Table 1. Example questions of three difficulty levels in the arithmetic task.

Low	Answer	Medium	Answer	High	Answer
3 + 4 = 6	F	13 + 18 = 51	F	7 × 3 − 12 = 19	F
4 + 2 = 6	T	61 − 12 = 49	T	63/3 − 32 = −19	T
2 + 7 = 4	F	52 − 67 = −8	F	78 + 11 × 3 = 71	F
3 + 6 = 9	T	−11 + 28 = 17	T	(21 − 13) × 4 = 32	T
5 + 2 = 8	F	−13 − 56 = −60	F	6 × 6 − 79 = −23	F