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The Effects of Psychological Stress on Reaction TimeJade VegaUniversity of Maryland University CollegeAbstractPsychological stress impacts, and has the potential to impact, many aspects of individuals’ lives, including physiological and emotional states. Research correlating anxiety, sleep deprivation, and other factors which can be closely aligned with psychological stress, indicate that perhaps psychological stress can lead to an increase in individual reaction time. This study recruited 100 adult participants who do not have any diagnosed mental disorders which could be the cause of their stress. Half of the participants were assessed and placed in a “significantly psychologically stressed” group, and half were considered non-significantly stressed. Participants then completed a simple, computer-based reaction time task. Results of the trials, which are inconclusive but suggest future research is warranted, are presented here. The Effects of Psychological Stress on Reaction TimeIntroductionPsychological stress affects each person differently, although its effects can include a wide range of emotional and physical symptoms. Stress may be associated with daily routines, or caused by sudden life changes and trauma. Individuals respond to and perceive their stress levels uniquely. Research has shown that significant stress can also cause increases in heart rate, blood pressure, and respiration rates (Costin, Rotariu & P?s?ric?, 2013). Stress can affect a person’s thoughts and feelings, behavior, and physiological state. Since stress can be distracting, it may affect a person’s ability to react as quickly to stimuli as those who are not experiencing significant stress. Many known factors influence reaction time, including arousal or states of attention, age, mental and physical fatigue. Several of the factors which affect reaction time can be effects of psychological stress. Several studies have studied the effects of stress on reaction time, although few have made the distinction of “mental” or “psychological” stress, and this factor is usually studied along with others. One study, for example, studied the effects of psychological stress on reaction time, along with studying the effects of gender and color of stimulus on reaction time. The study found that psychological stress "resulted in a significant decline in the reaction time" to a specific color in male participants (Venkates, Ramachandra, Baboo & Rajan, 2002, p. 560). It is difficult to draw specific conclusions about the role of psychological stress from this study, since a number of factors were being tested. It also only points to a decline in reaction time for males. A study published in "Language Learning" found that stress increases processing time for language skills (Rai, Loschky, Harris, Peck, & Cook, 2011). The study does not deal with simple visual stimuli, but involved testing the effects of several factors on foreign language readers' inferential processing during reading comprehension. Although the manner of testing is very different, the study does show that stress decreases comprehension, as well as reaction, time. Another study focused on the effect of premenstrual stress on audiovisual reaction times. The study, however, like many others, was not measuring effects of solely psychological stress- in this case, the factor of stress in premenstrual phases was found to result in decreased reaction times (Das, Gandhi, & Mondal, 1997). One study that focused strictly on the effects of stress and anxiety on reaction time relied predominantly upon experimentally induced stress (Farber & Spence, 1956). The effects of experimentally induced stress were unclear, and thus non-conclusive. Although there is a lack of study in regards to the particular effects of non-experimentally induced psychological stress on reaction time, many researchers have published findings that indicate stress may have a significant impact. Many researchers have noted the fact that significant, or excessive, stress can cause: anxiety, reduced concentration, sleep difficulties, and more (Swann, 2011). Jones and Hardy found that anxiety tends to result in an increased reaction time (1988). Sleep deprivation, another symptom which may be associated with psychological stress, has been found to play a role in increasing participant reaction time (Carlozzi, Horner, Kose, Yamanaka, et al., 2010). There have been enough findings about the effects of stress to lead researchers to believe psychological stress may impact reaction time, and this subject warrants further study. The hypothesis of this study is that stress increases reaction time. MethodParticipantsThere were 100 participants in this study. The participants were placed into two groups: Group A was comprised of participants who were experiencing significant psychological stress at the time of the study, and Group B included those who were not experiencing significant psychological stress. Each group contained 50 participants, with half of the participants being male and half being female in each group. Participants were recruited via an online system. A small cash incentive was offered to participants to compensate for the time needed to perform testing before the study. A disclaimer was added that any individuals who have received a DSM diagnosis of a psychological disorder did not qualify for this study. Researchers in this study were only interested in the effects of psychological stress that cannot be attributed to a psychological disorder. MaterialsTwo self-report paper examinations, the PSM- 9 measure of psychological stress and a Perceived Stress Scale were given to participants after initial interviews. A blood pressure cuff, sphygmomanometer, and stethoscope were used to measure participants’ blood pressure. A cardiovascular belt was used to measure heart and respiratory rates. The reaction time study was computer-based; only a computer was needed for the study itself. Design There were two conditions in this study: significantly psychologically stressed and not significantly psychologically stressed. Participants were evaluated by a psychiatrist in a short diagnostic interview, administered self-assessments of their stress levels, and given physiological tests (heart rate, respiratory rate, blood pressure) before being placed into the appropriate group. Participants’ reaction times to a simple computer-based task were then measured