I recently wrote a post on the EA forum about turning animal suffering to animal bliss using genetic enhancement. Titotal raised an thoughtful concern: "How do you check that your intervention is working? For example, suppose your original raccoons screech when you poke them, but the genetically engineered racoons don't. Is that because they are experiencing less pain, or have they merely evolved not to screech?"
This is a very good point. I was recently considering how we could be sure to not just change the expressions of suffering and I believe that I have determined a means of doing so. In psychology, it is common to use factor analysis to study a latent variables--the variables that we cannot measure directly. It seems extremely reasonable to think that animal pain is real, but the trouble is measuring it. We could try to get at pain by getting a huge array of behaviors and measures that are associated with pain (heart rate, cortisol levels, facial expressions, vocalizations, etc.) and find a latent factor of suffering that accounts for some of these behaviors.
To determine if an intervention is successful at changing the latent factor of suffering for the better, we could test for measurement invariance which is an important step in making a relevant comparison between two groups. This basically tests whether the nature of the factor loadings remains the same between groups. This would mean a reduction in all of the traits associated with suffering. This would also seem relevant for environmental interventions as well.
As an illustration: imagine that I measure wefare of a raccoon by the amount of screeching it does. A bad intervention would be taping the raccoons mouth shut. This would reduce screeching, but there is no good reason to think that would alleviate suffering. However, imagine I gave the raccoon a drug and it acted less stressed, screeched less, had less cortisol, and started acting much more friendly. This would be much better evidence of true reduction in suffering.
There is much more to be defended in my thesis but this felt like a thought worth sharing.