If you’ve ever gotten stuck in the jaws of a bureaucracy, you know that rules can do funny things to people. When people have a rule they can follow blindly, they tend to stop thinking because they don’t need to think.

The problem is that once you stop thinking, it can hard to start back up again.

With this idea in mind, a pair of psychologists from Israel recently ran a study looking at whether following rules can have a temporary effect on people’s intelligence. The basic design of their experiment was to have people follow a rule, then take an IQ test to see whether following the rule changed people’s IQ test results.

More specifically, participants kicked off the study by being given a list of words and asked to categorize the words according to a pre-defined rule. The participants than completed Raven’s Advanced Progressive Matrices, a kind of intelligence test.

What emerged was that doing the rule-following exercise before taking the IQ test led people to score an average of 10 points lower on the IQ test!

In other words, how you perform on a test of intelligence at a given point in time depends partly on your mindset, and doing a simple rule-following task can put you in a mindset where you perform significantly worse. Or to put it another way, following rules can make you (temporarily) less intelligent.

This study shows how rule-following impacts IQ score in a very blatant way, but there was also some previous research that clued the authors onto the idea that doing a simple word categorization exercise can change how you think (or don’t).

For example, the same researchers showed in a 2011 study that when people are told to apply a simple rule, their ability to subsequently infer new rules from information they’re given goes down. The title of that paper, “Mindset Changes Lead to Drastic Impairments in Rule Finding,” pretty much sums up the results. Along similar lines, a 2013 study found that being asked to apply an arbitrary rule may also lead people to pay more attention to irrelevant information.

It might seem a little surprising that something so simple can have such a big impact on how people do on an IQ test, but other research looking at problem solving has found that what state of mind people are in right before they’re asked to solve a problem can predict how they’ll solve that problem. For instance, it’s possible to predict using EEG whether people are more likely to solve a problem with insight (having an “aha” moment) or using a more methodical approach.

One of the things about the human brain is that it works in different ways in different situations. We’re all more intelligent at some points in time and less intelligent at others. And one of the times where we’re less intelligent appears to be when we’ve been following rules.