The present thesis deals with the psychological aspects of interrogative suggestibility of witnesses, victims and offenders involved in criminal investigation. The first part of the work offers a theoretical and literary overview of important theoretical findings on suggestibility in the field of psychology which underly the teoretici model of interrogative suggestibility by Gudjonsson and Clark. Their model is introduced in relation to selected psychological characteristics with an emphasis on practical overlap in forensic psychology and criminal practice. The theoretical part is concluded with a detailed introduction into the Gudjonsson scales of suggestibility - GSS 1 and GSS 2. In the empirical part of the thesis, the author focuses on adaptation and validation of GSS 1 in the Czech environment. The outcome of this work are the psychometric characteristics of the Czech version of the GSS 1, including detailed instruction for administration and evaluation and statistical norms for the czech population. Currently Czech criminalist dispose of no suitable psychodiagnostic assessment method to evaluate the interrogative suggestibility. Key words: interrogative suggestibility, GSS 1, Gudjonsson, psychodiagnostics

Interrogative suggestibility refers to the extent to which an individual internally accepts messages communicated during a formal questioning situation, as indicated by an external response. Research indicates low intelligence, poor memory and weak inhibitory control is associated with heightened suggestibility. Children with fetal alcohol spectrum disorder (FASD) may also display deficits in these key areas, indicating a potential vulnerability to suggestion. The present study compared levels of suggestibility among alcohol exposed and typical children. The findings indicate that children with FASD may be at heightened risk to suggestion following negative feedback or pressure. In addition, a large amount of the suggested material was elicited and internalized as truth by all children, dependent on question format. These findings have important consequences for future interrogative interactions with children with and without FASD, to ensure information is not presented and thus elicited in a suggestive manner. / Graduate

Master's thesis follows on bachelor thesis Specifics of children's testimony from the point of view of Psychology, expanding chapter about suggestibility. Theory involves phenomenon of suggestibility with emphasis put on Gudjonsson's concept of suggestibility in conjunction with interrogative events. Further chapters delve into scientific findings regarding hazardous factors enhancing or decreasing suggestibility of young witnesses, among others are age, cognitive and psychosocial factors. Thesis also presents the very own types of discovered and described interrogation techniques utilizing elements of suggestion like stereotype induction, leading questions, positive and negative consequences or peer pressure. Paper presents results of empirical research, reproduced experiment which was used as tool mapping suggestibility dangers among Czech children. Focused on pre-school children subjected to heavily suggestive interrogation about event they experienced, through later interviews it was measured to which extent highly suggestive interviews altered perceived reality.