Psychophysiological Assessment

1. ADAPTATION PERIOD
   Although the adaptation period has long been debated in psychophysiological research, few studies provide empirical data indicating its optimal duration.

The adaptation period is the time a participant spends in the experimental setting before baseline measurements or the experiment itself begin. In psychophysiological research and clinical practice, this period serves three purposes:

• it allows the participant to become familiar with the experimental setting;
• it reduces pre-session effects, such as tension carried over from daily life and the effects of differences in temperature, lighting and other environmental conditions;
• it allows the orienting response to subside and psychophysiological responses to stabilize. This is particularly useful during the first biofeedback (BFT) sessions.

Some authors (Arena & Schwartz, 2003) recommend an adaptation period of at least five minutes, although some participants—particularly those who are more anxious—may require more time.

In any case, it is sensible to tailor the adaptation period to the individual. If a participant’s tension remains high after five minutes, for example, the period can be extended. During this time, the participant may ask the practitioner questions, review examples and become more familiar with the procedure.

 

2. PSYCHOPHYSIOLOGICAL BASELINE
   The baseline measurement period follows the adaptation period, once the participant’s psychophysiological responses have stabilized. Its primary purpose is to observe and measure psychophysiological activity at rest. Practitioners generally need to compare resting values (the baseline) with values recorded under experimental or treatment conditions, because changes in raw scores—or percentage changes—depend on the starting baseline.

Baseline measurement is essential in cardiovascular research, for example, because measures of cardiovascular reactivity are almost always expressed relative to baseline.

Researchers do not agree on whether the eyes should be open or closed during baseline measurement. Schwartz (1995), for example, recommends closed-eye baseline measurements for conditions such as insomnia, whereas open-eye measurements may better reflect real-life conditions in cases involving headache or other symptoms.

 

3. STIMULATION PHASE
   Cognitive and/or physical stressors are administered to assess an individual’s psychophysiological reactivity and capacity for recovery.

Assessing reactivity and recovery capacity is useful in the evaluation and treatment of psychosomatic disorders and may also help predict risk factors for these disorders (Haynes et al., 1991).

There are two independent stress circuits (Haynes et al., 1991):

• The first involves the sympathetic branch of the autonomic nervous system (ANS). The hypothalamus organizes this pathway in response to input from cortical and subcortical structures. Its onset is rapid and it reaches peak effect quickly through the release of epinephrine and norepinephrine from nervous tissue and the adrenal glands.
• The second pathway is the hypothalamic–pituitary–adrenal (HPA) axis. The hypothalamus again performs a regulatory role, but here it triggers the pituitary gland to release ACTH (adrenocorticotropic hormone), which in turn stimulates cortisol release from the adrenal cortex. These effects develop more slowly and take longer to reach their peak.

 

4. POST-STRESS ADAPTATION PERIOD AND RECOVERY INDEX
   The duration of stress influences its effects: brief stress may make neurotransmitter systems more efficient, whereas prolonged stress may impair them. Persistent stress lowers norepinephrine, alters ACTH regulation, promotes cortisol release and suppresses the immune system.

The type of stress—physiological and/or psychological—also matters. When measuring psychological stressors, practitioners should bear in mind that cortisol responds most strongly to distress that is perceived as subjective, uncontrollable and psychologically significant (Diestberger, 1989).