Custom-made ARL sports tracking software was also used to gain 30 sets of co-ordinates each second for every person.
They were photographed on the day by the research team; with the physical attractiveness of each participant rated by three members of the research team to produce an averaged single attractiveness score.
This score was later matched with observations about how individuals grouped together.
Participants were asked to mingle while the researchers set up the study, and to form groups of any number and composition and raise their hand once this was done.
They were also directed to form new groups eight more times.
Study lead author Professor Jamin Halberstadt, of Otago University's Department of Psychology, said the study aimed to test the feasibility of the novel research approach and to answer several longstanding, fundamental questions about the first stages of social group formation.
"For one, we wanted to know if people group together based on physical traits that they share, such as gender or physical attractiveness," he said.
"We also wanted to find out if these traits predicted the physical position of individuals in their groups. Finally, we sought to determine if how close they stood to others would predict how cooperative they would be in a future group task."
The researchers found that on average, participants formed groups of six individuals, and that they were more likely to approach others of similar attractiveness.
"Women and attractive individuals were also more likely than men and unattractive individuals to be in the centre of their groups," he said.
"Our analysis could not confirm whether this was because they acted as 'social attractors', although this is the likely explanation - as we didn't find evidence that they were jumping into the middle of the group as it formed."
Finally, analysis of how close an individual stood to other members when the group formed showed that those who "submerged" themselves in their group put less effort into a later "foraging" task that required the entire group to co-operate.
The task involved gathering 500 one-inch washers, randomly scattered around the stadium, and depositing them one at a time in a large basin in a corner of the stadium.
"Participants who were closer on average to other participants at the beginning of the study were also the ones who were less cooperative at the end of it.
"This is consistent with a known association between anonymity and 'social loafing', but more research is needed to clarify what are the motivations behind, and the links between, the behaviours we saw."
Up until now, researchers of group behaviour have had to either sacrifice the spontaneity and freedom of movement of field observations, or the control and precise measurement of the laboratory setting.
"We've now found a happy medium by using a stadium-size laboratory and applying unobtrusive state-of-the-art tracking technology to participants' social behaviour."
