Stress in undergrads
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Transcript of Stress in undergrads
LOCUS OF CONTROL PREDICTS CORTISOL REACTIVITY AND SPEECH PERFORMANCE IN RESPONSE TO ACUTE
STRESS IN UNDERGRADUATE STUDENTS
Yvette Z. Szabo University o f Louisville
A ndrew C hang
California State University, Los Angeles
Cheryl C hancellor-Freeland San Jose State University
AbstractPrevious studies have found that an individual’s perception of control in a situation (Locus of Control; LOC) can serve as a protective factor that has physiological and psychological benefits. The present study examines LOC in an acute stress paradigm to examine the relationship between LOC and hypothalamic-pituitary-adrenal axis functioning as well as between LOC and performance. One hundred and thirteen participants at a metropolitan university were randomly assigned to either a stress or control condition. The stress condition consisted of the Trier Social Stress Test (TSST) while the control condition consisted of viewing a neutral travel video. Salivary cortisol was measured at four time points before and after exposure to the assigned condition. A mock job interview speech in the TSST was recorded and evaluated for performance on eight dimensions. LOC significantly predicted cortisol reactivity to the stressor in a multiple linear regression model. In addition, LOC was a significant predictor o f speech performance in a simple regression model. Cortisol was not related to speech performance, and LOC did not moderate this relationship, although LOC uniquely predicted speech performance. This research adds to a growing body of literature demonstrating physiological and functional influences of LOC orientation.
Keywords: locus of control, acute stress, cortisol, undergraduate students, Trier Social Stress Test, speech performance
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Although usually assumed to be only deleterious, stress has the potential to enhance, hinder or show no impact on the performance of an individual. How well individuals do in stressful situations, such as workplace performance reviews, test-taking, and formal presentations often depend on their perception of control and mastery. Stressful situations also activate the acute stress response, known as the body’s “fight or flight” response, a physiological and psychological response to physical and social demands. Many factors may influence the impact of stress, including detrimental or beneficial outcomes. Although perception of mastery seems to play an important role in success, it is not the only factor that is influential because the biological stress system may be still present and active. Both perception of control and mastery and the biological response have the potential to interfere with cognition and performance. While the literatures in both camps have developed separately, there is a need for understanding in their integration.
An individual can view a situation as a result of external or internal forces, known as one’s Locus of Control (LOC). LOC scores fall on a continuum between internal and external orientations. Lower LOC scores, or an internal orientation, indicate that one feels self-empowered and in control of his or her environment. Higher LOC scores, or a more external orientation, indicate that the individual feels they have less control of their environment and that outside forces shape his or her experience (Rotter, 1966). The extent of control individuals believe they have over their environment (LOC) can influence perceived stress levels, such that a greater perception of control is related to lower perceived stress (Anderson, 1977; Hellhammer, Wust, & Kudielka, 2009; Roddenberry & Renk, 2010). While perceived stress and physiological stress may be positively correlated, they are not extensions of one another
per se (van Eck, Berkhof, Nicolson, & Su- lon, 1996). Physiological stress is a result of nearly automatic cognitive and emotional appraisals of stimuli and perceived stress incorporates the individual’s perceptions of their ability to handle the situation. This indicates that LOC may not be associated with physiological stress in the same pattern as it is with perceived stress. However, few studies have looked at LOC following the direct manipulation of stress. Therefore, further research is needed to determine whether perceptions of control can moderate the physiological acute stress response.
The acute stress response is located within the body’s corticotrophin-releasing hormone system. Responses to events deemed dangerous or exciting begin with the activation of paraventricular corticotropin-releasing factor and arginine vasopressin neurons in the paraventricular nucleus of the hypothalamus (Hell- hammer, Wust, & Kudielka, 2009; O’Connor, O’Halloran, & Shanahan, 2000). Corticotropin-releasing hormone then stimulates the release of adrenocorticotrophic hormone (ACTH; O’Connor et al., 2000). ACTH stimulates the release of cortisol, a glucocorticoid from the adrenal glands, activating the fight- or-flight response, which includes increased heart rate, suppressed immune function, and inhibited digestion. Under normal transient stress conditions, cortisol helps to successfully defend against a threat, and then is terminated by initiating a negative feedback mechanism to inhibit the hypothalamus’s corticotropin-releasing factor production (Sapolsky, 1994). Cortisol has been demonstrated to be a reliable index of the hypothalamic pituitary adrenal (HPA) chemical cascade, and it is a common biomarker for stress (Hellhammer et al., 2009). For this reason, the HPA axis and cortisol have been a focal point of recent stress research. Particular emphasis has been on factors that may be associated with blunted or heightened stress responses.
