Vaske, J. and M. Donnelly. 2002. "Generalizing the encounter - norm - crowding relationship." Leisure Sciences 24(3-4): 255-269.

This article examines the theory that predicts that when encounters exceed a visitor's norm for seeing others, crowding will increase. Data from 13 different studies, which included both high- and low-density study sites, 12 different activity types and a total sample size of 10,697, is used in this study. Recreation encounters were measured by asking respondents to indicate the number of people they remembered seeing and crowding was measured using a a 9-point Likert scale. Individual encounter norms were determined by asking respondents to specify the highest number of encounters they would tolerate for a given situation. The study found that crowding was significantly higher for individuals who indicated more encounters than their norm. However, respondents only felt "Slightly" to "Moderately" crowded, indicating a medium strength relationship. This relationship was found for three different predictor variables: backcountry versus frontcountry; type of activity (e.g. canoers, hikers, hungers, anglers); and whether there conflict or no conflict. These findings highlight the importance of measuring all three concepts - encounters, perceived crowding and norms - to develop an understanding of how the existing conditions compare to the standards for the experience to be offered.

Stewart, W. and D. Cole. 2001. "Number of encounters and experience quality in grand canyon backcountry: Consistently negative and weak relationships." Journal of Leisure Research 33(1): 106-120.

This study explores one of the most common topics of outdoor recreation research, the relationship between encounters and the overall quality of recreation experience. Many previous studies have found a weak relationship between satisfaction with the recreation experience and the influence of encounters with other recreationists. The literature, however, is unclear whether this a finding related to methodological issues or whether it is a finding that reveals a fundamental lack of relationship. This study, therefore, uses a more novel research method, a diary-like method, to control for variation in person-based effects (e.g. differences in expectations and motivations between individuals) and a multi-item scale designed to capture more variation in total experience quality. A total of 185 overnight backpackers to the Grand Canyon National Park were surveyed to explore the relationship between number of encounters, crowding, solitude/privacy achieved, and overall experience quality. The results indicate that most backpackers were negatively affected by encountering more groups, but the resultant effect was small. The authors believe that this result implies that managers should be reluctant to justify use restrictions as an attempt to provide higher quality visitor experiences. Instead, managers need to develop a careful understanding of the regional supply and demand for different types of recreation experiences, including low density experiences, as these factors are more likely to provide the basis for wise decisions about use limits.

Hall, T. and B. Shelby. 2000. "Temporal and spatial displacement: Evidence from a high-use reservoir and alternate sites." Journal of Leisure Research 32(4): 435-456.

This study investigates the amount of temporal and spatial displacement behaviors used by visitors in response to crowding at popular reservoir in Oregon. Surveys of recreational users from the reservoir site itself (n=1,069) indicated that about half altered their behavior in some way because of crowding, primarily through altering the time of day, week or year that they came to the reservoir (42%) and secondarily through shifting their use to a different area of the reservoir or to another recreational area altogether (26%). The study also interviewed users at nearby alternative sites (n=169) and found about half of people these people used the reservoir less than in the past. However, only half of these people attributed their shift in behavior to crowding or undesirable conditions at the reservoir. Displacement was more likely to used as a behavior by those who have been using the reservoir for a longer period of time. Users who exhibit displacement behaviors also rated conflict with other users, lack of facility issues, and environmental degradation as a bigger problem The study has discusses in detail areas of similarity or discrepancy with past displacement research.

Manning, R. E. 1999. "Crowding in outdoor recreation: Use level, perceived crowding and satisfaction." In Studies in Outdoor Recreation: Search and Research for Satisfaction, Second Edition, 80-121. Corvallis: Oregon State University Press.

This chapter reviews the significant body of literature on crowding in recreation. Crowding is seen as one conflict mechanism. However, the postulated "satisfaction model" - where there is an inverse relationship between crowding and recreation - has generally not been well supported by empirical research. There are a number of reasons for this including: displacement of visitors sensitive to crowding, different personal definitions of crowding, psychological coping behaviors, types of people or group encountered, the place where the encounter takes place, whether the contacts between users are measured objectively or self-reported, and, most importantly, the fact that satisfaction is a multi-faceted concept that is influenced on partially by use level and perceived crowding. These research results have some important implications for management. In particular the author suggests that satisfaction is not an appropriate measure for managing use level and crowding. Management attention should be focused on contact levels (rather than use level) and on zones managed to encourage relatively homogenous groups in terms of party type, size, and behavior.

