Does daily Stroop interference measure day-specific ego depletion in working environments? A multilevel study on the measurement of available self-control.
8 January 2019 Jan Digutsch (S3555666)
First supervisor: Dr. Jessica de Bloom, Department of HRM & OB, Faculty of Business and Economics, University of Groningen, j.debloom@rug.nl
Second supervisor: Dr. Anita Keller, Department of Psychology, Faculty of Behavioural and Social Sciences, University of Groningen, a.c.keller@rug.nl
Abstract
Employees increasingly face self-control demands at work. According to the limited strength model of self-control (Muraven & Baumeister, 2000), these demands draw on a limited regulatory resource. Self-control exertion entails psychological costs, a state called ego depletion. The underlying mechanisms of ego depletion are not sufficiently investigated yet. This research paper examined both construct and criterion validity of Stroop interference as an objective measure for ego depletion which adds a unique way to investigate effects of depletion. Data shows empirical evidence for its discriminant validity; however, no evidence was found for its construct validity as neither ego depletion nor self-control demands constitute a significant predictor for Stroop interference. Implications and limitations of this specific Stroop task are discussed.
Keywords
Does daily Stroop interference measure day-specific ego depletion in working environments? A multilevel study on the measurement of available self-control.
1. Introduction
Because of technological progress, competitive markets, and an increasing focus on service orientation, employees are increasingly required to regulate their emotions, adjust and monitor their goal-directed behavior, and encourage themselves to perform highly demanding tasks (Cascio, 2003). These demands require the exertion of self-control to cope with (e.g., Diestel & Schmidt, 2012). According to Baumeister, Heatherton, and Tice (1994), self-control involves inhibiting, modifying, or overriding spontaneous and automatic reactions, urges, emotions, and desires that would otherwise interfere with purposive action sequences. Prior research has repeatedly revealed that exerting self-control entails psychological costs that immediately manifest as exhaustion, a state referred to as ego depletion (Hagger, Wood, Stiff, & Chatzisarantis, 2010).
The limited strength model of self-control (Muraven & Baumeister, 2000) constitutes a theoretical underpinning for research on the ego depletion effect according to which self-control processes draw on and deplete a limited regulatory resource. Because resources are assumed to be finite, people perform poorer on a self-control task after having already engaged in a previous task requiring self-control. Hence, caused by the exertion of a task requiring self-control at Time 1 (i.e., impulse control, resisting distractions, overcoming motivational barriers), subsequent self-control performance at Time 2 is impaired (Friese et al., in press). Since the first studies, the limited strength model of self-control has received broad empirical support by numerous empirical studies that replicated this effect (Dang, in press).
Konze, Rivkin, & Schmidt, 2017) and to what extent ego depletion is different from fatigue (Clarkson, Hirt, Austin Chapman, & Jia, 2011). Friese, Frankenbach, Job, and Loschelder (2017) argue that the doubts and criticisms about the ego depletion effect are substantial and challenging but at the same time, none of these critical issues seem to provide conclusive evidence that ego depletion does not exist. In our view, the controversy of ego depletion may also be related to the use of self-report measures in past research. The sole use of one data source increases common method bias which is described as variance that is attributable to the measurement method rather than to the constructs the measures represent (Podsakoff, MacKenzie, & Podsakoff, 2012). Combining different data sources such as self-report and more objective measures such as psychological tests may reduce common method bias. The only attempt of linking objective measures (i.e., blood glucose levels) with ego depletion could not be sufficiently replicated (e.g. Ainswort, Baumeister, & Boroshuk, 2016) and thus, prior research yet failed to implement objective measures for ego depletion. If such an objective measure can be developed, it has to take day-specific variance of ego depletion into account as several studies have demonstrated high levels of day-specific fluctuations in ego depletion (e.g. Konze, Rivkin, & Schmidt, 2017; Rivkin, Diestel, & Schmidt, 2016). Therefore, the application of multi-level modelling is indispensable. The failure of ego depletion literature to establish objective measures leaves a significant gap that might help to fully examine the nature and underlying processes of ego depletion. As such, the primary purpose of our study is to develop an objective measure for ego depletion which adds a unique way to investigate effects of depletion.
