Jason Schukraft

The subjective experience of time is a morally significant aspect of well-being. Critical flicker-fusion frequency (CFF) has occasionally been suggested as a proxy for the subjective experience of time. CFF, a measure of visual temporal resolution, is the threshold at which a rapidly flickering light appears to glow steadily. CFF thresholds have been measured in more than 70 different species across 30+ orders and 3 phyla. Values range from ~7 Hz to ~200 Hz. Putatively similar animals sometimes possess very different CFF thresholds. I tentatively estimate there is a ~40% chance that CFF values roughly track the subjective experience of time under ideal conditions.

At any given time there are more than a trillion managed honey bees. Globally, the number of managed colonies has risen steadily over the last twenty years and this growth will almost certainly persist, at least in the short term. Increases in demand for honey and (especially) commercial pollination services continue to outpace the increase in supply of managed bees. Asia, especially China and India, hosts the largest populations of managed bees and accounts for much of the recent growth in bee stocks. Commercial beekeeping techniques standardly treat managed bees as a resource from which to maximize the extraction of value. Beekeepers have a financial incentive to maintain the health of their colonies, but they have little reason to look after the welfare of individual bees. Managed bees suffer from a variety of problems, including pesticide exposure, poor nutrition due to inadequate access to natural forage, invasive hive inspections and honey harvest, stress from long-distance transport, and parasite and pathogen spread exacerbated by common management techniques.

Understanding differences in capacity for welfare and moral status could significantly affect the way we wish to allocate resources among interventions and cause areas. For instance, some groups of animals that exhibit tremendous diversity, such as fish or insects, are often treated as if all members of the group have the same moral status and capacity for welfare. Further investigation could compel us to prioritize some of the species in these groups over others. More generally, if further investigation suggested we have been overestimating the moral value of mammals or vertebrates compared to the rest of the animal kingdom, we might be compelled to redirect many resources to invertebrates or non-mammal vertebrates. To understand the importance of these considerations, we must first develop a broad conceptual framework for thinking about this issue.

In this post, four members of Rethink Priorities’ invertebrates team—Daniela R. Waldhorn, Marcus A. Davis, Peter Hurford, and Jason Schukraft—outline their views on the value, feasibility, and danger of quantitative estimates of invertebrate sentience. Marcus and Peter provide numerical estimates of sentience for each of the taxa we investigated for our invertebrate sentience project, Daniela offers a qualitative ranking of the same taxa, and Jason argues that we are not yet in a position to deliver estimates that are actionable and robust enough to outweigh the (slight but non-negligible) harm that publishing such estimates prematurely might engender.

Differences in the intensity range of valenced experience across species may affect how we ought to allocate resources to help different types of animals. Humans and other mammals likely share a roughly similar intensity range. It is unlikely that any species of animal possesses an intensity range that is exclusively extraordinarily mild. Some aspects of cognitive sophistication appear to be positively correlated with intensity range; other aspects of cognitive sophistication appear to be negatively correlated with intensity range. Affective complexity generally appears to be positively correlated with intensity range. There is as yet no good objective measure of valence intensity, though there is much interesting work ongoing in this area.

The subjective experience of time refers to how slow or fast time appears to pass for an individual. Animals with faster rates of subjective experience undergo more subjective moments per objective unit of time than animals with slower rates of subjective experience. Roughly speaking, animals with faster rates of subjective experience perceive the world as if it were slowed down compared to the perceptions of animals with slower rates of subjective experience. Based on human reports of alterations in the subjective experience of time, as well as general differences in behavior, neurology, and temporal resolution across animals, I estimate there is a ~70% chance that there exist morally relevant differences in the subjective experience of time across species.

In this, the final of three posts on features potentially relevant to invertebrate sentience, we assess 9 learning indicators, 4 navigational skills, and 7 mood state behaviors.

Other humans merit moral concern. We think many nonhumans merit moral concern too. But how do we know? And which nonhumans? Chimpanzees? Chickens? Bumblebees? Protozoa? Roombas? Rocks? Where and how do we draw a line?

Considering differences in the subjective experience of time may affect the proportion of resources we wish to allocate to different species. I’ve recently written two pieces on the subject. Counting somewhat conservatively, the two posts total more than 23,000 words. In this (much shorter) post I attempt to succinctly introduce the topic and convey my main conclusions. The aim is to create a digestible overview of my current thinking that imposes a smaller time burden on readers.

In this, the second of three posts on features potentially relevant to invertebrate sentience, we assess 5 drug responses, 5 motivational tradeoffs, and 5 feats of cognitive sophistication.

More than 99.9% of animals are invertebrates. There is modest evidence that some large groups of invertebrates, especially cephalopods and arthropods, are sentient. The effective animal activism community currently allocates less than 1% of total spending to invertebrate welfare. That share should rise so that we can better understand invertebrate sentience and investigate the tractability of improving invertebrate welfare.

Rethink Priorities reviewed the scientific literature relevant to invertebrate sentience. We selected 53 features potentially indicative of the capacity for valenced experience and examined the degree to which these features are found throughout 18 representative biological taxa. These data have been compiled into an easily sortable database that will enable animal welfare organizations to better gauge the probability that (various species of) invertebrates have the capacity for valenced experience. This essay details what we’ve done, why, and the strengths and weaknesses of our approach.

Are there differences in the characteristic intensity ranges of valenced experience across species? This question is important because the answer to it could affect the way we wish to spend our scarce resources helping different types of animals, including humans. For example, if the pains and pleasures of trout and salmon are but pale reflections of the pains and pleasures of cows and pigs, then in many instances we may be able to do more good helping mammals rather than fish.

In this, the first of three posts on features potentially relevant to invertebrate sentience, we assess 10 anatomical and evolutionary features and 5 types of noxious stimuli reactions.