The presented study is concerned with one aspect of the effect of a "whistleblower" or a person arousing or informing a different perspective on a collaborative problem-solving task. Its purpose is to find out, through an experiment, how a whistle-blower (which we called "Maverick") affects the facilitation of a breakthrough in a rule-discovery task. In the experiment two hypotheses were tested: 1) Collaborative problem-solving task is facilitated by contribution of member with different perspective. 2) Problem-solving task is facilitated more as the number of participant with a different perspective increases. In the experiment, several sets of figures were presented in three different settings (without a different perspective, with Maverick, three members with a different perspective), where a group of six members (one human and five conversational agents) collaboratively engaged in a rule-discovery task via a text-based chat system. The experiment revealed an interesting result to the effect that while a different perspective, overall, contributed to the facilitation of problem-solving such contribution was not statistically significant when it was presented by half of the members. The implications of the result were discussed by referring to the related literature in psychology.