Answer:
The correct answer is: an EEG
Step-by-step explanation:
An EEG (Electroencephalogram) is a test mainly used to acknowledge, test, and evaluate the electrical activity on the brain. This is done mainly by tracking brain wave patterns.
The premise is that certain brain wave patterns are healthy or normal, and the test is done to point out the anomalous brain wave patterns.
This test is used to diagnose encephalopathies, brain tumors, head injuries, and so on.
In conclusion, to the question: Dr. Billings studies brain wave patterns that occur when people are dreaming. He attaches a device to the outside of people's skulls to measure electrical activity in the brain during the dreams. What type of device is he using.
The correct answer is: An EEG.