Dr. Jennifer Groh

Mm-hmm.

And so the lower frequencies are audible to more people and are louder to people than the higher frequencies.

Well, I don't really know what the choices that are being made are by the people whose job it is to figure these kinds of things out.

But I'm sure that there's some thought being given to the receiver, you know, the people and what they can perceive.

So let's take a couple other examples of warning systems that humans use.

The gas in a gas stove doesn't have an intrinsic odor to it.

there's an odorant that's been added.

That rotten egg, yeah, exactly.

And so, you know, that was chosen a long time ago to be added.

And, you know, it turns out to be a good thing because it doesn't really smell like anything else.

It's not pleasant, but everybody can detect it.

I don't know of any cases of people that can't smell that unless they have a generalized anosmia where they can't smell anything.

Traffic lights are maybe a little bit of a less of a win because you've got red versus green.

And 6% of the population is red, green, colorblind, which operationally means not that you can't see a red stimulus or a green stimulus, but that you can't tell the difference, you know, whether or not something is red or green.

Right.

So if you do a color matching experiment, my understanding is something along the lines of

People with red-green colorblindness will map both red and green onto yellow and not be able to tell the difference.

It's not the kind of cartoon view of like it looks black and white.

And a lot of what is under this heading is really more an anomaly than a complete absence of an ability to distinguish red from green.

But back to our traffic lights.