Social Support as a Stress Buffer or Stress Amplier: The Moderating Role of Social Motives

Trials guidance: The Abstract should not exceed 350 words. Please minimize the use of abbreviations and do not cite references in the abstract. The abstract must include the following separate sections: Background. Social Support research shows that providing social support in socio-evaluative stress situations reduces participants´ stress responses. This stress-buffer effect of social support, however, does not hold for everybody and some studies even found a stress-amplifying effect of social support. Motive disposition research suggests that social motives (aliation and power) lead to differential and sometimes even opposing affective, and physiological responses to interpersonal interaction processes. We here integrate both lines of research and hypothesize that participants with strong aliation motives benet whereas participants with strong power motives do not benet from social support in terms of psychobiological responses to a given stressor. Further, participants with strong aliation and power motives are expected to respond to social support with an arousal of motive-specic affects and reproductive hormone responses (aliation: progesterone, power: estradiol, testosterone). In addition, we test whether women and men differ in the response to social support and in strengths of social motives. Methods. We aim to collect data of 308 participants (equal number of men and women) recruited at the local university of the authors. Participants´ social motives are assessed using a standardized measure in motive research (Picture Story Exercise) administered via a web-survey. In a following laboratory session, the Trier Social Stress designed for groups is used to experimentally induce psychosocial stress. One group of participants receives social support from a confederate of the experimenter whereas the control group does not. Stress responses will be assessed by a modied version of the state anxiety scale of the State – Trait Anxiety Inventory (Spielberger, 1970) and by physiological indicators of stress (cortisol, alpha-amylase gained from saliva samples) at seven points of measurement. Reproductive hormones will be analyzed from four out of these seven saliva samples. Heart rate and heart rate variability will be assessed continuously. We additionally measure participants´ performance in the interview (part of TSST) using a self-developed categorization system.


Introduction
Background and rationale {6a} SPIRIT guidance: Description of research question and justi cation for undertaking the trial, including summary of relevant studies (published and unpublished) examining bene ts and harms for each intervention.

Stress and Social Support
There is an extended body of research outlining that stress affects basically every physiological system (McEwen, 2000;Sapolsky et al., 2000) and signi cantly impairs subjective well-being (Feldman et al., 1999;Pemberton & Tyszkiewicz, 2016). Therefore, it is already mandatory that the WHO anticipates stress-related illness to develop to the second leading cause of disease in the coming decades (World Health Organization, 2001). Hence, it is essential to better understand the complexity of the concept of stress to be able to develop effective interventions. In the last decades a great deal of research has shown that social support, de ned as "social interactions or relationships that provide individuals with actual assistance or with a feeling of attachment to a person or group that is perceived as loving or caring" (Hobfoll & Stokes, 1988 & Cohen, 2005;Uchino, 2004). One of the leading explanations for this phenomenon is that social support unfolds a stress-buffering effect (Broadhead et al., 1983;Cohen & Wills, 1985) and can thus counteract the negative consequences of stress. For example, social support leads to lower mortality rates (Brummett et al., 2001;Rutledge et al., 2004), better recovery from surgery (Kulik & Mahler, 1989), and sport injuries (Bianco & Eklund, 2001). Yet, interestingly social support does not work as a stress buffer for everyone (Ditzen & Heinrichs, 2014). We assume that social support is perceived differently by individuals and investigate social motives (a liation and power motive, Schultheiss, 2008) as moderators. They in uence the perception of interpersonal relationships and should therefore also explain responses to social support.

Implicit Motives
Implicit motives are preferences for certain kinds of incentives and disincentives, which modulate reward experiences (Brunstein, 2010;McClelland, 1985;McClelland et al., 1989;Schüler et al., 2015;Schultheiss, 2008). Being relatively stable across time (such as personality traits), they drive, orient, and select behavior for summaries, see Brunstein and Schultheiss (2010). Motive research has focused on the three domains a liation, power, and achievement motives, of which we consider only the social motives in our study.
Individuals with a strong a liation motive (AFF) derive pleasure from a liative experiences (Dufner et al., 2015;Schultheiss, 2008). They have the desire for warm and friendly interpersonal relations (French, 1956), aim to feel socially related, want to experience reciprocal care and concern for important others (Atkinson et al., 1954;Schultheiss, 2008), and emotionally suffer from discord, rejection, and loneliness (Atkinson et al., 1954;Schultheiss, 2008;Weinberger et al., 2010). Situations in which these needs can be satis ed lead to an a liation-motive speci c affect such as joy, and feeling socially related (for a summary of the a liation motive see (Hofer & Hagemeyer, 2018).
Individuals with a strong power motive (POW) have the desire to have an impact on others and in uence others (in socially desirable and undesirable ways) to feel superior to others and gain or maintain reputation and prestige (Schmalt & Heckhausen, 2010;Winter, 1973). Simultaneously they aim to avoid defeat, other´s dominance and feelings of inferiority (Fodor, 2010). In brief, they have "the capacity to derive pleasure from having physical, mental, or emotional impact on other individuals or groups of individuals and to experience the impact of others on themselves as aversive" (Schultheiss, 2008, p. 606). The lack of opportunities in which others can be impacted or, even worse, situations signaling one´s inferiority function as stressors and lead to power-motive speci c affect (e.g. feeling inferior, experiencing limited control) and impaired well-being (Baumann et al., 2005;Hofer & Busch, 2011).
Social motives are also associated with speci c hormones (for an overview, see Schultheiss (2013); Schultheiss and Köllner (in press)). Being inferior, for example in a contest situation, has been associated with a decrease in testosterone in men with strong power motives (Stanton & Schultheiss, 2009). For high power-motivated women, motive frustration leads to a decrease in estradiol (Stanton & Schultheiss, 2009). Arousal of the a liation motive is accompanied by an increase in progesterone, for both sexes (Schultheiss, 2013;Schultheiss et al., 2004;Wirth & Schultheiss, 2006). Furthermore, social motives in relationship with stress have been associated with various parameters of health: blood pressure, immune system (McClelland et al., 1989), medication use and somatic symptoms (Schüler et al., 2009), or job burnout and physical symptoms . Summing up, previous research has con rmed that a liation and power motives lead to differential emotional, behavioral, and physiological responses to social cues.

