Crowding is a subjective, psychological state where an individual perceives a restriction of personal space and control due to the presence of too many people, distinct from objective physical density. It's not merely about the number of people, but the feeling of being confined or overwhelmed by them.

Its determinants include high physical density, a perceived lack of control over social interactions, unwanted social contact, and the violation of personal space. Cultural norms also play a role, influencing what an individual considers 'crowded'. When the presence of others interferes with personal goal attainment, the feeling of crowding intensifies.

The impact on psychological health and well-being can be significant. Prolonged crowding leads to increased physiological and psychological stress, heightened irritability, and sometimes aggression. It can impair cognitive functions like attention and concentration, reducing performance on complex tasks. Individuals may experience a sense of learned helplessness, feeling unable to control their environment, and might engage in social withdrawal to cope with overstimulation. This often results in increased anxiety, frustration, and a general negative emotional state, undermining overall well-being. Additionally, research suggests a decrease in prosocial behaviors, as individuals become more focused on self-preservation. These effects are particularly detrimental in chronic, uncontrolled crowding situations.