With just an fMRI, an algorithm, and the internet, researchers from Kyoto, Japan predicted with 60 percent accuracy what a person was dreaming about, Smithsonian magazine reports. The idea, like the process, isn't all that complicated: Our brains react measurably differently to different stimuli: looking at a book or a building doesn't cause the same reaction. So the Kyoto team had three people sleep in an fMRI for three-hour stints over 10 days, and hooked them up to an EEG, which used electrical signals from the body to track which stage of sleep the were in were in.
Early on, just a few minutes after falling asleep, dreams started coming in bursts. The scientists woke the subjects up soon after and asked them what they saw. (For each participant, they actually did that 200 times, presumably turning them into the Grumpiest People In The Universe.) The researchers wrote down the 20 most common things the subjects saw: people, buildings, etc. They then found images on the internet that matched those common things, showed them to the subjects while they were awake but still in the fMRI, and took a reading. That information was fed into a learning algorithm. When the subjects slept again, the algorithm spit back this '80s
