The Gudjonsson Suggestibility Scale (GSS) is a psychological test that measures suggestibility of a subject. It was created in 1983 in England by psychologist Gísli Hannes Guðjónsson, who had been a detective in Iceland. 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 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.Gudjonsson, GH. (1984). "A new scale of interrogative suggestibility", Personality and Individual Differences 5(3), 303–314. 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,Pires, R., Silva, DR., & Ferreira, AS. (2014). "The Portuguese adaptation of the Gudjonsson Suggestibility Scale (GSS1) in a sample of inmates". International Journal of Law and Psychiatry, 37(3), 289–294. Pires, R., Silva, DR., & Ferreira, AS. (2013). Portuguese adaptation of the Gudjonsson Suggestibility Scales (GSS1 and GSS2): Empirical findings. Personality and Individual Differences, 54(2), 251–255. Italian,Bianco, A. & Curci, A. (2015). "Measuring interrogative suggestibility with the Italian version of the Gudjonsson Suggestibility Scales (GSS)": Factor structure and discriminant validity. Personality and Individual Differences, 82, 258–265. Dutch,Merckelbach, H., Muris, P., Wessel, I., & van Koppen, P. J. (1998). "The Gudjonsson Suggestibility Scale (GSS): Further data on its reliability, validity, and metacognition correlates". Social Behavior and Personality, 26(2), 203–210. and Polish.Polczyk, R. (2005). "Interrogative suggestibility: Cross-cultural stability of psychometric and correlational properties of the Gudjonsson Suggestibility Scales". Personality and Individual Differences, 38(1), 177–186.
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. 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. Subjects may be asked to report these facts after a delay 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 twenty questions regarding the short story. The target questions can be separated into three types: leading questions, affirmative questions, and false alternative questions. Their purpose is to measure how much a participant "yields" to these questions. Additionally, there are five neutral questions. After 1987, the GSS was altered so that these five questions were included in the shift score as well.Singh, K. & Gudjonsson, GH. (1987). "The internal consistency of the "shift" factor on the Gudjonsson Suggestibility Scale." Personality and Individual Differences, 8(2), 265–266. This version is referred to as the Gudjonsson Suggestibility Scale 2, or GSS2.
Scoring Scoring can be broken down into two main categories: memory recall and suggestibility. Memory recall refers to the number of facts the subject correctly remembered during the free recall. Each fact is worth one point, and the subject can earn a maximum of forty points for this section.
The suggestibility section is broken into three subcategories-yield, shift, and total. Yield refers to the number of suggestive questions answered incorrectly, based on the original story. With each question being worth one point, subjects can score up to fifteen points on this section. If the subject engaged in two recall activities, the score for the second trial is not included in the scoring. Shift refers to any notable significant change in the participant's answers after they were told to go over their original answers and correct their mistakes. Subjects can also score up to fifteen points on this section. The total score refers to the sum of both the Yield and Shift scores.
In a sample of 195 people, the Yield 1 mean score was 4.9, with a standard deviation of 3.0. The Yield 2 mean score was 6.9, with a standard deviation of 3.4. The average Shift score was 3.6, with a standard deviation of 2.7. For total suggestibility (Yield + Shift), the average score was 8.5, with a standard deviation of 4.3. The average memory recall score was 19.2, with a standard deviation of 8.0.
Measures of reliability and validity Internal consistency scores between Yield 1 and Shift for the GSS range from −.23 to .28.Gignac, G. & Powell, M. (2009). "A psychometric evaluation of the Gudjonsson Suggestibility Scales: Problems associated with measuring suggestibility as a difference score composite". Personality and Individual Differences, 46(2), 88–93. Young, K., Powell, M. B., & Dudgeon, P. (2003). "Individual differences in children's suggestibility: A comparison between intellectually disabled and mainstream children". Personality and Individual Differences, 35(1), 31–49. Lee, K. (2004). "Age, neuropsychological, and social cognitive measures as predictors of individual differences in susceptibility to the misinformation effect". Applied Cognitive Psychology, 18, 997–1019. Internal consistency for the fifteen Yield and fifteen Shift questions were reportedly 0.77 and 0.67, respectively.
