Mere Presence Effects
The claim that a phone within sight drains cognitive capacity even when it is never touched, usually travelling under the name brain drain. The meta-analytic headline is a null. Andree Hartanto and colleagues' four-level meta-analysis of one hundred and sixty-six effect sizes from fifty-three samples across thirty-three studies, covering four thousand three hundred and sixty-eight participants, found no significant effect of mere smartphone presence on cognitive outcomes, with a confidence interval sitting across zero.
What it is
The null was not rescued by any moderator the authors tested: demographics, trait smartphone dependency, how presence was manipulated and how cognition was measured all left it unchanged. Their own scope statement is unusually direct and is the most quotable line in the literature, that there is little reason at present to think complete isolation from smartphones in a work environment would improve productivity and performance. The attribution field on this page is deliberately empty. The claim is usually traced to a 2017 paper by Ward and colleagues, which this vault has not read, and filling the field from memory is the error class the vault exists to avoid.
In effect
A pre-registered direct replication points the same way. Ariana Ruiz Pardo and John Paul Minda crossed phone location, on the desk, in a pocket or bag, or outside the room, with phone power on or off, giving six conditions, and tested an automated operation span task and a cue-dependent go/no-go task. The brain drain effect did not replicate, on either task. The practical reading is that a policy of removing phones from a workspace has no measured cognitive dividend to point to, whatever else may recommend it.
What it does not say
It does not say that having a phone nearby is harmless in every respect, only that across this body of work no effect on cognitive performance emerges. Both sides go on the page: a single 2023 study by Jan Skowronek and colleagues reports that the mere presence of a smartphone reduces basal attentional performance, and its published record was verified while its abstract was not read in this pass, so it is recorded rather than weighed. The meta-analysis is the better evidence and already absorbs that kind of heterogeneity. The replication's sample size is also not available to us.
Sources
- Hartanto, A., Lua, V. Y. Q., Kasturiratna, K. T. A. S., Koh, P. S., Tng, G. Y. Q., Kaur, M., Quek, F. Y. X., Chia, J. L., & Majeed, N. M. (2024). "The effect of mere presence of smartphone on cognitive functions: A four-level meta-analysis." Technology, Mind, and Behavior, 5(1), 1-14. Open access, abstract read in full; Hartanto first author. 166 effect sizes, 53 samples, 33 studies, 4,368 participants.
- Ruiz Pardo, A. C., & Minda, J. P. (2022). "Reexamining the 'brain drain' effect: A replication of Ward et al. (2017)." Acta Psychologica, 230, 103717. Open access, abstract read in full; pre-registered. Sample size not available.
- Skowronek, J., Seifert, A., & Lindberg, S. (2023). "The mere presence of a smartphone reduces basal attentional performance." Scientific Reports, 13, 9363. Published record verified, abstract not read. Recorded for balance, not weighed.
- Ward and colleagues (2017), the paper the claim is usually traced to, has not been read by this vault, which is why no originator is recorded here.