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the interplay of within-day fluctuations of Stroop interference and ego depletion (cf. Beal and Ghandour, 2011). So far, only one study (Rosen et al., 2016) included the Stroop task to examine day-specific effects of depleted self-control. However, in comparison to the study conducted by Rosen et al. (2016), the present study aims to not only use the Stroop task as a measure for diminished self-control, but to examine the interplay with ego depletion and self-control demands over the course of a work day over two consecutive weeks. Second, the construct validity is assessed by the relationship between day-level Stroop interference and day-level self-reported ego depletion (convergent validity) and between person-level Stroop interference and a person-level working memory test (discriminant validity). The usage of day-specific Stroop interference to measure ego depletion constitutes a unique contribution to the debate and addresses the limitations of current literature. Third, criterion validity is assessed by investigating both concurrent and lagged effects of day-level self-control demands on day-level Stroop interference. In current literature, daily effects for objective measures of ego depletion have not been investigated yet.
1.1 Stroop interference as an objective measure of ego depletion
depleted participants can be expected to perform worse on the Stroop task. In contrast to the traditional usage, this approach can help to adequately assess and compare the mechanisms and processes between self-report ego depletion and Stroop interference as an objective measure by comparing within-day fluctuations.
1.2 Stroop task and short-term memory
The construct validity of Stroop interference being a measure for ego depletion can be assessed by examining the convergent validity of the Stroop task with other, unrelated forms of cognitive tests. Stroop interference is assumed to be caused by automatic processes, which are defined as fast-acting, uncontrollable, capacity-free, and independent of conscious awareness or voluntary control (Neely & Kahan, 2001; Posner & Snyder, 1975). Therefore, since participants cannot refrain from accessing the meaning of the Stroop stimulus, the Stroop test is often viewed as a prime example of the automaticity of semantic activation (Küper & Heil, 2012).
measure for short-term memory, the digit span backwards is interpreted as a measure of working memory due to its reversal demand.
Hypothesis 1. Person-level Stroop interference is distinctive to (a) person-level digit span forward and (b) person-level digit span backwards.
1.3 Stroop interference and self-reported ego depletion
combined measure has been successfully used in several studies as it provided a more accurate picture of the data than the reaction time curve (e.g., Rossignol et al., 2009).
As seen in Figure 1, the concurrent effects of Stroop interference on self-reported ego depletion at each behavioral episode are investigated within a day. Therefore, it can be predicted that day-specific self-reported ego depletion is represented by the IES of day-day-specific Stroop interference.
Hypothesis 2. Day-level self-reported ego depletion (a) in the morning is positively related to day-level Stroop interference in the morning; (b) at noon is positively related to day-level Stroop interference at noon; (c) in the evening is positively related to day-level Stroop interference in the evening.
1.4 Self-control demands and Stroop interference
Although self-control has been demonstrated to predict several beneficial outcomes in different life domains (e.g., personal success; Baumeister & Vohs, 2004), there is also a growing body of evidence on the psychological costs of self-control. Frequent acts of self-control can lead to impairments in cognitive and behavioral control (Hagger, Wood, Stiff, & Chatzisarantis, 2010) as they comprise volitionally inhibiting, altering, and overriding of automatic or habitual responses (e.g., Gailliot & Baumeister, 2007). So far, performance impairments (e.g., Schmeichel, Vohs & Baumeister, 2003), physiological changes (e.g. Hagger et al., 2010) and acute depletion (e.g., Muraven, Tice & Baumeister, 1998) have been demonstrated. In the long term, psychosomatic changes (Gailliot, Plant, Butz & Baumeister, 2007), psychological strain (e.g. Schmidt & Diestel, 2015) and self-control deficits (e.g., Muraven & Baumeister, 2000) have been identified as potential consequences of self-control exertion.
indicators of short- and long-term consequences (e.g., Rivkin et al., 2015; Diestel & Schmidt, 2011; Hülsheger & Schewe, 2011). Muraven, Collins, Shiffman, and Paty (2005) suggest that research on self-control demands has to account for day-specific variance, which could be confirmed by several studies (e.g., Diestel, Rivkin, & Schmidt, 2015; Rivkin, Diestel, & Schmidt, 2014).
