Pain Experiment (image) University College London Caption Researchers from University College London use lasers to stimulate pain in a volunteer's hand. Sometimes only one laser would be activated, and sometimes both would be, unknown to participants. They were asked whether they felt one 'sting' or two, at varying distances between the two beams. The researchers recorded the minimum distance between the beams at which people were able to accurately say whether it was one sting or two. The ability to accurately discriminate the source of pain is known as 'spatial acuity' for pain. Credit UCL (University College London) Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.