Cortisol Reactivity and Speech Performance in Response to Acute Stress / 227
Few studies have examined LOC and cortisol reactivity in acute stress contexts. The scant available literature on LOC and physiological responses to stress is both limited and mixed. For example, some studies have demonstrated that a more internal LOC is associated with reduced physiological activation (Pruessner, Hellhammer, & Kirschbaum, 1999; Pruessner et al., 2005), and yet others found no association between LOC and physiological activation (Bollini, Walkter, Ha- mann, & Kestler, 2004; Pruessner et al., 1997). Flowever, varying methodologies seem to be confusing the state of the literature. For example, one study employed a cold-water stressor (Viena, Banks, Barbu, Schulman, & Tartar, 2012); another used computer tasks thought to induce a stress response (Pruessneret al., 1999) and still others used a combined speech and mental arithmetic psychosocial task (Pruessner et al., 1997). While the first two are well controlled laboratory measures, they lack generalizability outside of the lab environment. For applicability, a psychosocial stressor may have more ecological validity. Measures of cortisol have also been variable, one study used area under the curve cortisol over the length of the session (Pruessner et al., 1997; Pruessner et al., 2005), others correlated LOC with absolute cortisol output post-stressor (Viena et al., 2012) and others used change scores for the difference pre- and post-task (Bollini et al., 2004). Use of posttask values could be a large limitation due to individual differences in baselines. Delta cortisol values (i.e., post-talk minus baseline) may prove to be more informative to make comparisons across individuals or groups. While most studies used undergraduate student samples, another variation has been the gender representation, with a subsample of studies focusing on male participants (Pruessner et al., 1997). Importantly, measures of LOC have also differed. Across six studies of LOC and acute stress, four measures of
LOC were utilized. Differences in the construct measure may influence outcomes and conclusions. For example, some studies used the Questionnaire of Competence and Control, a combined measure of self-esteem and LOC (Pruessner et al., 1997; Pruessner et al., 1999; Pruessner et al., 2005). However, when studies have looked at the constructs of perceived control separate from self-esteem (e.g. Scarpa & Luscher, 2002), greater baseline perceptions of control, or less helplessness, predicted post-task change in cortisol, but this was not a validated measure of LOC. Variations in the construct measured may contribute to the diverse findings. Finally, some of these studies examined performance independently in the context of acute stress, but few have examined the moderating role LOC may play. Overall, regardless of condition, greater self-esteem and a more internal LOC on the LOC/self-esteem measure were associated with better performance (e.g. Pruessner et al., 1999). Still, the relationship between LOC and cortisol is mixed. This may be due to the breadth of stressors that have been employed. In sum, the generalizability of the results may be a function of the way in which the research questions have been assessed.
Past research has suggested a relationship between LOC and performance in a wide range of disciplines, such that a more internal LOC is associated with better workplace and public speaking performance (Bemardi, 2011; Judge & Bono, 2001; Spector, 1986). For example, in a meta-analysis on four self-evaluation characteristics, job satisfaction, and performance, a more internal LOC was associated with higher job performance (Judge & Bono, 2001). In college students with new jobs, a more internal LOC was associated with perceiving stress as positive and resulted in higher achievement in their work role (Bemardi, 2011). A meta-analysis on employee perceptions of control found
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that greater perceived control, comparable to an internal LOC, was related to greater motivation and performance, as well as lower self-reported physical and emotional distress (Spector, 1986). In terms of public speaking, a more internal LOC is associated with less self-reported anxiety about communicating with others, and a more external LOC is associated with less goal-directed speech and less motivation in communicating (Rubin, 1993). An internal LOC appears to provide a benefit for performance in a variety of settings; however, this body of research has not examined the role of physiological stress in these relationships.
One study examined the relationship between LOC and performance under varying levels of stress to determine ifboth internals and externals follow the Yerkes-Dodson hypothesis of performance, where arousal increases performance for low levels of arousal and then negatively impacts performance at high levels of arousal (Guar & Upadhyay, 1988). Overall, performance increased over the stress levels, peaking at moderate stress, consistent with the Yerkes-Dodson hypothesis. There was a significant interaction between stress and LOC, divided into external and internal using a median split, such that under severe stress, internals maintained the high performance but externals performed significantly worse. While this article is dated, it is one of the first that looked at the three factors (LOC, stress and performance) in an a priori design to examine respective relationships.
