All participants were asked to make sure to put their phones on silent with vibration deactivated. Then, participants worked on two cognitive tasks: One working memory task – called Automated Operation Span task (OSpan) – where people are asked to actively process information while holding other information in mind. For this specific task, they have to solve math equations while remembering random letters in the order presented. For the other task – the Raven’s Standard Progressive Matrices (RSPM) – participants had to identify the missing piece in a matrix pattern. This test is used to assess fluid intelligence and your performance depends to a large extent on the available attentional capacities to identify the underlying rule of the pattern matrix. Thus, both tasks are cognitively demanding and require people’s full attention. Consequently, any disruption in attention or additional process that takes away attention capacity harms performance in these tasks.

The researchers wanted to test the hypothesis that the mere presence of one’s own cellphone in immediate sight or reach would eat up attentional resources. They had two reasons in mind why this could be the case:

a) People may consciously draw attention and orient themselves towards the cellphone. Maybe thinking about what they are missing out on while doing the task at hand.

b) People may unconsciously inhibit automatic attention to the cellphone. The idea here is that the cellphone may attract automatic attention, but inhibition processes – which cost attentional resources – damp the orientation towards the desired object. Importantly, the authors argue that people are not aware of these inhibition processes, but they nevertheless can lead to decreased performance in cognitively demanding tasks.

What did they find?

Indeed, having one’s cellphone in sight (desk condition) led to lower cognitive capacity in both tasks (see figure) compared to the condition where the cellphone was in a different room (other room condition). If the cellphone was out of sight, but within immediate reach (bag/pocket condition), the results were more mixed: Here the researchers sometimes found a significant difference to the “other room” condition, but not always.