Psychophysiological Measurement

The text discusses various strategies for measuring activity in the brain, focusing especially on more recently developed techniques such as PET, SPECT, or MRI. There are, of course, other bodily systems and other techniques for measuring them, many of which rely on the electrophysical activity of the body.

  • EMG - Electromyography. An electromyogram records the action potential given off by contracting muscle fibers. A common example is the recording of facial EMG, in which either inserted electrodes or surface electrodes record the activity of muscles as they pose various expressions.

  • EGG - Electrogastrography. Electrogastrograms provide a record of smooth muscle activity in the abdomen. The contractions of the stomach or intestines, for example, can be measured by comparing the readings from a surface electrode attached to the abdomen with those of an electrode attached to the forearm. In the special case of measuring contractions in the esophagus, surface electrodes are attached to a balloon, which is "swallowed" by the person being measured. EGG may be used successfully to gain information about fear, anxiety, or other emotional states.

  • EOG - Electrooculography. Readings from electrodes placed around the posterior of the eyes are the basis for EOG. Electrical signals result from both small saccadic eye movements as well as more gross movements that can be directly observed. EOG can be used for measuring rapid eye movements during sleep.

  • EKG - Electrocardiography. EKG records changes in electrical potential associated with the heartbeat. Electrodes are placed at various locations on the body, and their recordings yield five waves that can be analyzed: P-waves, Q-waves, R-waves, S-waves, and T-waves. EKG may be used by psychologists to supplement observations relevant to stress, heart disease, or Type A behavior patterns.

  • EDA - Electrodermal Activity. Formerly called galvanic skin response, skin resistance, and skin conductance, EDA refers to the electrical activity of the skin. As activity in the sympathetic nervous system increases it causes the eccrine glands to produce sweat. This activity of the eccrine glands can be measured by EDA, regardless of whether or not sweat actually rises to the skin surface. The folklore of "sweaty palms" associated with a liar might be measured using this technique.

  • EEG - Electroencephalography. As discussed in the text, EEG provides information about the electrical activity of the brain, as recorded by surface electrodes attached to the scalp. EEG has been used in a variety of ways to gather information about brain activity under a wide range of circumstances.

  • Pneumography. Pneumographs measure the frequency and amplitude of breathing, and are obtained through a relatively straightforward procedure. A rubber tube placed around the chest expands and contracts in response to the person's inhalations and exhalations. These changes can then be recorded with either an ink pen or electrical signal.

    McGuigan, F. J. (1994). Biological psychology: A cybernetic science. Englewood Cliffs, NJ: Prentice Hall.