Reasons for Failure on the Class Inclusion Problem

When presented cutouts of cats and dogs and asked, Are there more/ fewer pets or dogs? children of CA 6 and 8 consistently responded as if E had asked them to compare dogs with cats, while children of CA 10 correctly responded to the intended class inclusion relation. For both younger groups but not for CA 10 Ss, errors increased as the numerical difference between cats and dogs increased. In a second experiment, the CA 6 and 8 Ss were reexposed to the problem but were either corrected for each error or asked the class inclusion question in a new form. After correction training, but not after new question training, Ss who had failed initially demonstrated success. Thus, the complex situation requiring proper referencing of words with pictorial symbols on the class inclusion test was shown to be a performance deterrent, and comprehension of the inclusion relation was shown to be independent of initial performance.