Motivation and emotion/Textbook/Motivation/Arousal
Motivation and Arousal
- 1 Motivation and Arousal
- 1.1 Introduction
- 1.2 Arousal's Contribution to Motivation
- 1.3 Theories of Arousal
- 1.4 Insufficient Stimulation and Underarousal
- 1.5 Excessive Stimulation and Overarousal
- 1.6 Sensation Seeking
- 1.7 Summary
- 1.8 Quiz
- 1.9 Key terms
- 1.10 See also
- 1.11 References
Arousal has been recognised through research to be a fundamental requirement for high cognitive and emotional functioning in both humans and animals (Miron, Parkinson & Brehm, 2007). By the end of this chapter it is expected that you will understand the mechanisms of arousal, the main theories or arousal (with focus on Drive Theory, the Inverted ‘U’ Hypothesis), and the effects of insufficient stimulation and underarousal and excessive stimulation and overarousal. We will also briefly examine Sensation Seeking and whether or not you, or someone you know takes part in arousal-seeking behaviours.
Arousal is operationally defined by sensory alertness, motor activity and emotional reactivity, and is the driving force behind the behaviour of all organisms according to their responses to stimuli (Miron, Parkinson & Brehm, 2007; Valdes et al., 2006). The three elements of the operational definition are influenced by the electrocortical, behavioural and autonomic mechanisms that provide a basic structure for understanding arousal's contribution to motivation (Pfaff, 2006, p. 77).
Mechanisms of Arousal
There are three mechanisms of arousal, electrocortical arousal that arouses the brain, behavioural arousal, and autonomic arousal that arouses the body. Often functioning independently, these three systems are only activated by the body when needed, this ensures conservation of energy and helps to limit adverse affects which come from overuse (Pfaff, 2006, p. 77).
Change to the frequency of brain waves through speeding up or slowing down is recognised as electrocortical arousal. Electrocortical arousal can be monitored through the use of an electroencephalograph (EEG), which permanently records the activity of various brain structures that are activated by electrical impulses generated by chemical processes (Nagai, Goldstein, Critchley & Fenwick, 2004). Electrocortical arousal can also be recorded through the use of Functional Magnetic Resonance Imaging (fMRI), which assesses blood flow through the brain to recognise various areas that respond to external stimuli and cognitive demands.
Behavioural arousal is measured through observable behaviours such as restlessness, tension, fidgeting, and muscle twitching (Chaplin, Hong, Bergquist, & Sinha, 2008). Alternatively autonomic arousal is recognised as a biological response, triggered by the nervous system which potentially can lead to sympathetic responses that include increased heart rate, pupil dilation, and changes in breathing (Moodie & Finnigan, 2005; Bradley, Miccoli, Escrig & Lang, 2008).
Nervous System Structures Involved in Arousal
|Reticular formation||Involved in sleep waking, alertness, and optimal brain arousal|
|Hypothalamus||Involved in appetitive and sexual behaviour, regulation of sympathetic nervous system and pituitary gland|
|Limbic system||Emotional behaviour and aggression|
|Cerebral cortex||Learning, remembering, planning, and performing motor acts|
|Sympathetic nervous system||Activates glands and smooth muscles during arousal|
|Parasympathetic nervous system||Maintains appropriate internal states during times of relaxation|
|Adrenal cortex||Secretes cortisol that regulates metabolism and stress response|
|Adrenal medulla||Secretes adrenaline and moradrenalin which are involved in activation of the body|
|Pituitary gland||Releases adrenocorticotropic hormone that stimulates adrenal cortex to release cortisol|
Arousal's Contribution to Motivation
Arousal is the energy source for behaviour; it is the primary key in the initiation, strength and persistence of all motivational behaviours (Pfaff, 2006, p. 2). You can be aroused without being motivated, yet you cannot be motivated without being aroused. Motivational arousal can increase and decrease with its level of intensity being guided by how an individual perceives a task. If a task is expected to be difficult the need for motivational arousal will increase, whereas if the task is expected to be easy motivational arousal will decrease (Miron, Parkinson & Brehm, 2007).
Theories of Arousal
Theories of arousal rest on the assumption that our bodies need to be in a state of physiological and psychological balance (Davydov, Shapiro, Golstein & Chicz-DeMet, 2007). If the body experiences excessive stimulation and overarousal, either physiologically or mentally, then arousal levels in the body increase. An increase in arousal levels will in turn motivate an individual to participate in behaviours which will reduce arousal levels back to the optimum level which is called optimal arousal (Davydov et al., 2007).
