There are different models used to describe escalation.
The contender-defender model traces escalation to Party's (the contender's) effort to take something from Other (the defender), alter reality at Other's expense, or stop Other's annoying behaviour.
If milder tactics fail, Party moves to heavier ones in an effort to prevail. In response to this offensive, Other may remain passive or escalate defensively. The conflict spiral model traces escalation to a vicious circle of action and reaction - the two sides escalate in response to each other.
Escalation is often best explained by invoking both models, viewing the progressively heavier tactics as either a contender-defender episode embedded in a broader conflict spiral or a conflict spiral that is part of a larger contender-defender dynamic.
The structural change model is built on the conflict spiral model. In this model there is a set of changes in the individuals and groups involved in conflict and the communities to which they belong. These changes are way stations in the cycle of escalation: they result from prior escalation and contribute to further escalation.
A cycle of escalation might, for example, start with Party's receipt of what it considers to be an insult from Other. If this makes Party angry and fearful about its image of adequacy, these emotional changes could produce a return insult from Party. This might then produce similar emotional changes in Other, encouraging still another insult. The cycle would then be complete, but it could be followed by further cycles, causing the conflict to become increasingly escalated.
Psychological changes take place in individuals, but they can also affect the behaviour of groups when they are widespread among group members. In addition to emotional changes (blame, anger, fear, and perceived threat to one's image), psychological changes include dehumanization, deindividuation, and the development of hostile attitudes, perceptions and goals. Dehumanization and deindividuation are similar in that they erode inhibitions that would otherwise prevent aggression. Party can become deindividuated in its own eyes, which also erodes inhibitions. Development of a goal of seeking revenge is a particularly potent structural change, which can produce heavily escalated behaviour long after an annoyance has been experienced.
Structural changes can also occur in groups. Group changes include:
Groups can also polarize, with their members moved from moderation to militance, as can the communities surrounding the conflicting parties. All of these changes result from prior escalation and contribute to further escalation.
Emotional changes are products of the moment and tend to disappear quickly once a conflict episode is over. But the other kinds of structural changes tend to persist as residues that injure the relationship between the parties. These residues make it hard for escalation to dissipate once it gets started and tend to encourage renewed conflict and escalation at a later time.