Behavioral scientists have long been interested in the behavior of men under different kinds of stress, and many studies have been made of men and their behavior on Arctic and Antarctic expeditions, during natural disasters, and in combat situations. But most of the studies have been hampered by their reliance on subjective reports and other kinds of secondhand or otherwise unreliable information. With the advent of the manned space program. a new urgency has been given to discovering exactly how men of different backgrounds react to hazardous, confining or highly unpredictable environments. The knowledge is needed both so that men for hazardous missions can be more rationally selected and so that the missions themselves can be designed to minimize psychological stress. The Tektite manned underwater habitat programs (SN: 10/3, p. 283) have provided behavioral scientists with a unique opportunity to observe men in the socially confined and stressful environment that will be characteristic of the National Aeronautics and Space Administration's Skylab program (SN: 10/10, p. 303); in fact, one of the major goals of the Tektite program was to provide an analogue to Skylab so that NASA coLld conduct the behavioral studies now in progress. NASA originally had wanted the Tektite missions to be a simulation of Skylab, but marine scientists, recognizing the immense potential for marine science work on dives from an undersea habitat, insisted that an exact simulation would seriously hamper scientific work. NASA agreed to a compromise when it was realized that having working scientists aboard would make Tektite a better analogue to Skylab. The Tektite aquanauts were thus not confined to the habitat, but they were constantly observed while inside it. The Tektite study, which ended this month, was exceptional not only in terms of numbers of persons observed and the length of time involved, but also in the detailed nature of the observations. Each of the four rooms in the twin cylinders of the habitat was under constant surveillance with wideangle television monitors and microphones. In a room in the Tektite command van in the craggy hills of St. John Island above Greater Lameshur Bay in the Virgin Islands, where the habitat is located, University of Texas students kept a 24-hour watch on the aquanauts, more than 40 of whom were studied. The operation was highly computerized; thus many of the students had and needed no special background in behavioral sciences. Each aquanaut's behavior was recorded on punch cards every 6 minutes while he was in the habitat (producing some 15,000 punch cards weekly), and any unusual behavior was recorded on videotape for later analysis at the University of Texas by Dr. Robert Helmreich, principal investigator for the NASA project. Activity was divided into several categories, including marine science work, solitary recreation, co-recreation. relaxation, sleep, maintainance of self and others, and communication, both with the surface and with fellow aquanauts. Types of movements and postures were also identified. Psychological testing and inventorying of each aquanaut team were completed before it entered the habitat. Once beneath the surface the team members had no other direct human contact, except among themselves, for as long as 30 days. The tests included standard ones, such as the Minnesota Multiphasic Inventory, plus a new life history questionnaire designed by Dr. Helmreich and Dr. Roland Radloff of the Naval Medical Research Institute, a consultant to the program. The two men are co-authors of a 1968 book on men under stress. This life history questionnaire has certainly been our most valuable instrument, says Dr. Helmreich. Tests such as the MMPi are valuable for psychiatric diagnosis but of limited usefulness when dealing with normal subjects. In addition, the aquanauts periodically filled out mood inventory cards while in the habitat and were given debriefings when they resurfaced. A prime objective of the debriefings was to obtain aquanauts' reports on their ..: ..... .