Forensic Science, Psychology and Human Cognition: When the Oregon attorney, Brandon Mayfield, was arrested for the Madrid bombings six years ago, the FBI's fingerprint examiners claimed they were 100% sure that his fingerprints were on the bag containing detonators and explosives. But they were wrong. And this sensational error has drawn attention ever since, to the widely held, but erroneous belief, that fingerprint identification is infallible. Cognitive psychologists and neuroscientists have challenged forensic science as a whole to raise its game; and acknowledge that errors in fingerprinting and other forensic disciplines are inevitable because of the architecture of cognition and the way our brains process information.

Claudia Hammond talks to Dr Itiel Dror, cognitive neuroscientist, whose groundbreaking studies first drew attention to the fact that individual forensic examiners can be swayed by context and affected by bias. Jim Fraser, Professor of Forensic Science from the University of Strathclyde and the Forensic Science Regulator for England and Wales, Andrew Rennison, discuss the steps being taken to amend procedures and protocols.

Testosterone and City Traders: Dr John Coates used to work on Wall Street as a derivatives trader, and during the Dot Com bubble became convinced that he was witnessing hormone surges and slumps in his fellow traders that amounted to clinical levels. His subsequent research at the University of Cambridge has established the size of the changes in the naturally occurring steroids like testosterone and cortisol changes and he's now trying to demonstrate in the laboratory how these changes actually affect decision making and the willingness to take risks.

The psychology of Would-be Suicide Bombers and Organisers of Suicide Missions: In the first study of its kind, Ariel Merari, Professor of Psychology at Tel Aviv University, has analysed failed suicide bombers in prison in an attempt to establish what motivated them to volunteer to kill themselves, and others.

Producer: Fiona Hill.