Present Study
In order to better understand the relationship between LOC, performance and cortisol, the present study evaluated these associations following an experimentally-induced, acute stress paradigm. In this process, we observed the relationship of perceived control with the biological stress response and performance on a public speaking task. This builds on
past research by addressing several of the methodological limitations identified above. Specifically, this study used Rotter’s LOC scale, a frequently employed measure of internal or external LOC across a wide range of domains, including psychotherapy outcomes and academic or occupational achievement (Baker, 1979; Parker, 2003). We also used an empirically-supported paradigm to induce psychosocial stress, the Trier Social Stress Test (TSST; Kirschbaum, Pirke, & Hellham- mer, 1993). The TSST includes both a public speaking and mental arithmetic component and has been demonstrated to induce a robust physiological response (Kirschbaum et al., 1993). Past research has examined perceived stress, which is not always representative of physiological activation (van Eck et al., 1996). Other research examined students during mid-term examination time, which introduces variables of preparedness and additional individual differences that may confound findings (Viena et al., 2012). Manipulating stress experimentally allows for the examination of factors that may influence the HPA response to acute stress. Another benefit of using the TSST is that every participant is introduced to the same stimulus, an acute stressor, in a controlled environment.
While both the public speaking and math portion have a synergistic effect in making the TSST a reliable stressor, public speaking has a more ecologically-valid role. Public speaking is widely reported to be one of the biggest fears, one that causes tremendous amounts of stress for people (Richmond & McCroskey, 1995). Conversely, verbal communication skills are also ranked as the most desirable characteristic for employers (National Association of College and Employers, 2011), indicating a need to better understand the factors influencing effective communication and what may mediate apprehension and anxiety. One such factor may be LOC. Furthermore, to our knowledge, no previous study has
Cortisol Reactivity and Speech Performance in Response to Acute Stress / 229
experimentally manipulated stress and examined the role LOC has on speech performance under stress. Therefore, the present study considered potential associations between LOC and performance following stress with the purpose of examining potential interplay between this perception and the biological stress system. Another goal is to establish the relationship between perceptions of control and actual performance under demanding and unexpected circumstances. In sum, the present study seeks to further clarify relationships of LOC on HPA functioning and speech performance in response to acute stress.
Hypotheses
The present study examines the relationships between LOC and both cortisol reactivity and speech performance in response to acute stress. The primary hypothesis is that there would be an inverse relationship with an internal LOC and cortisol reactivity, whereby a more internal LOC would predict a lesser degree of reactivity to the laboratory stressor. Our secondary hypothesis is that there will be a negative linear relationship between LOC and speech performance, such that a more internal LOC would predict better speech performance. Third, we examined whether stress differentially affects speech performance based on one’s LOC. We hypothesize that those with a more internal LOC will perform better on the public speaking task despite the relative increase in cortisol.
Methods
ParticipantsOne-hundred thirteen undergraduate stu
dents were recruited from psychology courses at a metropolitan university. To be eligible for the study, participants had to be at least 18 years of age and currently enrolled in an undergraduate psychology course. Exclusion criteria included presence of a neuroendocrine disorder, history of a psychological
disorder in the six months prior to the study, and currently taking psychoactive medications. The sample was 75.2% female and ages ranged from 18-41 (M = 19.79,50 = 3.05). In addition, participants were ethnically diverse (22% Caucasian, 4.4% African American, 22% Latino/Latina, 31% Asian, 17% other and 1.8% N/A).
All participants provided informed consent and received course credit for participation. The study protocol was approved by the local Institutional Review Board.
Measures
Screening and Demographics. Prior to the start of each research session, participants completed a brief screening questionnaire that asked about activities in the last hour. This was to ensure compliance with the pre-visit restrictions of not eating, drinking, smoking or exercising. It also evaluated whether the participant met eligibility criteria of not having a neuroendocrine disorder, not currently taking psychoactive medications, and not presenting with a psychological disorder in the past six months. Participants who did not meet eligibility criteria were not allowed to participate and those that violated pre-visit restrictions were rescheduled. Participants also completed a basic demographic form that inquired about age, gender, ethnicity, major, year in school, GPA, and English proficiency.
Locus of Control. To assess LOC, participants completed a 29-item self-report questionnaire, of which only 23 were scored (Rotter, 1966). The other six questions are filler questions. For each item, the participant was presented with two statements, one representing internal LOC and one representing external LOC. Instructions stated there was no right or wrong answer but to choose the statement that the individual agrees with most. Endorsing the external statement earned a score of a 1. Responses were summed to create a total score that ranged from 0-23, where lower
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scores indicate an internal LOC and higher scores indicate a more external LOC. The range for this sample was 5-19. Cronbach’s alpha for Rotter’s LOC scale has been reported to be between .65 and .80 (Lange & Tiggle- man, 1981; Rotter, 1966). Test-retest reliability over a two-year period has been reported to be .61 in a sample of Australian undergraduate students (Lange & Tiggleman, 1981).
