d. Overview Over the Present Studies

Our primary goal was to test the facilitating effect of implicit anger during task performance using cardiovascular measures. Moreover, we aimed to provide additional evidence for the IAPE model (Gendolla, 2012) idea that the effects of affect primes on effort-related cardiovascular response are emotion category-specific rather than valence-specific. If the effect is emotion category-specific, anger primes should have different effects than primes of other negative emotions that are associated with difficulty.

Therefore, we contrasted the effects of anger primes not only against a neutral prime control condition, but also against a sadness-prime condition.

According to the IAPE model, anger primes should lead to weaker PEP response than sadness primes, because anger is associated with ease whereas sadness is associated with difficulty. Previous studies were interpreted as lending support to this effect (Freydefont & Gendolla, 2012; Freydefont et al., 2012; Gendolla & Silvestrini, 2011), but

50 the absence of neutral prime control conditions left some ambiguity regarding the question if implicit anger has really a facilitating effect. In order to provide a more conclusive test, we ran two experiments, added a neutral-prime control condition, and used affect primes taken from two different databases of emotional faces in order to facilitate generalization of our findings. In accordance with the IAPE model, both studies tested the prediction of a linear affect prime effect on PEP response: PEP reactivity was expected to be weaker in the anger-prime condition than in the sadness-prime condition, with the neutral-prime control condition falling in between.

51 II.2.3. Study 1

This experiment investigated the facilitating effect of anger primes (vs. neutral and sadness primes) in the context of an attention-related mental concentration task, using facial expressions from the Radboud Faces Database (Langner et al., 2010) to manipulate implicit affect.

II.2.3.a. Method

Participants and Design

Sixty-two healthy undergraduate students from various disciplines of the University of Geneva (37 women, 24 men, mean age 21.67 years, SD = 0.43) were randomly assigned to a three-cell between-persons design (Prime: anger vs. neutral vs.

sadness)¹. Two participants were excluded from the statistical analyses because of incomplete data. Moreover, 6 participants were excluded because of extreme PEP reactivity scores, exceeding the grant mean of the entire sample for more than 2 SDs. The final sample included therefore N = 54 participants. Participation was voluntary and remunerated with a small amount of money (10 Swiss Francs, approximately 11 USD).

Affect Primes

Pictures of facial expressions from the Radboud Faces Database (Langner et al., 2010) were used as affect primes. The pictures were presented in black and white. Facial expressions of the same 4 individuals (2 women and 2 men) showing 3 different expressions (anger, neutral, or sadness) were used in the anger, neutral, and sadness experimental conditions, respectively (picture codes: Rafd090_01, Rafd090_02, Rafd090_03, Rafd090_04, Rafd090_07, Rafd090_08, Rafd090_09, Rafd090_10, Rafd090_14, Rafd090_19, Rafd090_36, Rafd090_38, Rafd090_57, Rafd090_58, Rafd090_71).

1 The distribution of women and men was balanced between the experimental conditions.

52 Apparatus and Physiological Measures

A Cardioscreen 1000 system (medis, Ilmenau, Germany) assessed electrocardiogram (ECG) and thoracic impedance signals (ICG) (see Scherhag et al., 2005 for a validation of the system). Four pairs of disposable spot electrodes were placed on the right and left sides of the base of the participant’s neck and on the right and left middle axillary lines at the height of the xiphoid. The signals were assessed with a sampling rate of 1000 Hz and analyzed with BlueBox 2.V1.21 software (Richter, 2010a).

The first derivative of the change in thoracic impedance was calculated and the resulting dZ/dt-signal was ensemble averaged over periods of 1 min using the detected R-peaks (Kelsey & Guethlein, 1990). To obtain PEP values (time interval in ms between R-onset and B-point, as defined by Berntson et al., 2004), B-point location was estimated based on the RZ interval as proposed by Lozano et al. (2007). If necessary, the B-point location was manually corrected as recommended by Sherwood et al. (1990). Additionally, we assessed systolic and diastolic blood pressure (in millimeters of mercury [mm Hg]) with a Vasotrac APM205A monitor (MEDWAVE^®, St. Paul, MN). This system uses applanation tonometry with a pressure sensor placed on the top of the radial artery on the wrist (see Belani et al., 1999 for a validation study). Systolic and diastolic pressure values were recorded each 10-15 heart beats, i.e. 4-5 measures per minute. Values were offline averaged over 1 min periods.

