De-confusing the THOG problem: The Pythagorean solution

Sources of facilitation for Needham and Amado's (1995) Pythagoras version o f Wason's THOG problem were systematically examined in three experiments wi th 174 participants. Although both the narrative structure and figural nota tion used in the Pythagoras problem independently led to significant facili tation (40-50% correct), pairing hypothesis generation with either factor o r pairing the two factors together was found to be necessary to obtain subs tantial facilitation (> 50% correct). Needham and Amado's original finding for the complete Pythagoras problem was also replicated. These results are discussed in terms of the "confusion theory" explanation for performance on the standard THOG problem. The possible role of labelling as a de-confusin g factor in other versions of the THOG problem and the implications of the present findings for human reasoning are also considered.