[Persuasive communications and regular blood donation: an experimental study].

This study aimed to: investigate yielding to the dependent variable "behavioral intent to become a regular blood donor", verify the impact of such communications on variance in the dependent variable, examine the single contribution of the external independent variable to the Rational Action Theory, and test the fit of the expanded Rational Choice Theory to the target behavior and sample. Only a post-test design and double-blinded procedure were used, randomly picking 405 university students for experimental groups 1 and 2, placebo control, and control only. The results showed: lack of yielding by the experimental groups; considerable percentage variance in the dependent variable explained by the independent variable in the experimental and placebo control groups; and satisfactory and significant correlations for variables in the expanded theory. Absence of yielding for the criterion variable was probably due to the time interval. The positive persuasive strategy accounted for the greatest variance in the dependent variable. Moral obligation showed the greatest impact on participants' intent to perform the behavior. The correlations corroborated the theoretical and methodological validity of the expanded theory.