Scientists at the Defence Science and Technology Laboratory in the UK have found that ensuring the laboratory animals' voluntary participation in experiments is the best way to arrive at reliable test results and reduce the discomfort of the research subjects. Some lab animals are being trained to take part in tests when it suits them and in the security of their own pens. Using this technique, the researchers are investigating the subtle neurological effects of nerve agents like the organophosphate pesticide, diazinon. Tiny transmitters are fitted into monkeys in order to remotely monitor their brains' electrical activity. They are then trained to do tasks such as distinguishing between shapes on a touch-sensitive screen.