Dr. Bach-y-Rita is a neurologist who has developed a device that allows blind people to see. The machine works by transmitting information from a small camera to a laptop, which then sends electrical signals to a small electrode matrix.
Depending on how bright a spot on the image is, that point on the matrix has either more or less current. By placing this electrode matrix on your tongue, and attaching the camera to your forehead, your brain associates the stimulation with sight sensations. During one of their tests, an assistant encourages a subject, blind mountain climber Erik Weihenmayer, to try looking at a candle.
Immediately, another assistant becomes excited and both Dr. Paul-y-Rita and Dr. Kamm describe some past experiences with subjects and the candle:
"So my question to you is: did you expect the candle flame to be taller shorter?
Again, we've had all sorts of remarks from children. For example, one said, 'Why is the flame so small? When I hold my hand over my birthday candles I can feel it all the way up.' So he was expecting the flame to go all the way up." - Dr. Paul-y-Rita
"I have one subject, Allison, who absolutely loves the wind; and, when I showed her the flame, she was like, 'Is that what wind looks like?'" - Dr. Kamm