Factors influencing high school and university students' abilities to solve a conditional proposition were examined. Ninety-four male and female Ss were administered a directed or nondirected form of questioning for the selection task. The classic task involves presenting four cards (red, blue, 5, 7) with a conditional proposition rule "Every card with red on one side has 7 on the other" and the instructions to select the cards that would show the rule to be true or false. Three tasks were administered (A, B, C) allowing an analysis of transfer effects between tasks. Task A comprised two combinations of conjunctions of p and q and their negations, task B had four, and task C had eight. It was found that (a) the number of combinations did not contribute to task difficulty, (b) the form of presenting information about what is on the other side of a card influenced task difficulty, and