Social support and social motives
Based on the evidence that both, social support and social motives, modulate the stress response, we aim to investigate to what extent the interplay of these two factors can contribute to further enlightenment of the stress-buffer effect. Social support situations are highly ambiguous leaving wide room for interpretation about, for example, one´s position in the social context, the intentions of the social support provider, and the quality of the social relationships. By this, they are prototypes of social interaction processes, which are full of incentives or disincentives for the social motives. They can, however, be perceived very differently by individuals with strong a liation in contrast to power motives and therefore elicit different physiological and psychological responses. Thus, social support might signal a positive and warm relationship for individuals with a strong a liation motive, but trigger feelings of weakness and inferiority in individuals with a strong power motive. In sum, we assume that social motives in uence the perception of social support provided by others and functions as a stress -buffer for a liation motivated individuals, and as a stress ampli er for power motivated people.
Social support, sex and gender Other moderators that are discussed to in uence participants´ response to social support are sex and gender ( (Knoll & Schwarzer, 2002). Thus, in the social support literature the resulting pattern about concerning sex differences is still inconsistent.
Sex differences have also been found in social motive research. Since the arousal of the a liation and power motive in a speci c situation is accompanied by the release of female reproductive hormones (estradiol, progesterone) and male reproductive hormone (testosterone), it is assumed, that this sex speci city should also be re ected in corresponding motive differences. Women are expected to show higher scores in a liation motives, and men are assumed to have higher power motives. This was clearly empirically supported for the a liation motive (Denzinger et al., 2016;Drescher & Schultheiss, 2016), whereas for the power motive the result pattern is less clear (Denzinger et al., 2016;Pang & Schultheiss, 2005). We assume that these motives are assumed to correlate with a concept on a broader level of abstraction, that is gender role self-concepts (GRSC; Athenstaedt, 2003). The individual GRSC is de ned as describing oneself with agentic traits like con dent or assertive (masculine GRSC) vs. with communal traits like empathic or cooperative (feminine GRSC). We assume that the inconsistent ndings reported above may be due to shared variance between sex, GRSC and motives. We aim to identify the speci c in uences of sex, GRSC, and social motives on stress-response to social support by considering them simultaneously and disentangling them in our statistical analyses.

Planned Research
The main objective of the present study is to test whether social motives and participants´ sex moderate the effects of social support in stressful situations. We use the Trier Social Stress Test for groups (Von Dawans et al., 2011) that is based on the TSST (Kirschbaum et al., 1993), which is an established stressinduction paradigm triggering strong psychobiological stress responses (Dickerson & Kemeny, 2004). Schultheiss et al. (2014) found that the TSST elicited differently strong cortisol responses for individuals with weak and strong implicit achievement motives which supports our assumption that the TSST might be a potentially suitable paradigm that reveals motive differences. Wiemers et al. (2015) concluded from their study that the TSST has a speci c arousal effect for the implicit power motive.
We vary from the classic TSST approach in the following points. While TSST studies usually focus on the detection of the stress hormone cortisol (Goodman et al., 2017;Liu et al., 2017), we add the analysis of reproductive hormones (progesterone, estradiol, testosterone), which allow us to examine the arousal of motives in the social support situations. We will further extend the TSST paradigm by analyzing participant´s responses in the interview (part of TSST) to gain an indicator for speech performance. Whereas in the classical TSST paradigm it is only announced that the speech will be recorded (as an additional stressor), we here will actually record the speeches and apply a simple evaluation system to assess speech performance as a variable that we assume to depend on stress.  Robles, 2007), the experimental group will receive social support during the TSST preparation phase. The control group will be also exposed to stress but receives no social support. To test the hypotheses (see below), self-reports (well-being, perceived stress, and motive-speci c affect), and biological parameters (heart rate, heart rate variability, cortisol, reproductive hormones) will be collected as displayed in Figure 1.
Objectives SPIRIT guidance: Speci c objectives or hypotheses.
We test the following hypotheses to investigate the role of social motives in the social support and stress relationship: Hypothesis 1: Effect of Stress Induction: Participants in both groups (social support vs. no social support) showed an increase in stress responses, comparable to previous studies. We expect a rise of the physiological parameter cortisol by at least 1.5 nmol/ml (Miller criterion, Miller et al., 2013).
Hypothesis 2: Social Support x Social Motive: The a liation motive moderates the effects of social support on stress responses.The higher participants´ a liation motive, the more they bene t from social support, i.e. they will express lower psychobiological stress responses (better self-reported well-being, less perceived stress, lower heart rate, higher HRV, lower levels of cortisol, and alpha-amylase). Whereas the a liation motive is expected to function as a stress-buffer, the power motive is assumed to function as a stress-ampli er. The higher participants´ power motive, the more they are negatively impacted by social support, i.e. g. they will report lower well-being, more perceived stress, higher heart rate, lower HRV, higher levels of cortisol and alpha amylase).
Hypothesis 3: Motive-Speci c Arousal Hypotheses: Participants with strong a liation and power motives, respectively, respond to social support with arousal of self-reported motive-speci c affect (i.e., a liation: joy, feeling socially related; power: feeling weak and inferior) and with an increase of motive-speci c reproductive hormone responses(a liation: progesterone, power: estradiol, testosterone). Hypothesis 4: Sex Difference Hypotheses: Women and men are hypothesized to differ in their social motives, with higher a liation and lower power motives in women than in men.Women and men will speci cally respond to social support with relative increases in estradiol and progesterone in women and testosterone in men.

