In one way or another, we’re all attached to our phones, whether we know it or not. Checking text messages, Instagram, or Facebook repeatedly throughout the day happens all the time in the modern world, but what separates the cell phone addicts from the casual browsers?

Psychologists at Temple University set out to identify what makes a cell phone addict in a new study. Published in the journal Psychonomic Bulletin & Review, the study examined what mental qualities a person exhibits when heavily using their phone, and what made certain people more attached to their phones than others. In particular, the researchers focused on whether certain mental processes associated with addiction differed in people attached to their phones. They found less ability to control impulses or delay gratification in people attached to their smartphones.

The study authors analyzed 91 undergraduate students as they completed questions and cognitive tests that tracked their impulse control, or their ability to avoid temptations and instant gratification. The researchers also measured the participants’ intertemporal preference, or their tendency to delay gratification for later rewards (such as choosing to put down their phones and complete homework). Intertemporal preference was measured with a test in which the students were given hypothetical choices between receiving a small amount of money immediately, or more money later.

Finally, the participants were asked to report how often they checked their phones for various things like texting and emails, as well as how often they used their phones for social media. These answers were compared to how they scored on cognitive function, impulse control, reward responses, and intertemporal preference. The researchers found that students who were more attached to their phones were also less likely to delay gratification in choices they made, and had poorer impulse control.

“Mobile technology habits, such as frequent checking, seem to be driven most strongly by uncontrolled impulses and not by the desire to pursue rewards,” said Henry Wilmer, a psychologist and an author of the study, in a statement. However, it’s unclear whether increased smartphone use leads to poor impulse control, or if a person’s natural inability to control their impulses leads to frequent phone checking.

The study suggests there may be more to learn about smartphone attachment or addiction, and what it says about specific brain activity. Past research has shown that being overly dependent on your phone can take a toll on your relationships, and that using your phone as an escape is connected with depression and anxiety.

“The findings provide important insights regarding the individual difference factors that relate to technology engagement,” co-author Jason Chein said in the statement. “These findings are consistent with the common perception that frequent smartphone use goes hand in hand with impatience and impulsivity.”

Source: Wilmer H, Chein J. Mobile technology habits: patterns of association among device usage, intertemporal preference, impulse control, and reward sensitivity. Psychonomic Bulletin & Review. 2016.