In 1943, Clark Hull proposed a linear relationship between arousal and performance ((Movahedi, Sheikh, Bagherzadeh, Hemayattalab & Ashayeri, 2007) that suggests the more aroused an athlete is the higher quality of his performance (Weinberg & Gould, 2007). The theory surrounds the belief that increased arousal will increase performance of the dominant response, whether it be learned or instinctive (Movahedi et al.).
In 1966, Spence and Spence took Hull’s theory and proposed a slightly adapted view, concentrating on the presence of stressors and overarousal. Spence and Spence referred to a learned response as habit strength, and arousal as drive in their explanatory equation that showed the outcome of a performance as dependent on three variables, incentive value, the strength of arousal, and an individual’s learned responses (McMorris, 2004, p. 246):
Drive theory is concentrated on the experience of learning new skills to complete a task, and the tendency to react instinctively when put under pressure (Weinberg & Gould, 2007). The influence of skill level on arousal and performance suggests that in the early cognitive stage of learning whilst completing an unfamiliar task under circumstances of increased arousal, an individual will act instinctively to the situation resulting in a less then moderate performance. If the same task were to be completed in the latter autonomous stage of learning with the same level of increased arousal, the level of performance is likely to be improved. This is because the instinctive response has been replaced with the correct learned response, and actions performed in heightened arousal are more likely to reflect previous experiences of the task. Learnt skills and behaviours, with practice, become habitual (Movahedi, et. al., 2007).
Drive theory has lost credibility relating to its application in real life situations, as research has been unable to support a linear relationship between drive (arousal) and performance. Instead, studies support a curvilinear relationship (Movahedi et al., 2007), with support against the theory showing an individual who is experienced in certain tasks may fail to complete them successfully under circumstances of high arousal (Weinberg & Gould, 2007). Evidence for the criticism can be recognised in the cases of athletes whose performance is outstanding in training yet do not perform well in front of a crowd. Such criticisms lead researchers away from the drive theory towards a different model known as the inverted ‘U’ hypothesis.
Inverted ‘U’ Hypothesis
In 1908 Robert Yerkes and John Dodson conceptualised a relationship between arousal and performance, putting forth the inverted ‘U’ hypothesis. Through recognising the different levels of arousal, ranging from underarousal to overarousal, Yerkes and Dodson were able to demonstrate a curvilinear relationship between arousal and performance within the inverted ‘U’ curve. The curve illustrates that the arousal level matched with a level of perceived task complexity could be an indicator of overall task performance.
The four main influences determining arousal's relationship with performance are;
- skill level,
- trait anxiety, and
- the complexity of the task
(Baechle & Earle, 2008, p. 167).
Knowledge of the four influences is able to help individuals, such as athletes, recognise how arousal affects their performance and facilitates them in exercising control over their arousal levels.
Yerkes and Dodson recognised through the inverted ‘U’ hypothesis that skill levels can increase an individual’s flexibility to perform at a high standard. The more skill a person has to complete the task, the better they can perform during states lesser or greater than their optimal arousal (Movahedi et al., 2007). If an individual lacks the skills required to complete the task correctly due the task being unfamiliar, high levels of arousal are likely to further decrease their performance. Whereas if they have previously obtained the skills needed because they are experienced in performing the task, they will be more likely to be able to correctly complete the task in greater then optimal arousal levels.
The second influencing factor that influences an individual’s optimum level of arousal is task complexity. Task complexity refers to the level of conscious attention a person needs to place on a task in order to complete it. Tasks that are low in complexity can tolerate a lower level of conscious attention and higher levels of arousal. This is possible because simple tasks require fewer decisions to be made. Tasks that are high in complexity and require a lot of decision-making require higher concentration, therefore lower levels of arousal are needed (Chamorro-Premuzic, 2007, p. 118). Driving on unfamiliar roads to get to a destination would be perceived as more complex than driving on a familiar road, such as trip from home to work. Driving on the unfamiliar road would require more conscious awareness for learning unfamiliar driving conditions, thus needing low levels of arousal in order to maintain optimal performance. Driving on the familiar road, travelling from home to work, would be able to tolerate higher levels of arousal and still maintain the optimal performance due to experience and learned skills regarding the familiar driving conditions.
