When it comes to art, only the real deal will do, according to a study into fake paintings.
Oxford University academics found that the brain responds differently to artwork depending on whether it is said to be authentic, or merely a good imitation.
The findings show that reaction to art is "not rational" as the viewer reacts to what they are told about a piece of work - regardless of whether it truly is genuine.
The research saw 14 people placed in a brain scanner and shown images of Rembrandt portraits, some of which were authentic and some of which were convincing fakes created by different artists.
While their brain signals showed they could not differentiate between the real and fake work, the response altered significantly depending on whether they were told it was a genuine Rembrandt or not.
Professor Martin Kemp, Emeritus Professor of the History of Art at Oxford University, said: "Our findings support what art historians, critics and the general public have long believed - that it is always better to think we are seeing the genuine article.
"Our study shows that the way we view art is not rational, that even when we cannot distinguish between two works, the knowledge that one was painted by a renowned artist makes us respond to it very differently. The fact that people travel to galleries around the world to see an original painting suggests that this conclusion is reasonable."
Being told a work was genuine activated a response in the area of the brain associated with reward - but being told a painting was not by Rembrandt triggered a variety of responses in parts of the brain linked to planning new strategies.
Those taking part in the study reported that they were studying the painting in those cases, trying to establish why it was not believed to be the genuine article.
Oxford University Professor of Physiology Andrew Parker, the study's senior author, said: "Our findings support the idea that when we make aesthetic judgments, we are subject to a variety of influences. It suggests that different regions of the brain interact together when a complex judgment is formed, rather than there being a single area of the brain that deals with aesthetic judgments."