Increased suggestibility is a greater tendency to accept and act on the suggestions of others.   A common example of increased suggestibility in action would be a trip sitter deliberately making a person believe a false statement without question simply by telling it to them as true, even if the statement would usually be easily recognizable as impossible or absurd. If this is successfully accomplished, it can potentially result in the experience of relevant accompanying hallucinations and delusions which further solidify the belief which has been suggested to them.
Increased suggestibility most commonly occurs under the influence of heavy dosages of hallucinogenic compounds, such as psychedelics, dissociatives, deliriants, and cannabinoids. This holds particularly true for users who are inexperienced or currently undergoing delusions and memory suppression. It's worth noting that this effect has been studied extensively by the scientific literature and has a relatively large body of data confirming its presence across multiple hallucinogens. These include LSD  , mescaline  , psilocybin  , cannabis  , ketamine  , and nitrous oxide  . However, anecdotal reports suggest that it may also occur to a lesser extent under the influence of GABAergic depressants such as alcohol and benzodiazepines.
- What is suggestibility? (Psychology Dictionary) | https://psychologydictionary.org/suggestibility/
- Carhart-Harris, R. L., Kaelen, M., Whalley, M. G., Bolstridge, M., Feilding, A., & Nutt, D. J. (2015). LSD enhances suggestibility in healthy volunteers. Psychopharmacology, 232(4), 785-794. | https://doi.org/10.1007/s00213-014-3714-z
- Kelly, S. F., Fisher, S., & Kelly, R. J. (1978). Effects of cannabis intoxication on primary suggestibility. Psychopharmacology, 56(2), 217-219. | https://doi.org/10.1007/BF00431853
- Cheong, S. H., Lee, K. M., Lim, S. H., Cho, K. R., Kim, M. H., Ko, M. J., ... & Lee, S. E. (2011). The effect of suggestion on unpleasant dreams induced by ketamine administration. Anesthesia & Analgesia, 112(5), 1082-1085. | https://doi.org/10.1213/ANE.0b013e31820eeb0e
- Whalley, M. G., & Brooks, G. B. (2009). Enhancement of suggestibility and imaginative ability with nitrous oxide. Psychopharmacology, 203(4), 745-752. | https://doi.org/10.1007/s00213-008-1424-0