Personality is the third factor influencing an individual’s optimum level of arousal. Whether a person is introverted or extraverted has been discovered as a leading factor in arousal seeking behaviours. As Eysenck (2006) concluded extraverts tend to dampen arousing effects, and thus seek out highly arousing activities in order to reach optimal levels of arousal (Chamorro-Premuzic, 2007, p. 118). Whereas introverts seek out less arousing activities because of their sensitivity to stimulation, needing only minimally arousing activities to reach their optimal level of arousal (Eysenck, 2006). This would suggest that an extraverted person would be able to perform better than an introvert if they were to complete the same highly stimulating activity.
Lastly, trait anxiety has been attributed to affecting each individual’s optimal arousal. Thoughts of failure, negative self-talk and lack of confidence tend to govern the cognitions of people with high trait anxiety (Patel, Omar & Terry, 2010), making even a simple task more complex and arousing. An individual with low trait anxiety is recognised as being able to handle a higher threshold of pressure, as they are less likely to enter into the same damaging thoughts (Baechle & Earle, 2008, p. 168). The higher the trait anxiety of an individual, the higher the likelihood of them perceiving a task as highly complex, and thus arousal levels will increase. The lower the trait anxiety, the more likely an individual is to believe they can successfully complete the task, consequently lowering task complexity and arousal levels. Trait anxiety can be measured through the State Trait Anxiety-Inventory developed by Spielber, Gorsuch and Lushene (1970), which has proven through research to show excellent psychometric properties (Hofmann, Heering, Sawyer & Asnaani, 2010).
The inverted ‘U’ hypothesis can be applied to taking steps towards achievement of goals, such as studying to pass an exam. The closer an individual is to experiencing optimal arousal, the more motivated they will be towards completing the task (Durand & Barlow, 2006, p. 448). Individual performance is shown to suffer when relaxed and under aroused or anxious and overaroused. When someone is alert to the situation and moderately aroused, optimal performance will be likely (Durand & Barlow, 2006, p. 448; Reeve, 2009, p. 347). For that reason, increasing arousal in someone who is underaroused will help to motivate them towards study behaviours, whereas increasing arousal in someone who has already reached their optimal level of arousal, or higher, will cause them to become less motivated and thus reduce their desire to study (Barkway, 2009, p. 182).
As recognised through the four main influences determining arousal's relationship with performance. an individual’s performance in a task depends on their level of experienced arousal, which fluctuates depending on how complicated or easy they perceive a task to be.
Research has failed to reveal many criticisms of the Yerkes and Dodson’s inverted ‘U’ hypothesis, yet it has come under the line of attack for its failure to recognise certain stressors being more influential than others, such as background anxiety in the form of life stress versus motivation (Ahmadi & Alireza, 2007). Yet the inverted ‘U’ hypothesis has proven its effectiveness as a tool for improving athletic performance, assisting athletes and their coaches through teaching them how to effectively adjust their arousal and reach their optimal level (Movahedi, et. al., 2007). This suggests that it may be more effective when used as a tool for recognising optimal levels of arousal than as an indicator for future performance.
Insufficient Stimulation and Underarousal
A low resting heart rate and shallow breathing have been recognised as in indicator of physiological underarousal (Baker, Tuvblad, Reynolds, Zheng et. al., 2009; Miccoli, Escrig & Lang, 2008). If a person is underaroused there is no driving force to motivate their behaviour and fulfil their needs (Miron, Parkinson & Brehm, 2007; Valdes et al., 2006).
The effects of insufficient stimulation, which is seen as a result of underarousal, can be approached through boredom and sensory deprivation research (Reeve, 2009, p. 375). Sensory deprivation refers to an individual’s sensory and emotional experience within an unchanging environment (Reeve, 2009, p. 375).
In their study, Mason and Brady (2009) took 19 volunteers from a sample of 200 and placed them in a sensory deprivation chamber which completely dampened sound and blocked out light. Each participant entered the chamber for a period of 15 minutes, and spent the time sitting on a padded chair. Before being chosen each participant was given a hallucinations scale questionnaire, out of 19 participants 9 scored in the upper 20th percentile, whilst the other 10 scored in the lower 20th percentile. Individuals in the upper percentile, those who were recognised as being predisposed to hallucinations, all recorded experiences of hallucinations and delusions whilst being inside the chamber. The remaining nine participants, not recognised as predisposed to hallucinations, also reported experiences of hallucinations or delusions yet to a lesser extent than the high percentile group.
