Table 1.

Mean percent correct and confidence ratings for the concrete and abstract versions of each SRS item

	Concrete			Context-free
Concept	% correct	Mean confidence	Weighted score	% correct	Mean confidence	Weighted score	95% CI for Cohen´s d
Item 1. Causation vs. correlation	86%	8.28	6.24	38%	6.83	− 2.19	0.945 [0.871, 1.019]
Item 2. Confounding variables	76%	8.15	4.69	55%	7.2	0.90	0.413 [0.348, 0.477]
Item 3. Construct validity	77%	8.38	4.81	71%	7.96	3.70	0.135 [0.073, 0.197]
Item 4. Control group	65%	7.55	2.56	66%	7.54	2.62	− 0.008 [− 0.070, 0.053]
Item 5. Ecological validity	60%	7.68	1.93	43%	7.67	− 0.90	0.281 [0.218, 0.344]
Item 6. Random assignment to conditions	52%	8.17	0.38	64%	7.8	2.44	− 0.234 [− 0.296, − 0.171]
Total score	70%	48.19	20.60	56.2%	44.99	6.56	− 0.629 [− 0.696, − 0.561]

The table contains the mean percentage of correct responses, mean confidence, and average weighted score separately for every item of the two versions of the SRS. The last column shows the effect size of the difference between weighted scores in the concrete and context-free items