For anyone else curious how they measured "cognitive ability", here's the relevant section from the paper[1]:
Børge Priens Prøve
The Danish Draftee Board administered the Børge Priens Prøve (BPP; Kousgaard, 2003) to the draftee sample. This 78-item test has a correlation of .82 with the full Wechsler Adult Intelligence Scale (Mortensen et al., 1989). We have access only to the composite BPP score, but a study of its four subtests demonstrated that Cronbach's alpha for the four tests, composed of verbal analogies, number sequences, letter matrices, and geometric figures, ranged from 0.72 to 0.82 (Hartmann & Teasdale, 2005).
International cognitive ability resource
MTurk participants completed the 16-item International Cognitive Ability Resource measure (Condon & Revelle, 2014). Alpha reliability was high (0.80), and strong convergent validity has been reported for the test (such as a correlation of 0.81 with the Shipley-2 measure of cognitive abilities: Condon & Revelle, 2014).
Børge Priens Prøve
The Danish Draftee Board administered the Børge Priens Prøve (BPP; Kousgaard, 2003) to the draftee sample. This 78-item test has a correlation of .82 with the full Wechsler Adult Intelligence Scale (Mortensen et al., 1989). We have access only to the composite BPP score, but a study of its four subtests demonstrated that Cronbach's alpha for the four tests, composed of verbal analogies, number sequences, letter matrices, and geometric figures, ranged from 0.72 to 0.82 (Hartmann & Teasdale, 2005).
International cognitive ability resource
MTurk participants completed the 16-item International Cognitive Ability Resource measure (Condon & Revelle, 2014). Alpha reliability was high (0.80), and strong convergent validity has been reported for the test (such as a correlation of 0.81 with the Shipley-2 measure of cognitive abilities: Condon & Revelle, 2014).
[1] https://sci-hub.ru/downloads/2021-09-02/07/rasmussen2021.pdf