In line with the strength model of self-control and empirical evidence for the negative effects of day-specific control demands on psychological strain, a negative relation between self-control demands and Stroop interference can be assumed. As predicted before, self-reported ego depletion is represented by Stroop interference and thus, similar empirical evidence on the effects of self-control demands on Stroop interference are expected. Consistent with that argumentation, the negative impact of self-control demands on Stroop interference should be found in a both concurrent and lagged manner: self-control demands that are experienced and reported at noon should predict Stroop interference at noon and in the evening. Concurrent and lagged effects of self-control demands on self-reported ego depletion have been empirically demonstrated in several studies (e.g., Rivkin, Diestel, & Schmidt, 2015, 2016; Sonnentag, Pundt, & Venz, 2016) and are thus expected for Stroop interference as well.
Hypothesis 3. Day-level self-control demands at noon are positively related to (a) day-level Stroop interference at noon and (b) day-level Stroop interference in the afternoon.
2. Method
2.1 Sample and procedure
In advance of the day-specific measurements, participants responded to a general questionnaire that assessed biographical variables and person-level constructs. Over 10 consecutive working days, three times per day (morning, lunch break, and evening), participants received e-mails in order to answer day-specific questions. After receiving the e-mails, the surveys were accessible for four hours. On weekends or public holidays, the diary study was suspended and continued on the next regular working day.
2.2 Measures
The daily questionnaires included the survey device (touch or non-touch), the survey place and survey dayas control variables. These three variableswere assessed and included in the analyses to control for their potential confounding influence. The daily questionnaires also included self-reported ego depletion, self-control demands and Stroop interference. The general questionnaire ahead of the daily questionnaires included demographical data, person-level Stroop interference and person-level digit span. In the day-specific-questionnaires, the items of self-control demands referred to situations within the last hours of work, while the items of ego depletion referred to momentary experiences. In the questionnaire that was sent at noon, all relevant items referred to “after the lunchbreak”.
Ego depletion. Five items were used to measure current ego depletion (e.g. “At the moment,
I feel increasingly less able to focus on anything.”). The scale was developed and validated by Bertrams, Unger, and Dickhäuser (2011), who intends to assess the psychological state of ego depletion proposed by Muraven and Baumeister (2000). All items were scored using a four-point intensity-rating format (1 = not at all; 4 = a great deal).
Stroop interference. In a computerized Stroop task, participants indicated the font color of
In line with Küper and Karbach (2015), trials started with the presentation of the stimulus for 2000 ms or until the subject respond, followed by a response-stimulus interval of 700 ms. In the general questionnaire, participants first performed two practice blocks (12 trials each) followed by four experimental blocks (24 trials each). In the daily questionnaires, participants performed one experimental block (12 trials each) in order to make the daily Stroop task as pleasant and short as possible.
Self-control demands. Items from Schmidt & Neubach (2010) were adopted to measure
day-specific self-control demands (e.g. “Today, I was not allowed to lose my self-control at work.”). The scale consisted of three subscales: impulse control, overcoming inner resistances, and resisting distractions. The items were scored on a five-point intensity rating format ranging from 1 (not at all) to 5 (a great deal).
Digit span. The digit span test is derived of the Wechsler Adult Intelligence Scale
2.3. Applicability of an inverse efficiency score (IES)
The IES is not always superior to separated analyses of reaction time and error rate, as illustrated by Bruyer & Brysbaert (2011). The authors suggest to only use the IES when the number of errors is small (< 10%) and when there is a high correlation between the reaction time and the error rate, indicating that both variables represent a single dimension. In our dataset, the error rate did not exceed 10% in the three Stroop conditions (incongruent = .10; congruent = .05; neutral = .04). Moreover, a high correlation between the reaction time and error rate of Stroop interference could be reported (γ = 0.49, p < .01). Taken together, results suggested that the needed conditions for IES transformation were given in this study.
2.4 Analytical procedure
3. Results
3.1 Preliminary analyses
Before testing the hypotheses, preliminary analyses were conducted in order to monitor the influence of cognitive and behavioral variables on Stroop interference. More precisely, the influence of trait self-control (the general level of self-control capacity), the day-specific intention to put effort into the Stroop task, and trait depletion monitoring (the extent to which participants monitor their mental resources) were tested. Trait self-control showed a non-significant relationship with Stroop interference in the morning (! = 1.66, n.s.), at noon (! = --8.66, n.s.), and in the evening (! = -8.54, n.s.). Also, Stroop effort intentions were not significant for morning (! = -24.08, n.s.), noon (! = -3.09, n.s.), and evening (! = -12.98, n.s.). In addition to that, depletion monitoring was not a predictor for Stroop interference in the morning (! = -12.07, n.s.), at noon (! = -9.24, n.s.), and in the evening (! = -4.99, n.s.).
