When given an unfixed challenge, accompanied by incentives like money or status, people will push themselves to the limits of their ability, increasing their heart rate and blood pressure in the process.
These findings support previous research indicating that high cardiovascular responses can be a sign of intense motivational and emotional states. Such findings are important because chronically elevated cardiovascular responses may lead to cardiovascular disease.
“A link between pronounced cardiovascular responses and negative health outcomes is by no means certain,” says lead study author Rex Wright, Ph.D., of the department of psychology at the University of Alabama at Birmingham, but most common models of heart disease and hypertension include an overworked cardiovascular system as a risk factor.
The study results are published in the February issue of the journal Psychophysiology.
Wright and colleagues compared the cardiovascular effects of challenges having fixed and unfixed goals. Fixed challenges -- such as a weight lifting competition -- require a specific performance level. Unfixed challenges allow people to perform as well as they choose, within their level of ability. Examples of unfixed challenges include a weight lifting competition where participants earn more money as they lift more weight, a persuasive speaking engagement or a university exam.
In the first of two experiments, 90 male college students were given either a fixed or unfixed challenge. Those in the fixed challenge group were instructed to press the button on a computer mouse every 10 seconds, while those in the unfixed challenge group were instructed to press the button as many times as possible.
Blood pressure and heart rate rose significantly more for those given the unfixed task compared with those who were only required to press the button every 10 seconds.
The researchers were also interested in measuring how the participants are motivated by status. They told one group of participants that the responses would be private, while others were told their responses would be assessed either by an undergraduate (a low-status observer) or a medical school professor (a high-status observer).
The presence of an observer created an even more pronounced response in terms of blood pressure and heart rate.
In the second experiment, 40 undergraduate women were given either fixed or unfixed tasks involving scanning pages full of jumbled letters. Those in the fixed challenge group were instructed to circle the letter “E” each time they heard a tone. Those in the unfixed group were instructed to circle as many “E”s as they could for the duration of the session.
Wright and colleagues were also interested in measuring how these participants were motivated by financial reward. They told half of the women they could earn a nickel for every two “E”s they circled, while the others were told they could earn a penny for the same task.
This experiment produced similar findings as were seen in the experiment in which men participated. Those who had the freedom to work as hard as they chose and who had the strongest incentives had the greatest cardiovascular responses, the researchers found.
Preparation of the study article was partially funded by a grant from the National Science Foundation.
Psychophysiology is the official peer-reviewed journal of the Society for Psychophysiological Research. For informationabout the journal, contact Gregory A. Miller, Ph.D., at (217) 333-6312.
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Psychophysiology