The influence of demand characteristics and expectancies in the measurement of salivary response

Abstract

The sensitivity of safivary response measures to demand and expectancies was studied. One hundred thirty-one college students were tested for increases or decreases in salivation under one of three conditions: (a) when tom to imagine the taste of another food more or less palatable than a target food; (b) when given a placebo pill that, they were told, would alter their salivation; and (c) INTRODUCTION Wooley (1973, 1977) propose that some of the problems encountered in the assessment of hunger and appetite might be overcome by the use of measures of salivation. They suggest that salivation measures, (Stunkard, 1959;Stunkard and Koch, 1964). Because of these assumed advantages of salivation measures over subjective ratings, the Wooleys and their colleagues have utilized these measures in studies of the sensitivity of obese and nonobese to caloric intake (Wooley et al., 1975b) and the effects of slow vs. rapid food consumption on hunger and palatability of food (Wooley et al., (1975a). Salivation has also been employed as a dependent measure in a study designed to assess the effectiveness of covert sensitization in treating overeating (Diament and Wilson, 1975).However, no studies have been conducted directly assessing the responsivity of salivation measures to suggestion and demand. Some data, however, are available that suggest that operant procedures and feedback can influence salivation in humans, and lower animals (Brown and Katz, 1967;Delse and Feather, 1968;Frezza and Holland, 1971;Miller and Carmona, 1967;Wells et al., 1973). Furthermore, and even more pertinent to the uses of the salivary response measure cited above, Barber et al. (1964) reported that subjects were able to alter salivation in line with the experimenters' directions to imagine that water placed on the tongue was a previously tasted solution of citric acid and that citric acid placed on the tongue was water.Wooley and Wooley (1973) cited some of the above studies as well as others that suggest that salivation cannot be consciously altered. However, no attempt was made in any of these studies to measure salivation using the procedure outlined by the Wooleys, nor were subjects exposed to a variety of demand or expectancy conditions. Thus, the present study was designed to investigate specifically whether subjects who received instructions could alter their salivary response to a target food. Some subjects received direct suggestions to modify their salivation; others received indirect suggestions. In addition, half of the subjects were instructed to increase salivation, while the remaining subjects were asked to decrease salivation. METHOD SubjectsOne hundred thirty-one undergraduate psychology students served as subjects and were randomly assigned to 1 of 12 groups according to a 2 x 2 Demand and Expectancy in Salivation 181x 3 x 2 factorial design, with palatability of selected food, direction of intended change, type of instruction, and time of assessment (a repeatedmeasures term) as factors. Dependent MeasuresThe procedure for measu...

Recording of Swallowing Events Using Electromyography as a Non-invasive Measurement of Salivation

“…Moreover, it is unpleasant for subjects to void saliva; the method does not allow online monitoring and thus requires interruption of the experiment. The ideal technique is non-invasive, does not interfere with appetite or craving for drugs, permits study of the change in salivary flow over time and minimizes the influence of demand characteristics and expectancies, which are also found to influence the salivatory response (Siegel & Hagen, 1982). It will therefore be a great advantage if subjects are not aware of the measurement of their salivation.…”