EA - Perceived Moral Value of Animals and Cortical Neuron Count by WillemSleegers

Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Perceived Moral Value of Animals and Cortical Neuron Count, published by WillemSleegers on August 25, 2023 on The Effective Altruism Forum.Publication noteWe initially drafted a writeup of these results in 2019, but decided against spending more time to finalize this draft for publication, given the large number of other projects we could counterfactually be working on, and given that our core results had already been reported (with permission) by Scott Alexander, which seemed to capture a large portion of the value of publishing.We're now releasing a lightly edited version of our initial draft, by request, so that our full results can be cited. As such, this is a 'blog post', not a research report, meaning it was produced quickly and is not to Rethink Priorities' typical standards of substantiveness and careful checking for accuracy.SummaryScott Alexander reported the results of a small (n=50) experiment on a convenience sample of his Tumblr followers suggesting that the moral value assigned to animals of different species closely tracks their cortical neuron count (Alexander, 2019a). If true, this would be a striking finding suggesting that lay people's intuitions about the moral values of non-human animals are highly attuned to these animals' neurological characteristics. However, a small replication on Amazon Mechanical Turk (N=263) by a commenter called these findings into question by reporting very different results (Alexander, 2019b). We ran a larger study on MTurk (n=526) (reported in Alexander, 2019c)) seeking to explain these differences. We show how results in line with either of these two studies could be found based on different choices about how to analyze the data. However, we conclude that neither of these approaches are the most informative way to interpret the data.We present our own analyses showing that there is enormous variance in the moral value assigned to each animal, with large numbers of respondents assigning each animal equal value with humans or no moral value commensurable with humans, as well as many in between. We discuss implications of this and possible lines of future research.IntroductionScott Alexander previously published the results of a small survey (n=50, recruited from Tumblr) asking individuals "About how many [of different non-human animals] are equal in moral value to one adult human?" (Alexander, 2019a)A response that 1 animal of a given species was of the same moral value as 1 adult human, could be construed as assigning animals of this species and humans equal moral value. Conversely, a response that >1 individuals of a given species were of the same moral value as 1 adult human, could be construed as suggesting that those animals have lower moral value than humans. In principle, this could also tell us how much moral value individuals intuitively assign to different non-human animals relative to each other (e.g. pigs vs cows).Alexander reported that the median value assigned by respondents to animals of different species seemed to track the cortical neuron count (see Alexander 2019d) of these animals conspicuously closely (as shown in Figure 1) and closer than for other potential proxies for moral value, such as encephalization quotient.This apparent correlation between the moral value assigned to animals of different species and their cortical neuron count is particularly striking given that Alexander (2019d) had argued in a previous post that cortical neuron count, specifically, was strongly associated with animal intelligence. Thus it might seem that the intuitive moral value assigned to animals of different species was closely linked to the intelligence of the animals. If so this would potentially, as Alexander put it, add "at least a little credibility" to intuitive judgments about the moral value of no...