Definition:  Tests designed to measure biological states.

       Description.  The intent of most of this type of testing is to link the physiological state with an educational or psychological measure.  For example, occupational stress might be correlated with measures such as heart rate or blood pressure.

Expecting broad classes of psychological and physiological phenomena to correlate, however, may represent a contemporary extension of the mistake committed by early psychologists.  They expected to find relations between many different types of physical tasks, physiological activities, and intelligence, but discovered that such correlations were absent or very small.  Over 100 years after early psychologists began the task, Cacioppo and Tassinary (1990) found that attempts to link physiological states to psychological operations remain problematic because of confusion about the relations among the categories of events measured.  They proposed that such relations be conceptualized as:

1. Outcomes, where many physiological events vary as a function of a single psychological operation with certain individuals or situations;
2. Markers, where a single physiological event varies with a single psychological operation with certain individuals or situations;
3. Concomitants, where many physiological events vary with a single psychological operation across a broad range of situations and individuals;
4. Invariants, where a single physiological event varies with a single psychological operation across a broad range of situations and individuals.

A practical contribution from physiological studies to of measurement and assessment practices is the Law of Initial Values (LIV; Wilder, 1957, 1967; Jin, 1992).  The LIV indicates that physiological responses to stimuli depend upon the pre-stimulus value of the physiological system.  As shown below, the higher the initial pulse rate, the larger will be the response to stimuli that decrease responding.  A person with a high pulse rate, as shown in Figure 2, is likely to evidence a greater change to a relaxing stimulus than a person with a moderate pulse rate.

Figure 6

Law of Initial Values