How to increase in a effective way survey response and retention rates in online panels is a burning issue.The research draws the attention to empirical evidence of phenomena that could be exploited in order to increase survey response, panel retention rates and data quality. The theory behind the methods for motivating people is considered. The level of reciprocity that the participant assigns to the relation is explored by estimating the degree of his trust in the inquirer and by evaluating if he sincerely complies with the norm of reciprocity in a 3 waves web-based pilot experiment carried out by the CASI Research Center at the University of Bergamo (Italy) within the PAADEL project (PAnel Agro-food and DEmographic in Lombardy). Results imply that stressing the reciprocity features of a relationship can’t increase survey response but can reduce panel attrition in web-based studies. The more respondents tend to lie, the less they are willing to participate in following panel waves. Furthermore the less inquirers enjoy the trust of people under investigations, the more panelists are likely to drop out and to non-respond. So two indices are proposed that can help panel managers to monitor the willingness to respond: the Pinocchio Ratio and the Candide Ratio. Nevertheless this study with the reported online experiments is not without limitations, since, for example, questionnaires were sent to all the members of a specific sub-population, thus it is not possible to extend the findings to the general population. The obtained outcomes seek further assessment in the early results of the forthcoming survey release, the fourth wave of the experiment, which is administered using the same questionnaire of the PAADEL representative households panel.