There was a study recently that basically debunked this theory. It was done by tracking real incidents through cameras in big cities in Europe. Long story short, the more people were there the more likely that someone offers help.
The study had some serious confounding issues which were not dealt with, though. For example, determining whether the bystanders were actually friends walking together with the target of the incident.
Also, the bystander effect deals with the probability of any individual helping out. It's still possible that there are two forces at play here: the declining probability of any individual helping vs the increasing probability that someone in an ever-larger group will still help despite the individual effect. It might be the case that there is a critical value N of bystanders where the second effect overpowers the first one.
Just a layman's guess here, but I strongly doubt the bystander effect is strong enough to overcome the chances of a single person helping. Note that for the bystander effect to happen, all the people in the vicinity have to not intervene, while for it to be defeated, it takes a single individual to act.
I doubt that as N increases the "network" effects are strong enough to overcome the chance that someone that will help, regardless of what the effect of "N-1" bystanders is, shows up.
That would be my guess as well, at least for large N. It might still show interesting behaviour for smaller group sizes, for instance a group of 2 vs a group of 6, or when the probability of a single person helping is comparatively low to begin with (for instance, in a bad neighbourhood known for scams).
The effect is informative regarding what to do when you need someone's help, though. Since the basis of the effect is the diffusion of responsibility, it helps to address a person directly when asking for help. Instead of asking whether anyone in the group can help with something, point to a particular person and ask them whether they can help. In this way, the refusal to help becomes explicit and people will be less likely do that. This is something I've observed from personal experience too.
In Europe, in a lot of countries there are programs such as the dutch BHV (BedrijfsHulpVerlener) program. Basically: companies need to have some people on staff with a basic first aid and fire evacuation training.
I have done this, and it has helped in mitigating the bystander effect. It means that there is a relatively large amount of people in the population that know what to do when accidents occur. IMO this makes bystanders who have done such programs to help, since they know how valuable time is in a lot of these situations.
Since I have done this training, whenever there is an accident on the streets and I am nearby, I will go help because I know what to do. And am therefor more likely to take initiative.
So I wouldn't immediately say this discount would be correct. It could also mean that some mitigation against the bystander effect is working.
"circumstance in which a party can be held liable for failing to come to the rescue of another party who could face potential injury or death without being rescued"
In contrast, in 2007 a man in Baghdad noticed an injured man by the side of the road, and stopped his car (containing 2 children) to help. He was immediately killed by the US military for doing so; they were watching from an Apache helicopter and shot him dead for stopping to help.
This, in combination with Good Samaritan Laws (https://en.m.wikipedia.org/wiki/Good_Samaritan_law) make it more likely that people in Europe will help out. I remember stories in China that people would avoid helping someone in lieu of being blamed for any further injury caused, they would be taking the blame.
You might want to actually read that article daliusd. The bystander effect is just hypothesis and hasn't actually been observed to my knowledge.
In the mentioned Kitty Genovese incident the numbers were inflated and while it isn't mentioned here, there actually were police reports while it was happening.
I think local laws also play some part in this. There have been cases where people who help the victims have been accused of having harmed the victims. If not that, they're hassled by Police and other investigators during the course of the investigation.
This is the reason why Good Samaritan law is being brought into effect across the world.
More culture than law - my personal experience is that sub cultures within rigid legal systems that do not make it a good idea to lend aid (China for example) will do so regardless because of their subculture value system.
The bystander effect is probably complete nonsense, there have been some recent studies that tried to replicate its findings and they found the opposite to be true.
Here in China, the bystander effect is kind of have its effects, I mean sometime in bigcities, if an old man fell off unconsciously, lots of people will pass by, maybe they feel unconfortable with that, but there are some case which the old people accuse the one who help them knocking them down, https://en.wikipedia.org/wiki/Xu_Shoulan_v._Peng_Yu , And CCTV has broadcast the case, and it cause a big discuss on the internet, and now lots of people, would not be a Good Samaritan when similar things happen, although have a guilty conscience.
