When there is university academic research, there has to be an ethics consideration and some of the experiments that were done in the past are no longer possible, because of the ethics considerations.
The ethics of experiments require certain criteria to be fulfilled. The experiment needs to be explained to the participants, however sometimes this means that some aspects of the experiment are not disclosed in the beginning, if the disclosure would affect the nature of the experiment. So often when the experiment is about people’s reactions, if they had known that that was being looked at, it is likely to affect their reaction, which would affect the experiment. However, afterwards they are supposed to have a full de-brief. Before the participants start, as much knowledge as is appropriate to not alter the experiment should be told to them, so that they have full knowledge of what is about to happen before the experiment starts.
The participants can change their mind at any point in time and can walk away. The people running the experiments have to accept their refusal to continue and should take no action whatsoever to try to dissuade them from leaving. Once the participant has said that they no longer wish to take part, the staff running the experiment should facilitate them leaving as easily as possible. Experiments should be carried out by volunteers, people who genuinely signed up of their own accord. They cannot be coerced into staying or locked in anywhere, if they want to leave.
The experiment should progress knowledge, sometimes an old experiment is run again, to see if what happened before still holds true, but often this can be the beginning of moving that old experiment forward, so there can be some slight changes to the old experiment that makes that work the starting point and then the new work takes that old knowledge in a new direction or maybe just further, if technology has improved and this makes a difference.
There are particular animal welfare issues, if the participants are not human, the animals should be well fed and cared for and subjected to the minimum of negative experience. What is allowed depends on the type of animal / organism, the more sentient, the greater restrictions.
This can create issues for experiments with people with dementia, as they may not be able to consent. So special consideration needs to be given. Experiments can still take place on people who cannot consent, but they need to be the type of person who would have agreed, to this needs to be verified. And it needs to bring knowledge forward of the kind of thing that would make the life of the person with dementia better, so that other people with that condition can have improved lives. The experiment also needs to be of very limited distress or negative experience to them. I have often seen the generosity of people with dementia, sign up for experiments, as they want to make the lives of those who come after them better.
Experiments improve knowledge, which makes life better for the next set of people. It is good to know that they are closely monitored for ethics to make them safe for the wellbeing of those taking part.