The diffusion of responsibility plays a role. If there are more people, you depend on the people around you to act. If you are alone, you are the only one responsible. For example, if you are in a room with someone else and that someone else faints and falls on the ground. If that was the case, you would possibly help the person or go ask for help. On the other hand, If you were with ten other people in a room and one person faints, you would possibly just not do anything(because you think that the people around you will do it) or you would wait for the others to react, then you help.
Audience Inhibition is when you don’t act normally/overreact. It is also when the person can’t make proper decisions. A good example is if you are on the train and you see this about 60 to 70 year old lady. You want to lend the seat to her, but you think for a moment, “is she younger than I think?” “What if I lend the seat to her and she says no?”. So audience inhibition fear or worry that they will reject you.
Arousal is a personal/physiological response to the conflict that can slow down your heart rate. The greater the arousal, the more chances of people helping.
Cost-reward is if you will get a reward for helping someone. The reward could be an actual reward or it could also be just that you feel good. The “cost” part of cost-reward is if you help someone, will it harm you/will it lead you to danger. If helping will benefit you or not is a big factor of helping
Similarity is another part of arousal. Similarity is something like the empathy of psychology. If you feel like that the person that is in need is similar to you(similar meaning same in age, gender, etc.) you would possibly help that person.
Mood is another important factor of intervening. How you feel and your mood can change your behavior. If you are in a good mood, you would possibly help someone that is in need. But what is you’re in a bad mood. Well people who are in a bad mood don’t usually help people.
Competence and experience is kind of a major factor. This is when you know that helping is what you need to do now because you’ve had the experience of helping. You can react quickly when you know what you are suppose to do.