29 巻 (2014) 5 号 p. 483-492
The purpose of this paper is to test the Spiral of Silence theory in Internet society. Even today Noelle-Neumann's Spiral of Silence Theory is an important topic on the formation of public opinion. In the Spiral of Silence Theory up to now, the willingness to speak out has been handled as a dependent variable. However, there is significant bias in the question as to what extent the willingness to speak out actually influences the number of times a person speaks out. In addition, snowball sampling has been used, even in regard to the distribution of opinions of persons close to an individual. Accuracy increases because the attitudes of direct close users can be studied; however, only a small portion of close users can be studied. One defect of this approach is that it is actually quite costly. We use as a dependent variable the actual number of `tweets' on Twitter rather than willingness to speak out. In addition, for the attitude of close users, we used machine learning to estimate the attitudes of persons the users came in contact with, and we quantified homogeneity. We used and combined social investigations and behavior log analysis. With these, we were able to adopt simultaneously the following to a model: 1) individuals' internal situations, which can only be clarified by a questionnaire. 2) the actual quantity of behavior and the structure of communication networks, which can only be clarified through analysis of behavior logs. In the result, we found that a person's perception that their opinion in the majority and estimated homogeneity had a positive effect on the number of times a person spoke out. Our results suggest that the spiral of silence in regard to actual speaking out on Twitter.