Failure of instructional set to affect completeness of taste adaptation

The effect of task instructions on taste adaptation was investigated in two experiments. In the first experiment, three groups of subjects received a 3-min flow of salt solution, over the anterior dorsal tongue surface and periodically gave magnitude estimates of its intensity. Each group had previously received different instructions suggesting the appropriate outcome of the adaptation experiment. Not all subjects showed adaptation, and the instructions had no significant differential effects. In the second experiment, subjects who were practiced in judging pulsatile taste stimuli were instructed to rate the intensity of a continuous salt stimulus as it disappeared, but this produced no increased adaptation. Several possible hypotheses are presented to account for this repeatedly observed failure of many subjects to completely adapt to taste stimuli.