The experiment by Mason and Brady (2009) supports theories of arousal, recognising that the brain prefers constant and moderate levels arousal from the environment, and is continuously attempting to achieve its optimal level of arousal (Davydov et al., 2007). Without external arousal the participant’s brains were left to rely on internal cognitive and behavioural methods to increase arousal.
Underarousal has been recognised as a common disposition of antisocial people and those who are involved in criminal and social deviant activities (Verschuere, Crombez, koster & De Clercq, 2006). Underarousal is also recognisable in disorders such as conduct disorder and antisocial personality disorder (Verschuere et al.).
Excessive Stimulation and Overarousal
Experiencing excessive stimulation and overarousal due to stress can be damaging.
Are you stressed?
The following quiz can provide an indication as to whether you may be experiencing levels of high arousal. If you score as stressed you may need to seek assistance to prevent further harm.
Increased heart rate, pupil dilation, and changes in breathing have been attributed to excessive stimulation and physiological overarousal (Moodie & Finnigan, 2005; Bradley, Miccoli, Escrig & Lang, 2008). The effects of excessive stimulation and overarousal can be recognised in the form of stress, as it triggers heightened levels of arousal and threatens optimal functioning.
According the the Australian Bureau of Statistics (2008) some of the main stressors affecting individual include serious illness, death, divorce or separation, mental illness, serious disability, abuse or violent crime, trouble with police, and witnessing violence. In 2008, 59% of Australians aged over 18 years reported experiencing a stressor in the past 12 months, with 21% of Australians reporting stress due to themselves or someone close to them having a serious illness, and another 21% reporting stress due to a death.
Behavioural Correlates of Sensation Seeking
People who have a high optimal level of arousal (HSS) are more likely to participate in stimulating and risky behaviours such as smoking, alcohol abuse, drug taking, extreme sports, and frequent sexual activity, whereas individuals who have a low optimal level of arousal (LSS) behave in ways which are less stimulating and take fewer risks (Roberti, 2004).
Physiological Correlates of Sensation Seeking
High sensation seekers (HSS) have a strong physiological arousal response to stimulation, as they have lower level of the platelet monoamine oxidase and dopamine, and higher levels of testosterone than low sensation seekers (LSS), making it more likely for HSS to act impulsively (due to low monoamine oxidase ) and be aggressive in competition (due to high testosterone) (Eensoo, Paaver, Harro & Harro, 2005; Carducci, 2009, p. 347).
Sensation seeking is a construct developed by Marvin Zuckerman in 1971 that has gradually become a personality trait (Roberti, 2004). Through engaging in risky behaviours a sensation seeker’s main objective is to raise levels of internal arousal, with the trait being defined by a willingness of an individual to take risks to fulfil a desire for new stimulation (Zuckerman, 2009. p. 343).
Sensation seeking traits can be measured using a self-report questionnaire developed by Zuckerman, the Sensation Seeking Scale (SSS). The scale measures the presence of four dimensions of sensation seeking in the participant, these being, thrill and adventure seeking, experience seeking, disinhibition, and boredom susceptibility (Carducci, 2009, p. 347; Roberti, 2004). The Zuckerman Sensation Seeking Scale gives a number value to each answer to give an overall accumulative score for each of the four dimensions. The scores then rank the behavioural tendencies of the participant, with low scores indicating low sensation seekers (LSS) and higher scores indicating high sensation seekers (HSS) (Walker & Broughton, 2009, p 54).
Individuals who score high on thrill and adventure (HSS) may participate in behaviours such as fast driving, whereas individuals who score low (LSS) may tend to drive to the speed limit. Experience-seeking individuals may seek arousal in trying unusual foods, such as insects. Disinhibited thrill seekers tend to seek heightened arousal from risking social behaviours like shoplifting, and boredom susceptibility thrill seekers do their best to avoid falling into routines (Carducci, 2009, p. 347; Walker & Broughton, 2009, p 54).
A study conducted by Martins, Storr, Alexandre and Chilcoast (2009) recognises that high sensation seekers are more likely to use recreational drugs such as ecstasy, marijuana, alcohol and tobacco when compared to low sensation seekers. The study delved further, recognising a strong correlation between a high sensation seeker using drugs and drug use within their group of friends. Similar studies such as Yanovitzky (2005) have supported these results suggesting associations between high sensation seeking and any drug use. Results indicate that sensation seekers look towards drugs to provide them with a quick boost in arousal.
