Children are increasingly active consumers in the media world and are thus confronted with a wide range of information. Making good decisions in such an environment is a major challenge. Weighting valid information in decision-making is an important skill that children must learn and apply. Yet, how do children weight information and which weights do they use? We developed a measuring instrument for children's weighting of advices by cue validity – the so-called Space Treasure Hunt. It is an easy to understand, child-friendly decision game. By anchoring it in the reality of children's media lives, we are able to assess the influence of familiarity and affect on children's decision making. During a treasure hunt in game situated in outer space, children are confronted with various characters who provide contradictory advice regarding where to find treasures. One of the advice-givers was an expert (valid cue), whereas the other advice-giver varied in terms of its media familiarity and affect. In our study (N = 372), we found that media familiar characters had a strong influence on children's decision-making. Media idols showed an assimilation effect, meaning that children followed the expert's advice the least often when it contradicted their media idol. Conversely, media familiar but less liked characters showed a contrast effect, meaning that children followed the expert's advice most often when it contradicted the media familiar, less liked character. Moreover, we found differences between children in terms of a three-way split: One third of the children, respectively, systematically followed the expert's advice, the media idol, or made their decisions unsystematically. We discuss how our results indicate the use of different weights in children's decision making.