Having a smartphone in reach reduces brainpower even when switched off, finds report

'Similar cognitive costs would not be incurred by the presence of just any product'

The more people depend on their smartphones, the more they seem to suffer from their presence (iStock-Ridofranz )

The mere presence of a smartphone reduces cognitive capacity, adversely affecting the brain’s ability to hold and process data at any given time, according to a new study.

Having a smartphone within reach, even if it’s switched off or placed face-down, causes “brain drain”, say researchers from McCombs School of Business at the University of Texas.

They also found that the more reliant people are on their smartphones, the more they seem to suffer from their presence.

“Results from two experiments indicate that even when people are successful at maintaining sustained attention – as when avoiding the temptation to check their phones – the mere presence of these devices reduces available cognitive capacity,” reads the report.

“Moreover, these cognitive costs are highest for those highest in smartphone dependence.”

In the first experiment, 520 people were told to put their smartphones in Silent mode and place them either face-down on their desk, in their pocket or bag, or in another room.

They were then asked to complete a number of tests “intended to measure available cognitive capacity”, including the Automated Operation Span task and a 10-item subset of Raven’s Standard Progressive Matrices.

The researchers found that the participants who put their phones in another room “significantly outperformed” those who had their phones on their desks, and “slightly outperformed” those who stowed their phones away in a pocket or bag.

In the second experiment, 275 people were told to either put their smartphones in Silent mode or switch them off completely, and place them either face-up on their desk, in their pocket or bag, or in another room.

They also had to complete a selection of tasks, and were asked a series of questions designed to assess how reliant they are on their smartphones.

The researchers found that the participants who said they were most dependant on their smartphones performed worse in the tests, but only if their handset was placed on their desk or in a pocket or bag.

Whether a smartphone was on or off, or placed face-up or face-down on a desk made no difference.

“The present research identifies a potentially costly side effect of the integration of smartphones into daily life: smartphone-induced ‘brain drain’. We provide evidence that the mere presence of consumers’ smartphones can adversely affect two measures of cognitive capacity – available working memory capacity and functional fluid intelligence – without interrupting sustained attention or increasing the frequency of phone-related thoughts.

“Consumers who were engaged with ongoing cognitive tasks were able to keep their phones not just out of their hands, but also out of their (conscious) minds; however, the mere presence of these devices left fewer attentional resources available for engaging with the task at hand.”

They add that “similar cognitive costs would not be incurred by the presence of just any product”, as “few, if any, stimuli are both so personally relevant and so perpetually present” as consumers’ own smartphones.

“Ironically, the more consumers depend on their smartphones, the more they seem to suffer from their presence – or, more optimistically, the more they may stand to benefit from their absence,” said the researchers.

They believe that “defined and protected” periods of separation from smartphones – not unexpected periods of separation – “may allow consumers to perform better not just by reducing interruptions but also by increasing available cognitive capacity”.