Acute Stress Manipulation. The TSST takes approximately 15 minutes and involves both a speech and math task (Kirschbaum et al., 1993). First, experimenters led participants into a room with a table that had a video camera and two judges. The room was kept regulated (e.g. temperature and light) and was free of decor. Participants prepared for the speech for three minutes in a different room and were instmcted that they would not be able to use their notes during the speech. At the end of three minutes, participants were asked to stand behind a line placed between the wall and the camera and gave a five minute speech in which they were instructed to “state your ideal job and convince the committee why you are the best candidate for the job.” If participants paused for longer than 20 seconds, they were prompted by the main judge with “You still have more time, please continue.” Following the speech, participants completed a five minute mental arithmetic task counting aloud backwards from 2083 subtracting by 13 each time. These tasks were completed in the presence of two judges that were instmcted to maintain emotionless and only speak using scripted statements.
Speech Performance. As part of the TSST, each speech was recorded and evaluated by a team of two judges on a scale of 8-40. A 5 point Likert Scale (1 = Poor, 5 = Great) was used for each of eight characteristics of performance (Organization, Persuasiveness, Content, Clarity, Volume, Speed, Professionalism, and Friendliness). Examples of criteria assessed are maintaining eye contact,
consistently making friendly expressions such as smiles or gestures (friendliness), and keeping a constant pace of speech (speed). These characteristics were based on criteria suggested in studies of job interview performance and forms for evaluating interview performance (Hollandsworth, Kazelskis, Stevens & Dressel, 1979; McCarthy & Goffin, 2004). Inter-rater reliability was computed to be Cohen’s k = >.90.
Cortisol Reactivity. Participants gave four saliva samples during the study to assess salivary cortisol. The experimenter instmcted the participant to chew for one minute on cotton swabs that were placed inside Salivette® tubes with cotton swabs (Sarstedt AG & Co., Numbrecht, Germany). To ensure compliance, the experimenter remained in the room during the minute but turned away as the participant returned the cotton cylinder to the tube without using their hands. The samples were kept at 5 °C until analysis with ELISA assays with Expanded Range High Sensitivity Salivary Cortisol Enzyme Immunoassay Kit (Salimeterics LLC, State College, PA). All samples were analyzed in duplicate for reliability purposes. The first sample was considered the baseline sample and peak cortisol was the larger of the two samples given at 10 and 20 minutes post-task.
Procedure
Participants completed the experiment individually. All experiments were conducted between 12 and 6 pm to account for circadian rhythm cycles of cortisol (Kudielka, Schom- mer, Hellhammer, & Kirschbaum, 2004). The study began with informed consent and with an introduction phase where the experimenters clarified any questions about procedure and anonymity. Participants then gave their first baseline saliva sample and completed an eight minute neutral task which was part of a larger study, the results of which are not discussed in this paper.
Cortisol Reactivity and Speech Performance in Response to Acute Stress / 231
All participants were then randomly assigned at a 2:1 ratio to either the stress or control condition, respectively. Those in the stress condition completed the TSST. Participants in the control condition watched a neutral travel video for 15 minutes in lieu of the TSST. All other procedures were identical for each condition. After completing their assigned task, participants completed another neutral task that took approximately ten minutes. Saliva samples were collected before and after the task at ten minute intervals. Participants then had a 20 minute resting phase where they completed several questionnaires, including Rotter’s LOC scale and demographic information. Other questionnaires collected were part of a larger study and included a questionnaire on fitness and exercise, sleep habits and coping skills. After the resting phase, participants gave a final saliva sample and were debriefed.
ResultsThis study examined the relationships be
tween LOC, speech performance and cortisol reactivity in a sample of undergraduate students at a metropolitan university. Of the 113 participants, 7 participants were removed for missing cortisol values, 4 were removed for having cortisol responses greater than 3 standard deviations from than the mean and 3 were removed for not completing the LOC questionnaire. This left a sample of 99 participants for data analyses: 65 in the stress condition and 34 in the control condition. Subjects who were removed from analyses did not differ in age (t —.649, p > .05) or ethnicity (j2 = 5.63, p > .05). They were, however, more likely to be in the experimental condition compared to the control condition (y l = 4.3,p = .04).
Gender has been shown to have a significant main effect on cortisol responses to the TSST (Kirschbaum et al., 1993), so gender was added as covariate predictor to models with cortisol variables a priori.
