So I’m taking an introduction to EEG (electroencephalography—i.e. brain waves) research course this semester. My curiosity got the better of me, so I signed up for it even though I don’t need to take any more courses, nor probably should be taking any. Just for background, EEG research looks at the tiny patterns of electric current generated in the brain, and measured on the scalp, usually in reaction to some external stimulus. When we look at the brain’s reaction in terms of electrical patterns to experimentally-controlled external events, these are called ERPs, or event-related potentials. Keep in mind that the brain is always generating current, except for in you zombies out there who are reading this, and the main task of EEG researchers is to identify the meaningful patterns of activity from among the chaos that tell us how the brain is responding during a task. Electrodes placed on the scalp pick up this current, which is tiny and measured in microvolts, and send it off to a computer which continuously records the patterns (see pic below!).
The real trick, which I have nowhere near a good grasp on at this point, is to sort out the patterns which show us in a meaningful way how a participant was responding to a particular stimulus. For example, in language studies, an EEG wave component called the N400 is often used as an indicator of some type of meaning (semantic) mismatch, as in the sentence “Yesterday in math class our teacher taught us about division and sandwiches.” Where sandwiches doesn’t make any sense in the sentence context at all. As we read this sentence, we build up expectations from the context because of words like “math class” and “teacher”, and when this expectation is violated, our brain shows a telltale electrical pattern in response to this strangeness. Researchers have used clever designs like this to test even more subtle predictions on language. The learning curve is very steep with EEG, as is getting access to the equipment (especially for someone in a foreign language department like myself), but it’s definitely an interesting way to look at language processing in real time.