Neurophysiological correlates of post-hypnotic alexia: a controlled study with Stroop test.
To clarify whether hypnotically-induced alexia was able to reduce the Stroop effect due to color/word interference, 12 volunteers (6 with high and 6 with low hypnotizability according to Stanford Hypnotic Susceptibility Scale Form C) underwent a Stroop test consisting of measuring, both in basal conditions and during post-hypnotic alexia, the reaction times (RT) at appearance of a colored word indicating a color. In basal conditions, RT were greater in case of incongruence. In highly hypnotizable participants, the interference was less pronounced during post-hypnotic alexia (-34%, p = 0.03). During alexia, late positive complexamplitude was also greater for congruent than incongruent conditions (p < 0.03), and cardiovascular response to stress was less pronounced as well. In participants showing low hypnotizability, no reduction of Stroop effect was detected during post-hypnotic alexia. Posthypnotic alexia is therefore a real and measurable phenomenon, capable of reducing the color-word interference and the haemodynamic effects of the Stroop test.
Casiglia
Edoardo
E
Department of Clinical and Experimental Medicine, University of Padova, Via Giustiniani, 2, I-35128 Padova, Italy. edoardo.casiglia@unipd.it
Schiff
Sami
S
Facco
Enrico
E
Gabbana
Amos
A
Tikhonoff
Valérie
V
Schiavon
Laura
L
Bascelli
Anna
A
Avdia
Marsel
M
Tosello
Maria Teresa
MT
Rossi
Augusto Mario
AM
Haxhi Nasto
Hilda
H
Guidotti
Federica
F
Giacomello
Margherita
M
Amodio
Piero
P
D000328:Adult; D001143:Arousal / Q000502:physiology; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology*; D003118:Color Perception / Q000502:physiology; D004411:Dyslexia, Acquired / Q000503:physiopathology* / Q000523:psychology; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D006990:Hypnosis / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D011930:Reaction Time / Q000502:physiology; D012660:Semantics; D012815:Signal Processing, Computer-Assisted; D057190:Stroop Test; D013404:Suggestion