A few weeks ago I published results of a small (n = 50) survey showing that people’s moral valuation of different kinds of animals scaled pretty nicely with the animals’ number of cortical neurons (see here for more on why we might expect that to be true).

A commenter, Tibbar, did a larger survey on Mechanical Turk and got very different results, so I retracted the claim. I wasn’t sure why we got such different results, but I chalked it down to chance, or perhaps to my having surveyed an animal-rights-conscious crowd who thinks a lot about this kinds of things vs. Tibbar surveying random MTurkers.

Now David Moss, from effective altruist organization Rethink Priorities, has looked into this more deeply and resolved some of the discrepancies.

The problem is that I did a terrible job explaining my procedure (I linked to the form I used, but the link was broken when Tibbar did his survey). In particular, I included the line:

If you believe [animals have moral value] in general, but think some specific animal I ask about doesn’t work this way, feel free to leave the question blank or put in “99999”, which I will interpret as “basically infinity”