New forms of grouping used to conduct scientific research in collaboration with people outside the scientific community are growing, known as crowd science. One way to involve the crowd is with citizen science projects, that are researches involving joint efforts between professional researches and citizens in the collection and analyses of data. The benefits brought by this cooperation in citizen science projects are profitable for both researchers and citizens: more hours of work devoted to the project and reduced costs of scientific research; increased literacy and technology knowledge for the citizens; stimulated connections among researches and people; and, finally, an enjoyable experience for the public. The huge amount of data to be collected and analyzed needs a great number of participants helping the professional scientists. Advances in information technology have helped in involving a higher number of people through the web, however the methodologies used to increase motivations to participate are still a crucial issue in citizen science online projects. In this paper, we test the interaction with the professional researchers as a technique to increase citizen scientists’ motivations to contribute. Our explorative findings quantify the motivations increase to participate in citizen science projects brought by this technique and moderated by the effect of age. These results are useful to better manage citizen science projects and could be extended also to other crowd based activities.