In trying to determine the ability of communication to mold attitudes, Hovland contributed to the growing body of research that indicated a single message is unlikely to uproot firmly held convictions.
The study on one-sided and two-sided arguments posed this question: which method is most persuasive?
At the time of the research, there was still a war to be fought in the Pacific after defeating Germany, though many people felt the war was soon to be over. The government wanted to put the message across to soldiers that there was still work to be done and persuade them of this point of view. This presented Hovland with a unique opportunity to measure attitudes about the war, developed the communication messages differing by one variable, and determine the effect upon the men.
Hovland prepared two radio spots explaining that the war was far from over and would take at least two more years. But before the men heard the message, they were given preliminary questionnaires to see how long they believed the war would last. If they said less than one and a half years, they were considered to be opposed to the argument that the war would be long. However, if they said longer than one and a half years, they were considered as favoring the argument.
Then, half of the platoons heard a message giving the argument from one side and the other half of the platoons heard the message with both sides of the argument presented.
By comparing information such as birthdate and education of these anonymous questionnaires, the researchers could see the effect of the one-sided message on those soldiers who were initially favorable and those who were initially opposed. And the same is true for the two-sided message. Take note of the following chart:
|
Initially opposed (%)
|
Initially favorable (%)
|
|
| One-sided argument |
36
|
52
|
| Two-sided argument |
48
|
23
|
note: the percents are the net effect of change
Clearly, presenting both sides is more persuasive to those soldiers who were initially opposed to the message whereas presenting only the side favoring the argument was most persuasive to those who already held that belief.
There is another interesting point in the study in that the one-sided argument was more persuasive to men with less education. Rather, men who had graduated high school were significantly more persuaded by the two-sided argument.
In addition, further study has indicated the pitfalls of a poor two-sided argument. Merely stating contradictory arguments is not enough. These arguments must also be logical or the entire message may be perceived with distrust if opposing information is presented in a softer light. Furthermore, the ability for a two-sided argument to persuade a receiver has a second prong to the effect: the receiver may actually be inoculated to counter arguments in the future by persuasive communication that addresses counter arguments from the start.
It is particularly apropos to note the make up of the audience when preparing communication. Severin and Tankard write of this experiment and highlight "the complexity of attitude change -- that variables in the message sometimes interact with other variables, such as personal characteristics of the audience." (Severin and Tankard p. 184)