Based on these findings, these variables were not included as control variables in further analyses.
3.2 Descriptive analyses
Table 1 displays the descriptive statistics, internal consistencies (Cronbach’s alpha), and correlations among the study variables. As will be shown, all study variables revealed satisfactory consistencies.
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To illustrate the development of Stroop interference over time, Figure 2 displays the trajectories within a day, a week, and the two weeks. In addition to that, the trajectories of self-reported ego depletion were added into the plots in order to get a visual impression of its relationship with Stroop interference.
3.1 Test of Hypotheses
As illustrated in Table 1, both digit span forward and backwards did not show a significant correlation with Stroop interference in the morning, at noon, and in the evening, indicating that both tests seem to measure distinct constructs. Hence, hypothesis 1 was supported.
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Table 2 to 4 display multilevel estimates, standard errors, and t-values for all variables predicting Stroop interference in the morning, at noon, and in the evening, respectively. For Stroop interference in the morning, Model 1 showed a significant improvement over the Null Model (χ2 = 12.0, df = 3, p < .001), with survey day being a significant predictor for day-level Stroop interference in the morning. However, Model 2 did not show an improvement over Model 1 (χ2 = 0.2, df = 1, n.s.), indicating that self-reported ego depletion in the morning did not predict Stroop interference in the morning. Therefore, Hypothesis 2a was not supported.
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For Stroop interference at noon, Model 1 showed a significant improvement over the Null Model (χ2 = 223.8, df = 3, p < .001), with no variables being a significant predictor for day-level Stroop interference at noon. However, Model 2.1 does not show an improvement over Model 1 (χ2 = 0.6, df = 1, n.s.), indicating that self-reported ego depletion at noon did not predict Stroop interference at noon. Therefore, Hypothesis 2b was not supported. Model 2.2 also did not show an improvement over Model 1 (χ2 = 0.4, df = 1, n.s.), indicating that self-control demands at noon did not predict Stroop interference at noon. Therefore, Hypothesis 3a was not supported.
--- Please insert Table 4 about here ---
self-control demands in the evening did not predict Stroop interference in the evening. Therefore, Hypothesis 3b was not supported.
4. Discussion
Based on the limited resource model of self-control, the present study examined the validity of day-level Stroop interference as an objective measurement for day-level self-reported ego depletion that was assumed to be negatively affected by day-level self-control demands. Data obtained from participants working in the service sector provided empirical evidence that person-level Stroop interference and person-level digit span are indeed two distinctive measures. Given the fact that the digit span test is known to be a measurement of short-term memory (Kasper et al., 2012), the findings lent support that the Stroop test measures a cognitive resource, as proposed in the theoretical section of this study. However, no support was found for the hypothesized relationship between day-level Stroop interference and day-level self-reported ego depletion, as well as day-level Stroop interference and day-level self-control demands. There are theoretical and methodological explanations for the lack of empirical evidence for the hypothesized relationships between Stroop interference, reported ego depletion, and self-control demands.
Bearing these potential shifts in mind, the authors assume that people become prone to disinhibited behavior. Hence, a decreased Stroop performance of participants over the day could be possibly rather due to motivational and attentional shifts rather than an effect of ego depletion. Consequently, it is possible that motivational shifts have a mediating effect on the relationship between self-control exertion and Stroop interference. When a person exerts self-control (e.g., job demands occurring at work), the willingness to further exert self-control in a second task (for example by completing the Stroop task) may be reduced because the person wants to protect his or her resources from further depletion. Shifts in motivation are, therefore, a consequence of perceived depletion with the goal to conserve current states of depletion. Findings by Muraven et al. (2006) and Hockey (2011) support that assumption by showing that some patterns of depletion represent the desire to conserve energy, that is, people with high levels of depletion seek to conserve remaining energy.
