Confined individuals who report habitability problems generally direct their complaint at a physical aspect of the environment, perhaps because it is more acceptable to complain about equipment than about a fellow confinee. However, as arrangements for living and working in space become better established, habitability issues can be expected to take on a subtler tone and to involve relationships as well as physical conditions. One such relational issue is the need for privacy. This area is not often discussed in terms of spaceflight needs; because of its perceived importance, we shall review privacy research at some length.
Meaning and Functions
The term "privacy" conjures up a variety of meanings. It is used to describe the need for ample space; visual, physical, or psychological separation; low population density; control over space, possessions, or information; freedom of activity; and many other concepts.
 Popular responses to the term fall into four broad categories: "aloneness," "controlling access to space," "no one bothering me," and "controlling access to information" (Wolfe and Golan, 1976). Three of these categories involve managing one's direct interactions with others; the fourth involves controlling information about oneself. Privacy in the informational sense reflects a concern not only about immediate events, but also about future events (Laufer, Proshansky, and Wolfe, 1976). It is the informational aspect of privacy that has changed dramatically with the introduction of computers, occasioning much of the recent concern over privacy issues.
Various definitions of privacy have been proffered by researchers and analysts who seek to understand the role of privacy in human development and functioning. A central element in these definitions is the ability of individuals to choose if, when, and to what extent they interact with, and thereby reveal themselves to others. For example (Margulis, 1974, vol. 6, p.1):
Margulis (1977) outlines three basic functions of privacy. The first and least central function involves the management of the interaction between self and others. This function assumes that roles and relationships are reasonably well understood and that the individual is seeking the most rewarding level of interaction with others. A higher order function is concerned with defining self in relationship to others. This function involves role definition and the presentation of self, and includes what Goffman (1959) refers to as "image management." The third and most central function of privacy regulation is concerned with self identification. By means of this function, privacy becomes the mechanism for distinguishing between the self and others. This function is demonstrated by its converse. In certain, situations the destruction of privacy is used to break down the notion of self identity and individuality (Goffman, 1961) as when prisoners or soldiers have their clothing removed, and after some period, are issued uniforms.
Theorists of privacy have long admonished that privacy involves having neither too much nor too little interaction. Interaction can  expose oneself to others; however, it also exposes others to self. Privacy represents the ideal balance or "homeostasis" between forces to be open versus closed (Altman, 1975), with dissatisfaction resulting when the optimal balance is not maintained (Sundstrom, 1977). However, this balance is not a static one. People seek to withdraw when they feel overly exposed, and seek exposure when they feel excluded, in a constantly correcting process.
Individuals observe others and seek information about others, assumedly because they need to judge the appropriateness of their own beliefs and behavior.10 People also voluntarily expose aspects of their personality to others. One explanation for this latter behavior is that the individual must be known if he is to be accepted and affirmed. In addition, there is an "expectation of reciprocity" associated with voluntary personal disclosures (Derlega, Wilson, and Chaiken, 1976). A revelation by one individual carries an expectation that the demonstrated trust will be returned by a revelation by the other. In this way, self disclosure itself becomes a means of access to needed information.
Bases of Needs
The rights of an individual to privacy and the rights of others (frequently the state) to information sometime come into conflict, with legal decisions swinging first one way and then the other (Levin and Askin, 1977). However, the fact that an individual has a right to privacy is well accepted in our culture. Western societies, with their belief in the distinctiveness and unique contribution of the individual, would be expected to value privacy more than societies with different philosophical orientations. This raises the question of whether the need for privacy is a culturally specific phenomenon or whether it is a generalized phenomenon, common to all members of the species.
Altman (1977) has performed an ethnographic analysis of various cultures and has concluded that privacy regulation is a culturally universal process. In those societies where contact among individuals is necessarily high, alternative approaches have evolved to  counteract these intrusions. The particular practices vary with the cultured but include the seeking out of secret private areas, flexible arrangement of structures, and cultural restraints on social interactions. He cites the Pygmies of Zaire as an example of a society which has developed an unusual method of privacy regulation. This group alternates between periods of very high physical and social interaction and periods of separation, with the periods of separation lasting up to several months. These cycles are repeated year after year. Altman (1978) concludes from the various societies he has studied that (p. 78):
Apparently, privacy in some form is necessary for individual and group survival, and those societies that survive have found their own, sometimes unique, mechanisms for ensuring an acceptable level of separateness.