Kuentzel, W. F. and T. A. Heberlein. 1992. "Cognitive and behavioral adaptations to perceived crowding: A panel study of coping and displacement." Journal of Leisure Research 24(4): 377-393.

This study uses data collected from a panel of boaters at the Apostle Islands National Lakeshore in 1975 and a subsequent resurvey (n=397) in 1985 to test the relationship of perceived crowding in 1975 to attitude changes (cognitive coping strategies), and behavioral shifts (intrasite displacement and discontinued participation at the Apostle Islands). The researchers present a hierarchical crowding model that proposes that crowding is the first copping mechanism used by those feeling crowded, intrasite displacement is used by those feeling more crowded displacement to other sites by those feeling most crowded. However, the results of this study found no support for the hierarchical crowding model. Instead, those who felt most crowded were more likely to use a intrasite displacement behaviors and avoid the more crowded islands. The use of cognitive coping strategies were not significantly related to crowding scores and those boaters who stopped coming to the Apostle Islands did so for reasons other than crowding. These findings indicate that intrasite displacement provides an adequate coping strategy for boaters at the Apostle Islands. The notion that increasing use levels will necessarily drive the most sensitive users away is not supported among boaters at the Apostle Islands. This may related to specific factors related to the Apostle Islands, not as crowded as other areas and diversity of sites, and the lack of good substitutes for the majority of Apostle Islands boaters.

Shelby, B., J. J. Vaske and T. A. Heberlein. 1989. "Comparative analysis of crowding in multiple locations: results from fifteen years of research." Leisure Sciences 11: 269-291.

This study uses a comparative analysis of 35 studies, which represent the views of over 17,000 people in 59 different recreation settings, to study crowding in outdoor recreation. All the studies use a single-item nine-point Likert scale to assess visitor judgments of crowding. If the nine-point scale is divided to reflect the percentage of respondents experiencing at least some crowding, crowding scores ranged from 12% -100% with a mean of 57%. The comparative analysis suggested that crowding is influenced by a range of factors including time, resource availability, accessibility and convenience, and management strategy. While factors that were found not to influence crowding included region of the United States, whether the activity was consumptive or non-consumptive, and the methodology used to collect the data (on-site surveys or mailed surveys). This study also reexamined earlier work to that looked to use crowding ratings to identify areas with potential carrying capacity problems. In general, crowding does help to identify carrying capacity problems. Areas with crowding in the 35%-50% range appear to "no problem" areas. Areas with crowding in the 50%-65% range should be looked at closely, while in areas with more than 65% crowding there is definite problem. If visitor numbers and impacts are an important part of the experience, it makes sense to freeze use levels immediately when crowding reaches 65% or greater. When more than 80% of visitors feel crowded the only management option to manage these areas for high-density experiences.

Westover, T. N. and J. R. J. Collins. 1987. "Perceived crowding in recreation settings: an urban case study." Leisure Sciences 9: 87-99.

This study, unlike much of the work on crowding and conflict in recreation, investigates crowding at Potter Park, an urban park in Lansing, Michigan. A total of 154 parks users were surveyed for their perceptions of crowding, inappropriate behavior and dissimilar others. Overall these findings demonstrate relatively low levels of perceived crowding even though there were relatively high visitor numbers. However, compared to outdoor and wilderness recreation studies, this study did find that actual use levels were more closely associated with crowding evaluations than in other studies. A number of factors may have influenced these results including small park size and lack of visual screening. It may also be that the perception of visitor densities in urban parks is less value-laden than it is in outdoor recreation and based more on visual levels than on beliefs about appropriate use levels. Other factors and their relationship to perceived crowding were also investigated including socio-economic status. Individuals with higher socio-economic status were less likely, rather than more likely as has been the case in outdoor recreation studies, to perceive crowding, and particularly during high use time. This may be the result of a wider range of experience and expectations that match actual experience more closely. Moreover, the higher proportion of well-educated people during low use times may suggest that these individuals may have a wider range of site choices and avoid the park during times when they expected it be unacceptably crowded. Other factors such as

Chambers, T. W. M. and C. Price. 1986. "Recreational congestion: some hypotheses tested in the forest of Dean." Rural Studies 2(1): 41-52.

