What do you see: a rabbit? or a duck?
More than a 100 years after it was first sketched, a drawing has sparked huge reaction after being shared on social media.
Some see a rabbit and others will see a duck - but are you able to see both alternatively?
What you see (and how fast you see it) could indicate how quickly your brain works - and how creative you are.
The duck-rabbit drawing was first used by American psychologist Joseph Jastrow in 1899 to make the point that perception is not only what one sees but also a mental activity.
Mr Jastrow's research was based on how quickly one can see the second animal and how fast participants could change their perception of the drawing to switch between the two animals.
The faster you can do this this, the quicker your brain works and the more creative you are, the research suggested.
At different times during the year, the result of the test seem to change.
During the Easter period, people are more likely to see a rabbit first but in October, seeing the duck first is more common.
The images was first published anonymously in a German magazine called Fliegende Blätter, with the caption "Which animals are most like each other?".
[This article was originally published in February 2016]
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