If privacy is a general need of man, one might ask whether humans are alone in this quest for privacy. Westin (1967) proposes that the need for privacy, rather than being an expression of a human's special ethical, intellectual, and artistic needs, is an expression of animal origins. He observes that virtually all animals seek separation and solitude. Although animals in captivity appear to tolerate repeated invasions of their privacy, reduced fecundity and other aberrant behaviors in such animals indicate a failure in adaptation, and suggest that privacy may be important to the normal physiology of many species, even when particular individuals have never lived in a private environment.
Berscheid (1977) suggests that, since the need for privacy seems to have biological and evolutionary roots, individual variance in the strength of such a need may have genetic, as well as learned components These genetic components may correlate in some way with other aspects of personality such as a tendency toward extroversion or introversion. Studying large numbers of twin girls, Scarr (1969) found that genetic factors account for more than half the within family variance associated with introversion/extroversion. How the introversion/extroversion variable corresponds to privacy related behavior is largely unexplored, although as Berscheid notes, an interesting start has been made by Marshall (1975) who found evidence of  a relationship between privacy orientation and scores on an introversion/extroversion measure. Bersheid poses several questions whose answers could be informative to the relationship between personal characteristics and privacy. Do introverts have different and/or more successful ways of protecting themselves from excess social stimulation than do extroverts? How does the interaction between a person's status on the introversion extroversion dimension and his privacy state affect such dependent variables as aggression, susceptibility to influence, emotionality, group membership, friendship, interaction patterns, etc.? Understanding such relationships, or more broadly the relationship between personal characteristics and privacy needs, could help in predicting an individual's adaptation to closed and demanding environments such as that of space.
Privacy is controlled by four behavioral mechanisms: (1) verbal content and structure, (2) nonverbal behavior (i.e., body language), (3) environmental mechanisms, and (4) culturally based norms and customs (Margulis, 1977). Verbal and nonverbal privacy in space can be expected to mimic similar behavior on Earth (although as indicated in chapter VII, both verbal and nonverbal communication can be expected to be impeded in space). Culturally based norms will take time to evolve in space. A fruitful avenue of privacy regulation appears to lie in the manipulation of the environment.
Individuals use the environment and the physical objects in the environment to help define themselves as distinct from others. Clothing, personal space, and personal possessions become not just property with a fixed economic value, but extensions of the person. For instance, it is a well recognized phenomenon that an individual who has had property burglarized experiences a keen sense of personal invasion, whether or not anything is taken.11
Privacy regulation through structural arrangements has direct applicability to space. Archea (1977) warns that although most studies of structural arrangements have overemphasized the normative or symbolic association of architectural design, the attributes implicit in the physical arrangement are of primary importance. Archea proposes a model of spatial behavior in which visual access and visual exposure are the two key aspects of privacy regulation.
 Visual access is the ability to monitor one's spatial surroundings by sight; visual exposure is the probability that one's behavior will be visually monitored. The crux of Archea's thesis is that the arrangement of the physical environment regulates the distribution of information upon which interpersonal behavior depends. A central element in the relationship of visual access or exposure to privacy is the use of gradients or changes in the visual scene. These gradients can be abrupt (barriers) or gradual (lighting). Archea refers to the process of controlling behavior or adjusting position to achieve a desired level of privacy as "selective conspicuousness." Architectural privacy has been found to correlate with psychological privacy, and both forms have been related to job satisfaction and, for some tasks, with job performance (Sundstrom, Burt, and Kamp, 1980). The efficacy of architectural arrangements in privacy regulation has been shown also by Baum and Davis (1980).
One of the environmental limitations of spaceflight is that individuals are confined to a small area. It has long been understood that when individuals are so restricted, both physical and psychological symptomatologies result. At one time the medical problems associated with high density confinement were thought to be related to an increased opportunity for the spread of communicable disease (as discussed in Loo, 1973; Stokols, 1972; Desor, 1972). It is now known that the physical transmission of disease accounts for only a minor part of the problems of restricted individuals (Dubos, 1970). Of far greater importance to both physical and psychological health is the generalized factor of stress. Experiments with rodents have shown that cramped quarters give rise to reduced fecundity, hormonal pathologies, and reduced life span (Kiritz and Moos, 1974) with very high densities related to prostration, convulsions, and sudden death (Christian, 1963). Humans are rarely subjected to such extreme conditions, and assessment of the effects of high density on people must rely on the observation of more subtle symptoms. Information is based either on relatively intense but brief laboratory experiments, or else on less severe but more prolonged experiences in natural settings.
