Although the negative affect model may work in a laboratory, it is unclear how much it would work in the real world, as escape in real life would not be as easy as simply walking out of a door. It is also thought that temperature could not be the only reason for aggression during hot summer days e.g. in summer, people experience greater social contact by being outside an increasing amount. It could also be a biological explanation. For example, the production of testosterone increases when you get hot (Anderson and Anderson, 1998). The relationship between temperature and aggression is not as simple as either the linear model or the curvilinear model, as other variables may affect the relationship.
Crowding, another environmental stressor, is the unpleasant sensation that too many people share the same space. It is personal in how much it affects us, as it depends on how comfortable we feel in the close presence of others, and also how peoples perception of crowding leads to them reacting to certain levels of density. Calhan (1962) conducted an animal experiment into crowding leading to aggression. He placed an expanding rat population into a small area, and observed that they soon began sexually assaulting and killing each other, which confirms a link between crowding and aggression. Research into crowding in Australian clubs done by Macintyre and Hamel (1997) showed that the level of crowding in each nightclub was related to the number of observed aggressive incidents. This is a field experiment, meaning it has ecological validity and is not artificial and so can be applied to real life. However, they did not get participant consent for observations, which raise ethical issues. It seems clear that crowding is related to aggression, but the relationship is complex as crowding involves social context effects – crowding at party of friends may not frustrate a person as much as crowding in a shopping mall. This could lead to deindividuation, and intensify already there aggressive tendencies as a person may feel that as they have lost their self identity, they have less chance of getting caught for their actions and that they themselves are not contributing in a bad way to any crowd.
Kelley (1985) found no relationship between aggressive assault and population density, which contradicts the theory that crowding is directly liked to aggression. In a club, there may have been a schema effect. People may feel they should contribute to crowd violence, as they want to fit in, and could also be influenced by alcohol, which could reduce awareness of any damage caused to themselves or others.
Noise is another environmental stressor. Noise is an unwanted sound that brings about a negative response, usually produced by sounds that are too loud and unpredictable. Laboratory studies have illustrated the negative effect of noise. Glass and Singer (1972) gave participants arithmetic sums to work on while listening to very loud, random music. The participants were surprisingly able to complete the task, but when asked to proof read their work in a quiet environment, they performed badly. An explanation for this could be that they concentrated very hard on what they were doing to overcome the noise but they became increasingly frustrated which shows up when they no longer had to concentrate to shut out the noise. This gives the notion that noise is just a cue, as noise and no prior cue (no frustration) did not lead to aggressive behaviour. However, there is evidence that noise acts like any other stressor by increasing the activity of the ANS (autonomic nervous system) e.g. increased heart rate. Evans et al (1998) provided evidence for an indirect link between noise and aggression. In the study it was found that children who lived under flight paths experienced high blood pressure and stress hormones. It is possibly, however, that the children were simply woken by the plane noise and it was tiredness not the noise that caused them to become stressed. Other experiments have confirmed Evans’ conclusions by showing a direct link.
Donnerstein and Wilson (1976) investigated whether having a sense of control would decrease aggression. They found that who has some control over the noise showed lower levels of aggression. This could be because with control over noise, you can be prepared as you are controlling it however when noise is out of your control, you cannot prepare for anything. The experiment showed that noise had to be combined with another negative stimulus to become aggression.
Environmental stressors (temperature, crowding and noise) can increase arousal. This may or may not lead to aggressive behaviour, as it depends on the nature of the situation and how the individual perceives it.
