Even knowing that in this short clip there is absolutely someone drowning I still have doubt, but the lifeguard who doesn’t have that context is already half way to the person by the time I’m sure.
They have also been staring at the same pool for hours and their brain is ignoring all the visual noise that is distracting you. They also have the benefit of stereo vision and sound.
Also helps that in this instance, most have rubber rings and if you see an empty rubber ring, that in itself would trigger concerns and focus.
(Which is also why the lifeguards here are told to approach from the side, less likely to be grabbed on the head that way.)
> They have also been staring at the same pool for hours and their brain is ignoring all the visual noise that is distracting you.
I'd suspect mental fatigue would counteract any benefits you'd get from increased filtering. Which, I assume, is why life guards are generally rotated regularly.
> They also have the benefit of stereo vision and sound.
Sound might not be of much help here because drowning is usually something that happens quietly (as the linked site also explains).
Drownings in progress are often quiet, but that doesn't mean there aren't useful audio cues (splashing that stops, a kid who is no longer laughing or shouting, etc)
In general, I would assume, like with driving, the job of the lifguard is a bit automatic, where the mind on its own filters out the ones, which might need stronger attention.
It was very boring, and keeping my mental acuity sharp towards the end of shifts was a problem. Take care swimming late in the day.
Also, I don't ever swim in public pools anyone. We had to shut down the cast member pool one 4th of July because it was so dirty and so soiled, we couldn't see to the bottom of the deep end (6 feet / ~2m) and it presented a drowning hazard. The pool was closed for like 3 days after that while we waited for the water turbidity to go down.
In theory a public pool under proper management should be cleaner than a private pool which almost certainly isn’t being professionally managed.
Chlorine in pH balanced water with the right hardness is surprisingly effective. Pro tip, if you can smell “chlorine” it probably means the pool is dirty and doesn’t have enough chlorine left in the water. The smell is not chlorine in the water, it’s the result of the chlorine burning off as it oxidizes contaminants.
Guards typically have discrete areas they cover, and within those boundaries you can check for a certain number of people and boundary crossings. By doing things like mentally running through the list/number of people in your area and noting the higher-risk ones, it's a little less mentally taxing than you might think. Combined with some overlap between guard stations and regular rotations between areas, coverage can be pretty good. The real difficulty comes in when you start adding numbers of people- the boundaries become less clear, the number of high-risk swimmers increase, and the total cycle time through everyone you're covering increases such that your margin of error between a situation presenting and your time to react starts decreasing.
Anecdotally, I always found the behavior changes from a normal to tired swimmer to be one of the easier parts. Lack of forward motion, intense focus on the activity of swimming itself, falling behind from a group. Again, it's more difficult the more crowded an area becomes.
https://youtu.be/Gka9TFwqoVs?t=60 https://youtu.be/FTtHOZfV_qA?t=47 https://www.straitstimes.com/singapore/drowning-detection-sy... https://swimeye.com/
1) I was already primed to find someone drowning; I knew based on the video title that there was someone in danger. For a lifeguard, it's probably common that they'll go through entire shifts without having to jump in.
2) Even after identifying the right kid, I had doubt: I wasn't 100% sure until the lifeguard jumped in and confirmed my choice.