Final answer:
The two reasons why a bystander to an emergency is unlikely to help when there are other bystanders present are diffusion of responsibility and the bystander effect.
Step-by-step explanation:
The two reasons why a bystander to an emergency is unlikely to help when there are other bystanders present are diffusion of responsibility and the bystander effect.
Diffusion of responsibility occurs when individuals assume that someone else in the group will take action, so they feel less responsible to help. This happens because the responsibility is spread across the number of witnesses to the emergency. For example, if there are many witnesses to an attack, each person may assume that someone else has already called for help.
The bystander effect is a phenomenon where individuals are less likely to offer assistance in an emergency when there are other people present. They may believe that someone else will step in and help, or they may experience social influence and conform to the inaction of others.