In the laboratory, the effects of high density on arousal have been somewhat equivocal. However, the preponderance of recent evidence favors the notion that high density does result in stress related arousal, as measured both by skin conductance (Calhoun, 1963) and by performance measures (Aiello, Epstein, and Karlin,  1975a). In a natural setting, stress arousal has been found to affect health and performance; physiological measures show trends in the same direction (Epstein and Karlin, 1975). In humans, high blood pressure is often associated with stress. Various studies have shown that elevated blood pressure accompanies high density, although in most of these studies other stressors were also present (D'Atri and Ostfeld, 1975; D'Atri, 1975; Harburg, Erfurt, Hauenstein, Chape, Schull, and Schork, 1973; Harburg, Schull, Erfurt, and Schork, 1970; Lang,1950).
In recent years, researchers have emphasized the importance of the psychological perception of crowding as distinct from the objective condition of high density. (For a review, see Stokols, 1978b.) Crowding is a far more complex variable than density, and a person in a high density situation may or may not feel "crowded." Stokols (1976) identifies three theoretical perspectives on crowding: stimulus overload, behavioral constraint, and ecological formulations. Stimulus overload relates perceptions of crowding to the excessive levels of stimulation that frequently accompany high density. Behavioral constraint focuses on the stresses which follow from restrictions on freedom. Ecological formulations emphasize the shortages of resources which often accompany high density living.
Several environmental variables have been found to influence how crowded an individual feels. High density within a dwelling and in private spaces such as in home or working areas are more closely related to stress response than are high densities outside or in public areas. Relational variables also influence the perception of crowding. Friends require less distance than strangers, informal groups less than formal, etc. One's assumptions about the situation also affect how crowded an individual feels. If individuals believe that they are able to control the situation, for instance, by having the option of leaving, their perception of crowding is reduced (Stokols, 1979; Glass and Singer, 1972; Sherrod, 1974). Predictability or expectation about the occurrence or duration of confinement also has an important influence on reducing feelings of being crowded (Glass and Singer, 1972).
There are differences among individuals in their perceptions of crowding. Altman (1975) reports that self directed, high self esteem persons have lower spatial needs than individuals searching for identity, and laissez faire individuals have lower spatial needs than authoritarian individuals. Similarly, subjects who report an external locus of control perceive a greater degree of crowdedness than do internal locus of control subjects (Schopler and Walton, 1974).
 However, Baron, Mandel, Adams, and Griffen (1976) suggest that the relationship between perceived locus of control and perception of crowding may be quite complex. In their study, internals demanded less distance than externals only when subjects did not feel cramped; when feeling cramped, internal locus of control subjects demanded more interpersonal distance than externals. Hackworth (1976) has shown that frustrations concerning crowding translate into other sensitivities. Subjects who reveal a trait preference for large personal space show increased annoyance to an auditory stimulus following high density confinement; subjects with low requirements for personal space show a slight decrease in sensitivity following the same confinement.
Several investigations have revealed gender differences in response to crowding. In laboratory studies, crowded men were found to respond more negatively, and crowded women less negatively, than their less crowded counterparts (Freedman, Levy, Buchanan, and Price, 1972). Similarly, crowded women rated themselves as less aggressive, and crowded men rated themselves as more aggressive, than similar but noncrowded subjects. These findings and others (Stokols, Rall, Pinner, and Schopler, 1973) suggest that women become more cohesive and cooperative, whereas men become more remote and competitive, under conditions of acute crowding. However, a recent study of long term crowding indicates that, over time, women pay a high price for their socially adaptive behavior. Aiello, Epstein, and Karlin (1975b) found that chronic crowding results in women perceiving themselves to be more crowded, and being less satisfied with their situation, than were similarly crowded men. Also, crowded women reported more health related problems, and showed less group stability over time, than did their male counterparts.
Taken together, these studies suggest that there are individual differences in the perception of crowding which may relate to other personal characteristics and which could be predictive of confinement tolerance.
Several studies refer to the "territoriality" of confined individuals in describing their privacy seeking behavior. However, true territoriality is less obvious in the human than in other species. Sundstrom and Altman (1974) observe that most animals show highly stereotypic territorial behavior, whereas humans show considerable territorial flexibility. These authors conclude that the human  territorial response is probably learned and may be just one of many techniques for achieving privacy.
In only a few cases has the specific need to control particular spaces been identified in confinement. In the University of California, Berkeley, "Penthouse" studies, it was reported that subjects staked out territories for their own personal use and became hostile when others violated these rights (Cowan and Strickland, 1965). Several Russian confinement experiences also have concluded that there is a specific need for personal space (Leonov and Lebedev, 1975, p. 86), and in the submarine experience, the lack of personal space was identified as a cause of stress (Earls, 1969). Yet even in these examples it is not clear whether the felt need was for separate space per se, or for control over interactions with others. Further evidence of the chameleon quality of the territorial need in humans comes from studies of Esser and his colleagues (Esser, 1973; Esser, Chamberlain, Chapple, and Kline, 1964). These researchers found that in confined settings with only a few desirable areas, the more dominant confinees exhibited territorial behavior, claiming for themselves the preferred spaces. However, in a uniform setting, the more dominant members did not act in a territorial manner, but rather moved freely throughout all the available space.