However, Stroop incongruence did not linearly decrease over the course of the day, as assumed by motivational shift theory. As shown in Figure 2, data showed a V-shaped development, with high values (lower Stroop performance) for morning and evening and lower values (higher Stroop performance) for noon. Furthermore, preliminary analyses have shown that neither the extent to which participants seek to conserve energy by monitoring their resource depletion, nor the general self-control capacity, nor the Stroop effort intentions significantly predicted Stroop interference. Therefore, motivational shifts do not seem to be a more valid explanation for the development of Stroop interference over time.
of their device). Even though the survey day, place, and device were included as control variables in the analyses, internal validity (when variations in the dependent variables are attributable to variations in the independent variable) might have suffered. This is a crucial limitation as the reaction time differences in cognitive test are often very small (e.g., Küper & Heil, 2012). Consequently, Stroop interference as measured in this study is likely to suffer from disadvantages inherent to field studies in comparison to lab studies.
regulatory resources or shifted their motivation or attention. In other words, doing the Stroop task for two minutes was fun rather than an exhaustive test that is seen as a burden.
4.1 Theoretical and practical implications
From a theoretical perspective, this study made the first documented attempt to validate Stroop interference as a measure for self-reported ego depletion in a diary study. So far, literature strongly focused on self-report measures to examine ego depletion and its underlying mechanisms. Although empirical evidence for its validity could not be found, the implementation of the Stroop task within a diary study contributes to our knowledge about ego depletion and its consequences on a behavioral level in various ways. First, Stroop interference may not represent a valid objective measure for ego depletion and is not linked to self-control demands. Consequently, these findings contribute to the growing body of evidence against the limited strength model of self-control (Muraven & Baumeister, 2000). Second, the implementation of the Stroop task within a diary study with three measurements per day over two consecutive weeks helps to assess the interplay of within-day fluctuations of Stroop interference and self-reported ego depletion, as mentioned by Beal and Ghandour (2011). In this study, no main effects of Stroop interference on related variables could be found, indicating that it does not measure ego depletion directly. Hence, the relationship between ego depletion and behavioral outcomes that are assumed to draw on regulatory resources seems to be more complex than expected. Third, this study is the first one to compare and display the trajectories of ego depletion and Stroop interference within a day and over workdays. Thus, researchers are able to derive conjectures about its relationship and possible mediators and moderators that influence their relationship.
behavioral outcomes (i.e., work tasks). However, this cannot be certainly answered as more empirical data in larger and more diverse samples are necessary.
4.2 Directions for future research
There are several directions for future research that could help to further explain the relationship between ego depletion and the Stroop task as an objective measure for it. First, in combination with the disadvantages of a field study for reaction time tasks, it seems that the shortened version of the Stroop task is not exhaustive enough to capture the subtle differences between the three conditions of Stroop performance. Thus, the computation of Stroop interference (the difference between the incongruent and neutral condition) may be affected by error variance caused by the limited number of items and the short task duration. Future research should, therefore, extend the length of each Stroop task. The latter seems to be the more economical alternative, as all of the three conditions demand the exertion of self-control resources to some extent. Second, it would be beneficial if more time was invested in a more comprehensive theoretical framework. By taking the findings of this study into account, the relationship between ego depletion and its behavioral outcomes does not seem to be a linear one and, therefore, it is likely that there are ‘hidden’ mediators or moderators that influence their relationship. Future research should address the question which variables influence the relationship between a subjective measure (“I feel mentally exhausted”) and objective performance that is supposed to draw on the same cognitive and regulatory resource.
4.3 Conclusion
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Tables
Table 1. Means, Standard Deviations, Internal Consistencies (Cronbach’s Alpha) and Intercorrelations of Study Variables
Variable 1 2 3 4 5 6 7 8 9 10 11
1. Stroop interference morning - 0.10 0.06 0.01 0.00 -0.03 0.00
2. Stroop interference noon 0.09 - 0.11 -0.01 0.01 -0.01 0.03
3. Stroop interference evening -0.16 0.18 - -0.08 -0.05 -0.03 0.01
4. Ego depletion morning 0.20 -0.16 -0.08 (0.94) 0.63 0.60 0.26
5. Ego depletion noon 0.15 -0.03 -0.15 0.87 (0.95) 0.74 0.31
6. Ego depletion evening 0.11 -0.11 0.04 0.82 0.82 (0.96) 0.29
7. Self-control demands 0.17 -0.02 0.02 0.46 0.41 0.42 (0.88)
8. Digit span forward -0.12 -0.04 0.12 -0.08 -0.16 -0.01 0.04 -
9. Digit span backwards 0.11 -0.22 -0.01 -0.06 -0.13 0.07 0.11 0.71 -
10. Age 0.04 0.06 0.19 -0.17 -0.02 -0.11 -0.08 -0.10 -0.18 -
11. Gendera -0.10 0.00 0.12 -0.12 -0.08 0.11 -0.02 0.18 0.20 0.08 -
M 64.62 38.70 57.53 1.81 1.81 2.05 2.81 8.32 7.47 35.83 1.50
SD 74.72 50.85 45.59 0.63 0.69 0.77 0.77 2.16 1.91 12.89 0.51
Note: Cronbach’s alpha for day-level variables is mean averaged over all measurement days. All correlations are person-level correlations (N = 40-51). Correlations above the diagonal are day-level correlations.