Delta cortisol was log transformed to reduce positive skewness, all other variables met assumptions for normality. All means and standard deviations presented are untransformed. The criterion of significance was .05.
Manipulation Check
To assess the effectiveness of the TSST at inducing psychosocial stress, a univariate analysis of covariance (ANCOVA) was conducted comparing delta cortisol in nmol/L (Peak-Baseline) between the stress (M = 2.26, SD = 3.82) and control (A^-.19, «S!D=1.00) conditions. Gender was added as a covariate. This analysis showed a significant main effect of manipulation, F (1,98) = 7.37, p < .01, partial eta-squared = .071. Gender as a covariate did not reach significance, F (1, 98) = 2.51,/? =.12. This demonstrates the TSST was successful in producing a physiological response in those who completed it compared to those in the control group.
Hypothesis 1: LOC and Cortisol Reactivity to Acute Stress
To test the hypothesis that LOC would significantly predict cortisol reactivity to an acute stressor, a multiple hierarchal regression was performed for the experimental condition. In the first step, gender accounted for 7.8% of the variance in delta cortisol, F (1, 63) = 5.29, p = .025. Gender was a statistically significant individual predictor of delta cortisol, b = -2.51,/? = 025. When LOC was included in the second step, the model accounted for 16.4% of the variance in cortisol reactivity, F (2, 62) = 6.06,/? = .004. LOC was a significant individual predictor, b = .340,/? = .014, such that a more external LOC predicted higher increases in cortisol to the acute stressor. Gender remained a statistically significant individual predictor, b = -2.521, p = .019, such that males demonstrated higher cortisol reactivity. Table 1 shows the full multiple regression model.
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Table 1 Hierarchical Multiple Regression Predicting Cortisol from LOC
b SEB PStep 1 (R2 = . 078)Gender -2.51 1.09 -.278*
Step 2 (A R2= .086)Gender -2.52 1.05 -.280*LOC .340 .135 .293*
Note: Total Model R^.164, *■= p < .05
Hypothesis 2: LOC predicting SpeechPerformance
To test the hypothesis that LOC would significantly predict performance on the speech of the TSST, a simple regression was performed. The model was significant and explained 6.1% of the variance in speech performance, F (1, 62) = 4.04, p = .049. LOC was a significant individual predictor of speech performance, b = -.434, p = .049, such that a more internal LOC predicted better performance on the speech portion of the TSST.
Hypothesis 3: Moderation o f LOC in predicting speech performance
Due to LOC’s association with both delta cortisol and speech performance, a moderation model was used to test whether LOC moderated the effect of cortisol responses on performance. LOC and delta cortisol reactivity were added in the together into the first step of a multiple regression model. The overall model predicted 9.0% of the variance in speech performance, but was marginally significant, F (2, 61) = 3.021,/? = .056. LOC was a significant individual predictor, b = -.51, p =.02, but cortisol reactivity was not, b =.28, p= .\l. In the second step, a LOC and cortisol interaction term was added to the model. The overall model predicted 12% of the variance in speech performance but was only marginally significant, F (3, 60) = 2.74, p = .051. LOC remained a statistically significant predictor,
b= -.65, p = .009. Neither delta cortisol nor the LOC by cortisol interaction term predicted speech performance. This regression model is shown in Table 2.
Table 2 Hierarchical Multiple Regression Predicting Speech Performance
b SEB PStep 1 (R2 = .090)Delta Cortisol .275 .197 .176LOC -.511 .221 -.291*
Step 2 (AR2= .03)Delta Cortisol -.902 .842 -.577LOC -.650 .240 -.370**Delta Cortisol X LOC .090 .063 .795
Note: Total Model R ^ . 120, *=p < .05, ** =p<.01
Discussion
This research sought to determine how perceptions of control affected biological reactions to acute stress and how those perceptions affected subsequent speech performance. Several key findings emerged from our investigations. First, LOC predicted cortisol reactivity to a laboratory stressor. Participants with a more external LOC responded with higher cortisol responses to the TSST, supporting our first hypothesis. This indicates that if subjects view themselves as not having control over their environment, they are more likely to demonstrate a greater physiological response to an experimental paradigm. Our findings are in contrast with some prior research. For example, Bollini and colleagues (2004) concluded that cortisol did not differ based on LOC orientation after using a noise stressor. This inconsistent finding may be due to differences in reactions to stressors utilized, the evaluative piece present in the TSST or the measure of LOC used. Conversely, our findings are consistent with research by Lundberg and Frankenhae- user (1978), who concluded that individual
Cortisol Reactivity and Speech Performance in Response to Acute Stress / 233
differences in subjective and physiological responses to stress (e.g. cardiovascular, adrenal medullary, and adrenocortical reactions) are influenced by the extent to which the individual feels events are outside their ability to control them.