Procedure

The study procedure had been approved by the local ethical committee. The experiment was run in individual sessions. After having signed informed consent, participants were seated in a comfortable chair in front of a computer screen. The experimenter attached the blood pressure cuff and the electrodes and left the participant alone. The procedure started with some biographical questions. Then participants indicated their affective state with 2 items of the positive (happy, joyful) and 2 items of the negative (sad, depressed) scales of the UWIST mood check list (Matthews, Jones &

Chamberlain, 1990). As in previous studies (Freydefont et al., 2012; Freydefont &

Gendolla, 2012), 2 adjectives assessing anger (angry, irritated) were added. Participants responded to the 6 items (“Right now, I’m feeling) on 7- point scales (1 - “not at all”, 7 -

53

“very much”). These ratings were made to monitor participants’ affective states before the affect priming procedure.

Next, we recorded cardiovascular baseline activity (8 min). During this period participants watched a hedonically neutral documentary film about Lithuania. Then participants received instructions (“Please respond as quickly and accurately as possible”) for an adapted version of the d2 mental concentration test (Brickenkamp & Zillmer, 1998). Task trials started with a fixation cross (1000 ms) followed by pictures of facial expression from the Radboud Faces Database (13 ms). In each condition, half of the pictures showed emotional expressions (according to the experimental condition), while the other half showed neutral expressions. Pictures were immediately backward masked (133 ms) with a grey-scale random dot pattern, which was followed by a stimulus of the d2-task. Participants had to indicate by pressing “yes” or “no” keys if the presented stimulus was a “d” with exactly 2 apostrophes. Distracters (“d” with 1, 3 or 4 apostrophes or “p” with 1 to 4 apostrophes) appeared randomly during the task. The stimuli appeared on the screen until the response was entered, but maximally for 2000 ms. Responses were followed by the message “response entered”. In case of no response, the message “please answer more quickly” appeared. To keep performance time and the number of presented primes constant between the conditions, these messages were presented for 4000 ms minus participant’s reaction time. The inter-trial interval was 2000 - 5000 ms (random) to prevent habituation effects. Participants worked on 48 experimental trials. Before the experimental trials, participants had performed 10 training trials with correctness feedback and only neutral facial expressions. No correctness feedback was given during the task to avoid affective reactions (e.g., Kreibig, Gendolla, & Scherer, in press) that could interfere with the affect primes’ effects.

After the task, participants rated experienced task difficulty, mobilized effort, subjective value of success, their felt capability, and the importance of success on 7-point scales (1 - not at all, 7 - very much). Moreover, the same affect items that had been assessed at the beginning of the experiment were rated to control for possible affect prime effects on participants’ affective state. Finally, a funnel debriefing procedure was run, asking to the participants to describe the study’s purpose and what they had seen during the trials. Participants who mentioned “flickers” were asked about their content.

54 II.2.3.b. Results

Cardiovascular Baselines

Baseline values were calculated by averaging cardiovascular values of the last two minutes of the habituation period (Cronbach’s αs > .96)². Cell means and standard errors appear in Table 1. One-way ANOVAs found no significant differences between the three experimental conditions for any cardiovascular index (ps > .09). Preliminary statistical analyses found also no gender effect on any cardiovascular baseline values (ps > .12).

Table 1: Means and Standard Errors (in Parentheses) of the Cardiovascular Baselines Values for the Experiment 1.

Anger primes Neutral primes Sadness primes

PEP 101.72

Note: PEP = pre-ejection period (in ms), SBP = systolic blood pressure (in mmHg), DBP

= diastolic blood pressure (in mmHg), HR= heart rate (beats/min).

2 We calculated the cardiovascular baseline values from the 5 last min of the habituation period, because there was a decline in assessed values over the first 3 min. For the last 5 min of the habituation period, the values were stable and did not differ significantly from one another (ps .78).

55 Cardiovascular Reactivity

Cardiovascular reactivity scores for PEP, SBP, DBP, and HR were determined by subtracting cardiovascular baseline values from the averaged 1-min scores of cardiovascular activity during task performance. Preliminary analyses found no significant gender effects on any cardiovascular index (ps > .06). Also, ANCOVAs found no significant associations between baseline values and reactivity scores (all ps > .08).

