The brain knows more is stored in visual long-term memory than we can report

If your visual long-term memory storage is virtually perfect, then when you happened to press the wrong button during a visual recognition memory experiment you would detect that motor error as such. That is, your brain should know when you are about to commit an error during a visual long-term memory experiment, even before you press the button. This is exactly the prediction we tested in this study. Electroencephalograms were recorded from 50 subjects who viewed 500 photographs of real-world objects for a subsequent recognition memory test in which the confidence of their judgments were also collected. Here we show that subjects’ brains knew they were making mistakes during the recognition memory test at the time of button press, indicating that sufficient memory representations were available to executive control mechanisms to know that errors were being committed. Our findings show that people's choice behavior in visual long-term memory experiments misses information that is available to other high-level mechanisms of the brain.