Suggestibility suppression is defined as a decreased tendency to accept and act on the suggestions of others. A common example of suggestibility suppression in action would be a person being unwilling to believe or trust another person's suggestions without a greater amount of prior discussion than would usually be considered necessary during every day sobriety.
Although this effect can occur as a distinct mindstate, it may also arise due to interactions between a number of other effects. For example, a person who is currently experiencing mild paranoia combined with analysis enhancement may find themselves less trusting and more inclined to think through the suggestions of others before acting upon them, alternatively, a person who is experiencing ego inflation may find that they value their own opinion over others and are therefore equally less likely to follow the suggestions of others.
Alcohol has been shown to decrease suggestibility in a dose-dependent manner, while its withdrawals increases suggestibility. A large proportion of individuals who come in contact with law enforcement personnel are under the influence of alcohol, including perpetrators, victims, and witnesses of crimes. This has to be taken into account when investigative interviews are planned and conducted, and when the reliability of the information derived from such interviews is evaluated.
Suggestibility suppression is often accompanied by other coinciding effects such as irritability and ego inflation. It is most commonly induced under the influence of GABAergic depressants. It may also be induced in an inconsistent manner under the influence of moderate dosages of stimulant compounds, particularly dopaminergic stimulants such as nicotine, amphetamine, and cocaine. However, the specific situations in which suggestibility suppression will or will not occur under the influence of these compounds remains unpredictable and seemingly depends on the individual's gender or specific personality traits.
Compounds within our psychoactive substance index which may cause this effect include:
Anecdotal reports which describe this effect within our experience index include:
- Santtila, Pekka; Ekholm, Magnus; Niemi, Pekka (1998). "Factors moderating the effects of alcohol on interrogative suggestibility". Psychology, Crime & Law. 4 (2): 139–152. doi:10.1080/10683169808401754. ISSN 1068-316X.
- Santtila, Pekka; Ekholm, Magnus; Niemi, Pekka (1999). "The effects of alcohol on interrogative suggestibility: The role of State-Anxiety and mood states as mediating factors". Legal and Criminological Psychology. 4 (1): 1–13. doi:10.1348/135532599167707. ISSN 1355-3259.
- Gudjonsson, Gisli; Hannesdottir, Kristin; Petursson, Hannes; Bjornsson, Gudbjorn (2002). "The effects of alcohol withdrawal on mental state, interrogative suggestibility and compliance: an experimental study". The Journal of Forensic Psychiatry. 13 (1): 53–67. doi:10.1080/09585180210122682. ISSN 0958-5184.
- Netter, P.; Müller, M.J.; Neumann, A.; Kamradik, B. (1994). "The influence of nicotine on performance, mood, and physiological parameters as related to smoking habit, gender, and suggestibility". The Clinical Investigator. 72 (7). doi:10.1007/BF00207480. ISSN 0941-0198.
- Amigó, Salvador; Ferrández, Claudia (2015). "Experiencing Effects of Cocaine and Speed with Self-Regulation Therapy". The Spanish Journal of Psychology. 18. doi:10.1017/sjp.2015.50. ISSN 1988-2904.