The GSS2 showed higher internal consistency than the GSS1. Test-retest reliability was reportedly 0.55. Overall, Shift scores showed the lowest internal consistency, at 0.11.Gudjonsson, G. H. (1997). The Gudjonsson Suggestibility Scales manual. Hove: Psychology Press Other scores were significant. External validity, tested with the Portuguese version of the GSS, showed no correlation between interrogative suggestibility and factors of personality,Costa, P. T., & McCrae, R. R. (2000). NEO PI-R, Inventário de Personalidade NEO Revisto. Manual profissional. Adaptação de M. P. Lima & A. Simões [NEO PI-R, NEO Personality Inventory-Revised, professional manual. Portuguese adaptation of M. P. Lima & A. Simões].Lisbon: CEGOC-TEALima, M. P. (1997). NEO-PI-R: Contextos teóricos e psicométricos — “Ocean” ou “Iceberg”? [NEO-PI-R: Theoretical and psychometric contexts — “Ocean” or “Iceberg”?]. Doctoral thesis. Coimbra, Portugal: Coimbra University nor interrogative suggestibility and anxiety.Silva, D. R. (2006). O Inventário de Estado-Traço de Ansiedade (STAI) [The State-Trait Anxiety Inventory (STAI)]. In M. M. Gonçalves, M. R. Simões, L. S. Almeida, & C. Machado (Coords.), Avaliação psicológica: Instrumentos validados para a população(2ª ed., Vol.1, pp. 45–60). Coimbra: QuartetoSpielberger, C. D. (1983). Manual for the State-Trait Anxiety Inventory, STAI (Form Y). Palo Alto, CA: Consulting Psychologists Press. Immediate recall and delayed recall correlated negatively with all suggestibility scores.
Uses in the justice system Use in criminal proceedings The GSS is used most often in criminal justice systems. The human memory has been known to be unreliable, as is eyewitness testimony. But Western countries rely strongly on such testimony, and wrongful convictions based on incorrect eyewitness testimony have been publicized, raising this as an issue to the wider public.
The GSS allows psychologists to identify individuals who may be susceptible to giving false accounts of events when questioned. The GSS could be useful in a situation where a defendant is being interrogated or cross-examined.Willner (2011). "Assessment of capacity to participate in court proceedings: a selective critique and some recommendations". Psychology Crime and Law, 17(2), 117–131. There is evidence that GSS scores vary between inmates and the general population. In the general population, high scores on the GSS are associated with an increased likelihood of false confession.Gudjonsson, G. H. (2003). The psychology of interrogations and confessions. A handbook. West Sussex: John Wiley & Sons.Klaver, J.R., Lee, Z., & Rose, V.G. (2008). "Effects of personality, interrogation techniques and plausibility in an experimental false confession paradigm". Legal and Criminological Psychology, 13(1), 71–88. Pires (2014) studied 40 Portuguese prisoners and found that inmates had higher suggestibility scores than the general population. This group had the lowest scores in the immediate recall portion of the GSS, suggesting that their higher suggestibility was due to their lower memory capacity.
Possible explanations for this may be that the inmates participated in the study voluntarily, and were told that participation would have no negative effect on them. Therefore, even for inmates with antisocial personality disorder, the study took place in a "cooperative atmosphere". Inmates who had a negative attitude toward the test situation or the examiner had decreased vulnerability to suggestion. Additionally, repeat offenders were more resistant to interrogative pressure than those without prior convictions; this may be due to their experience in interrogation settings. Studies have found that GSS scores are higher in people who confess to crimes they did not commit, than in people who are more resistant to police questioning.
The use of the GSS in court proceedings has been met with mixed responses. In the United States, courts in many states have ruled that the GSS does not meet either the Frye standard or the Daubert standard for the admissibility of expert testimony. In Soares v. Massachusetts(2001),Soares v. Massachusetts, 51 Mass.App.Ct. 273, 745 N.E. 2d 362 (2001) for example, the Massachusetts Appeals Court stated that the case was "devoid of evidence demonstrating either the scientific validity or reliability of the GSS as a measure of susceptibility to suggestion or appropriate applications of the test results."