The one-question conservation experiment reconsidered

The "extraneous reason" hypothesis, proposed as an explanation of failure in the traditional two-question conservation task, was re-examined. Two experiments were conducted involving 372 Greek children, 6-8 years old. The experiments provided evidence that the children's successful performance in the conservation task does not depend on asking them one or two questions but is causally related to their efficiency in carrying over information from the pre-transformation display. On the basis of these results, the "verbal interference hypothesis" was considered as a supplementary explanation for the children's erroneous performance in the two-question conservation task.