Second, LOC negatively predicted speech performance, such that a more internal LOC predicted better performance on a public speaking task, supporting our second hypothesis. While, to the best of our knowledge, this is the first study to examine speech performance and LOC, this is consistent with somewhat similar studies done with introductory college students. One study demonstrated those with an internal LOC were more likely to use facilitating anxiety and this relationship decreased as LOC became more external (Butterfield, 1964). The author described facilitating anxiety as highly adaptive and motivating in a stressful situation compared to debilitative anxiety, which is more maladaptive in that it limits success in a stressful situation, consistent with the Yerkes Dodson hypothesis of arousal. Similarly, students with a more external LOC showed higher test anxiety compared to those with an internal LOC, however, exam performance was not measured (Choi, 1998). In a study that used a mental arithmetic stressor (Walsh, Wilding & Eysenck, 1994), those with an internal LOC had a higher probability of giving a correct answer than those with an external LOC. Rotter (1966) also hypothesized that those with a more internal LOC would have a greater ability to control how they performed in certain environments, while those with an external LOC would exhibit greater difficulty maintaining performance.
Third, to confirm that LOC’s relationship to cortisol did not drive the subsequent relationship between LOC and speech performance, a multiple regression was run predicting speech performance from both LOC and cortisol. The overall model was
only marginally significant; this may be due to low power (post hoc power analysis = .66) from three predictors or, perhaps, shared variance between delta cortisol and LOC. However, despite this, LOC predicted speech performance and this was not attenuated by cortisol. This demonstrates that LOC predicts speech performance independent of increased cortisol and should be investigated in larger samples.
LimitationsThere were a few limitations that should
be addressed. First, this was a convenience sample taken from college students enrolled in an introductory psychology course. Additionally, this sample was primarily female, which is representative of the ratio of males to females in the psychology department at the university. Both factors limit our ability to generalize the findings outside of this population. Future research should recruit more male participants in order to better examine these relationships and examine community populations. Males had significantly higher reactivity to the laboratory stressor in the final model. While some research has shown gender differences are due to estrus cycle variations (e.g. Kirschbaum et al., 1999), our lab has not replicated menstrual cycle or oral contraceptive gender differences, so our analyses controlled for gender and did not stratify by gender.
Additionally, our measure of speech performance, while formatted on empirical work, was created within our lab. Future research could be done assessing these criteria and could explore other areas of performance. It is worthy to note that the criteria assessed are consistent with recent descriptions highlighting the importance of examining variables such as content, and voice quality as well as eye contact and facial expressions (Scherer & Volk, 2011).
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Broader Implications & Future Directions
To our knowledge, this research was the first to examine LOC, speech performance and cortisol reactivity using a laboratory stressor paradigm. We were able to demonstrate that cortisol did not account for the relationship between LOC and speech performance, indicating that LOC is an independent predictor for both cortisol reactivity and speech performance. In summary, this body of research demonstrates that LOC predicts both cortisol reactivity to an experimental stressor and performance on a public speaking task in a racially diverse sample of undergraduate participants.
This research adds to a growing body of literature that demonstrates functional differences between those with an internal LOC and those with a more external LOC. In terms of mental health, some research has shown a more internal locus of control to be associated with lower depression (e.g. Gray-Stanley et al., 2010), though unrelated to anxiety (Wamecke, Baum, Peer, & Goreczny, 2014). While LOC’s stability as a personality characteristic is largely accepted, Legerski, Cornwall, and O’Neil (2006) determined that LOC is not stable, such that an internal LOC can become more external. In this study, the authors concluded this happened in reaction to layoffs in a steel working plant and were a reflection of the real constraints and opportunities an individual experiences in chronic unemployment or underemployment situations. Further, psychotherapy research has shown that LOC can be malleable and changes toward a more internal LOC over the course of therapy (Baker, 1979). Future research should examine whether one can manipulate perceptions of control, perhaps by priming an internal LOC to determine whether this develops resistance to mood and physiological reactivity. Further, chronic and acute stress often interact to predict disease (e.g. McEwen & Stellar, 1993) so the
impact of LOC on chronic stress may also be an important area to consider.
