The Gudjonsson suggestibility scale (GSS) was created in 1983 by Icelandic psychologist Gísli Hannes Guðjónsson.
To measure suggestibility, Gísli created a scale that was relatively straightforward and could be administered in a wide variety of settings.
[1] 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.
[1] Although originally developed in English, the scale has been translated into several different languages, including Portuguese,[2][3] Italian,[4] Dutch,[5] and Polish.
[6] 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.
To make the assessment more difficult, subjects may be asked to report these facts after 50 minutes in addition to immediately following the story.
Leading questions contained some "salient precedence" and are worded in such a way that they seem plausible and lend themselves to an affirmative answer.
[1] The person under interrogation is told in a "forceful manner" that there are errors in their story, and they must answer the questions a second time.
Yield refers to the number of suggestive questions answered incorrectly, based on the original story.
[2] The GSS allows psychologists to identify individuals who may be susceptible to giving false accounts of events when questioned.
[17][18] Pires (2014) studied 40 Portuguese prisoners and found that inmates had higher suggestibility scores than the general population.
"[19] In the same year, the Wisconsin Supreme Court, in Summers v. Wisconsin affirmed the trial court's decision to exclude the defense's expert testimony on the GSS because it was "vague regarding what information or insights the expert could offer that would assist the jury and the scientific bases of these insights.
"[21] Experts have linked GSS suggestibility to the voluntary aspect of Miranda waivers during legal proceedings.
[22] Despite this, there are very few appellate cases in which the GSS has been presented to a court with any reference to whether a waiver of Miranda rights by a suspect was voluntary.
This study found that suggestibility, as assessed by the GSS, appeared to be unrelated to "Miranda comprehension, reasoning, and detainees' perceptions of police coercion".
When matched with adult offenders on IQ and memory, juveniles were much more susceptible to giving into interrogative pressure (Shift), specifically by changing their answers after they were given negative feedback.
Research has shown that the high levels of suggestibility demonstrated by people with intellectual disabilities are related to poor memory for the information presented in the GSS.
[16] People with intellectual disabilities have difficulty remembering aspects of the fictional story of GSS because it is not relevant to them.
[16] Another context in which the GSS is sometimes used is as part of the assessment of whether people accused of a crime have the capacity to plead to the charge.
[8] These numbers serve as a possible explanation for why studies have not found "theoretically meaningful correlations" between the Shift sub-scale and other external criteria.
Researchers argue against the use of a Total suggestibility composite due to evidence that Yield 1 and Shift scores do not significantly correlate with each other.
[26] Findings showed that instructed fakers not performing a concurrent task scored significantly higher on yield 1 compared with "genuine interviewees".
[26] These results suggest that an increase in cognitive load may indicate an attempt at faking on the yield portion of the GSS.
[26] One possible issue with the GSS is its validity – whether it measures genuine "internalization of the suggested materials" or simply "compliance with the interrogator".
Participants internalized more suggested information after yield 1, and made more compliant responses during the shift portion of the assessment.
[28] The results of this study showed that those who had recovered memories had a lower average suggestibility scores than those who did not have a history of sexual abuse – 6.7 versus 10.6.