There are six responses that scientists commonly look at to study emotions. These are heart rate, blood pressure, blood volume, electrodermal responses, muscle potential, and brain wave patterns, or electroencephalograms (EEGs). All are controlled by the nervous system.
Heart Rate This is the physiological response we think of first in connection with emotional situations, both because we recognize a thumping heart so clearly and because of the heart`s mythic role as the center of emotions, where love, rage, and hatred supposedly hold sway.
Blood Pressure This term refers to the force exerted by the heart to push blood out of the arteries. There are great changes in blood pressure during highly charged emotional states.
Blood Volume Bloods vessels can constrict and dilate (expand), which alters the rate of blood flow through them. When we grow pale with fear, the flow of blood to our faces has been restricted (vasoconstriction). In a person whose face is red with embarrassment, in contrast, the blood vessels are dilating, increasing the flow of blood to the face (vasodilation).
Electrodermal Responses The skin, like all of the rest of our bodies, can conduct electricity. During strongly emotional states we sweat, and the added moisture makes the skin better able to conduct electricity than at other times. The degree of conduction can be measured by placing metal electrodes on the skin.
Muscle Potential Muscles often give us visible signs of emotion – the tightening of the jaw when angry, the activation of the facial muscles that form a smile. Each use of a muscle generates a burst of electricity, which scientists can measure to obtain an estimate of emotional activity.
EEG (Electroencephalogram) The brain also emits electrical waves that can be measured by placing electrodes on the skull. The resulting pattern of waves is called an electroencephalogram, or EEG for short. There are four types of brain waves, but only two are frequent in adults: alpha waves, which are the rhythm of the awake and relaxed adults, and beta waves, which indicate an alert or excited state.
References :
William W. Grings and Michael E. Dawson, Emotions and Bodily Responses, New York : Academic Press, 1978.
Marvin R Levy, Mark Dignan, Janet H Shirreffs, Essentials of Life & Health, Fourth Edition, Random House, New York, 1984.
