A psychometric evaluation of the Gudjonsson Suggestibility Scales : problems associated with measuring suggestibility as a difference score composite

The current paper provides a detailed examination of the psychometric properties of the Gudjonsson Suggestibility Scales (Gudjonsson, 1997) which have been widely used to measure individual suggestibility. Several fundamental problems associated with the Shift and Total Suggestibility subscales are identified and discussed. Two arguably more conceptually coherent methods of scoring the Shift subscale (‘Shift-positive’ and ‘Shift-negative’) are introduced. A confirmatory factor analytic model based on two oblique factors and relative answering regression effects between corresponding items was tested and supported based on a sample of 220 children. Based on a latent variable estimation approach, the internal consistency reliabilities associated with the Shift subscale scores were found to be unacceptably low. Consequently, we propose that until the problems associated with Shift-standard and Total Suggestibility is addressed successfully, use of the GSS should be limited to the Yield subscale.