According to Goodhart's Law "the act of measuring something changes it". Just like adding a hot thermometer to a cold solution raises the temperature slightly. Inserting a psychologist into a foreign environment has the potential to change everything and anything in that environment. Naturalistic observation is defined as watching behavior in the real-world without trying to manipulate the situation. This is a good start but it is time scientists agree that simply the act of studying a group or single subject changes the output slightly.
The Jane Goodall chimpanzee studies are a great example of the flaws that inevitably come with naturalistic observation. Although Goodall's work is brilliant and ground breaking in many fields, psychology included, her presence was know by the subject. Although her subjects were chimps and unaware of what she was doing, Goodall was foreign to the world of the chimps and her presence had to change the chimps behavior slightly. There are picture of Goodall playing with the chimps and they use her like a children's playground. Although she is not manipulating anything in the scenario, her presence in the jungle changes the chimps behavior because they are exploring something new and strange.
The goal of all Naturalistic studies is to gather information in the purest way possible, without any impact. Sadly this is unattainable I am in no way saying that naturalistic studies should all be thrown out; what I am saying is that they are certain degree is error in each study, because according to Goodhart's law it is impossible to measure something without changing it. It is for this reason that I believe that psychologists must use caution when preforming naturalistic studies to minimize the impact their presence may have on a situation.