J. Hoffman in the New York Times writes in ”Taking mental snapshots to Plumb our inner selves’, about the work of R. Hurlburt (here), who is attempting to document the contents of consciousness. The method is to fit a person with a random beeper and instructions to record everything they are aware of when the beeper sounds. The people were later interviewed about each recorded moment of consciousness.

After hundreds of introspective interviews, Dr. Hurlburt still hesitates to generalize from his findings. But he has observed that the basic makeup of inner life varies substantially from person to person.

“My research says that there are a lot of people who don’t ever naturally form images, and then there are other people who form very florid, high-fidelity, Technicolor, moving images,” he said. Some people have inner lives dominated by speech, body sensations or emotions, he said, and yet others by “unsymbolized thinking” that can take the form of wordless questions like, “Should I have the ham sandwich or the roast beef?”

In a 2006 book, “Exploring Inner Experience,” Dr. Hurlburt suggests that these differences may be linked to personality and behavior. Inner speakers tend to be more confident, for example, and those who think in pictures tend to have trouble empathizing with others.

Many feel that this is not a very objective experiment. How do we know that people can or do report their conscious awareness in an isolated moment with accuracy, nothing added and nothing missed.

It may be that turning introspection into a science is as impractical as “trying to turn up the gas quickly enough to see how the darkness looks,” as William James wrote in 1890.

But Dr. Hurlburt remains hopeful. Maybe, he said, “it is possible with our modern technology to take a flash picture in the dark.”