Vaughan at Mindhacks writes about a 1938 study that employed an extremely creepy methodology that would certainly be illegal today:
[P]sychologist James Hartley wrote in and mentioned a remarkable study from 1938 where researchers hid under the beds of students to record their conversations.
The study was published in the Journal of Social Psychology and was titled “Egocentricity in Adult Conversation” and aimed to record natural conversations untainted by researcher-induced self-consciousness.
Our sensibilities have changed, though what about those ABC Primetime, hidden-camera "experiments" that present unwitting subjects with emotionally distressing scenarios? It's one thing to include someone in a psychological experiment when they've volunteered and have given adequate informed consent; it's quite another to subject people to distressing experimental manipulations without their knowledge or permission. True, there is no expectation of privacy out in public, but subjecting people to upsetting manipulations and recording their reactions seems like emotional abuse and an invasion of psychological privacy to me.
Of course, we're all the subjects of field experimentation as businesses and political consultants subject us to experiments in which we've been assigned to particular marketing conditions for comparison with other conditions, all without our knowledge that we're participants in research. I'm okay with that, so long as they don't conduct field research from under our beds.