The Gudjonsson suggestibility scale (GSS) is a psychological test that measures suggestibility of a subject. It was created in 1983 by Icelandic psychologist Gísli Hannes Guðjónsson. It involves reading a short story to the subject and testing recall. This test has been used in court cases in several jurisdictions but has been the subject of various criticisms.
History
The Gudjonsson suggestibility scale (GSS) was created in 1983 by Icelandic psychologist Gísli Hannes Guðjónsson. Given his large number of publications on suggestibility, Gísli was often called as an expert witness in court cases where the suggestibility of those involved in the case was crucial to the proceedings. To measure suggestibility, Gísli created a scale that was relatively straightforward and could be administered in a wide variety of settings. He noticed that while there was a significant body of research on the effects of leading questions on suggestibility, less was known about the effects of "specific instruction" and "interpersonal pressure". Previous methods of measuring suggestibility were primarily aimed at "hypnotic phenomena"; however, Gísli's scale was the first created to be used specifically in conjunction with interrogative events.
His test relies on two different aspects of interrogative suggestibility: it measures how much an interrogated person yields to leading questions, as well as how much an interrogated person shifts their responses when additional interrogative pressure is applied. The test is designed specifically to measure the effects of suggestive questions and instructions. Although originally developed in English, the scale has been translated into several different languages, including Portuguese, Italian, Dutch, and Polish.
Method
The GSS involves reading a short story to the subject, followed by a general recall activity, a test, and a retest. It begins with a short story being read to the subject:
Anna Thomson of South Croydon was on holiday in Spain when she was held up outside her hotel and robbed of her handbag, which contained $50 worth of traveler's checks and her passport. She screamed for help and attempted to put up a fight by kicking one of the assailants in the shins. A police car shortly arrived and the woman was taken to the nearest police station, where she was interviewed by Detective Sergeant Delgado. The woman reported that she had been attacked by three men, one of whom she described as oriental looking. The men were said to be slim and in their early twenties. The police officer was touched by the woman’s story and advised her to contact the British Embassy. Six days later, the police recovered the lady’s handbag, but the contents were never found. Three men were subsequently charged, two of whom were convicted and given prison sentences. Only one had had previous convictions for similar offences. The lady returned to Britain with her husband Simon and two friends but remained frightened of being out on her own.
The subject is instructed to listen carefully to the story being read to them because they will have to report what they remember afterward. After the researcher reads the story aloud to the participant, the subject is asked to engage in free recall in which they report everything remembered of what was just read. To make the assessment more difficult, subjects may be asked to report these facts after 50 minutes in addition to immediately following the story. This part of the assessment is scored based on how many facts the subject recalls correctly.
The second part of the assessment consists of the actual scale. It consists of twenty questions regarding the short story: fifteen questions being suggestive and five being neutral. The fifteen suggestive questions can be separated into three types of suggestibility: leading questions, affirmative questions, and false alternative questions. Their purpose is to measure how much a participant "yields" to suggestive questions.
Leading questions contained some "salient precedence" and are worded in such a way that they seem plausible and lend themselves to an affirmative answer. A leading question on the GSS would ask, "Did the woman's glasses break in the struggle?"
Affirmative questions were those that presented facts that did not appear in the story, but that contain an affirmative response bias. An example of an affirmative question would be "Were the assailants convicted six weeks after their arrest?"