Hypothesis 5: Speech Performance Hypotheses:
Participants who receive social support show better presentation performance in TSST interviews than participants in the no-social support group. This relationship is moderated by social motives. Participants in the social support group perform better when a liation motive is high and perform worse when power motive is high.
Exploratory Hypothesis: Gender Role Self-Concepts On an exploratory level, we plan to investigate the association of self-reported gender role self-concepts with social motives and their moderating role on whether individuals with either sex bene t from social support or not.
The study is based on a mixed within-and between subject design. The within subject factors are participants stress responses (self-reports, biological markers) across the steps of the TSST procedure (see Figure 1). The between subject factors are experimental groups (social support vs. no social support), social motives, and participants´ sex. Gender role self-concepts, as well as other control variables will be assessed as controls and entered as covariates into the analysis models. Allocation will be based on a 1:1 ratio. There will be no cross-over into the experimental group.

Methods: Participants, Interventions And Outcomes Study setting {9}
SPIRIT guidance: Description of study settings (eg, community clinic, academic hospital) and list of countries where data will be collected. Reference to where list of study sites can be obtained.
The study will be conducted in the laboratory of sports psychology of the Department of Sports Science at the University of Konstanz, Germany. The analyses of hormones, and alpha amylase will be performed in the biochemical laboratory of the Institute for Medical Psychology in Heidelberg, Germany.

Eligibility criteria {10}
SPIRIT guidance: Inclusion and exclusion criteria for participants. If applicable, eligibility criteria for study centres and individuals who will perform the interventions (eg, surgeons, psychotherapists).

Primary inclusion criteria
The following criteria must be ful lled to participate in the study: The participants have given informed consent to all aspects of the study (agreement with video recording, hormone collection).
The participants must be at least 18 years old and speak German as their native language.

Primary exclusion criteria
If the participant meets the following criteria, they will be excluded from study participation: Previous participation in stress experiments as well as psychology and sports students from the 5th semester.
Physical or mental illness, nicotine consumption, drug use, a body mass index (BMI) of 30 or more, and any regular use of medication (including hormonal contraception) lead to exclusion from the experiment, as they are factors that could in uence the physiological stress response (Foley & Kirschbaum, 2010).
Who will take informed consent? {26a} SPIRIT guidance: Who will obtain informed consent or assent from potential trial participants or authorised surrogates, and how (see Item 32).
The participants will receive the study information sheet and give their informed consent in the screening online survey (for more details see Appendix B.1) before the lab session. If they ful ll the inclusion criteria, they will be invited to the lab session. Here the participants will again read the study information sheet and sign the informed consent (for more details see Appendix C.1 and C.2).

Additional consent provisions for collection and use of participant data and biological specimens {26b}
SPIRIT guidance: Additional consent provisions for collection and use of participant data and biological specimens in ancillary studies, if applicable.
Participants data and biological specimens will only be interpreted in ancillary studies, following the participants' informed consent.

Interventions
Explanation for the choice of comparators {6b} SPIRIT guidance: Explanation for choice of comparators.
Since stress research has already clearly shown that the TSST reliably induces stress (Kirschbaum et al., 1993), we refrain from comparing a stressed vs. non-stressed group. Instead, we focus on the role of social support by comparing a socially supported group of subjects with a non-socially supported group. At the same time, we analyse the moderating role of social motives, which we capture as continuous variables.
Intervention description {11a} SPIRIT guidance: Interventions for each group with su cient detail to allow replication, including how and when they will be administered.

Web-survey prior to the lab session
The participants complete an online questionnaire (Limesurvey) at home. Here, the eligibility criteria are checked, the implicit motives are assessed by using a Picture Story Exercise (Schultheiss & Pang, 2007) and gender role self-concepts (Zimmermann et al., 2011), as well as other control variables will be measured. The exercise and sports activity questionnaire (Fuchs et al., 2015) will be administered to test a related but different research question (for more details see appendix B.3). Participants, who are eligible for the study will be invited to the laboratory session via e-mail. Participants con rmed their agreement that they will be contacted by e-mail and learn that e-mail addresses will be deleted after having made the appointment.
Lab session Figure 1 shows the schematic procedure of data collection. It starts with a general preparation phase, where the baseline measurement of the physiological parameters (hormones), the control variables, and psychological variables (self-reports about well-being, stress-experience and motive-speci c affect) takes place. In the preparation phase for the TSST-G, the participants prepare for the task. The participants in the experimental group receive social support during this phase, while the participants in the control group do not receive any social support. Finally, there will be a 45-minute period of rest during which repeated physiological as well as the psychological questionnaires will be taken. A detailed procedure can be found in the study protocol (see Appendix A).

