What colour is your fridge? What do cows drink? If you said "milk," then try this test to find out why.

Double Trouble stretches your brain's attentional abilities to the limit. Three words appear on the screen: one at the top, and two at the bottom. Click on the word at the bottom of the screen that correctly describes the colour of the word at the top. For example, if the word at the top of the screen is written in red, you should answer by clicking the word "red" at the bottom of the screen.

In this test:

So to get maximum points, provide as many correct answers as you can, as quickly as possible.

Performance tips:

Your score on this test contributes to:

The contribution of each test to each performance category is based on a "factor analysis" that looked at how tests tend to clump together when measuring a massive set of data. The results were published in Neuron in 2012 (Hampshire, Highfield, Parkin, & Owen, 2012), where it was referred to as "Colour-Word Remapping." The exact contribution of each test to each performance category may change as more data is collected.

Getting distracted?

The Double Trouble task is our take on a widely-discussed phenomenon known as the Stroop effect (Stroop, 1935). This refers to the increased difficulty in naming the print colour of a word when the text of that word refers to a different colour. For example, people are slower to name the colour of red ink when the word written in it is "green".

This difficulty in colour naming vanishes when the meaning of the word is the same as the text colour (e.g. "red" written in red ink) or is a nonsense syllable (e.g. "kyshqw" written in red) and is diminished for unrelated words (e.g. "window" written in red) (Scheibe et al, 1967). This effect is thought to be the result of interference from automatic word recognition; we access the meaning of words without consciously trying to.

We have made the Double Trouble task even harder than the classic Stroop task. In our version, you do not only have to say the colour word, but you also have to distinguish between two possibilities. This requires an extra cognitive step because you have to remap information from one representation to another, making it more cognitively demanding and engaging for your brain.

We have conducted many studies looking at how the brain is able to focus attention in tasks like this. By using fMRI to scan people's brains while they were performing really boring tasks (e.g. the Sustained Attentional to Response Task), we found that the right frontal areas of the brain help us to sustain attention (Manly et al., 2003). Damage to this area results in poor concentration abilities (Robertson, 2003).

Performance in Double Trouble is roughly equivalent to many everyday tasks that require focusing on what is important and blocking out the rest. That can be as simple as blocking out background conversations when you're trying to work, but it also applies to attempts to manipulate you. Marketers use words ("Fresh! Simple! Revolutionary!") that automatically make your brain think happy thoughts about their products, but you may be better off ignoring those associations and focusing your attention on more important factors—like price.

Decision making can be improved by becoming aware of how your performance in Double Trouble isn't always perfect. Identify when your attention is at its weakest, and slow down to overcome your automatic reactions to focus on what is truly relevant. Luckily, real life usually does not have a 90-second time limit.

Unfortunately, because it is so automatic, the Stroop Effect is difficult to escape. There are rumours that during the Cold War, even well-trained Russian spies could be detected if presented with a test like Double Trouble; if they hesitated when they saw "синий" (the Russian word for "blue"), chances are they spoke Russian as a first language.

These tests are also used to help detect brain injuries—and other cognitive deficits. A 2014 episode of Mythbusters used a test similar to Double Trouble to see if performance deteriorated in the presence of a member of the opposite sex. Good news if you play Double Trouble with your spouse around, though: the myth was busted.