Contractes de conreu

The depletion manipulation was partly effective. Participants in the attention control (depletion) condition (n = 55) reported having controlled their attention to a greater extent than no control participants (n = 55; t(108) = 2.26, p < .05; M attention control = 4.91, SD = 1.78 vs. M no control = 4.20, SD = 1.50), but did not rate the task as more difficult than those in the no-control condition (t(108) = -.42, p = .68; M attention control = 3.31, SD = 1.95 vs. M no control = 3.45, SD = 1.69).

Participants in the mindfulness breathing (n = 55) reported higher decentering than no induction participants (n = 55; t(108) = 2.65, p < .05; M mindfulness induction = 3.03, SD = .60 vs. M no induction = 2.70, SD = .70), but did not show higher levels of Curiosity (t(117) = 1.15, p = .25; M mindfulness induction = 3.50, SD = .81 vs. M no induction = 3.31, SD = .88). Both mindfulness subscales shown good internal consistency ( = .84 and .71 for curiosity and decentering, respectively) and were positively correlated (r = .58, p < .0001).

Following the attention control task, participants in the depletion condition reported higher PA than non-depleted ones (t(108) = 2.24, p < .05; M attention control = 2.66,

SD =.68 vs. M no control = 2.37, SD = .70), but not higher NA (t(108) = .57, p = .57; M

attention control = 1.26, SD =.38 vs. M no control = 1.23, SD = .24). Both mood subscales immediately following the attention control task showed good internal consistency ( = .87 and .72 for PA and NA, respectively) but were not significantly correlated (r = .14, p = .15).

It should be noted that ego-depletion studies generally demonstrate no relationship between depletion and mood, although at times there is an increase in negative affect due to the aversiveness of depleting tasks (see Hagger et al., 2010). In contrast, the current participants reported significant postdepletion increases in PA, indicating that they might have seen the task as being more interesting. Importantly, however, PA was not correlated to aggression (see Table 4.2, section 4.4.3.1). So any

differences in the experimental outcomes would not be related to differences in participant’s mood following depletion.

Both mood subscales also showed good internal consistency ( = .91 and .77 for PA and NA, respectively) and were positively correlated (r = .63, p < .0001) when given following the TCRT task. No differences were found between the four between subjects group on PA (F(3,106) = .63, p = .60) or NA (F(3,106) = .45, p = .72).

4.4.5 Moderation of mindfulness induction on the link between depletion and

direct aggression

4.4.5.1 Levels of blast intensity

Figure 4.2. Effect of level of provocations on blast intensity.

Error bars indicate standard error of mean. Scale goes up to 8 as a maximum.

As typically found in studies varying provocation from the opponent (e.g., Anderson et al., 2008; Lawrence & Hutchinson, 2013a, 2013b; see also Study 2 in Chapter 3), intensity was significantly affected by level of provocations (F(1.31, 142.94) = 42.15,

p < .001; Figure 4.2). Specifically, participants delivered more intense blasts on high

2.00; p < .0001), and on low provocation compared to no provocation (M = 2.61, SD = 2.50; p < .0001).

A comparable pattern of results was revealed when we performed a 2 (sex) by 3 (provocation level) mixed analysis ANOVA, in which blast intensity was still affected by level of provocations (F(1.31, 141.01 = 41.40, p < .001), but not by its interaction with sex (F(1.31, 141.01) = 1.09, p = .32). The main effect of sex is shown in Table 4.3, in which males delivered a significantly higher blast than females following low provocation. Sex differences on no provocation were approaching significance.

Table 4.3.

Sex differences on blast intensity on each provocation level

Level of provocations Males (n = 52) Females (n = 58) t M (SD) M (SD)

No provocation 3.08 (2.89) 2.21 (2. 03) t(90.31) = 1.80, p = .08

Low provocation 3.82 (2.24) 3.00 (1.69) t(94.26) = 2.13*

High provocation 4.35 (2.29) 3.94 (2.06) t(108) = .98, p = .33

*_{p < .05;}**_{p < .01;}***_{p < .001}

The moderation model was tested across three provocation levels, using a bootstrapping method, with 95% bias-corrected confidence intervals (based on 5,000 bootstrap resamples, N = 110). All predictors were mean-centered. Results in Table 4.4 depict that Hypothesis 2a was partially supported such that there was significant effect of mindfulness induction on the link between depletion and blast intensity under no provocation and low provocation, but not under high provocations. In other words, under no provocation and low provocation, depleted participants who received mindfulness induction delivered lower levels of blast intensity than depleted ones with no induction; whereas non-depleted participants with mindfulness induction displayed comparable blast intensity with non-depleted ones with no induction (See Figure 4.3). Additionally, depletion (Hypothesis 1a) and mindfulness influenced unprovoked, but not provoked direct aggression. Specifically,

those who were depleted or did not received mindfulness induction delivered higher levels of blast intensity under no provocation only.

