Neurolab

Though we don't think about it much, the force of gravity profoundly effects human experience as we go about our daily lives here on Earth. In contrast to birds and aquatic animals, most of the large turning movements humans make are in a gravitationally horizontal plane. We are used to seeing most objects from our normal upright head orientation. But the experience of living in weightlessness is quite different for humans. Your life is not fettered to a single plane. You can move in any direction, and work upside down if you want to. Astronauts on previous flights have reported that when working upside down, they frequently experience striking visual illusions as to what seems "up" and "down", and say they have difficulty recognizing familiar objects in unfamiliar orientations. When these illusions happen, they seem to trigger space sickness. The specific goal of our experiments is to quantify and model these problems, and see whether they persist on long duration flights. We're trying to reverse-engineer the mind, and figure out the rules it uses to combine sensory cues. We know people differ in terms of how much weight they give to visual cues relative to inner ear cues in judging the vertical here on Earth. Can we predict whether they will have problems when they fly in space ? Do astronauts eventually develop a more robust orientation ability ? Or does the human evolutionary heritage and our lifetime of mono-oriented experience with our environment constrain what we can learn to do ? Knowing the answers to these questions will help us figure out what kinds of preflight training and spacecraft interior architectures will reduce disorientation and space sickness. Inevitably we'll also better understand the role vision can play in spatial orientation here on Earth, both in normal individuals, and in patients with inner ear disease.

This is an example of one of the virtual environments we used for the experiments. This image is generated in realtime and in stereo and seen by the astronauts while wearing the head-mounted display (see picture below).

Crew member Jay Buckey performing an experiment using the NASA virtual environment generator during STS-95 (April 1999)

Here's a stereo-pair (crossed fusion) of a scene from our experiment.

Oops, no gravity!