Our analysis included both the study of vote migration intention signalized by the subjects’ second opinion and the correlation of such migration intention with the EEG activity recorded during our simulation of voting. Our results strengthened the role of VDS in voting decision making by showing significant correlations between the concepts of argument credibility (e(ai)) and importance (i(ai)) and the decision determinant variables µ(Y) and µ(N), as well between these determinant variables and the brain activity recorded during argument analysis (E and I epochs) and voting decision (V epoch). However, we have also observed that VDS accounted for at most 25% of vote decision in the studied population, a fact also observed in other studies and supported by Brazilian polls (Ibope, 2005) showing that media campaign contributed at most with 30% of vote influence. The literature points to other factors that, in addition to media propaganda, also influence the voting decision and could explain the remaining 70%. As a matter of fact, the actual influence of media campaign on voting decision is still controversial. Notwithstanding this apparent conflict, it is possible to understand the actual role of VDS on vote decision if we consider that:
a) the vote vi decision of the individual i is determined in his/her own VDSi, whose determinant variables µi(Y), µi(N) are defined in his/her individual IESi and PESi; and
b) the cardinality of the intersection of the VDSi of all voters with the generic VDS idealized by marketers determines how influential it is on the election results.
In such a context and in the case of the Brazilian referendum analyzed here, this intersection is estimated to be around 30%. As a consequence, it may be stated that the study of the VDSi dynamics is of crucial importance to the understanding of vote decision. Our analysis allowed us to forecast the final election results with a very good accuracy. To the best of our knowledge, our approach and results represent a novelty in the study of political decision. As such, although encouraging, they must be taken with due caution and we hope that it may stimulate further research along the lines discussed here.