General preparation phase
In each lab session, three participants will arrive between 5:00 and 5:15 pm outside the laboratory and will be led individually to their own preparation room (so that they cannot contact each other). First, they will be asked to read the study information sheet again and then will provide their written consent (for details see Appendix C.1 and C.2). Afterwards, the participants will generate their participant code via paper and pencil format, which ensures that the saliva samples, as well as other collected data, can be stored anonymously. Then they complete a short day-screening questionnaire, (see Appendix D) on the computer which will assess control variables (a. o., sports, medication intake, smoking, caffeine-and alcohol consumption). Afterward they will be asked to wear the pulse belt which contains a Polar H10 sensor (Polar Electro UK Ltd., Warwick, UK). To put on the belt, the experimenter leaves the room. After that, the participants will provide an initial saliva sample at measurement time T0(-11min) and will complete the rst test battery including different questionnaires on the computer (hereafter: psychological questionnaire).
Preparation phase TSST-G without social support.
For the preparation phase, each participant sits in a separate room. Here they receive the written instructions for the upcoming interview (see Appendix E). After they have had 10 minutes of preparation time for this task, they give a saliva sample (T1, 0min) and complete the psychological questionnaire again. Subsequently the participants are individually led to their places in front of the panel.
Preparation phase TSST-G with social support.
The preparation phase is identical with the described scenario for the participants without social support, with the exception that the experimenter introduces a female confederate as a student assistant that can assist the participant if he or she needed. The female confederate provides passive social support for the rst ve minutes, ostensibly working on the computer. In the second ve minutes of the preparation phase, the confederate gives active social support and also notes the reactions of the participants (for a detailed procedure, see Appendix F). At the end of the 10-minute preparation period, the confederate asks the participant for a saliva sample (T1, 0min) and to complete the psychological questionnaire again. Then rooms are changed. All other instructions are the same as in the group without social support.

TSST -G
Our procedure is based on the TSST-G developed by Von Dawans et al. (2011). Each participant is required to present his or her interview individually in front of the panel for three minutes at a time. During this time, they are interrupted in a standardized manner by the panel (for more details see Appendix G). After that, they give a saliva sample (T2, +12min) and complete the psychological questionnaire. In the following, each participant has to perform the arithmetic task three times for 30 seconds. When this task is nished, they give another saliva sample (T3, +20min). During this whole procedure, the participants are recorded with a microphone and a camera. The experimenter then leads the participants individually from the TSST-G test room to the respective preparation rooms. There they again ll in the psychological questionnaire.
Finally, the experimenter leads all subjects to the TSST-G testing room and provides a debrie ng about the aim of the study (see Appendix I). Questions are answered as needed. The participants receive their payment and are dismissed.
Criteria for discontinuing or modifying allocated interventions {11b} SPIRIT guidance: Criteria for discontinuing or modifying allocated interventions for a given trial participant (eg, drug dose change in response to harms, participant request, or improving/worsening disease).
Participants can discontinue the study at any time without giving any reason. They will still receive their payment.
Strategies to improve adherence to interventions {11c} SPIRIT guidance: Strategies to improve adherence to intervention protocols, and any procedures for monitoring adherence (eg, drug tablet return, laboratory tests).
The entire study takes place under controlled laboratory conditions and adherence with the study protocol is closely monitored.
Relevant concomitant care permitted or prohibited during the trial {11d} SPIRIT guidance: Relevant concomitant care and interventions that are permitted or prohibited during the trial.
Study participants will be screened for medication, caffeine intake, smoking, sports and heavy meals prior to the experiment. Chronic illness and medication intake are de ned as exclusion criteria for the study.
Provisions for post-trial care {30} SPIRIT guidance: Provisions, if any, for ancillary and post-trial care, and for compensation to those who suffer harm from trial participation.
The TSST has not been linked to any adverse consequences, so no harm from trial participation is expected. At the end of the study, a detailed debrie ng takes place, the experimenter inquires about the subjects' condition and is available for questions.

Outcomes {12}
SPIRIT guidance: Primary, secondary, and other outcomes, including the speci c measurement variable (eg, systolic blood pressure), analysis metric (eg, change from baseline, nal value, time to event), method of aggregation (eg, median, proportion), and time point for each outcome. Explanation of the clinical relevance of chosen e cacy and harm outcomes is strongly recommended.

Manipulation check social support
To check whether social support was received as such by the participants, a modi ed version of the received support subscale of the Berlin Social Support Scale (BSSS; Schulz & Schwarzer, 2003) will be used (see Appendix H, T6(+65min)). Item wording was adapted to the study context. Two items from the original scale were deleted because they refer to instrumental support, and the social support in this study rather refers to emotional and informal social support. The item "This student assistant was there for me when I needed her" is also counted as instrumental support according to Schulz and Schwarzer (2003), but it can also be understood as emotional support and therefore remains included. Items are rated on a 4-point Likert scale ranging from 1 (not true) to 4 (exactly true). The original version of the received support scale has good internal consistency (α = .83). In addition, participants will be asked directly whether they received support from the student assistant and whether they found this support helpful.