and statistically analyzed to determine whether or not there is a significant difference in reaction time between groups. ProcedureUpon realizing that there was a lack of data in the scientific community regarding the relationship between stress and reaction times, the research team discussed experimental ideas and completed a Review Board Form (RBF), also referred to as an IRB form. A copy of this form can be found in the Appendix. After participants volunteered to participate in the study, they were given an appointment time to undergo further diagnostic testing, in order to place them in the correct groups. In order to rule out any participants with symptoms that may meet the criteria for a DSM-V diagnosis of a psychological disorder, a brief diagnostic MINI interview was given to all participants. MINI stands for “mini-international neuropsychiatric interview". The interview lasted for approximately fifteen minutes. Following the interview, all remaining participants were given self-assessments. The first self-assessment was a psychological stress measure, or PSM. The PSM-9 is a 49-item self-report measure of psychological stress (Lemyre?& Lalande-Markon, 2009). Participants answered questions relating to their personal perceptions of stress in their lives for the four or five days prior to assessment. A perceived stress scale, consisting of ten questions related to the participants’ perceptions of events in the past month, was then administered. The Perceived Stress Scale, PSS, assesses "the extent to which respondents find their lives unpredictable, uncontrollable, and overloaded" (Al kalaldeh & Shosha, 2012, p. 45). These aspects are important in order to understand individuals' stress experience, including the severity. PSS has been shown to be an effective way to measure the relationship between individuals' perception of stress and their risk for diseases and behavioral disorders (Al kalaldeh & Shosha, 2012). Understanding participants' perceptions of their stress levels was crucial in order to place them into the appropriate groups. After the self-report measures were administered, physiological data were taken. Since significant stress may impact a person’s resting heart rate, respiratory rate, and/or blood pressure, all of these were measured. In order for a participant to be placed into the psychologically stressed group, they needed to have one abnormal rate which may be indicative of a stress-induced reaction. For example, acute stress has been known to increase systolic blood pressure. If a participant had an increased systolic rate, combined with scores evaluated by a professional as indicating high levels of stress, they were placed into the significantly psychologically stressed group. Overall, participants were placed into the psychologically stressed group if they: were not experiencing stress as a byproduct or symptom of a psychological disorder, indicated on self-report measures that they feel overwhelmed with stress, and had some sort of abnormal physiological rate (heart, respiratory, or blood pressure). Participants had a short break after the physiological tests, and proceeded on to the computer-based simple reaction time task. In the task, participants were shown a visual stimulus and needed to react to the stimulus as quickly as possible. In each trial, the screen was white for short times, which varied with each trial, and then a color would appear on the screen. As soon the color appeared, the participants were to press any key. This trial was repeated 20 times and information about their reaction times was gathered and statistically analyzed.During the statistical analysis of data collected, means for the reaction times of each group were calculated. Standard deviations and standard errors of the mean for the samples were also calculated. A two-sample unpaired t test was performed to calculate the t and p values for the data. An alpha level of .05 was employed to determine the significance of the difference. ResultsThis study was aimed at discovering what, if any, relationship exists between psychological stress and reaction time. Researchers believed that significant psychological stress would distract individuals, and produce emotional and physiological symptoms that would result in their reaction times being lower than non-stressed persons. Data was collected from all 100 participants’ trials and statistically analyzed. The mean reaction time for the psychologically stressed group was .476 seconds. The mean reaction time for the non-psychologically stressed group was .347 seconds. The results are shown in the figure below. The standard deviation of the psychologically stressed group’s reaction times was .406. The standard error of the mean of was .057. The standard deviation of the non-stressed group’s reaction times was .224. The standard error of the mean was .032. T test calculations were performed with 98 degrees of freedom. The t value for this data was 0.0516. The two-tailed p value of this data was calculated to be 0.0516. This is not quite statistically significant. However, it is important to note that this is close to statistical significance; future studies may yield results that indicate a stronger statistical relationship. Figure 1.1 Mean of psychologically stressed and non-psychologically stressed reaction timeslefttopDiscussionThis study attempted to discover whether or not non-experimentally induced psychological stress has an impact on reaction time. While there was a difference, it is not conventionally considered to be quite statistically significant. This study is one of the only that has focused solely on psychological stress and reaction time. Its findings provide support for the hypothesis that stress impacts reaction time, although future research and more conclusive results regarding this type of stress are needed. A theoretical implication of this study is that persons who are psychologically stressed may take longer to react. Although the results are not highly significant and are preliminary, future research could shed light upon further implications. Being able to quickly respond to situations, especially dangerous ones, in everyday life is vitally important. Individuals who experience significant psychological stress may be at a disadvantage when participating in sports and daily activities, such as driving. Measures of psychological stress, such as the diagnostic interview and self-assessments utilized in this study, are