The original finding and its honest caveat

Ward, Duke, Gneezy and Bos’s 2017 study with nearly 800 smartphone users at the University of Texas at Austin placed participants in one of three conditions: phone on the desk face-down, phone in their pocket or bag, or phone in another room entirely. Participants then completed working memory and fluid intelligence tests while being instructed to give full attention to the tasks. Those whose phones were in another room performed significantly better than those with phones on the desk, with the pocket/bag condition intermediate between the two.

The honest caveat belongs here: two subsequent replication attempts have produced null results. Hartmann et al. (2020) found no evidence of the effect on memory tasks, and a 2022 ScienceDirect replication using the same tasks and conditions as Ward et al.’s second experiment also failed to find the effect. The article presents this as a real and mechanistically plausible phenomenon with a contested replication record, not as settled science. The practical recommendation it supports — removing the phone from the work environment — remains defensible regardless of where the replication debate ultimately lands.

The proposed mechanism: suppression as a cognitive load

The mechanism Ward et al. proposed is specific and does not require conscious distraction. The smartphone is a habitual trigger for a wide range of reward-seeking behaviours — checking messages, scrolling, searching for information. When the phone is present and visible, these habitual impulses are continuously activated and must be continuously suppressed. The suppression is effortful and consumes the same working memory resources that the primary cognitive task requires. The person is not distracted in the sense of attending to the phone — they may be attending fully to their work — but the ongoing active inhibition of phone-related impulses is consuming cognitive capacity that would otherwise be available for the task.

The dependency moderator is the most theoretically important finding in the study. The cognitive costs were amplified for people scoring high on smartphone dependency — those for whom the habitual associations between phone and reward-seeking behaviour are strongest. This moderator has a specific implication for the mixed replication record: if the brain drain effect is real, it would be most reliably detected in high-dependency populations and most difficult to detect in general population samples that include many low-dependency individuals who experience little suppression load.

A distinct but related mechanism: notification attentional capture

Stothart, Mishkin and Yehnert’s 2015 research found that seeing a message notification — even without reading it, even without responding — decreases performance on an ongoing task. The attentional cost of a notification is equivalent to the cost of actually reading and responding to it, because seeing the notification automatically triggers mental simulation of its possible content and the social obligation to respond. The attentional capture mechanism is distinct from the suppression mechanism: one is externally triggered by a visible cue, the other is internally generated by habitual impulse. Both operate before the person has consciously decided to engage with the device.

Together the two mechanisms establish that smartphones impair cognitive performance through at least two distinct channels, and that both operate without conscious engagement with the device. The practical implication is that the relevant intervention is not self-control in the moment but environmental design: removing the phone from the visual and cognitive field eliminates both channels simultaneously.

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The dose-response gradient

The location gradient across Ward et al.’s conditions is the most operationally useful finding for entrepreneurs: desk performance was worst, pocket/bag intermediate, and another room best. The pocket/bag condition is intermediate because the phone is not visible — eliminating external attentional capture — but remains within physical reach, maintaining a lower level of suppression load. The other-room condition eliminates both channels simultaneously.

Moving the phone to another room is not an act of self-discipline. It is a one-time environmental design decision that eliminates both impairment mechanisms for the duration of the work session.

The classroom natural experiment

The London School of Economics study by Beland and Murphy (2015) of mobile phone bans in 91 UK secondary schools provides real-world ecological evidence that phone presence affects cognitive performance. Following school-wide phone bans, average test scores improved by 6.4%. The effect was not uniform: lower-achieving students showed improvements of 14.23%, while higher-achieving students showed almost no change. This pattern is consistent with the dependency moderation: students with lower academic achievement may also have higher smartphone dependency, making them more susceptible to the suppression load mechanism and therefore gaining the most from its removal.

If the experience of being unable to concentrate — the persistent pull of the phone even during work that matters to you — is significantly affecting your wellbeing or sense of control, that is worth acknowledging beyond the productivity framework. UK: Samaritans (116 123, free, 24/7). Mind (0300 123 3393). International: internationaltherapistdirectory.com.

A book worth reading alongside this

Stolen Focus by Johann Hari is the most accessible and research-grounded treatment of the full ecosystem of attention disruption — including smartphone design, notification architecture, and the social conditions that make phone separation feel costly. Hari’s account of the attention economy and how it is structured to maximise the habitual approach impulses that the suppression load mechanism requires maps directly onto the Ward et al. finding. For any entrepreneur who wants to understand not just what the phone is doing to their cognitive capacity in the moment but how the design choices that produced that dependency were made, this is the most readable and most practically useful starting point.

Have questions about this article?

If any part of this article raised questions you want to explore further, courbot.co is built for exactly that. It is courben.co’s AI assistant, designed around the psychology of entrepreneurship. Ask it anything from this article.

If the attention and concentration difficulties described here are significantly affecting your wellbeing, speaking with a psychologist is the right next step. UK: Samaritans (116 123, free, 24/7). Mind (0300 123 3393). BACP: bacp.co.uk/search/Therapists. Crisis Text Line — text HOME to 741741 (US, UK, Canada, Ireland). International: internationaltherapistdirectory.com.

This article is for educational and informational purposes only. Sources: Ward, A.F. et al. (2017), Journal of the Association for Consumer Research, 2(2), 140–154. Stothart, C. et al. (2015), Journal of Experimental Psychology: Human Perception and Performance. Beland, L-P. & Murphy, R. (2015), CEP Discussion Paper No. 1350, London School of Economics.