Further, performance in a public speaking paradigm is ecologically valid, but this is not the sole area of performance that could be experimentally examined. Tasks that focus on executive functioning, the ability to apply past experience to future activity, or working memory may provide additional insight into areas of performance influenced by LOC. Both of these domains (memory and executive functioning) have been shown to be influenced by stress (e.g. Holmes & Wellman, 2009) and may be a promising area of future research. The present study focused on cortisol due to associations with memory, mental health vulnerability and hippocampal volume (e.g. Dickelmann, Wilhelm, Wagner, & Bom, 2011; Frodl & O’Keane, 2013; Stetler & Miller, 2011). However, other markers of stress physiological may also be examined.
LOC is an orientation that primes how individuals view the environment and their role in situations. LOC may have diverse implications for success in clinical, occupational and academic settings and merits future research for the extent that they can be explored and manipulated.
AcknowledgementsThis research was conducted within the
Psychology department of San Jose State University as a part of the work of the International Neuroeconomics Institute (INI) lab. This was partially made possible through a grant from the National Institute of General Medical Sciences (#5T34GM008253-23) to the MARC program at San Jose State University. Additionally, we wish to acknowledge the members of the INI lab at San Jose State University for their help in data collection.
Cortisol Reactivity and Speech Performance in Response to Acute Stress / 235
ReferencesAnderson, C. R. (1977). Locus of control, coping behav
iors, and performance in a stress setting: a longitudinal study. Journal o f Applied Psychology, 62(4), 446^151.
Baker, E. K. (1979). The relationship between locus of control and psychotherapy: A review of the literature. Psychotherapy: Theory, Research & Practice, 16(3), 351-362.
Bcmardi, R. A. (2011). The relationships among locus of control, perceptions of stress and performance. Journal o f Applied Business Research, 13(4), 1-8.
Bollini, A. M., Walker, E. F., Hamann, S., & Kestlcr, L. (2004). The influence of perceived control and locus of control on the cortisol and subjective responses to stress. Biological Psychology, 67(3), 245-260.
Butterfield, E.C (1964). Locus of control, test anxiety, reactions to frustration and achievement attitudes. Journal o f Personality, 32(3), 355-370.
Choi, N. (1998). The effects of test format and locus of control on test anxiety, Journal o f College Student Development, 39(6), 616-620.
Diekelmann, S., Wilhelm, L, Wagner, U., & Bom, J. (2011). Elevated cortisol at retrieval suppresses false memories in parallel with correct memories. Journal o f Cognitive Neuroscience, 23(4), 772-781.
Frodl, T., & O’Keanc, V. (2013). How does the brain deal with cumulative stress? A review with focus on developmental stress, FIPA axis function and hippocampal structure in humans. Neurobiology o f Disease, 52, 24-31.
Gray-Stanley, J. A., Muramatsu, N., Heller, T., Hughes, S., Johnson, T. P., & Ramirez-Valles, J. (2010). Work stress and depression among direct support professionals: the role of work support and locus of control. Journal o f Intellectual Disability Research, 54(8), 749-761.
Guar, S.D. & Upadhyay, H.S. (1988). Performance as a function of stress and locus of control, Journal o f Personality <6 Clinical Studies, 4(1), 85-88.
Hellhammer, D. K., Wust, S. & Kudielka, B.M. (2009). Salivary cortisol as a biomarker in stress research, Psychoneuroendocrinology, 34, 163-171.
Hollandsworth, J.G., Kazclskis, R., Stevens, J. & Dressel, M.E. (1979). Relative contributions of verbal, articu- lative, and nonverbal communication to employment decisions in the job interview setting, Personnel Psychology, 32(2), 359-367.
Holmes, A., & Wellman, C. L. (2009). Stress-induced prefrontal reorganization and executive dysfunction in rodents. Neuroscience & Biobehavioral Reviews, 33(6), 773-783.
Judge, T. A., & Bono, J. E. (2001). Relationship of core self-evaluations traits—self-esteem, generalized self-efficacy, locus of control, and emotional stability—with job satisfaction and job performance: A meta-analysis. Journal o f Applied Psychology, 56(1), 80-92.
Kirschbaum, C., Kudielka, B. M., Gaab, J., Schommer, N. C., & Hellhammer, D. H. (1999). Impact of gender, menstrual cycle phase, and oral contraceptives on the activity of the hypothalamus-pituitary-adrenal axis. Psychosomatic Medicine, 61(2), 154-162.
Kirschbaum, C., Pirke, K., & Hellhammer, D. H. (1993). The ‘trier social stress test’: A tool for investigating psychobiological stress responses in a laboratory setting. Neuropsychobiology,28(1-2), 76-81.
Kudielka, B.M., Schommer, N.C., Hellhammer, D.H., & Kirschbaum, C. (2004) Acute HPA axis responses, heart rate, and mood changes to psychosocial stress (TSST) in humans at different times of day, Psychoneuroendocrinology,29, 983-992
Lange, R.V. & Tiggleman, M. (1981). Dimensionality and reliability of the Rotter I-E locus of control scale. Journal o f Personality Assessment, 45(4), 398^406.
