This study investigated the effect of a placebo introduced as a cognitive stimulant on working memory, as reflected by the P300 ERP amplitude in humans. Placebos are forms of treatment prescribed for the psychological benefit of the patient, rather than a physiological effect. The treatment is inert, but can have a negative or positive effect based on how the drug is introduced. It was hypothesized that because human cognition is affected by placebo, working memory may improve if the placebo was introduced as a cognitive stimulant. This was quantified through the 2-back task and ERP recordings. Participants were divided into a placebo group and a control group (no placebo pill) and completed two blocks of the 2-back task. One block occurred prior to taking the placebo and the second block occurred ten minutes after ingesting the pill. The control group did not receive a pill. Results indicated that the placebo condition had higher improvement between Block 1 and Block 2 when responding to matches, than the control group. The P300 amplitude showed increased amplitudes in Block 2 as compared to Block 1, for the placebo group in the central and frontal areas of the brain, in comparison to the control groups who had lower amplitudes indicative of more cognitive load. These results show the effectiveness of expectation in humans, and how perception can be primed to show an intended effect due to a placebo.


Herzmann, Grit

Second Advisor

Mellizo, Philip


Neuroscience; Psychology


Neuroscience and Neurobiology | Psychology

Publication Date


Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis



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