However, preliminary repeated measures ANOVAs found a highly significant time main effect on PEP reactivity, F(4, 51) = 5.79, p < .001, η² =.10, our main dependent variable.

Focused comparisons revealed a significant decrease in PEP reactivity between the first (M = -1.96, SE = 0.49) and the second minute of task performance (M = -0.98, SE = 0.38), t(53) = 3.02, p > .01, while no significant differences emerged between the last 4 minutes (ps > .16). This suggests that participants disengaged after the first minute of the task—an effect that was already observed in a previous study (Silvestrini & Gendolla, 2007).

Considering this finding, we restricted our further analyses of cardiovascular reactivity (and performance indices) to the first minute of task performance. We tested our predictions about a linear increase in effort-related cardiovascular response with a priori contrast analyses, which are the most powerful statistical tool for this (Rosenthal &

Rosnow, 1985; Wilkinson & Task Force for Statistical Inference, 1999).

56 Table 2: Means and Standard Errors (in Parentheses) of the Reactivity Scores of the Cardiovascular Values during the Concentration Task of the Experiment 1.

Anger primes Neutral primes Sadness primes

DBP 1.38

(0.95)

3.69

(0.88)

1.56

(1.12)

HR 1.38

(0.96)

2.18

(1.00)

2.64

(1.05)

Note: SBP = systolic blood pressure (in mmHg), DBP = diastolic blood pressure (in mmHg), HR= heart rate (beats/min).

PEP reactivity

In contrast to our hypothesis about a linear increase in PEP response from the anger-prime to the sadness-prime condition, with the neutral-prime condition falling in between, the linear contrast of PEP reactivity during the first minute of the task was not significant (p > .46). However, the orthogonal quadratic contrast was significant, F(1, 51)

= 4.80, p < .04, η² =.08. Moreover, focused cell comparisons revealed that anger primes led to a significantly weaker PEP response (M = -0.87, SE = 0.62) than neutral primes (M

= -3.59, SE = 1.02), t(51) = 2.31, p < .03, η² =.09 (see Figure 1). No significant differences emerged between the sadness-prime and neutral-prime cells, or between the anger-prime and sadness-prime conditions (ps > .12).

57 Figure 3: Cell means and standard errors of cardiac pre-ejection period reactivity (in ms) during the first minute of task performance processed in the Experiment 1.

SBP reactivity

Also the linear contrast on SBP reactivity during the first minute of performance was not significant (p > .79), while the orthogonal quadratic contrast was reliable, F(1, 51) = 7.18, p < .02, η² =.12. Cell means are depicted in Figure 2. Focused comparisons revealed significantly weaker SBP reactivity in the anger-prime condition (M = 1.79, SE

= 1.52) than in the neutral-prime condition (M = 9.66, SE = 3.26), t(51) = 2.51, p < .02, η²

=.11. Moreover, reactivity in the neutral-prime condition was also significantly stronger than in the sadness-prime condition (M = 2.76, SE = 1.83), t(51) = 2.20, p < .04, η² =.08.

The difference between the anger-prime and sadness-prime conditions was not significant (p > .80).

58 Figure 4: Cell means and standard errors of systolic blood pressure reactivity during the first minute of task performance processed in the Experiment 1.

DBP and HR reactivity

Cells means and standard errors appear in Table 2. Neither linear (ps > .37), nor quadratic contrasts were significant (ps > .09) for DBP and HR responses during the first minute of performance.

Task Performance

Given that we had restricted the analysis of cardiovascular response to the first minute of task performance, also performance indices in terms of reaction times (in milliseconds) for correct responses and the percentage of correct responses were analyzed for the first task minute. Three-cell one-way ANOVAs revealed no significant prime

59 effects on the percentage of correct responses (ps > .57, M = 97.56%, SE = 0.01) or reaction times (ps > .35; M = 732.01, SE = 16.56).

