> Cafe goers tasted the cookies and provided feedback via a survey. Survey results were aggregated and the results were sent back to Vizier.

This, from the paper, is a great start on measuring deliciousness. But if you go to that effort, why not provide a benchmark? Such as the existing chocolate chip cookie recipe or the average scores from 10 random chocolate chip cookie recipes?

As a reader, I might suspect that performance was not that great compared to baselines but that the authors were able to mask it by making this qualitative claim ("the cookies were delicious") -- which I'm sure was still true!

But it really is not a very great start on measuring deliciousness.

Like said elsewhere in this thread, if after a few batches the algorithm optimizes into a local maximum gully that some people don't like, but others really love, then the ones that dislike it will stop taking the cookies and thus stop rating them.

But does that mean they're less delicious? Nobody knows! Because certainly the first and foremost great start on measuring deliciousness, is doing research on what is deliciousness, and are there any good methods to measure deliciousness that can be compared with other literature and research, and if that fails, either measure something else or defend why you chose a target metric that can't be measured properly. The latter being valuable if your way of measuring is novel and you think it's better than what has been used so far in the field. But you gotta provide a good argument for that, and the method used in this experiment wasn't particularly novel, simply flawed.

I mean you can be all giggly-googly about it, but food science is a thing.

This technique is known as anchoring and should be used alongside a descriptive scale when making subjective comparisons.

Yep. There's a lot of pre-existing science that this research ignored ...

This really assumes that there is one-true-deliciousness factor, which is patently false if the spaghetti sauce optimization exists. (in which the previously unknown chunky sauce actually was discovered to be a non-trivial market segment)

This seems more like a spanning/optimization problem (how to cover the majority of preferences while not needing too many varieties) than an actual optimization problem, but then again it's just a sample use case to use to sell their API, so they probably didn't think too hard about it.

To the extent that deliciousness is a physiologically measurable phenomenon, or there are proxy measures that correlated with it, yes, there is an objective way. You give large numbers of people cookies and have them rate it. Tastes vary but generally if you make something with umami, crunch, fat, and sugar, people will say it is delicious.