Visual evoked potentials in hypnosis: A longitudinal approach

• Published in: International journal of clinical and experimental hypnosis 1981-01, Vol.29 (1), p.77-86
• Main Authors: Zakrzewski, Kajetan, Szelenberger, Waldemar
• Format: Article
• Language: English
• Subjects: Adult; Evoked Potentials; Female; Humans; Hypnosis; Vision, Ocular - physiology; Visual Pathways - physiology
• ISSN: 0020-7144; 1744-5183
• DOI: 10.1080/00207148108409145

Visual Evoked Potentials (VEP's) were recorded in 5 healthy 20-24 year-old-females during hypnosis, hypnosis after the suggestion of blindness, and in 3 waking conditions. VEP's were recorded in these conditions 10 times within each S on different days. Both within-Ss and between-Ss analyses showed a tendency of VEP N-250 latencies (and possibly also amplitudes) to increse in hypnosis when compared to the waking state. Overall, these changes tended to be rather small. No changes were found in the earlier VEP waveform components, and some tendencies noted in the later P-300 component were largely nonsignificant. Decrease in N-250 amplitudes after the hypnotic suggestion of blindness was significant for the whole group, but was difficult to interpret, since amplitude in this condition was not significantly different from the wake control condition N-250 amplitude. The results are considered preliminary, and a few possibilities of confirming and/or explaining them using somewhat more stringent methodology are discussed. The within-Ss approach is recommended for future studies of evoked potentials in hypnosis.