Answer:
the bystander effect.
Step-by-step explanation:
The bystander effect: The term bystander effect is also referred to as bystander apathy or bystander intervention. This is one of the psychological phenomenon which explains that an individual has got the least tendency of helping the other person in an emergency when there are other person present in the given situation competitively when the individual is alone.
Hence, in an emergency, the observers are more likely to intervene if there are no other witnesses present at the moment.
In the question above, Mrs. Blake's experience best illustrates the bystander effect.