Orientation, navigation, spatial memory difficulty and vision problems during re-entry and after landing can affect an astronaut’s performance during missions. Dr. Charles M. Oman and colleagues are studying three-dimensional spatial memory and navigation with the aim of developing four types of design, assessment, training and procedural countermeasures. These include spacecraft and work-area design standards, methods for assessing inflight and post-flight oscillopsia (a disorienting vision problem where the perceived world appears to careen), and preflight training techniques to help astronauts quickly learn the three-dimensional layout of the International Space Station and emergency egress routes. The project will also look at the effect of training module orientation on in-flight direction vertigo. The research includes studies that employ virtual reality research capabilities at York University and MIT. Six sets of experiments are involved.
Overview
Visual Orientation, Navigation and Spatial Memory Countermeasures
Principal Investigator:
Charles M. Oman, Ph.D.
Organization:
Massachusetts Institute of Technology
Technical Summary
Our specific aims were:
- To quantify how environmental geometric frame and object polarity cues determine human visual orientation, to support engineering and design of spacecraft work areas;
- To develop reliable means for quantifying head-movement-contingent oscillopsia;
- To determine whether preflight virtual reality techniques can improve astronaut 3D spatial memory and navigation abilities by reducing direction vertigo, and teaching ISS configuration and emergency egress routes; and
- To improve astronaut teleoperation performance by taking into account the mental object rotation and perspective-taking abilities of individuals while training and during operations.
By June 2007, we completed all four specific aims and all six experimental series originally planned. York University studied:
- visual frame and polarity effects in tilted rooms and in an immersive visual virtual environment (IVY), examining the effect of room aspect ratio and observer field of view;
- the perceptual upright as measured using a new OCHART method ("p" vs. "d" letter recognition) and analyzed results using a linear vector summation model; and
- quantified oscillopsia during Coriolis stimulation using a new visual feedback technique. The p/d method provides us with a way of assessing the perceptual vertical without requiring the subject to make a judgment of tilt with respect to the gravitational vertical a constraint that has confounded many previous investigations of perceived vertical in ground and zero gravity experiments (e.g., Witkin, Mittlestaedt, Howard, Oman). Experiments in IVY, manipulating the floor/ceiling aspect ratio of simple frame interiors, demonstrated that the surface perceived to be "the floor" depends on the aspect ratio in a predictable way that could be mathematically modeled. Several additional experiments were also performed. One showed that the strength of the levitation visual reorientation illusion depends on scene content (scene viewed), rather than geometric field of view (view seen). Another showed that the weighting of visual and non-visual cues for orientation was affected by Parkinsonism.
Massachusetts Institute of Technology (MIT) completed a series of four "relearning reoriented spacecraft modules" experiments, designed to simulate the training experience of astronauts who learn the interiors of individual spacecraft modules in a locally upright configuration in ground simulators, but who have to make spatial judgments when the modules are assembled in a different flight configuration. We showed that subjects remember each module in a visually upright, canonical orientation, and therefore had to make mental rotations in order to inter-relate the two modules. This year MIT tested different flight configurations, and found that performance was best when visual verticals were co-aligned, intermediate for 180 degree orientations, and worst when modules were rotated through 90 degrees. Our results account for the visualization difficulties and disorientation previously reported by Apollo, Mir and ISS astronauts when transiting certain areas of their spacecraft. The result could be easily translated into a design standard for space stations and docked vehicle operations. MIT also completed two ISS emergency egress training studies of 3D, six degree of freedom navigation performance, quantifying the effect of training in a locally vs. globally upright configuration, with and without smoke obscuration. Most subjects learned quickly, but performance correlated with individual 3D mental rotation and perspective-taking skills. This study, led by Dr. Aoki, won the 2007 Young Investigator Award from the Aerospace Medical Association's Space Medicine Branch. This year, we also compared performance of subjects trained using with a non-immersive laptop display with a similar sized group tested last year using an immersive display. Although immersive displays better simulate the vestibular and haptic cues required to orient spatially, our subjects performed almost as well using the laptop. Finally, as planned, MIT completed development of a space telerobotic training simulator, and showed that individual mental rotation and perspective-taking abilities influence performance during training.
Results of these studies have been presented at several international meetings, and full manuscripts have been published or are currently in submission. Dr. Oman also published a review article on visual orientation in microgravity which summarizes our research in a broader context.