Elementary math in elementary school: the effect of interference on learning the multiplication table

Cognitive Research: Principles and Implications

Table 1 Statistical information about the stimuli. Each participant learned the same 16 multiplication facts, which were grouped into 2 low-similarity sets and 2 high-similarity sets (different grouping for each participant)

Participant	Similarity in…		Similarity of the set trained in week 1	Average operands size in…
Participant	Low-similarity sets	High-similarity sets	Similarity of the set trained in week 1	Low-similarity sets	High-similarity sets
1	2, 2	11, 11	High	6.75	6.00
2	2, 2	11, 11	Low	6.25	6.50
4	2, 2	11, 11	Low	6.69	6.06
6	1, 1	11, 12	High	6.50	6.25
7	1, 2	11, 11	Low	6.44	6.31
9	0, 1	11, 11	Low	6.44	6.31
11	1, 1	10, 11	High	6.13	6.63
12	2, 2	11, 11	Low	6.44	6.31
13	2, 2	10, 10	High	6.56	6.19
16	2, 2	10, 10	High	6.63	6.13
19	2, 2	10, 10	Low	6.88	5.88
23	1, 1	10, 11	High	6.13	6.63
25	2, 2	12, 12	High	6.44	6.31
27	1, 1	10, 10	Low	6.81	5.94
31	2, 2	11, 11	High	6.56	6.19
33	0, 1	10, 11	Low	6.56	6.19
34	2, 2	11, 11	High	6.00	6.75
Average	1.56	10.76		6.48	6.27

Each set was learned in a separate week (4 weeks overall), in counterbalanced order (either low–high-low–high or high-low–high-low). We made sure that the low-similarity sets were not easier than the high-similarity sets in terms of problem size