Table 2. Multilevel estimates for predicting Stoop interference in the morning Stroop interference (morning)
Null Model Model 1 Model 2
Effects γ SE γ SE γ SE Fixed effects Intercept 59.43** (5.89) 94.47** (12.54) 94.84** (12.60) Survey Day -6.59** (2.09) -6.65** (2.11) Survey Device -38.40 (37.41) -40.64 (37.96) Survey Place 1.05 (10.57) 1.61 (10.65)
Ego depletion (morning) 7.00 (13.57)
Random effects
Level 1 intercept variance (day level) 11522.6 11213.4 11238.6
Level 2 intercept variance (person level) 0 0 0
- 2*log (lh) 4046.0 4034.0 4033.8
Δ - 2*log (lh) 12.0** 0.2
df 3 1
Note: Interview Device, Interview Place, and Ego depletion (morning) are day-level variables (Level 1).
Table 3. Multilevel estimates for predicting Stoop interference at noon
Stroop interference (noon)
Null Model Model 1 Model 2.1 Model 2.2
Effects γ SE γ SE γ SE Fixed effects Intercept 45.43** (5.98) 59.58** (11.65) 59.01** (11.67) 59.77** (11.66) Interview Day -3.24 (1.83) -3.19 (1.83) -3.30 (1.84) Interview Device -8.15 (25.44) -9.38 (25.55) -7.79 (25.51) Interview Place -12.45 (7.29) -12.76 (7.31) -12.91 (7.31)
Ego depletion (noon) -7.27 (12.64)
Self-control demands (noon) -1.41 (10.47)
Random effects
Level 1 intercept variance (day level) 7846.0 7834.3 7770.9 7616.3
Level 2 intercept variance (person level) 401.1 578.6 584.6 564.9
- 2*log (lh) 3719.2 3495.4 3494.8 3495.0
Δ - 2*log (lh) 223.8** 0.6 0.4
df 3 1 1
Note: Model 2.1 and 2.2 are included into one table to minimize the number of tables. Both models only differ in
their main effects, both Null Model and control variables are identical.
Interview Device, Interview Place, and Ego depletion (noon) are day-level variables (Level 1).
Table 3. Multilevel estimates for predicting Stoop interference at noon
Stroop interference (evening)
Null Model Model 1 Model 2.1 Model 2.2
Effects γ SE γ SE γ SE Fixed effects Intercept 57.34** (6.25) 85.43** (11.32) 84.02** (11.23) 89.28** (11.79) Interview Day -5.31** (1.79) -5.30** (1.77) -5.95** (1.89) Interview Device 13.65 (24.89) 13.85 (24.54) 14.23 (26.23) Interview Place -0.50 (6.54) 0.95 (6.60) -0.62 (7.01)
Ego depletion (evening) -5.04 (11.52)
Self-control demands (noon) -7.42 (9.94)
Random effects
Level 1 intercept variance (day level) 7198.0 7035.7 6341.6 7322.5.3
Level 2 intercept variance (person level) 586.1 645.1 636.4 674.1
- 2*log (lh) 3627.8 3396.2 3393.6 3392.1
Δ - 2*log (lh) 231.6** 2.6 3.1
df 3 1 1
Note: Model 2.1 and 2.2 are included into one table to minimize the number of tables. Both models only differ in
their main effects, both Null Model and control variables are identical.
Interview Device, Interview Place, and Ego depletion (noon) are day-level variables (Level 1).
Figures
Figure 1: Research model
concurrent effect; autoregressive effect; lagged effect
Ego depletion
Morning Noon Afternoon
Ego depletion Ego depletion
Stroop
interference interferenceStroop interferenceStroop
