like i’m watching blue planet and i’m yelling at the tv!
there’s all these yimmer yammer hand-wavey scientific rigor lines where it’s like ‘we may believe that these animals do on occasion have a base brain-related impulse that allows them to experience feelings somewhat like to those of friendship’ or whatever in the script on top of footage that they then describe as ‘it seems as though these two groups [of fish, different species] are old friends…’ in an almost whimsical manner.
can’t they give them some credit! they have eyes and a face, why is it so insane to think they can’t experience friendship or love or joy just like us? ‘buhhu uhhh its only accurate science if we only observe observable behavior’ why?? you’re neglecting a whole part of any living thing’s experience! inner life can’t be hand waved away! even for a mollusk!
and people loved doing this on reddit as well – oh actually your cat doesn’t understand love or joy or humor, it is simply reacting to the physical warmth of your lap, they don’t actually care for you. don’t worry, depth and emotion does not exist!
There is, though. The easiest one being that a sentient creature will react differently to it’s outside world, most importantly in an unpredictable manner. Think about a fish reacting to it’s surroundings and then picture a cat. One will very likely do the same thing given the same circumstances. The other won’t.
So would a fish that’s eaten a device that administers a small electric shock at random intervals and with random intensities. I don’t think that eating such a device made the fish suddenly sentient, but it would suddenly change the outcome of your test.