Answer: Naturalistic observation
Step-by-step explanation:
Naturalistic observation is researching technique used in studying .It includes observing targets involved in research in their natural surrounding. Activities, movement ,changes etc of subject are noticed by the researchers. This mechanism is usually used by psychologist.
According to the question,researcher is taking help of naturalistic observation method for observing helping behavior of people based on gender towards shoppers carrying overloaded packages.This mechanism involves natural environment in which study about people is being carried out.