Final answer:
The Hawthorne Effect threatens the accuracy of psychological research by causing people to change their behavior when they are aware they're being observed.
Step-by-step explanation:
The primary reason why the Hawthorne Effect would threaten to negate the quality of a person's research in psychology is because when people know they are being observed, they often change their behaviour. This effect occurs as individuals modify their performance or behavior due to the awareness that they are under observation, which can be unavoidable in some research studies. The Hawthorne Effect introduces an artificial element to the research because subjects must be aware that they are being observed, potentially leading to data that does not accurately represent natural behaviors.