Love is blind

As with so many of Shakespeare's words, they have a universal human application.

But now research has shown there is a scientific basis to his phrase 'love is blind'.

It seems that feeling love for someone - whether partner or child - leads to areas of the brain associated with critical judgment switching themselves off.

It was a situation plain to the character Jessica in Shakespeare's The Merchant of Venice, when she confessed to her lover: 'But love is blind and lovers cannot see/the pretty follies that themselves commit.'

In the modern world the research findings may help explain why actress Leslie Ash has been accused of turning a blind eye to suggestions of marital discord, even after she ended up in hospital with a collapsed lung and cracked rib.

Her husband, ex-footballer Lee Chapman, was accused of assaulting her, but was released when his wife insisted her injuries were the result of a boisterous sex session. The couple have emphatically denied any allegations of assault.

The research may also shed light on Nancy Dell'Olio's decision to stick with England football manager Sven Goran Eriksson despite his affair with TV presenter Ulrika Jonsson.

Dr Andreas Bartels, who led the research at University College London's Wellcome Department of Neuro-imaging, said: 'The findings suggest that once we are closely familiar with a person, the need to assess their character and personality is reduced, bringing us closer to explaining why it is that love

makes us blind.' In the study, Dr Bartels's team carried out tests to compare the effects of romantic love for a partner and a mother's love for her child.

They used magnetic resonance imaging (MRI) equipment to monitor levels of activity in the various areas of the brain as 20 women were shown pictures of their children.

The team found that the patterns of brain activity measured in response were distinctly similar to those identified in

an earlier study looking at the effects of romantic love on the brain.

Activity in several key areas of the brain's 'reward system' - the same areas stimulated by food and drink or monetary gain - overlapped precisely, says a report in the journal Neuroimage.

Significantly, areas of the brain which remained inactive also matched up.

They included parts of the prefrontal cortex - crucial to critical assessment - and the amygdala, which is associated with negative emotions, aggression and fear.

However, there were differences between romantic and maternal love, with the area of the brain that includes its ' arousal switches ' , the hypothalamus, being activated only through romantic love and not by that for our children.

Dr Bartels added: 'Both romantic and maternal love are highly rewarding experiences that are linked to the perpetuation of the species, and have a closely linked biological function of crucial evolutionary importance.

'Our research enables us to conclude that human attachment deactivates networks used for critical social assessment and negative emotions, explaining the power of love to motivate and exhilarate.'

TV psychiatrist Dr Raj Persaud said: 'This explains why we take so long to see the flaws in those we idealise because of our love.

'They only become apparent after our initial ardour has cooled, allowing previously suppressed brain areas to awaken.'