In a recent experiment, Rogers (1978) offered confined subjects an opportunity to purchase specific amenities, inluding extra space which could be turned to personal use. He found that although extra space was sometimes purchased, this space was added to the public area and was not used as individual space.
The evidence, then, suggests that for the human, personal and exclusive use of an area is probably less important than the privacy requirement which such space would address. This finding allows us to search for solutions to the privacy problem in space which do not depend on the personal allocation of territories within the habitat.
Privacy in Space
When one looks at space confinement, one is forced to conclude that many of the familiar avenues of privacy maintenance are blocked, while methods that can be used to break down feelings of personal identity and individuality, such as are employed in prison, are naturally present in the environment. In space, personal property is necessarily limited. Physical space is also severely restricted, leading both to forced interactions and lack of opportunity for personal  territory. Close contact leads to problems of information management, since the individual can be observed by others almost continuously. This situation increases the probability that the individual will be "caught unaware" in behavior he would rather keep private.12
On Earth, lack of privacy resulting from physical constraints would be compensated for by cultural norms. Space has yet to develop these cultural norms. In fact, confinement generally seems to work against privacy maintenance, as individuals engage in greater self disclosure than they would ordinarily. The limited number of personal interactions available to the space traveler, together with the lack of new inputs, result in compressed familiarity without the opportunity found in more conventional relationships to develop shared values. Self disclosure leads to reciprocal self disclosure, which can lead to rejection.
Even in the absence of rejection, it is easy to envision how escalating self disclosure could leave individuals feeling manipulated and out of control, both of themselves and of their relations with others. The problem is likely to be exacerbated by a strong group commitment. Having volunteered to the project, the participant would feel pressured to accept all aspects of the situation, including violations of privacy. Some even argue that the element of a public, as opposed to a private project, further reduces the individual's right to privacy (Kelman, 1977, p.180).
It has been found that if individuals will be forced, eventually, to reveal something about themselves that is damaging to their image, they can reduce the negative impact of the disclosure by revealing it quickly at the beginning of a relationship (creating the impression that they relate honestly), and only to selected individuals (thus recruiting these individuals to help keep the secret from others). For a discussion of these points see Jones and Archer (1976) and Jones and Gordon (1972). However, revealing negative information, even quickly and selectively, does not guarantee a positive response. If the disclosure is seen to be appropriate and socially rewarding, it may result in greater attraction toward the discloser (Jourand, 1959, 1971; Worthy, Garry, and Kahn,1969). However, a disclosure that is  perceived as inappropriate or unrewarding may be unrelated to acceptance (Jourand and Landsman, 1963; Thompson and Seibold, 1978), or a disclosure can relate negatively to acceptance (Kiesler Kiesler, and Pallak, 1967; Culbert, 1968; Weigel, Dinges, Dyer, and Straumfjord, 1972; Wheeless and Grotz, 1976).
Individuals with limited means of protecting their privacy respond either by "acting out," e.g., by behaving aggressively toward others, or by withdrawing (Wolfe and Golan, 1976). In confinement, acting out has been rejected as a viable coping mechanism. Withdrawal has become the hallmark of the confinement experience, and this withdrawal behavior may have roots in the need for privacy. Although withdrawal in some form will probably be employed by space travelers, there is reason to believe that even this solution will be less advantageous in space than in the usual confinement experience. In space, crewmembers must depend on each other for their day to day survival. Individuals in a threatening situation prefer to be m the company of others, not only for the acceptance, verification and comforts that individuals provide each other, but also for safety As long as a high level of interdependence exists in space, withdrawal behavior in spaceflight is likely to be either curtailed or highly specialized.
Although spaceflight will limit the use of many privacy mechanisms, the use of other mechanisms could be improved and expanded. Anything that would help emphasize a person's individuality could be expected to help offset privacy loss. If some, even small area could be designated to an individual, for instance for storage, it could be decorated to reflect private style. Decorating an area seems to have positive connotations; for instance, the quality and diversity of college room decorations have been found to be predictive of commitment to the university life (Vinsel, Brown, Altman, and Foss, 1980). Personally selected clothing could also help the individual maintain separateness. On Skylab. astronauts found particular fault with their clothing (Cooper, 1976). Although this complaint centered on the drabness of the clothing, it should be noted that garments failed to distinguish among individuals, perhaps another basis for the objection. Better use of available space could also alleviate the privacy problem. For instance' Skylab crews suggested that individual sleeping areas be separated further (Blush, 1982).