Test battery of psychological questionnaires
Participants are asked to complete the psychological questionnaire a total of 7 times (see Figure 1).
Well-being will be captured via 6 items (short version A) from the Multidimensional Well-being questionnaire (MDBF; Steyer et al., 1997). The items start with "Right now I feel…" and will be continued with one of the following adjectives: good, bad, alertness, fatigue, relaxed, and restlessness. The participants will be able to rate them on a 5-level scale which will be labelled from not at all too very. A slightly modi ed version of the trait anxiety scale of the State -Trait Anxiety Inventory (Spielberger, 1970) will be used to assess the momentary anxiety of the participants. A total of 6 adapted items are included, which can be answered on a 5-point scale, "How big do you think your fear is at the moment?", "How much do you feel physically uncomfortable right now?", "How strong is your need to leave the situation?", "How tense is your feeling right now?", "How much are you in control of the situation?", "How stressed do you feel? ". Per our knowledge, no standardized motive-speci c affect questionnaire exists so far. We therefore created an adjective list which is theoretically derived from McClelland ś (1985) early work and added adjectives that have been used in more recent research (Job et al., 2012) (see selfdetermination theory, Ryan & Deci, 2000). Participants indicated for 7 items how they feel right now by using a 7-point response scale (1: not at all to 7: very much). The items are "socially-related", "calm" (a liation motive speci c affect) (the item "relaxed" from the MDBF questionnaire will also be used in the analysis for the a liation motive), "strong", "excited", "enthusiastic" (power motive), and "competent" and "self-determined" as additional items representing achievement and autonomy motive-speci c affect, respectively (see appendix J). Construct validity of this motive-speci c affect scale will be checked.

Social Motives
Implicit social motives are measured using the Picture Story Exercise (Schultheiss & Pang, 2007) which is the most frequently used measure to assess implicit motives. Key validity criteria are met, interrater reliability is good, and retest reliability is satisfactory (Schultheiss & Köllner, in press; Schultheiss & Pang, 2007); for further discussion see (Schüler et al., 2015). The PSE will be part of the online questionnaire prior to the lab session (for validity of computer version of PSE, Bernecker & Job, 2011). Participants will be instructed that they will see six different pictures and for each of them, they should write a ctional story with a beginning, middle, and end. The pictures will be presented for 15 sec and then a text box will appear, where they can type their story. Questions that help participants to organize their stories will be presented above the pictures (e.g, "What is happening right now? Who are the characters?). For each story, the participants will have four minutes. After 3 min 30 sec, a small reminder will appear asking them to nish the story. After the four minutes have elapsed, the next picture will appear. The six pictures couple by the river, nightclub scene, sorrow, beachcombers, NewPic32, NewPic9 will be presented, for more details see appendix B.3. As recommended (Schultheiss & Pang, 2007), two experienced coders will score the stories for the power and a liation motive according to Winter's scoring manual (Winter, 1994) (Interrater reliability is expected to be between ICC = .80-.90). Disagreements between coders will be resolved by discussion (Schultheiss & Pang, 2007). Motive scores will be corrected by word count. For further details about test administration and scoring procedure see Schultheiss & Pang (2007).
All participants will complete a short German version of the Bem Sex Role Inventory, to screen for GRSC (Zimmermann et al., 2011).

Physiological measures
Endocrine measurements Saliva samples will be collected for the recording of cortisol, alpha amylase and reproductive hormones.
Approximately 10ml of saliva will be dispensed through a straw into Salicaps (IBL International, Hamburg, Germany) (see Appendix K for instructions). After the study, all saliva samples will be frozen and stored at -20°C. Hormone and enzyme levels will be analysed at the stress biomarkers lab at the Institute of Medical Psychology, Heidelberg University Hospital.

Alpha-amylase
Alpha-amylase is recorded in U/mL. The concentration is derived from the same seven salvia samples as used for the cortisol analysis and will be determined by a kinetic colorimetric test. The reagents for this will be obtained from DiaSys Diagnosic Systems (Holzheim, Germany).

Reproductive hormones
Reproductive hormones (testosterone, estradiol, and progesterone) will be recorded in pg/ml. Four saliva samples will be collected using Salicaps (IBL International, Hamburg, Germany) at the measurement time points T0(-11min before TSST-G), T1(TSST-G onset), T3(after the arithmetic task), and T6 during rest (+65min after TSST-G onset). Hormone concentrations will be determined by biochemical analysis in the laboratory. The following kits from IBL will be used for analysis: Testosterone Luminescence Immunoassay, 17 beta -Estradiol Saliva Luminescence Immunoassay, Progesterone Luminescence Immunoassay.

ANS measurements
Heart rate and heart rate variability will be measured with a Polar H10 sensor (Polar Electro UK Ltd., Warwick, UK). The sensor is placed in a pulse belt that the participants will wear around their chest. With the help of a Polar station and an iPad, the participants' data is transmitted wirelessly and in real time.

