When people learn and remember information, it is often accompanied by a feeling of subjective confidence about whether or not information has been learned and accurately remembered. These subjective feelings of confidence are often related to actual memory performance, but are sometimes incorrect. The investigators have previously shown that applying high definition transcranial direct current stimulation (HD-tDCS) over the dorsolateral prefrontal cortex leads to more accurate feelings of subjective confidence, at least when subjects are asked for their confidence about future memory performance. Accurate confidence judgments are useful in that they may later subsequent behavior, and inaccurate ones may be costly. For example, a student who erroneously believes that studied material was learned may stop studying and not do well on a test. Individuals who have a feeling-of-knowing about the answer to a general knowledge question will continue to search their memory, whereas individuals who do not have a feeling-of-knowing will stop searching their memory. Individuals who are confident they know the answer to a question are more likely to answer it. In this study, the experimenters are testing the effects of brain stimulation on subjective awareness of memory (termed metamemory monitoring) and how people use those subjective judgments (termed metamemory control). The approach taken is to have participants visit the laboratory on 3 visits and receive brain stimulation while completing memory and metamemory tasks.

Inclusion Criteria:

• Healthy, right-handed adults ages 18-35. English spoken since age 5. Normal or corrected-to-normal vision.

Exclusion Criteria:

• Participants will be excluded if they have chronic skin disease or a medical skin condition, or an unhealed open wound on the scalp, face, neck, or forehead near the electrode location.
• Participants will be excluded if they self-report significant medical, neurological, or psychiatric illness and/or a history of substance abuse