In one experiment, people who were walking across a college campus were asked by a stranger for directions. During the resulting chat, two men carrying a wooden door passed between the stranger and the subjects. After the door went by, the subjects were asked if they had noticed anything change.

Half of those tested failed to notice that, as the door passed by, the stranger had been substituted with a man who was of different height, of different build and who sounded different. He was also wearing different clothes.

Despite the fact that the subjects had talked to the stranger for 10-15 seconds before the swap, half of them did not detect that, after the passing of the door, they had ended up speaking to a different person. This phenomenon, called change blindness, highlights how we see much less than we think we do.

A gorilla who became a cult figure in crime-ridden South Africa after he was shot confronting an armed robber on the run died on Wednesday, the Johannesburg Zoo said.

Max, a 200 kg (440 pound) ape, rose to fame in 1997 after being wounded by a terrified gunman who made the mistake of jumping a moat into his zoo enclosure while fleeing police.

Max was shot as he fiercely defended his territory. He also vented his anger on two policemen in pursuit, biting one on the buttocks and arm.

The secret in making virtual skin seem real is all to do with light. Dr Jensen found that light did not just bounce from surfaces such as marble and skin.

Instead light beams penetrate below the surface and scatter at different points.

Italian researchers carried out tests on 12 men and 12 women who had fallen in love during the previous six months.

They found that men had lower levels of testosterone than normal, while the women had higher levels of the hormone than usual.

"Men, in some way, had become more like women, and women had become like men," Donatella Marazziti of the University of Pisa told New Scientist magazine.

Libya: Did you even try?

Mozambique: Automatic weapons on a flag are especially bad.