Speech performance
The participants will be videotaped while they complete the tasks (interview and arithmetic task) in front of the panel. The video sequences showing the recording of the interview will be coded for speech performance using a self-developed coding system. This system includes three quality criteria: the information content, the presentation style, and the perceived competence of the participants. The assessment of the information content is based on a checklist for the evaluation of a presentation according to Ascheron (2019). The content is scored on the following 5 items, "structure/ organization", "comprehensibility of content", " ow", "information content" and "message". These items will be rated on a scale that ranges from 1 (very good) to 6 (unsatisfactory). A modi ed questionnaire of Ascheron (2019) will be used to evaluate the presentation style. Two items (intonation, English quality) were left out because intonation overlaps with another item (emphasis), and English quality is irrelevant because the study will be conducted in German. The presentation style is rated on the basis of the following 5 items: "speed", "intelligibility", " emphasis ", "body language" and "eye contact", whereby we added the latter item to complement the construct in more detail. The items will be scored using a six-point scale (1: very good to 6: unsatisfactory). Since there is no suitable measurement tool for the assessment of perceived competence in the literature, we determined 5 items that should enable a differentiated evaluation of this construct. The following items will be also scored on a six-point scale: "technical language/vocabulary", "use of ller words", "use of everyday language", "interest" and "persuasiveness". Construct validity of this competence scale will be checked.

Participant timeline {13}
SPIRIT guidance: Time schedule of enrolment, interventions (including any run-ins and washouts), assessments, and visits for participants. A schematic diagram is highly recommended (see gure at http://www.spirit-statement.org/publications-downloads/).
The timeline for participants is displayed in Figure 1.

Sample size {14}
SPIRIT guidance: Estimated number of participants needed to achieve study objectives and how it was determined, including clinical and statistical assumptions supporting any sample size calculations.
It is intended to recruit 154 participants (77 women).This sample size was calculated using a power analysis G*Power 3.1 (Faul et al., 2009), with an additional 20% added to compensate for possible dropouts.

Recruitment {15}
SPIRIT guidance: Strategies for achieving adequate participant enrolment to reach target sample size.
The recruitment will be done by yer distribution in the University of Konstanz, as well as an entry in an online platform where experiments are offered by the departments of psychology and linguistics.

Assignment of interventions: allocation
Sequence generation {16a} SPIRIT guidance: Method of generating the allocation sequence (eg, computer-generated random numbers), and list of any factors for strati cation. To reduce predictability of a random sequence, details of any planned restriction (eg, blocking) should be provided in a separate document that is unavailable to those who enrol participants or assign interventions.
Participants will be randomly assigned into the social-support or no-social support group, based on their arrival time in front of the laboratory.

Concealment mechanism {16b}
SPIRIT guidance: Mechanism of implementing the allocation sequence (eg, central telephone; sequentially numbered, opaque, sealed envelopes), describing any steps to conceal the sequence until interventions are assigned.
The participants do not have any information in which group they will be assigned to, nor do they know that the other participants may be undergoing a different form of the experiment.

Implementation {16c}
SPIRIT guidance: Who will generate the allocation sequence, who will enrol participants, and who will assign participants to interventions.
Depending on the order in which the participants arrive before the laboratory, they may or may not receive social support.

Assignment of interventions: Blinding
Who will be blinded {17a} SPIRIT guidance: Who will be blinded after assignment to interventions (eg, trial participants, care providers, outcome assessors, data analysts), and how.
The participants will be blind to the condition, until the end of the experiment. The advertisement for the study states that we are investigating the relationship between verbal creativity and physiological reactions (for the exact wording of the cover story see appendix B.1). The experimenter, as well as the confederate, know who will be in which condition. The TSST-panel will not know who is in which condition. The coders of the motive measure are also condition blind.
Procedure for unblinding if needed {17b} SPIRIT guidance: If blinded, circumstances under which unblinding is permissible, and procedure for revealing a participant's allocated intervention during the trial.
The participants will be debriefed about the aims, as well as the group assignments in the study (for more details, see appendix I).

Data collection and management
Plans for assessment and collection of outcomes {18a} SPIRIT guidance: Plans for assessment and collection of outcome, baseline, and other trial data, including any related processes to promote data quality (eg, duplicate measurements, training of assessors) and a description of study instruments (eg, questionnaires, laboratory tests) along with their reliability and validity, if known. Reference to where data collection forms can be found, if not in the protocol.
In the section "Outcomes 12b" the measures for psychological and physiological parameters are explained in detail.

Plans to promote participant retention and complete follow-up {18b}
SPIRIT guidance: Plans to promote participant retention and complete follow-up, including list of any outcome data to be collected for participants who discontinue or deviate from intervention protocols.
Participants will receive 30 Euro payment at the end of the lab session independently of whether or when participants decide to discontinue the study. To promote participant adherence with the appointment and study protocol, they will receive a reminder e-mail after having lled in the web-survey and one day before their lab appointment.

Data management {19}
SPIRIT guidance: Plans for data entry, coding, security, and storage, including any related processes to promote data quality (eg, double data entry; range checks for data values). Reference to where details of data management procedures can be found, if not in the protocol.
The questionnaire data will be downloaded from Limesurvey and stored on the university server. The psychological questionnaire from T2, which were collected by paper and pencil format, as well as heart rate, and heart rate variability will be stored in an excel table by the study experimenter directly after the study. The video le will also be saved directly after the experiment, on a laptop of the sport psychology lab and a back-up server. The saliva samples will be sent to the biochemical laboratory of the Institute for Medical Psychology in Heidelberg, Germany. To guarantee the accuracy of the analyses, 10% of the cortisol samples, as well as 20% of the samples for the reproductive hormones will be double-determined. The signed consent forms of the participants will be collected in a folder laboratory of the sports psychology department in Konstanz. Only the experimenter will have access to the data, which will be stored for 10 years on a server of the University.