inherently subjective. The study is limited by the fact that these determinations about levels of stress are subjective. Different measures, such as tests which included varied types of stimuli (ie. Reacting to different colors, etc.) may have yielded more reliable results. Another limitation of the study is that the reaction time tasks were short, and beyond the first set of 20 trials, were not repeated. Repeated tasks, and thus more data collected, may have yielded more conclusive results. Future research could incorporate more reaction time tests, larger sample size and perhaps more varied methods of testing them. More rigorous assessment methods, such as longer diagnostic interviews, may also be a component of future studies. Self-assessments that reveal more information about participants’ history with stress and any accompanying symptoms may also be useful in placing participants into groups to reduce possible error or individual bias. Everyday life tends to be more work and stress than time for individuals to rest. As a result, many people suffer from significant levels of stress. Stress has been linked to many short-term and long-term physical and emotional complications. Understanding the effects of stress can lead researchers and individuals to better understand how stress works, and thus how to better prevent its deleterious effects. AppendixReview Board FormTitle of Experiment: The Effects of Psychological Stress on Reaction TimeName(s) of Researchers: Jade VegaBriefly describe the purpose of the experiment.The purpose of the experiment will be to examine the relationship between significant psychological stress and reaction time. Who will be the participants? How will they be chosen?The participants will be adults who do not have any psychological disorders, and who do not qualify for a DSM-V diagnosis. Recruitment and sign-ups for the study will be online, and participants will be screened by a psychiatrist before other assessments to ensure that it is not likely their stress is attributable to a psychological disorder. How will confidentiality be maintained? How will you identify data associated with each participant? Confidentiality will be maintained by using study codes for all documents containing information about participants, which only primary researchers will have access to. No dates of birth or other identifying information, beyond basic information, will be collected and after the study this identifying basic information will be destroyed. Are there any potential risks, physical or psychological, to participants? If so, what? How will you, as the researcher, minimize these risks?There will be no physical risks posed to participants. The tests that will be administered to determine participants’ stress levels may create more stress for some individuals. To minimize this additional stress, self-assessments will be kept brief and physiological tests will be basic- heart rate, blood pressure, and respiratory rate. Heart rate and respiratory rate will be measured simultaneously.Describe your debriefing procedures.Participants will be asked whether, at any point during the initial phases or study itself, they felt suspicious or unclear about the procedure. We will also assess participants' states of mind before they leave; we will ask if they have any further questions, how they are feeling (if they are feeling at least the same as when they arrived- if not, referred for counseling), and asked if they have any ways to improve similar studies in the future. We will also request participants not to reveal information about the study to others, thank them for their participation, and provide them with the head researcher's contact information in case any future questions or concerns arise.Describe the procedures of the study. Give enough detail so that the Board can make a judgment about your study.Once suitable participants (adults without a DSM diagnosis) are recruited, they will be administered brief physiological (heart rate, respiratory rate, and blood pressure) and psychological (self-report information about stress in their lives, brief interview with a psychiatrist to rule out any persons whose stress may be attributed to a mental disorder) assessments. This information will be used to place participants into two groups: participants that are significantly psychologically stressed at the time of the study, and participants who are not significantly psychologically stressed. Participants will complete a short, computer-based test which asks them to respond to a visual stimulus by pressing any key. Reaction times will be recorded by the computer and statistically analyzed. Jade Vega 11/22/13__________________________________________Researchers Signatures (may be electronic)DateReferencesAl kalaldeh, M., & Shosha, G. (2012). Application of the perceived stress scale in health care studies. an analysis of literature.?International Journal of Academic Research,?4(4), 45-50.Carlozzi, N., Horner, M., Kose, S., Yamanaka, K., Mishory, A., Qiwen , M., & Nahas, Z. (2010). Personality and reaction time after sleep deprivation.Current Psychology,?29(1). Costin, H., Rotariu, C., & P?s?ric?, A. (2013). Identification of psychological stress by analyzing electrocardiographic signal.?Environmental Engineering & Management Journal?,?12(6), 1255-1263.Das, S., Gandhi, A., & Mondal, S. (1997). Effect of premenstrual stress on audiovisual reaction time and audiogram.?Indian Journal of Physiology and Pharmacology,?41(1). Farber, I., & Spence, K. (1956). Effects of anxiety, stress, and task variables on reaction time.?Journal of Personality,?25(1). Lemyre , L., & Lalande-Markon, M. (2009). Psychological stress measure (psm-9): integration of an evidence-based approach to assessment, monitoring, and evaluation of stress in physical therapy practice. Physiotherapy Theory & Practice,?25(5-6), 453-62.Rai, M., Loschky, L., Harris, R., Peck, N., & Cook, L. (2011). Effects of stress and working memory capacity on foreign language readers' inferential processing during comprehension.?Language Learning, 187-218.Swann, J. (2011). Understanding the common triggers and effects of stress.?British Journal of Healthcare Assistants,?5(10). Venkatesh, D., Ramachandra, D., Baboo, N., & Rajan, B. (2002). Impact of psychological stress, gender and colour on visual response latency.?Indian Journal of Physiology and Pharmacology,?46(3). ................
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