The Reliability and Validity of Salivation as a Measure of Individual Differences in Intrinsic Arousal. Report from the Project on Motivation and Individual Differences in Learning and Retention.

Two studies were reported which attempted to estimate the stability and construct validity of human salivary response as a measure of individual differences (IDs) in physiological arousal. Twenty-second base line estimates and 20-second response levels to four drops of lemon juice were measured, with the former value being removed from the latter to form the salivary score for a given subject. The first study obtained a test-retest correlation over 24 hours for the net salivation score of 0.78 (N = 25; p<.001). The second study involved the measurement of the threshold of fusion of paired light flashes [two-flash threshold (TFT)], a previously validated index of arousal, as well as salivation. The correlation between net salivation and TFT on 25 subjects was -.57 (p<.01). It was concluded that the salivary measure has demonstrated promising psychometric properties for use in ID research. (Author)