Table 4.4.

Moderation models with bootstrapping method, using depletion as predictor, mindfulness as moderator, blast intensity as outcome

Model tested No provocation Low provocation High provocation B SE B SE B SE Depletion (c1) 1.24 ** .45 .62 .37 .42 .41 Mindfulness induction (c2) -.95 * .45 -.62 .37 -.62 .41 Depletion x mindfulness (c3) -1.90 * .90 -1.55* .74 -1.25 .82 R2on interaction 3.63%* 3.79%* 2.07%

Conditional effect of depletion without mindfulness

2.19*** .64 1.40** .52 Conditional effect of depletion with

mindfulness

.29 .64 -.15 .52

Note. B = unstandardised regression coefficient; SE = standard error; R2= variance increase

*

p < .05;**p < .01;***p < .001

Figure 4.3. Mindfulness × depletion effect on blast intensity across provocation levels. Error bars indicate standard error of mean, asterisk indicates significant (p < .05) decrease in

As no personality variables were significantly associated with blast intensity under no provocation (see Table 4.2), the moderation analysis was repeated only for blast intensity delivered under provoked aggression. For clarity of presentation, the partial effects of covariates are presented separately (Table 4.5). Under low provocation, mindfulness continued to moderate the effect of depletion on blast intensity (c3: B =

-1.42, SE = .70, p < .05). The total variance uniquely attributable to the interaction slightly dropped from 3.79 to 3.13% (F(1, 102) = 4.10, p < .05). With the inclusion of SP, blast intensity on low provocation was affected by significant main effects of depletion (c1: B increased from .62 to .73, p < .05), and mindfulness induction (c2: B

slightly dropped from -.62 to -.67, p < .05). Those higher in SP also delivered higher levels of blast intensity under low provocation.

Under high provocation, there was still no significant interaction effect (c3: B = -.89,

SE = .81, p = .27), main effect of mindfulness (c2: B dropped from .42 to -.74, p = .07),

or depletion (c1: B increased from -.62 to -.67, p = .10) on blast intensity. The

proportion of the total variance in the outcome due to the interaction dropped from 2.07% to 1.00% (F(1, 102) = 1.22). None of the hypothesised covariates significantly predicted blast intensity under high provocation.

Supporting Hypothesis 3, controlling for personality variables yielded a similar pattern of results for the moderation of mindfulness induction on the link between depletion and blast intensity on no provocation, and low provocation, but not on high provocation. In addition, depleted participants delivered higher blast intensities except on high provocation.

Table 4.5

Partial effects of control variables for moderation models with bootstrapping method, using depletion as predictor, mindfulness as moderator, blast intensity as outcome

Covariates Low provocation High provocation

B SE B SE

Sex -.67 .38 - -

AQ Physical aggression .19 .25 .48 .26

STAR Provocations .55* .25 .29 .28

Covariates Low provocation High provocation

B SE B SE

PANAS NA2 .68 .49 .57 .55

Note. B = unstandardised regression coefficient; SE = standard error; R2= variance increase

*

p < .05;**p < .01;***p < .001

4.4.5.2 Maximum blast latency

During the TCRT, only 77 participants out of 110 delivered maximum blasts to the opponents. We firstly carried out censored survival analyses using Cox regressions to assess the extent to which individuals were more likely to administer the maximum blasts as a function of the experimental conditions. Our proposed model was not significant (2

= 2.93, p = .40). The likelihood of delivering the maximum blast to opponent was not predicted by mindfulness (Wald = 1.41, p = .23, CI [.34, 1.31], exp(B) = .6), depletion (Hypothesis 1b: Wald = .51, p = .47, CI [.42, 1.50], exp(B) = .79), or the interaction between mindfulness and depletion (Hypothesis 2b: Wald = 2.68, p = .10, CI [.85, 5.86], exp(B) = 2.24).

We repeated the censored survival analyses to assess the maximum blast latency as a function of the experimental conditions and the hypothesised covariates (i.e., sex and physical aggression). Our final model was significant (2

= 17.63, p < .01}, supporting Hypothesis 3. The point at which participants delivered the maximum blast to opponent was influenced by the interaction of mindfulness and depletion (Wald = 5.32, p < .05, CI [1.20, 8.86], exp(B) = 3.25) and the main effect of sex (Wald = 8.60, p < .01, CI [1.28, 3.41], exp(B) = 2.09). Interestingly, depleted participants with mindfulness induction, and females were more likely to administer the maximum blast during the TCRT. The influence of physical aggression was approaching significance (Wald = 3.79, p = .052, CI [1.00, 1.89], exp(B) = 1.37), but not the main effect of depletion (Wald = 2.13, p = .14, CI [.32, 1.18], exp(B) = .61) or mindfulness (Wald = 2.16, p = .14, CI [.29, 1.19], exp(B) = .60).

