Gísli was born on 26 October 1947 to Guðjón Aðalsteinn Guðmundsson and Þóra Hannesdóttir.[4] His twin brother joined the Reykjavík Criminal Investigation Police while he chose to study economics at Brunel University London (BSc, 1975), but changed to psychology whilst in his second year.[5][6] He completed his studies at the University of Surrey (MSc, 1977; PhD, 1981).[7] In 1982, together with MacKeith he coined the term memory distrust syndrome, to describe those who distrust their own memories and are motivated to rely on external (non-self) sources to verify the accuracy of memories.[8]
Gísli's expert testimony was the basis for the convictions of the Birmingham Six and Guildford Four being overturned.[12] He created the Gudjonsson suggestibility scale to measure how susceptible someone is to coercion during an interrogation. An author of several books, Gudjonsson was a coauthor on the American Psychology-Law Society (AP-LS) White Paper by Saul Kassin et al. (2010) titled "Police-induced confessions: Risk factors and recommendations."[13]
Selected list of publications
Psychology brings justice: the science of forensic psychology (Crim Behav Ment Health. 2003;13(3):159-67)
^Kassin, Drizin, Grisso, Gudjonsson, Leo, & Redlich (2010). Police-induced confessions: Risk factors and recommendations. Law and Human Behavior, 34, 3-38.