Many students learn English words with apps on their phones. Do they really remember the words? Researchers collected many studies and put the results together. Students who used phones usually learned more words than students who used paper lists.

But many of the studies were small or short. Also, good apps make you remember answers and review words again later. So the app's way of teaching may help more than the phone itself.

Vocabulary apps are popular, but do they work better than paper word lists? Meta-analyses, which combine the results of many studies, say yes. One review of 33 studies found a large positive effect for learning words with mobile devices, and another review of 45 studies with more than 2,000 learners reached a similar conclusion.

However, a researcher named Burston checked the quality of the studies. Out of 291 language-learning studies, only 19 were strong enough to trust, and four vocabulary studies among them found no difference at all. In addition, most apps include quizzes and spaced review, which are known to help memory without phones. This means the real power may come from how the app makes you practise.

Studying vocabulary on a smartphone feels efficient, and meta-analyses appear to confirm it. A 2019 synthesis of 33 studies reported a large positive effect of mobile-assisted vocabulary learning, and a 2021 meta-analysis of 45 studies involving 2,374 learners estimated a large effect for technology-assisted word learning, with mobile and out-of-class learning performing especially well.

But the results look less impressive once study quality is examined. In a 2015 review, Burston found that only 35 of 291 language-learning studies met minimal conditions of sample size and duration, and only 19 could reliably support conclusions. In a later review of 1,144 references, just 84 studies qualified; their average effect was large, but the authors detected clear publication bias and extremely high heterogeneity.

Another problem is the comparison itself. Mobile groups are often compared with learners using traditional methods such as paper lists, while apps typically add retrieval quizzes, spaced review and audio. These features are effective with or without a phone, so the device and the method are confounded. A novelty effect may also inflate short-term results. Learners should therefore choose apps that make them recall words and review them over time.