When we analysed the effect of mindfulness and ego depletion on maximum blast latency separately for males and females, the findings varied (Figure 4.4).

Figure 4.4 Sex differences in maximum blast latency. Error bars represent standard error of mean, asterisk indicates that participants delivered the maximum blast sooner (p < .01).

For females (n = 36), the depletion x mindfulness induction model was significant (2

= 7.95, p < .05). Depleted females who received mindfulness induction were

more likely to deliver the maximum blast (Wald = 5.81, p < .01, CI [1.42, 29.98],

exp(B) = 6.65). There were no significant main effects of depletion (Wald =.41, p = .52, CI [.28, 1.92], exp(B) = .73), or mindfulness induction (Wald = 3.40, p = .07, CI [.11, 1.07], exp(B) = .35) on maximum blast latency.

For males (n = 41), the depletion x mindfulness induction model was not significant (2

= 1.19, p = .76). Maximum blasts latency was not predicted by depletion (Wald = .58, p = .45, CI [.30 to 1.71], exp(B) =.71), mindfulness induction (Wald = .02, p = .89, CI [.43, 2.64], exp(B) = 1.06), or interaction between conditions (Wald = .24, p = .62, CI [.37, 5.31], exp(B) = 1.40).

4.4.5.3 Correlation between blast intensity and maximum blast latency

For participants who had delivered the maximum blast (N = 77), there were negative correlations between maximum blast latency and blast intensity across levels of provocation (r = -.43 on no provocation, r = -.59 on low provocation, and r = -.39 on high provocation; all significant at p < .0001). Specifically, higher blast intensities were delivered by those who had delivered the maximum blast to the opponent

earlier in the TCRT. The correlation persisted when analysed separately for males and females, except on high provocation. On high provocation, the correlation between maximum blast latency and blast intensity became non-significant for females (r = -.30, p = .08).

4.4.6 Moderation of mindfulness induction on the link between depletion and

indirect aggression

The moderating effect of mindfulness induction on the link between depletion and each indirect aggression item was analysed separately, also using a bootstrapping method (Table 4.6). As in Study 2, to survive Bonferroni corrections (p < .01), we used 99% bias-corrected confidence intervals. Mindfulness induction did not moderate the relationship between depletion and indirect aggression (Hypothesis 2c). Additionally, there were no significant main effects of depletion or mindfulness induction on indirect aggression (Hypothesis 1c).

Table 4.6.

Moderation models with bootstrapping method, using depletion as predictor, mindfulness as moderator, rating of opponent as outcome

Model tested Aggressive Skilful Competitive Fair Play again

B SE B SE B SE B SE B SE Depletion (c1) .20 .24 -.09 .24 .09 .24 .40 .32 -.02 .30 Mindfulness induction (c2) -.06 .24 .06 .23 .16 .24 -.04 .32 .24 .30 Depletion x mindfulness (c3) .03 .48 -.25 .47 -.04 .47 -.11 .63 -.72 .60 R2on interaction 0% 26% 0% .30% 1.31%

Note. B = unstandardised regression coefficient; SE = standard error; R2= variance increase

*

p < .05;**p < .01;***p < .001

As suggested in section 4.4.3, no sex differences were found in any of the indirect aggression ratings (p = .06 to 50), so we did not break down moderation models by sex (see Table 4.7 for sex differences in ratings of indirect aggression).

Table 4.7.

Sex differences based on rating of opponent

Indirect aggression Males (n = 52) Females (n = 58) t M (SD) M (SD) Aggressive 3.94 (1.31) 4.24 (1.16) t(108) = -1.28, p = .21 Skilful 4.75 (1.37) 5.03 (1.01) t(108) = -1.22, p = .23 Competitive 4.87 (1.31) 5.31 (1.10) t(108) = -1.94, p = .06 Fair 4.40 (1.87) 4.71 (1.41) t(94.46) = -.95, p = .35 Play again 5.46 (1.70) 5.26 (1.46) t(108) = .67, p = .50 * p < .05;**p < .01;***p < .001

The moderation analyses for ratings of the opponent skill, fairness, and participants willingness to play against the same opponent were repeated by including the hypothesised covariates based on the prior significant zero-order correlations between covariates and rating indirect aggression (Table 4.8; see again Table 4.2, in which no personality variables were significantly associated with ratings of opponent aggressiveness and competitiveness). Nevertheless, there was no effect of experimental conditions on ratings for these items (Hypothesis 3). Those who were higher in NA following depletion task rated the opponent as being less skilful, and a less willingness to take part in a task with the same opponent again. The positive impact of curiosity on participants’ willingness to take part in a task with the same opponent again nearly survived Bonferroni correction (p < .011).

