Table 1. Results of the mixed model linear regressions for RTs using the product of the operands as independent variable.

ADDITION	intercept [ms]	std error	t-value	slope [ms/u]	Slope std error	t-value
Different Operands	2060	36	58	23.7	0.4	56.4
Tie Problems	1868	32	58	7.2	0.6	13.2
MULTIPLICATIONS	intercept [ms]	std error	t-value	slope [ms/u]	Slopestd error	t-value
Different Operands	2406	55	44	35.0	0.6	61.2
Tie Problems	2139	45	47	10.5	0.7	15.8