Task Rating

Three-cell one-way ANOVAs of participants’ ratings of task difficulty (M = 1.81, SE = 0.16), mobilized effort (M = 2.74, SE = 0.21), and the subjective value of success (M

= 5.11, SE = 0.18) found no significant effects (ps > .38). However, a one-way ANOVA of felt capability for the task was significant, F(2, 51) = 6.32, p < .01, η² = .04. Focused comparisons found that subjective capability in the sadness-prime condition (M = 5.78, SE = 0.27) was significantly lower than in the anger-prime cell (M = 6.70, SE = 0.10), t(51) = 3.53, p < .01, η² =.19. Most relevant, sadness primes led also to significantly lower subjective capability than the neutral primes (M = 6.38, SE = 0.15), t(51) = 2.16, p

< .04, η² =.08. This suggests higher task demand (which is inverse to capability; see Wright, 1998) in the sadness-prime condition. Moreover, ratings of the importance of success were also influenced by the manipulation, F(2, 53) = 3.39, p < .04, η² =.12.

Focused comparisons found that success was rated as less important in the sadness-prime condition (M = 5.22, SE = 0.26) than in both the anger-prime (M = 5.95, SE = 0.22), t(51)

= 1.96, p =.05, η² =.07, and neutral-prime cells (M = 6.19, SE = 0.33), t(51) = 2.46, p <

.03, η² =.10. This suggests that the high task demand in the sadness-prime condition was bound up with low success importance. No significant difference was found between the anger-prime and the neutral prime conditions (p > .53).

Affect Rating

As in our previous studies, we summarized the two positive affect and the two reverse-coded negative affect items of the UWIST scale to mood sum scores for the measures taken before and after the task (Cronbach’s as > .67). A 3 (prime) x 2 (time) mixed model ANOVA of the mood scores revealed no significant effects (ps > .38; before task: M = 5.20, SE = 0.18; after task: M = 5.23, SE = 0.15).

We additionally tested with an ANCOVA for possible significant associations between the post-task affect scores and the reactivity score of PEP, on which we had found significant manipulation effects. This association was not significant (p > .09).

60 Funnel Debriefing

In the funnel debriefing, no participant spontaneously reported to have seen emotional expressions during the task. 55% of the participants reported to have seen faces during the trials. Of these participants, 525% could only distinguish the faces’ gender. No participant made a link between the emotional expressions and effort mobilization.

II.2.3.c. Discussion

The present experiment investigated the facilitating effect of anger primes on effort-related cardiac response. Based on the IAPE model (Gendolla, 2012), we had predicted that anger primes that were processed during task performance would result in weaker effort-related PEP response than neutral primes and sadness primes. Our findings only partially supported our hypotheses. Preliminary analyses had found that prime effects only occurred during the first minute of the task, presumably because participants disengaged after the first minute. This was not anticipated, because in our previous priming studies (e.g., Gendolla & Silvestrini, 2011), we did not observe such habituation effects. But it is of note that other studies have found that the influence of affect primes can decrease with time and habituation (Murphy, Monahan, & Zajonc, 1995; neutral primes. This supports the IAPE model idea of a facilitating effect of implicit anger during performance. However, also the PEP response in the sadness-prime condition tended to be weaker than in the neutral prime condition. This is not in accordance with our predictions. We interpret this finding in the context of the affect prime effects on participants’ ability and importance of success ratings.

Participants in the sadness-prime condition evaluated their ability as lower than participants in the anger-prime and neutral-prime conditions, suggesting higher task demand in the sadness-prime condition, because demand is inverse to ability (see Wright, 1998). Additionally, the importance of success in the sadness-prime condition was

61 significantly lower than in the other two cells. This suggests that participants in the sadness-prime condition have disengaged, because the high effort that was necessary due to the high subjective demand was not justified, because success importance was relatively low (see Wright, 1998; Stewart, Wright, Hui, & Simmons, 2009; Wright &

Dismukes, 1995)—an effect that is in accordance with the principles of motivational intensity theory (Brehm & Self, 1989). SBP response corresponded to that of PEP, as already found in previous studies (e.g., Gendolla & Silvestrini, 2011; Silvestrini &

Gendolla, 2011c). This can be explained as being caused by cardiac contractility effects, which can systematically influence systolic pressure by their impact on cardiac output (Silvestrini & Gendolla, 2009a, 2009c).