Con dentiality {27}
SPIRIT guidance: How personal information about potential and enrolled participants will be collected, shared, and maintained in order to protect con dentiality before, during, and after the trial.
The participants will generate their own code that allows to merge the data of the web surveys with the data gained in the laboratory.
Plans for collection, laboratory evaluation and storage of biological specimens for genetic or molecular analysis in this trial/future use {33} SPIRIT guidance: Plans for collection, laboratory evaluation, and storage of biological specimens for genetic or molecular analysis in the current trial and for future use in ancillary studies, if applicable. Saliva samples will be stored at the biochemical lab at Heidelberg University Hospital for at least two years after completion of the study and will then be discarded.

Statistical methods
Statistical methods for primary and secondary outcomes {20a} SPIRIT guidance: Statistical methods for analysing primary and secondary outcomes. Reference to where other details of the statistical analysis plan can be found, if not in the protocol. Statistical analysis will be performed using the freely available software R-Studio (current version: R version 4.0.2; (Team, 2017)) for statistical analysis and graphs. We will use a nested random effect regression as a multi-level regression approach that allows the intercept to vary with participants to account for the fact that the dependent variables are assessed multiple times. The regression model will be built by sequentially adding predictors after an intercept-only model and its random intercept (random = 1 | ID) has been speci ed. Every newly added predictor (social support condition, social motive, sex), or interaction-term (condition x social motive, condition x sex, social motive x sex and condition x social motive x sex) is stored as a separate regression model in R-studio to allow for a nal comparison of all stages of model-speci cation. All predictors are kept in a regression model when a further predictor or interaction-term was added to that model. Main and interaction effect models were compared using ANOVAS.

Interim analyses {21b}
SPIRIT guidance: Description of any interim analyses and stopping guidelines, including who will have access to these interim results and make the nal decision to terminate the trial.
No interim analyses or stopping guidelines are planned.
Methods for additional analyses (e.g. subgroup analyses) {20b} SPIRIT guidance: Methods for any additional analyses (eg, subgroup and adjusted analyses).
There are exploratory analyses planned on the association of self-reported gender role self-concepts with social motives and their moderating role on psychobiological responses to social support.
Methods in analysis to handle protocol non-adherence and any statistical methods to handle missing data {20c} SPIRIT guidance: De nition of analysis population relating to protocol non-adherence (eg, as randomised analysis), and any statistical methods to handle missing data (eg, multiple imputation).
Only data from individuals who have fully completed the TSST protocol will be included in the nal analyses. Missing data are completed by multiple imputation.
Plans to give access to the full protocol, participant level-data and statistical code {31c} SPIRIT guidance: Plans, if any, for granting public access to the full protocol, participant-level dataset, and statistical code.
Study protocol, data and statistical codes will be published on Open Science Framework (OSF).
We will guarantee that the data are still accessible after they will be published by choosing publishing houses that support an open data policy. Furthermore, we will inform researchers about the openness of our data (e.g., state repositories in publications, aim to publish in journals that use badges for open data), and explicitly invite members of our speci c scienti c disciplines to reuse the data (i.e., in collaborations, at conferences, in talks, and poster presentations).

Oversight and monitoring
Composition of the coordinating centre and trial steering committee {5d} Trials guidance: Provide information on the composition, roles and responsibilities of the coordinating centre and trial steering committee and all groups providing day to day support for the trial. There will always be a group running the trial day-to-day and providing organisational support and knowing how often they will meet, plus information on other committees providing oversight such as a Trial Steering Committee, and how often they will meet over the course of the trial, is what we need for item 5d. We do not need names of staff.
SPIRIT guidance: Composition, roles, and responsibilities of the coordinating centre, steering committee, endpoint adjudication committee, data management team, and other individuals or groups overseeing the trial, if applicable (see Item 21a for data monitoring committee).
This study is a collaboration project between principal investigator of the University of Konstanz, Constance, and the co-PI at the Institute for Medical Psychology in Heidelberg, Germany. Day to day support for the study will be provided by two principle investigators, who hold responsibility for the study execution, a study coordinator and 4 assistants who participate in data collection (e.g., social supporter, experimenter, plenary members in TSST). The whole team will meet once a week. There is no stakeholder or public involvement group.
Composition of the data monitoring committee, its role and reporting structure {21a} SPIRIT guidance: Composition of data monitoring committee (DMC); summary of its role and reporting structure; statement of whether it is independent from the sponsor and competing interests; and reference to where further details about its charter can be found, if not in the protocol. Alternatively, an explanation of why a DMC is not needed.
There will be no data monitoring committee (DMC), as our participants will not undergo any unproven intervention. Therefore, there will be no safety concerns for our participants and thus no committee is needed for this study.

Adverse event reporting and harms {22}
SPIRIT guidance: Plans for collecting, assessing, reporting, and managing solicited and spontaneously reported adverse events and other unintended effects of trial interventions or trial conduct.
No adverse side effects have been reported with the TSST protocol.
Frequency and plans for auditing trial conduct {23} SPIRIT guidance: Frequency and procedures for auditing trial conduct, if any, and whether the process will be independent from investigators and the sponsor.
Not applicable.
Plans for communicating important protocol amendments to relevant parties (e.g. trial participants, ethical committees) {25} SPIRIT guidance: Plans for communicating important protocol modi cations (eg, changes to eligibility criteria, outcomes, analyses) to relevant parties (eg, investigators, REC/IRBs, trial participants, trial registries, journals, regulators).
Protocol amendments will be routinely reported to the ethics committee.

