Where's the control group? The study seems to compare two skills in bilingual kids only. It's interesting, but it doesn't seem to tell us anything about the adv

Where's the control group? The study seems to compare two skills in bilingual kids only. It's interesting, but it doesn't seem to tell us anything about the advantage of speaking 2 languages.. like single language kids could read 2x as fast and the results wouldn't change.. or those words may happen to be easy ones anyway (seems somewhat likely if they happened to occur if those combinations of letters happened to appear in both languages).