Table 4.8.

Moderation models with bootstrapping method, using depletion as predictor, mindfulness as moderator, rating of opponent as outcome, controlling for covariates

Model tested Skilful Fair Play again

B SE B SE B SE Depletion (c1) -.01 .23 .52 .31 .13 .28 Mindfulness induction (c2) .01 .23 -.13 .31 .06 .28 Depletion x mindfulness (c3) -.40 .47 -.21 .62 -.40 .58 R2on interaction .65% .09% .39% Covariates: MAAS - - -.23 .27 - - SCS - - -.41 .34 - - AQ Total .42 .31 - - - - AQ Verbal aggression .10 .21 - - - - STAR Provocations - - .35 .32 - - STAR Frustrations - - .03 .32 - -

Model tested Skilful Fair Play again

B SE B SE B SE

TMS Curiosity - - - - .45* .17

PANAS NA1 -1.09** .37 - - -1.70** .45

Self-harm - - .62 .52 - -

Note. B = unstandardised regression coefficient; SE = standard error; R2= variance increase

*

p < .05;**p < .01;***p < .001

4.4.7 Correlation between blast intensity and indirect aggression

A significant correlation between blast intensity and indirect aggression was found in rating of the opponent’s fairness, such that participants evaluate the opponent that they had blasted with more intense blasts as being more fair (Table 4.9).

Table 4.9.

Bivariate correlations between blast intensity and rating of opponent

Indirect aggression No provocation Low provocation High provocation

Aggressive -.05 -.05 .00 Skilful .01 .06 .14 Competitive -.09 -.15 -.12 Fair .08 .24* .27** Play again -.02 .05 .10 *_{p < .05;}**_{p < .01;}***_{p < .001} Table 4.10.

Correlations between blast intensity and rating of opponent based on sex

*

When we broke down the correlations by sex (Table 4.10), we found that the correlation between blast intensity and rating of opponents’ fairness was more pronounced in males than in females. Females evaluated opponents that they had blasted with more intense blasts as being less competitive.

4.4.8 Moderation of mindfulness induction on the link between depletion and

self-control performance

Table 4.11.

Overall change in handgrip performance

Depletion No depletion

Change 1 Change 2 Change 1 Change 2

Mindfulness induction -7.04 -6.25 -2.33 -2.56

No mindfulness -17.93 -12.41 -9.86 -12.61

Note. Higher positive scores indicate better self-control on all measures. Values represent the

changes in mean time that participants squeezed the handgrip pre-TCRT task (Change 1) and post- TCRT task (Change 2).

Table 4.11 shows the changes in self-control performance as measured by mean differences between handgrip duration at baseline and pre-TCRT task (Change 1) and post-TCRT task (Change 2). Change 1 and Change 2 were positively correlated (r = .72, p < .0001).

Table 4.12.

Moderation models with bootstrapping method, using depletion as predictor, mindfulness as moderator, changes in handgrip performance as outcome, controlling for covariates

Model tested Change 1 Change 2

B SE B SE Depletion (c1) -5.14 3.33 -3.20 3.22 Mindfulness induction (c2) 9.23 ** 3.27 8.26** 3.17 Depletion x mindfulness (c3) .69 6.56 -4.68 6.34 R2on interaction .01% .44% Covariates: Sex 13.98*** 3.28 6.22 3.33 SCS -5.82 3.03 - - AQ Physical Aggression - - -5.23* 2.05

Note. B = unstandardised regression coefficient; SE = standard error; R2= variance increase

Change 1 = mean time differences between handgrip duration at baseline and pre-TCRT task; Change 2 = mean time differences between handgrip duration at baseline and post-TCRT task

*

The significantly correlated personality factors (i.e., sex and trait self-control at Change 1; sex and trait physical aggression at Change 2; see again Table 4.2) were entered into the moderation models (Table 4.2). The effect of depletion at Change 1 (Hypothesis 4a) and Change 2 (Hypothesis 4b) on handgrip performance was not moderated by mindfulness induction. Mindfulness induction alone predicted handgrip performance at both time points after controlling for these covariates. In addition, a better handgrip performance at Change 1 was shown by females. A better handgrip performance at Change 2 was shown by those with lower levels of physical aggression. Sex differences in handgrip stamina are presented in Figure 4.5.

Figure 4.5. Sex differences in handgrip stamina. Higher positive scores indicate better self- control in Change 1 (pre-TCRT task) and Change 2 (post-TCRT task). Error bars represent standard error of mean, asterisk indicates significant (p < .001) sex differences in handgrip

stamina.

4.5 DISCUSSION