Try the full version of Marvin Zuckerman’s Sensation Seeking Scale (SSS) for your self! Are you a low or high sensation seeker?
Arousal is triggered through responses to stimuli and is recognised as a combination of sensory alertness, motor activity and emotional reactivity. Research supports the hypothesis that arousal is the driving force behind both human and animal behaviours.
The mechanisms of arousal (electrocortical, behavioural, and autonomic) are important in arousal of the brain, behaviours and body, as they play key roles in the initiation, strength and persistence of all motivational behaviours. Theories of arousal are also of great importance as the Drive Theory and the Inverted ‘U’ Hypothesis are effective tools for recognising arousal’s affects on individual performance and can facilitates them in exercising control over their arousal levels. The inverted ‘U’ hypothesis has illustrated four main influences that determine arousal’s relationship with performance, these being skill level, personality, trait anxiety, and the complexity of a task. Each of these four influences can cause a person to experience insufficient stimulation and underarousal (seen in boredom), excessive stimulation and overarousal (stress), or to achieve the main objective of optimal arousal. With knowledge of these influences, as individuals, we can attempt to self regulate and manage our own levels of arousal in order to gain optimal experiences.
- Sensation seeking (Book chapter, 2011)
Ahamadi, K., & Alireza, K. (2007). Stress and Job Satisfaction among Air Force Military Pilots. Journal of Social Sciences, 3, 158-163. Retrieved from http://web.archive.org/web/20090419132448/http://www.scipub.org/fulltext/jss/jss33159-163.pdf
Australian Bureau of Statistics, (2008). General Social Survey, Australia, 2002. Australian Bureau of Statistics. Retrieved from http://www.abs.gov.au/AUSSTATS/abs@.nsf/Lookup/4159.0Main+Features12006
Baechle, T. R., & Earle, R. W. (2008). Essential of Strength Training and Conditioning. Winsor, ON: National Strength and Conditioning Association
Baker, L. A., Tuvblad, C., Reynolds, C., Zheng, M., Lozano, D. I., & Raine, A., (2009). Resting heart rate and the development of antisocial behaviour from age 9 to 14: Genetic and environmental influences. Development and Psychopathology, 21, 939-960. doi 10.1017/S0954579409000509
Barkway, P., (2009). Psychology for Health Professionals. Chatswood, NSW: Reed International Books Australia
BBC, (2010). Sensation Seeking Scale. Retrieved from http://www.bbc.co.uk/science/humanbody/mind/surveys/sensation/index.shtml
Bradley, M. M., Miccoli, L., Escrig, M., & Lang, P. J. (2008). The pupil as a measure of emotional arousal and autonomic activation. Psychophysiology, 45, 602-607. doi:10.1111/j.1469-8986.2008.00654.x
Carducci, B. J. (2009). The Psychology of Personality: Viewpoints, Research, and Applications. Maldon, MA: Wiley-Blackwell
Chamorro-Premuzic, T., (2007). Personality and Individual Differences. Oxford, UK: Blackwell Publishing
Chaplin, T. M., Hong, K., Bergquist, K., & Sinha, R. (2008). Gender Differences in Response to Emotional Stress: An Assessment Across Subjective, Behavioral, and Physiological Domains and Relations to Alcohol Craving. Alcoholism: Clinical and Experimental Research, 32, 1242-1250. doi:10.1111/j.1530-0277.2008.00679.x.
Davydov, D. M., Shapiro, D., Golstein, I. B., & Chicz-DeMet, A. (2007). Moods in everyday situations: Effects of combinations of different arousal-related factors. Journal of Psychosomatic Research, 62, 321-329. doi:10.1016/j.jpsychores.2006.10.021
Durand, V. M., & Barlow, D. H. (2006). Essentials of Abnormal Psychology (4th Edition). Belmont, CA: Wadsworth.
