An experimental study of influences on the perceived likelihood of seeking genetic testing: "nondirectiveness" may be misleading

It has been suggested that decision making involves the implicit weighing up of those advantages and disadvantages of possible options considered relevant at the time the decision is made. If this is so, the information that people have most readily available at the time of the decision would influence the decision outcome. The study reported here experimentally evaluates the effect of manipulating the issues on which individuals focus as a way of investigating subtle directive influences. Participants (n = 104) were interviewed about their anticipated likelihood of opting for testing for hereditary hemochromatosis. All participants were given standard information about hemochromatosis, including a description of the disorder as causing progressive damage over many years and an explanation that treatment is most effective if begun before the age of 30 years. Individuals were randomly allocated to groups according to age group (30 years and under, or over 30 years) and gender. Those allocated to the positive group were then encouraged to focus on positive aspects of the previously given information by considering the extent to which statements applied to them, whereas the negative group focused on negative aspects. The control group focused on an unrelated disease. Analyses of variance indicated that the focusing manipulation affected the likelihood of opting for testing. This effect interacted with age of respondent: in participants over 30, the positive group ratings of likelihood of testing increased, whereas in the negative group they decreased; in participants 30 and under, both the positive and negative groups showed an increased desire to be tested. The control group did not alter significantly. The relevance of these findings to "nondirective" approaches to genetic counseling is considered.