According to Siegal’s hypothesis, despite having concrete operational abilities some children are not successful in conservation tasks. Social factors, such as repetition of question asked by an adult experimenter alter the manifestation of existing cognitive abilities. This study varied the following aspects of conservation tasks: symmetrical vs. asymmetrical power relation. The children in the study were asked to solve three different conservation tasks (quantity of continued material, length, and number). Each task was repeated twice; once with an adult experimenter and once with a child experimenter. Results show that children’s responses were affected by social factors only in a certain tasks. In other tasks children’s responses remained unaffected in both situations. This suggests that there exists an interaction between the experimenter and the task, and that the affect of social factor is mediated by a particular characteristic of the task. Results indicate that the modifying factor is the task difficulty.