Answer:
bystander effect
Step-by-step explanation:
Bystander effect: In social psychology, the term bystander effect is defined as the phenomenon in which an individual's in-capabilities of helping someone else in need due to the mere presence of the other person.
According to the researchers, a bystander is less likely to help the other person even in an emergency due to the presence of another person as compared to the situation when he or she is alone.
In the question above, the psychological phenomenon is known as a bystander effect.