Antipsychotic placebo increases electrophysiological indices of stimulus processing and accelerates reaction times on a particular semantic task

Poster Session B - Sunday, April 14, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Aidan Schottler-Raymond¹ (aidan.schottler-raymond@mail.mcgill.ca), Mingyi Diao¹, Ilya Demchenko¹, Jingyan Quan¹, J. Bruno Debruille¹; ¹McGill University

When we are consciously perceiving a stimulus we are also aware that it is us who is perceiving it. This means that the representations activated by the stimulus are bound to representations of the self. The impact of this binding on the processing of the stimulus remains unclear. To examine this, we manipulated self-representations by using an antipsychotic placebo, as taking this may add a layer of self-representation. Indeed, with it, participants may represent themselves both as they usually do and as being under the influence of a drug. Two tasks were used to explore the effects of that manipulation on stimulus processing: a classical semantic categorization task and a control self-referential task that focused only on the usual self of the participant. In the semantic task, participants of the antipsychotic placebo group (N=43) displayed greater P2- and late positive potential- (LPP) event-related potential (ERPs) amplitudes, as well as faster reaction times than the participants of the no-pill group (N=43). No such differences were found in the control task, whereas the amplitude of the N400 ERP was significantly reduced by the placebo in both tasks. As a fully deceptive antipsychotic placebo was used, our results may have an impact on the understanding of the cognitive deficits of schizophrenia patients and on the placebo aspect of the effects of the medications they are taking. Further research in this area should focus on these patients whose self-representations have been hypothesized to be fragmented.

Topic Area: LANGUAGE: Semantic