Table 3. Outcomes of the meta-analysis of unmatched features on transfer.

		Unmatched feature at training
		Intervention effects								Heterogeneity
Feature category	Transfer feature	k	N	n	d	SE	95% CI	z	p	Q	I2	p
Stimulus type
	Digits	10	15	564	0.357	0.136	0.091–0.623	2.631	0.009	21.545	58.228	0.010
	Letters	3	9	233	0.337	0.169	0.006–0.668	1.998	0.046	3.019	33.752	0.221
	Words/nonwords	8	18	482	0.294	0.159	−0.017 to 0.606	1.855	0.064	19.026	63.209	0.008
	Objects	3	22	136	0.403	0.174	0.062–0.744	2.316	0.021	0.571	0.000	0.752
	Spatial location	5	10	286	0.360	0.411	−0.446 to 1.166	0.875	0.382	42.027	90.482	< .001
Stimulus domain
	Verbal	5	14	246	0.018	0.136	−0.248 to 0.283	0.130	0.897	4.382	8.711	0.357
	Visuo-spatial	4	11	257	0.643	0.423	−0.185 to 1.472	1.522	0.128	29.480	89.824	< .001
Stimulus modality
	Auditory	2	6	121	0.128	0.288	−0.437 to 0.693	0.443	0.658	2.394	58.236	0.658
	Visual
Response modality
	Spoken	12	26	672	0.401	0.103	0.199–0.602	3.899	0.000	18.192	39.533	0.077
	Manual
Serial recall
	Verbal	6	11	305	0.173	0.150	−0.122 to 0.468	1.151	0.250	8.219	39.167	0.145
	Visuo-spatial	6	10	279	0.138	0.121	−0.990 to 0.376	1.140	0.254	4.810	0.000	0.440
	All	10	21	490	0.158	0.077	0.008–0.308	2.064	0.039	21.254	20.014	0.215
Complex span
	Verbal	8	11	416	0.046	0.103	−0.155 to 0.248	0.452	0.652	7.340	4.636	0.394
	Visuo-spatial	7	16	379	0.183	0.103	−0.019 to 0.386	1.776	0.076	1.467	0.000	0.962
	Cross-domain
	All	12	27	649	0.112	0.072	−0.029 to 0.253	1.562	0.118	9.728	0.000	0.782
Backward span
	Verbal	3	3	178	0.144	0.153	−0.315 to 0.644	0.673	0.501	5.113	60.885	0.078
	Cross-domain
	All	4	4	239	0.354	0.258	−0.152 to 0.860	1.372	0.170	11.298	73.446	0.010

k = number of studies; N = number of effect sizes; n = number of participants.