Although self expression can contribute to one's sense of identity and therefore can help protect privacy, not all means of self expression can be considered desirable for spaceflight. Men on the  first Skylab flight were reported to have accentuated their personal idiosynchrasies. Yet personal mannerisms have been found to be a Source of great annoyance with increased time m confinement (Grumman Aerospace Corp., 1970). Expressing one's individuality through clothing, decor, or physical separation could help space travelers maintain their identities without the irritation that follows in response to such personal expressions as gum snapping, knucklecracking, or foot tapping.
One method that has been employed successfully in circumventing privacy loss through self revelation is replacing depth of disclosure with breadth of disclosure (Jones and Archer, 1976). This technique is often used by individuals wishing to protect their privacy but who feel themselves forced to respond to the disclosure of another. The responding individual reveals something about himself or herself, or perhaps several things, but does not reveal anything that he or she considers sensitive. The demand for reciprocity has been superficially satisfied while avoiding unwanted revelation. Unfortunately, here again confinees may be at a disadvantage. Altman and Haythorn (1965) have found that control subjects (not confined) naturally employed this technique, whereas similar but confined subjects exchanged information at a high level of intimacy.
Friends display less disclosure reciprocity than strangers (Derlega et al., 1976). This may be because the norm of selfdisclosure reciprocity is stronger at the beginning of a relationship than at later stages (Altman, 1973). Regardless of the mechanism, the result is that friends regulate privacy more effectively than strangers, and are less likely to engage in destructive self revelation. If friends tend not to invade each other's privacy, there would be advantages in either selecting crews from among those with established relationships, or in encouraging friendships (not just working relationships) before confinement is attempted.
Perhaps the most important privacy need in space is to familiarize potential crewmembers with the environmental pressures they will encounter, and to help them understand both the value of group cohesion and the necessity of personal separation. As we have seen, privacy is required for the normal functioning of the individual. But individual privacy is also important for the effective functioning of the group. Group pressures can hamper an individual's judgment, even to the point where simple sensory information cannot be correctly perceived (Asch, 1951, 1956). When the individual becomes indistinguishable from the group, he or she is unable to contribute  anything further to the group. One method of encouraging continuing group contribution is to permit anonymity in offering suggestions or in voting on issues. However, a better method would be to develop an attitude of cooperation and acceptance within the group that allows individuals to contribute without fear of either retribution or ridicule.
There is one other major aspect of privacy relating to spaceflight which should be mentioned. This concerns the intrusion of outsiders on the privacy of the group as a whole. Several Russian studies have revealed dramatically negative reactions of confined individuals to outside observation (Lebedev, 1975, pp. 83, 85). It is readily understood how such observation would be viewed as particularly offensive, since the person making the observation remains safe and unexposed. This lack of relational symmetry adds the dimension of "subject object" to an already strained privacy arrangement. Several episodes that have occurred in space may have had some relationship to the perceived intrusion by outsiders on the group. Astronauts on Apollo 7 removed the sensors which were providing the ground with a record of their physiological functions. Also, it has been reported that cosmonauts on Soyuz 36 shut off their radio contact with the ground. A candidate incident also occurred on Skylab 4. The crew had decided among themselves to circumvent established procedures involving space sickness, forgetting that their conversation was monitored by mission control. The encounter which followed is thought to be responsible for a general atmosphere of friction which lasted throughout much of the mission. Although, in this case, the astronauts could not convincingly claim that they had a right to alter procedures, their behavior indicated that they felt their privacy had been wrongfully invaded. Group privacy rights of spacecrews can be expected to be come an increasingly important issue.
10 Festinger first focused on the notion that a primary function of group affiliation is the evolution of~ one's own feelings and beliefs, i.e., self identification (Festinger, L.; Informal Social Communication, Psychological Review , 57, 271 282, 1950). This area, which is known as "social comparison theory" continues to spawn informative research.
11 Irving Altman (1975, op. cit.) discusses this phenomenon in terms of the "contamination" of the personal possessions by the intruder.
12 Kelman notes that control over our ability to preserve an image is reduced when we find ourselves in a situation where we must respond spontaneously, immediately, or within severely restricted options (Kelman, Herbert C., Privacy and Research with Human Beings. J. of Social Issues , 33(3), 169 195 (Summer, 1977)).