Legerski, E. M., Cornwall, M., & O’Neil, B. (2006). Changing locus of control: Steelworkers adjusting to forced unemployment. Social Forces, 84(3), 1521-1537.
Lundberg, U. & Frankcnhacuscr, M. (1978). Psychophys- iological reactions to noise as modified by personal control over noise intensity, Biological Psychology, 6, 51-59.
McCarthy, J. & Goffin, R. (2004). Measuring job interview anxiety: Beyond weak knees and sweaty palms, Personnel Psychology, 57(3), 607-637.
McEwen, B. S., & Stellar, E. (1993). Stress and the individual: mechanisms leading to disease. Archives o f Internal Medicine, 753(18), 2093-2101.
National Association of Colleges and Employers. Job Outlook Survey 2011, retrieved from http://www. naceweb.org/Research/Job Outlook/Job Outlook, aspx
O’Connor, T.M., O’Halloran, D.J., & Shanahan, F. (2000). The stress response and the hypothalamic-pituitary-adrenal axis: from molecule to melancholia, Quarterly Journal o f Medicine, 93, 323-333.
Parker, A. (2003). Identifying predictors of academic persistence in distance education. Usdla Journal, 77(1), 55-62.
Pruessner, J. C., Baldwin, M. W., Dedovic, K., Renwick, R-, Mahani, N. K., Lord, C., Meaney, M. & Lupien, S. (2005). Self-esteem, locus of control, hippocampal volume, and cortisol regulation in young and old adulthood. Neuroimage, 28(4), 815-826.
236 / College Student Journal
Pruessner, J.C., Gaab, J., Hellhammer, D.H., Lintz, D., Schommer, N., & Kirschbaum, C. (1997), Psycho- neuroendocinology, 22(8), 615-625.
Pruessner, J.C., Hellhammer, D.H., & Kirschbaum, C. (1999). Low self-esteem, induced failure, and the adrenocortical stress response. Personality and Individual Differences, 27,477-489.
Richmond, V.P., & McCroskey, J.C. (1995). Communication: Apprehension, avoidance, and effectiveness (4th ed.). Scottsdale, AZ: Gorsuch Scarisbrick.
Roddenberry, A., & Rcnk, K. (2010). Locus of control and self-efficacy: potential mediators of stress, illness, and utilization of health services in college students. Child Psychiatry & Human Development, 41(4), 353-370.
Rotter, J. B. (1966). Generalized expectancies for internal versus external control of reinforcement. Psychological monographs: General and applied, 50(1), 1-27.
Rubin, A. M. (1993). The effect of locus of control on communication motivation, anxiety, and satisfaction. Communication Quarterly, 41(2), 161-171.
Sapolsky RM. 1994. Why Zebras Don't Get Ulcers: A Guide to Stress, Stress-Related Diseases, and Coping. New York: W.H. Freeman.
Scarpa, A., & Luscher, K. A. (2002). Self-esteem, cortisol reactivity, and depressed mood mediated by perceptions of control. Biological Psychology, 59(2), 93-103.
Scherer, R. C., & Volk, M. (2011). Research on public speaking. Voice and Speech Review, 7(1), 287-291.
Spcctor, P.E. (1986). Perceived control by Employees: A Meta-Analysis of Studies concerning Autonomy and Participation at Work, Human Relations, 39(11), 1005-1016.
Stetler, C., & Miller, G. E. (2011). Depression and hypo- thalamic-pituitary-adrenal activation: a quantitative summary of four decades of research. Psychosomatic Medicine, 73(2), 114-126.
Viena, T.D., Banks, J.B., Barbu, I.M, Schulman, A.H., & Tartar, J.L (2012), Differential effects of a mild chronic stress on cortisol and S-IgA responses to an acute stressor, Biological Psychology, 91(2), 307-311.
Van Eck, M., Berkhof, H., Nicolson, N., & Sulon, J. (1996). The effects of perceived stress, traits, mood states, and stressful daily events on salivary cortisol, Psychosomatic Medicine, 58, 447-458.
Walsh, J.J., Wilding, J.M., & Eysenck, M.W. (1994). Stress responsivity: The role of individual differences. Personality Individual Differences, 16(3), 385-394.
Wamcckc, A. J., Baum, C. A., Peer, J. R., & Goreczny, A. J. (2014). Intercorrelations between Individual Personality Factors and Anxiety. College Student Journal, 45(1), 23-33.