Many studies have failed to find an adverse relationship between crowding and visitors responses. This study looks to test a number hypotheses which may explain these past results including: influence of environmental and site factors; amount of vegetation at a site and its influence on site lines; displacement in terms of timing or choice of site; absence of expectations; or impact of investment in getting to the site. Overall the study found most support for the vegetation, displacement and no-expectations hypotheses, with less convincing support for the environmental and investment hypotheses. Overall, the researchers find that the results of this study restore some credibility to the visitor satisfaction/density model. From a management perspective, the implications of this research are that there are clearly crowd-adverse and less crowd-averse sub-groups. Management actions that attempt to disperse all recreational pressures and facilities evenly through a recreational area may only cause conflict with the crowd-adverse sub-group, and is not necessary to ensure the satisfaction of another sub-group. The natural tendency of different sub-groups to segregate into areas of different intensity of use should not be thwarted.

Hammitt, W. E., C. D. McDonald and F. P. Noe. 1984. "Use level and encounters: Important variables of perceived crowding among nonspecialized recreationists." Journal of Leisure Research 16(1): 1-8.

This study looked at the perceptions of crowding amongst non-specialized recreationists - innertube floaters - on the Hiwassee River in Tennessee. Regression analysis was used to test the comparative contribution of four variables identified in earlier research as part of perceived crowding model: use level, visual encounters, crowding expectations, and user feelings toward crowding. Only 47% of the variance among innertube floaters was explained by these variables, while 43% was explained by just the two variables of use level and reported visual encounters. As compared to studies of more specialized recreational users such as backcountry hikers or river rafters, much less variance perceived crowding was explained by expectations and feelings. This result makes good theoretical sense as non-specialized recreationists are not likely to have a developed norms or expectations concerning appropriateness or have much commitment to the activity in terms of equipment, trip planning or overall importance.

Shelby, B., T. A. Heberlein, J. J. Vaske and G. Alfano. 1983. "Expectations, preferences and feeling crowded in recreation activities." Leisure Sciences 6(1): 1-14.

This study investigates perceived crowding amongst different types of recreation users - hunters, canoers and river floaters. Self-reported questionnaires were administered in six different studies with a total response rate of over 3000 individuals. For each study, the users were asked to report on how many contacts they had with other users, the number of contacts they had expected during their recreational activity and what was their personal preferences as to how many contacts they could tolerate during their recreation activity. The study found support for four hypotheses: 1) people experiencing more contacts will feel more crowded, 2) people will feel more crowded if the number of of encounters exceeds preferences, 3) people will feel more crowded if the number of encounters exceed preferences, and 4) because perceived crowding involves a cognitive evaluation, models including expectation and preference variables will better explain perceived crowding than contact alone. From a management perspective, perceived crowding can be reduced by providing a range of recreation opportunities that allow users to make choices in line with their preferences and by improving the accuracy of user expectations.

Gramann, J. H. 1982. "Toward a behavioral theory of crowding in outdoor recreation: An evaluation and synthesis of research." Leisure Sciences 5(2): 109-126.

In this paper, research studies on crowding in recreation are analyzed critically and compared to dominant paradigms in social psychology: crowding as stimulus overload and crowding as social interference. In the stimulus overload model, crowding perceptions are greatest when the level of social stimulation exceeds desirable levels and the individual is unable to reduce that stimulation through adaptive strategies. In the social interference model, negative perceptions of density are due to perceived interference with important psychological needs (either because of number and proximity of other or due to objectionable behaviors) or perceived spatial requirements. Early research on crowding focused on social carrying capacity, with number and frequency of encounters being seen as relating directly to overall satisfaction levels. However, research results discredited this perspective and social psychological views of crowding, taking into account differential interpretations of the social environment, seem to have more to offer. This paper finds strong evidence within the recreation crowding and conflict literature to support both the social stimulus model and behavioral aspects of the social interference model. Psychical crowding effects of the social interference model is postulated only for very high density recreation situations.

Becker, R. H. 1981. "Displacement of recreational users between the Lower St. Croix and Upper Mississippi Rivers." Journal of Environmental Management 13: 259-267.

This study investigates whether their is a relationship between user density and visitor satisfaction on the Lower St. Croix and Upper Mississippi Rivers. When the rivers were viewed on their own, users on both the Mississippi and the St. Croix were equally satisfied with their experience. Like many other crowding studies, this finding seems to indicate their was no relationship between density and user satisfaction. However, when the two rivers were considered together it was found that some users who were bothered by high use levels on the St. Croix shifted their activity to the Mississippi. Users on the St. Croix were more inclined towards social aspects of recreation while users on the Mississippi were inclined towards experiences of solitude and less human influence in terms of pollution, facilities or boat traffic. The authors conclude that this study demonstrates that their is a clear relationship between user density and satisfaction, but studies that do not account for displacement or other coping behaviors fail to find this important relationship.