Dissemination plans {31a}
SPIRIT guidance: Plans for investigators and sponsor to communicate trial results to participants, healthcare professionals, the public, and other relevant groups (eg, via publication, reporting in results databases, or other data sharing arrangements), including any publication restrictions.
The results of the study will be submitted for publication in peer-reviewed scienti c journals.

Discussion
Trials guidance: This should include a discussion of any practical or operational issues involved in performing the study and any issues not covered in other sections.
COVID-10 regulations (if necessary) -The research team will be tested with Corona rapid tests before each data collection.
-Participants will only be included upon negative Corona testing within 24hrs before the lab-session, or if there is complete vaccination protection.
-The rooms in which the experiment takes place will be su ciently vented before the arrival of the participants.
-The participants, the experimenter, the social support provider and the panel will wear medical masks.
-The materials that the participants will touch during the experiment will be cleaned with sanitizer beforehand.
-After the test, all surfaces will be disinfected, and the rooms will be aired again. The minimum distance of 1.5 will be maintained at all times.
-The participants will be advised in the reminder e-mail for their lab session to appear only if they do not show cold symptoms and have not had contact with an infected Covid person.
Since data collection could last several months, we might have to adjust these regulations as necessary.

Trial status
Trials guidance: Authors should report the protocol version number and date, the date recruitment began, and the approximate date when recruitment will be completed.
Data collection is scheduled to begin in July 2021. The protocol is the version of the July, 5, 2021. The data collection should take place until spring 2022.

Abbreviations
Trials guidance: If abbreviations are used in the text they should be de ned in the text at rst use, and a list of abbreviations should be provided.

Declarations
Trials guidance: All manuscripts must contain the following subheadings: Trials guidance: Please acknowledge anyone who contributed towards the article who does not meet the criteria for authorship including anyone who provided professional writing services or materials. Authors should obtain permission to acknowledge from all those mentioned in the Acknowledgements section.
See our editorial policies for a full explanation of acknowledgements and authorship criteria. If you do not have anyone to acknowledge, please write "Not applicable" in this section.
Group authorship (for manuscripts involving a collaboration group): if you would like the names of the individual members of a collaboration Group to be searchable through their individual PubMed records, please ensure that the title of the collaboration Group is included on the title page and in the submission system and also include collaborating author names as the last paragraph of the "Acknowledgements" section. Please add authors in the format First Name, Middle initial(s) (optional), Last Name. You can add institution or country information for each author if you wish, but this should be consistent across all authors. Please note that individual names may not be present in the PubMed record at the time a published article is initially included in PubMed as it takes PubMed additional time to code this information.

Acknowledgements
We thank Tatjana Stauss and Milena Müller for their assistance in re ecting the anticipated process of data collection critically.

Authors' contributions {31b}
SPIRIT guidance: [31b] -Authorship eligibility guidelines and any intended use of professional writers.
Trials guidance: The individual contributions of authors to the manuscript should be speci ed in this section. Guidance and criteria for authorship can be found in our editorial policies. Please use initials to refer to each author's contribution in this section, for example: "AB is the Chief Investigator; she conceived the study, led the proposal and protocol development. CD contributed to study design and to development of the proposal. EF was the lead trial methodologist. All authors read and approved the nal manuscript." JS and BD are the principal investigators; they designed the study, supervised the proposal and protocol development. AH contributed to study design and wrote the rst draft of the proposal. All authors read and approved the nal manuscript.

Funding {4}
SPIRIT guidance: Sources and types of nancial, material, and other support.
Trials guidance: All sources of funding for the research reported should be declared. You will be required to include a copy of the original funding document and an English translation of this document as an additional le on submission, which will be checked against this declaration. The role of the funding body in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript should be declared.

Availability of data and materials {29}
SPIRIT guidance: Statement of who will have access to the nal trial dataset, and disclosure of contractual agreements that limit such access for investigators.
Trials guidance: Please do not include any baseline or pilot data in your study protocol. The Editorial O ce will ask you to remove this if it is included. Please declare here who will have access to the nal trial dataset and disclose contractual agreements that limit such access for investigators.
The principle investigators will have access to the nal trial dataset. Furthermore, it will be made accessible as described above.
Ethics approval and consent to participate {24} SPIRIT guidance: Plans for seeking research ethics committee/institutional review board (REC/IRB) approval.
Trials guidance: Trials do not consider study protocols for studies without ethical approval. You will be required to provide a copy of the original ethical approval document and an English translation of this document as an additional le on submission, which will be checked against this declaration. The name of the ethics committee that approved the study and the committee's reference number (if applicable) should be declared. Details of authors' intentions to obtain consent to participate in the study from participants (or their parent or legal guardian in the case of children under 16) should be declared. "eg.
ABC Ethical Review Board ABC123456. Written, informed consent to participate will be obtained from all participants" The authors received approval from the ethics committee of the University of Konstanz (35/2018).

Consent for publication {32}
SPIRIT guidance: Model consent form and other related documentation given to participants and authorised surrogates.
Trials guidance: Please do not include any baseline or pilot data in your study protocol. The Editorial O ce will ask you to remove this if it is included. If you have included any details, images or videos relating to an individual person, written informed consent for the publication of these details must be obtained from that person (or their parent or legal guardian in the case of children under 18) and declared in this section. Please also state whether you will be willing to provide a model consent form on request.
If this section does not apply, please state "Not applicable".