In summary, the present findings bring support to the idea that implicit anger has a facilitating effect during task performance—effort-related cardiac response in the anger-prime condition was lower than in the neutral anger-prime condition. Moreover, no evidence was found that the affect primes induced conscious affective states or that participants were aware of the affect primes’ content. However, given that the present study revealed other unanticipated—though post hoc explicable—results for the effect of implicit sadness, we conducted a second experiment to provide more conclusive results about implicit anger vs. sadness primes’ effect on effort-related cardiac response.

62 II.2.4. Study 2

In this experiment, anger, neutral, and sadness primes were presented during task performance as in Experiment 1. However, we used affect primes from a different database and applied the same priming procedure as in previous studies (e.g., Gendolla &

Silvestrini, 2011). In accordance with the IAPE model (Gendolla, 2012), we expected again a linear affect prime effect on PEP response: PEP reactivity was anticipated to be weaker in the anger-prime condition than in the sadness-prime condition, with the neutral-prime control condition falling in between.

II.2.4.a Method

Participants and Design

Forty-nine healthy undergraduate students from various disciplines of the University of Geneva (28 women, 21 men, mean age 21.08 years, SD = 0.35) were randomly assigned to a 3-cell (Prime: anger vs. sadness vs. neutral) between-persons design³. Data of 9 participants had to be excluded from the statistical analyses because of incomplete data, leaving a final sample of N = 40. Participation was voluntary and remunerated with a small amount of money (10 CHF, approximately 11 USD).

Affect Primes

Low contrast, low resolution, grey scale, front perspective pictures of averaged human facial expressions from the Average Karolinska Directed Emotional Faces (AKDEF), (Lundqvist & Litton, 1998) were used as affective stimuli. Half of the faces were female (AKDEF pictures FNES, FSAS, FANS) and half were male (AKDEF pictures MNES, MSAS, MANS).

3 The distribution of women and men was balanced between the experimental conditions.

63 Apparatus, Physiological Measures

Apparatus and measures were identical with Experiment 1, except for blood pressure assessment. In this study we assessed SBP and DBP with a Dinamap ProCare 300 monitor, (GE Medical Systems Information Technologies Inc., Milwaukee, WI), which uses oscillometry. A blood pressure cuff (DuraCuf) was placed above the brachial artery of participants’ left arm. The cuff automatically inflated in 1-min intervals during habituation and task performance periods. Assessed values were stored on hard drive and later analyzed offline.

Procedure

The study had been approved by the local ethical committee. The experiment was run in individual sessions and the procedure was very similar to that of Experiment 1. After having signed consent, participants were seated in front of a computer. The experimenter attached the blood pressure cuff and the electrodes and left the participant alone. The procedure started with biographical questions. Then participants indicated their affective state with 2 items of the positive (happy, joyful) and 2 items of the negative (sad, depressed) scales of the UWIST mood check list (Matthews, Jones & Chamberlain, 1990) on 7- point scales (1 - “not at all”, 7 - “very much”)⁴.

After these ratings, we recorded cardiovascular baseline activity as in Experiment 1 (8 min). After this, participants received the instructions (“Please respond as quickly and accurately as possible”) for the adapted version of the d2 mental concentration test (Brickenkamp & Zillmer, 1998). Task trials started with a fixation cross (1000 ms), followed by pictures of facial expression (26 ms—the presentation time was longer, because the administered averaged facial expression had much lower contrast than the affect primes in the first experiment). In each condition 1/3 of the faces showed an emotional expression (anger vs. sadness) while the other 2/3 showed emotionally neutral faces. This procedure has been found to be the most effective in the present priming paradigm (Silvestrini & Gendolla, 2011b). The facial expression pictures were immediately backward masked with a random dot pattern (133 ms), followed by the

4 Due to an error, we did not assess participants’ anger ratings as in the first study. However, as Experiment 1, also our previous studies administering anger primes and assessing explicit anger have not revealed any evidence that the anger primes made participants explicitly angry (Freydefont et al., 2012; Freydefont &

Gendolla, 2012).

64 task stimulus. From here on, the trial structure was identical with that of Experiment 1.

Participants worked on 36 trials after a training session with 10 trials including correctness feedback and only neutral facial expressions.

After the task, participants made the same task-related ratings as in the previous

After the task, participants made the same task-related ratings as in the previous

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