Eensoo, D., Paaver, M., Harro, M., & Harro, J. (2005). Predicting drunk driving contribution of alcohol use and related problems, traffic behaviour, personality and platelet monoamine oxidase (MAO) activity. Alcohol and Alcoholism, 40, 140-146. doi:10.1093/alcalc/agh135
Eysenck, H. J., (2006). The biological basis of personality. Brunswick, NJ: Transaction Publishing
Hofmann, S. G., Heering, S., Sawyer, A. T., & Asnaani, A. (2010). How to Handle anxiety: The Effects of Reappraisal, Acceptance, and Suppression Stratagies on Anxious Arousal. Behaviour Research and Therapy, 47, 389-394. doi:10.1016/j.brat.2009.02.010
Lutheran Church of Austrlia, (2010). Personal Stress Scale. Retrieved from http://web.archive.org/web/20060828111835/http://www.lca.org.au/resources/lmm/stressquiz.pdf
Martins, S. S., Storr, C. L., Alexandre, P. K., and Chilcoast, H. D., (2009). Adolescent Ecstasy and other drug use in the National Survey of Parents and Youth: the role of sensation-seeking, parental monitoring and peer’s drug use. Addictive Behaviour, 33, 919-933. doi:10.1016/j.addbeh.2008.02.010.
McMorris, T. (2004). Acquisition and performance of sports skills. England: John Wiley & Sons
Miron, A. M., Parkinson, S. K. & Brehm, J. W. (2007). Does happiness function like a motivational state?. Cognition and Emotion, 21, 248-267. doi:10.1080/02699930600551493
Moodie, C., & Finnigan, F. (2005). A comparison of the autonomic arousal of frequent, infrequent and non-gamblers while playing fruit machines. Addiction, 100, 51-59. doi:10.1111/j.1360-0443.2005.00942.x.
Movahedi, A., Sheikh, M., Bagherzadeh, F., Hemayattalab, R., & Ashayeri, H. (2007). A Practice-Specificity-Based Model of Arousal for Achieving Peak Performance. Journal of Motor Behavior, 39, 457–462. doi: 10.3200/JMBR.39.6.457-462
Nagai, Y., Goldstein, l. H., Critchley, H. D., & Fenwick, P. B. (2004). Influence of sympathetic autonomic arousal on cortical arousal: implications for a therapeutic behavioural intervention in epilepsy. Epilepsy research, 58, 185-193. doi:10.1016/j.eplepsyres.2004.02.004
Patel, D. R., Omar, H., & Terry, M. (2010, September 28). Sport-related Performance Anxiety in Young Female Athletes. Journal of Paediatric and Adolescent Gynecology. doi:10.1016/j.jpag.2010.04.004
Pfaff, D. (2006). Brain arousal and information theory: neural and genetic mechanisms. Cambridge, MA: Harvard University Press.
Rai, U., & Singh, I. (2009). Personality Type and Cued Vigil Performance. Journal of the Indian Academy of Applied Psychology, 35, 107-111. Retrieved from http://medind.nic.in/jak/t09/i1/jakt09i1p107.pdf
Reeve, J. (2009). Understanding motivation and emotion (5th ed). Hoboken, NJ: Wiley
Roberti, J. W. (2004). A review of behavioural and biological correlates of sensation seeking. Journal of Research in Personality, 38, 256-279. doi:10.1016/S0092-6566(03)00067-9
Spielberger, C. D. (2004). Encyclopedia of applied psychology. Amsterdam: Elsevier Academic Press
Spielberger, C. D., Gorsuch, R. L., &Lushene, R. E. (1970). State-Trait Anxiety Inventory. Palo Alto, CA: Consulting Psychologists Press
Valdes, J. L., Maldonado, P., Recabarren, M., Fuentes, R., & Torrealba, F. (2006). The infralimbic cortical area commands the behavioral and vegetative arousal during appetitive behavior in the rat. European Journal of Neuroscience, 23, 1352-1364. doi:10.1111/j.1460-9568.2006.04659.x
Verschuere, B., Crombez, G., koster, E. H., & De Clercq, A., (2006). Antisociality, underarousal and the validity of the Concealed Information Polygraph Test. Biological Psychology, 74, 309–318. doi10.1016/j.biopsycho.2006.08.002
Walker, L., & Broughton, P. (2009). Motorcycling and leisure: understanding the recreational PTW rider. Surrey, England: Ashgate Publishing Company
Weinberg, R. S., & Gould, D., (2007). Foundations of sport and exercise psychology. United States: Human Kinetics
Yanovitzky, I., (2006). Sensation seeking and alcohol use by college students: examining multiple pathways of effects. Journal of Health Communication, 11, 269-280. doi:10.1080/10810730600613856
Yerkes, R. M., & Dodson, J. D. (1908). The relation of strength of stimulus to rapidity of habit formation. Journal of Comparative Neurology and Psychology, 18, 459-482. doi: 10.1002/cne.920180503