Manning, R. E. and C. P. Ciali. 1980. "Recreation density and user satisfaction: A further explanation of the satisfaction model." Journal of Leisure Research: 329-345.

This paper makes an effort to understand the user density-satisfaction relationship through both a theoretical examination and empirical research. From a theoretical perspective, density only becomes a negative situation when densities get high enough to be seen as crowding. The paper also reports empirical research from four different rivers in Vermont and represents a survey size of 866. In this case density was measured by asking respondents to report the number of people they had reported on the sampling day and their satisfaction level on a ten point scale. No relationship was found between density and user satisfaction. Four possible explanations for thing finding were explored: cognitive dissonance, no expectations, product shift and displacement. The authors found only limited evidence for the latter three explanations, but their methods were very preliminary in nature. Interestingly, despite their discussion of the difference between density and perceived crowding the research measures user density, while later research in the field has consistently measured perceived crowding.

Vaske, J. J., M. P. Donnelly and T. A. Heberlein. 1980. "Perceptions of crowding and resource quality by early and more recent visitors." Leisure Sciences 3(4): 367-381.

This study explores the relationship between the year boaters made their first trip to the Apostle Island National Lakeshore and their current evaluations of the resource. A survey of 647 boaters in 1975 was divided into three groupings: 1) those whose first visit to the islands prior to the areas national designation in 1970 (n=214), 2) those whose first island trip occurred between 1971 and 1974 (n=197) and those who made their first visit during 1975 (n=236). While the three visitor groups did not encounter significantly different numbers of other users, the earliest visitors were more likely to feel that there were too many boaters and campers using the islands and more likely to express feelings of feeling crowded. Earlier visitors also perceived significantly greater levels of environmental damage. The research finding support the notion that visitors' expectation will influence their perceptions of the current conditions of recreation areas, and more recent visitors may have different expectations about what is appropriate.

Stokols, D. 1978. "In defense of the crowding construct". In Advances in Environmental Psychology: Volume 1, The Urban Environment, edited by A. Baum, J. E. Singer and S. Valins, 111-130. Hillsdale: Lawrence Erlbaum Associates.

This chapter reviews the psychological research literature on crowding as of 1978. While not focused specifically on crowding in recreation, it examines some of the theoretical underpinnings of crowding research. The article reviews the debate between those who believe that crowding should be seen simply as a condition of the environment, namely high density or spatial restriction, and those who feel crowding can be best understood as a motivational state involving the need for more space or increased privacy or reduced stimulation. These two approaches are the labeled the physicality and psychological approaches. The article concludes that the latter perspective is more appropriate (subsequent literature into recreation conflict and crowding supports this position) and describes in some detail the implications of a crowding construct. The crowding construct essentially sees crowding as a phenomenon that is the result of both environmental and behavioral dimensions and leads to both coping strategies and negative behavioral effects (when coping is unsuccessful).

Heberlein, T. A. and J. J. Vaske. 1977. Crowding and visitor conflict on the Bois Brule River. Madison, Water Resources Center, University of Wisconsin-Madison.

This study describes the results of a study that interviewed nearly three thousand canoers, tubers and fisherman as they left the upper Bois Brule river. Despite high user levels, up to 308 visitors on a ten mile stretch, there was no relation between use levels and satisfaction. Use level was related to perceived crowding and feeling crowded is one aspect of overall satisfaction. The authors suggest this study casts further doubt on an econometric model of carrying capacity.

Baum, A. and S. Koman. 1976. "Differential response to anticipated crowding; psychological effects of social and spatial density." Journal of Personality and Social Psychology 34(3): 526-536.

This paper is an example of the research work in social psychology that has become an important theoretical foundation for much of the work in recreation conflict and crowding research. In this paper, the results of experiment examining the independent and interactive behavioral responses to the effects of anticipated social and spatial density. One aspect of the study focused on perceptions of crowding and it found that perceptions of crowding were influenced to different degrees by personal expectations of numbers of people, whether the subjects expected structured or unstructured environments and the sex of the subject. In general the data suggest that social consequences of high density are more salient than spatial consequences. Crowding is a joint experience of social and spatial conditions and it is important to recognize the psychological differences between social and spatial density. Many studies have failed to account for this important distinction as well as specific intervening conditions that influence the numerous potential consequences of high density.