Younger generations are often accused of going around glued to their phones (although the rise of the silver surfer means this isn’t strictly fair). Even though you can argue that means infinite knowledge and information at your fingertips, a new study has shown smartphones can also reduce our brain power and a specific type of intelligence. 

It’s all down to our attention continuously wandering towards our phones, which the researchers argue in their study published in the online Journal of the Association of Consumer Research is reducing our available cognitive capacity.

They decided to test the “brain drain” hypothesis, which posits that knowing our smartphone is in the vicinity uses up “limited-capacity cognitive resources, thereby leaving fewer resources available for other tasks and undercutting cognitive performance.”

The brain has a finite pool of attention resources – the “limited-capacity” cognitive resources – that control both attention and other cognitive processes. When these resources are used to try and prevent automatic attention going towards our phone, we are tying up these resources, making them unavailable to carry out other tasks, meaning the performance of these tasks suffer.

The researchers discovered that just by having a smartphone in your eye line, you are more likely to fail at simple tasks and remembering things, and this holds true when your phone is in your pocket, your bag, or even in the next room.

To study this, they conducted experiments testing 520 university students on their memory and intelligence while in the presence of their phones. The participants answered exam questions that tested mathematics, memory, and reasoning, while their phones were randomly assigned to be on their desk, in their pocket, in their bag, or in the next room.

The results showed that those who kept their phone on their desk (in eyesight) scored 10 percent lower on questions that tested focus and memory. They also reacted slower to speed tests. In fact, even when their phones were turned off or on “do not disturb” mode, if they were on the desk, the participant scored lower than those whose phones were in the next room.

This means smartphones diminish a person's working memory capacity and "fluid intelligence" – the ability to solve novel problems independent of already stored information, which is called “crystallized intelligence”.

Unsurprisingly, they found that the negative effects of having your phone nearby was greater for those who self-identified as being dependent on their phones. They think this effect is not because the smartphone user’s mind is being distracted by thoughts of checking for messages, but rather their mind is concentrating on trying not to be distracted, at the expense of the performance of the task at hand.

"Your conscious mind isn't thinking about your smartphone, but that process – the process of requiring yourself not to think about something – uses up some of your limited cognitive resources,” concluded lead author Dr Adrian Ward in a statement. “It's a brain drain."