NT$200. Each participant was tested individually. 3.1.2. Stimuli and procedure The stimuli and procedure were similar to Study 1, with two exceptions. In Study 2, the CES-D (Radloff, 1977) was used rather than the SWLS. The students took the Chinese version of the CESD (Chien & Cheng, 1985). Participants rated each statement on a 4-point scale (0 = rarely or never; 3 = mostly or always). In addition, the students completed the FFMQ (Baer et al., 2006, 2008). The students took the Chinese version of the FFMQ (Chang, Lin, & Huang, 2010). Participants rated each statement on a 5-point scale (1 = never; 5 = always). 3.2. Results The criteria for selecting the high-capacity and low-capacity groups were identical to those in Study 1. There were 18 participants in each group. Table 1 shows the characteristics of these two groups. The performance of the high-capacity group during the active inhibition task was significantly better than that of the low-capacity group [t(34) = 10.39, p < .01]. These two groups did not differ in terms of age or gender [t(34) = 0.11, p > .10 and chi-squared (1) = 0.13, p > .10]. The relationships between the capacity for active inhibition and PoM and CES-D scores were evaluated via a one-tailed independent t-test (Table 1). The high-capacity group scored higher on the PoM than did the low-capacity group [t(34) = 1.90, p < .05]. In addition, the high-capacity group scored lower on the CES-D than did the low-capacity group [t(34) = 2.38, p < .025]. The relationship between the capacity for active inhibition and FFMQ scores was evaluated by a one-tailed independent t-test (Table 1). There was a significant difference between the highcapacity group and the low-capacity group in terms of the acting with awareness facet of the FFMQ [t(34) = 3.67, p < .001]. There were no significant differences between these two groups in terms of the other four FFMQ facets (ps > .09). 3.3. Discussion A positive measure and a negative measure of psychological well-being were used to examine the effects of capacity for active inhibition. The relationship between the capacity for active inhibition and peace of mind, which was tested in Study 1, was replicated in Study 2. High-capacity participants had more peace of mind than did low-capacity participants. Moreover, the present study indicates that high-capacity participants were less likely to be depressed than were low-capacity participants. The FFMQ results showed that people with higher capacities for active inhibition were more capable of focusing on the current task without becoming distracted. This finding is consistent with the idea that active inhibition is important for the cognitive operations of filtering irrelevant information and focusing on the current goal. 4. General discussion The present study investigates the role of active inhibition in psychological well-being and mindfulness. We hypothesized that active inhibitory control plays an important role in emotion regulation, and is especially crucial in inhibiting unwanted, irrelevant
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emotional information. Hence, people with a higher capacity for active inhibition are more likely to enjoy better psychological well-being. Consistent with this hypothesis, Studies 1 and 2 show that in comparison to the low-capacity group, people with higher capacities for active inhibition had more peace of mind (measured using the PoM; Lee et al., in press), higher satisfaction with life (measured using the SWLS; Diener et al., 1985), and were less likely to be depressed (measured using the CES-D; Radloff, 1977). In addition, Study 2 shows that people with higher capacities for active inhibition were less likely to become distracted and were more capable of focusing on their current goals (measured using the FFMQ; Baer et al., 2006, 2008) than were people with low capacities for active inhibition. This finding is consistent with the hypothesis that people can use active inhibition to exclude unwanted, irrelevant information. Although the present study demonstrates the importance of active inhibitory control for psychological well-being and mindfulness, the hypothesized role of active inhibition in controlling interference from emotional distractors has not been directly examined. In order to test this hypothesis, we developed an emotional flanker task and examined the impact of active inhibition on performance (Chao & Lee, in preparation). The results supported our hypothesis that active inhibition can reduce interference from emotional distractors. When an emotional distractor was precued, participants benefited in that they responded to the target more promptly. In addition, we found that when participants did not actively inhibit the precued distractor, the distractor precue seemed to lose its benefit. In other words, the benefit was due to intentional, active inhibition rather than due to automatic inhibition, such as emotion-based inhibition of return (Chao, 2010b). These findings further support the idea that active inhibition can help to reduce interference from emotional distractors. The findings of the present study have important implications. First, we have shown that active inhibitory control is important for psychological well-being. In addition, we suggest that the process of active inhibition is important for achieving mindfulness, especially the acting with awareness facet thereof. The present study also suggests future research. First, the finding that active inhibition requires cognitive resources to operate (Chao, 2010a, 2011) implies that active inhibitory control may fail under cognitive load. This is consistent with the finding that thought suppression under load makes the to-be-inhibited information even more accessible (Wenzlaff & Wegner, 2000). A testable prediction is that under long-term cognitive load (for instance, due to anxiety or excessive worries), people cannot filter inappropriate thoughts and emotions. Consequently, psychological well-being may suffer. Second, Joormann and Tran (2009) have recently demonstrated that people with high self-reported rumination are less able to forget emotional information intentionally. The relationships among the capacity for active inhibition, intentional forgetting, rumination, and well-being deserve further investigation. Finally, although the present study shows a close correspondence between the capacity for active inhibitory control and psychological well-being, the causal relationship between these variables has not yet been elucidated. Further studies on active inhibitory control training will provide important information regarding this causal relationship. Acknowledgements This work was supported by grants from the National Science Council of Taiwan to Y.-C. Lee (NSC 99-2410-H033-056) and H.-F. Chao (NSC 96-2629-S-033-002 & NSC 97-2511-S-033-006-MY2).
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