I had more trouble understanding how nest deprivation could be equivalent to “**** me, make it stop. Like someone slicing into my leg with a hot, sharp live wire.” So I looked up the underpinnings of this metric, in Ch. 6 of the book they build their analysis on (pg. 6-9 is the key material).
They base this on the fact that chickens pace, preen, show aggressive competition for nests when availability is limited, and will work as hard to push open heavy doors to access nests as they will to access food after 4-28 hours of food deprivation. Based on this, the authors categorize nest deprivation as a disabling experience that each hen endures for an average of about 45 minutes per day.
This is a technically accurate definition, but I still had trouble intuiting this as equivalent to a daily experience of disabling physical pain equivalent to having your leg sliced open with a hot, sharp live wire.
Researchers are limited to showing that chickens exhibit distress during nest deprivation, or, in more sophisticated research, that they work as hard to access nest boxes as they do to access food after 4-28 hours of food deprivation.
I am suspicious of the claim that these methods are adequate to allow us to make comparisons of physical and emotional pain across species. This is especially true with the willingness-to-work metric they use to compare the severity of nest deprivation and starvation on chickens.
Willingness-to-work is probably mediated by energy. After starvation, chickens will be low-energy, and willingness-to-work probably underestimates their suffering. A starving person would like to do 100 pushups to access an all-you-can-eat buffet, but physically is unable to do so. If he’s also willing to do 100 pushups to join the football team, does that mean that keeping him off the team is as bad as starving him?
People show distressed behaviors in the absence of suffering. I bite my fingernails pretty severely. Sometimes, they even bleed. It’s not motivated by severe anxiety in those moments. It’s just force of habit. Chickens may be hardwired by evolution to work hard to access nests, without necessary suffering while they do so.
Our perceptions of how distressed a behavior is is culturally-specific, not to mention species-specific. I pace and walk around the neighborhood when I’m thinking hard. People get piercings and tattoos. People fight recreationally. We don’t assume that people are experiencing high emotional distress in the moments they choose to do these things. Why do we assume that about chickens?
I’ve spent too long writing this comment, so I’m going to just stop here.
This is a technically accurate definition, but I still had trouble intuiting this as equivalent to a daily experience of disabling physical pain equivalent to having your leg sliced open with a hot, sharp live wire.
Nest deprivation could be in the bottom half of the disabling pain intensity range. Ren put their tattoo experiences described as “**** me, make it stop. Like someone slicing into my leg with a hot, sharp live wire.” near the high end of disabling. Also, the latter just sounds excruciating to me personally, not merely disabling, but we discussed that here.
Besides the evidence you mention, they also mention vocalizations (gakel-calls), which seem generally indicative of frustration across contexts (dustbathing deprivation, food/water deprivation, nesting deprivation), and hens made more of them when nest deprived than when deprived of food, water or dustbathing in Zimmerman et al., 2000, although in that study, the authors discuss the possibility that nest deprivation gakel-calls are more specific and not necessarily indicative of frustration:
In the period Frustration, the number of gakel-calls was higher in treatment Nest than in the other treatments. This might mean that in this treatment the level of frustration was higher. However, this is not supported by higher levels of other behaviours indicative of frustration in treatment Nest compared to the other treatments. An alternative explanation for the higher number of gakel-calls in treatment Nest is suggested by the occurrence of the gakel-call under natural circumstances. The gakel-call is given before oviposition and probably has evolved as a signal towards the rooster McBride et al., 1969; Thornhill, 1988 . According to Meijsser and Hughes 1989 , the performance of the gakel-call is related to finding a suitable nest site, also under husbandry conditions. Another explanation is offered by the motivational model proposed by Wiepkema 1987 . It implies that the gakel-call under these circumstances is an emotional expression of the detection of a prolonged mismatch between actual ‘‘no nest site found’’ state and desired state ‘‘find a suitable nest site’’ and is an indication of frustration. Both oviposition and the detection of a prolonged mismatch could at the same time contribute to the occurrence of gakel-calls. The surplus of gakel-calls in treatment Nest compared to the other treatments might be the gakel-calls specifically related to oviposition.
This latter finding might account for the difference in temporal characteristics of gakel-calls between treatment Nest and the treatments Water and Dust. Gakel-calls in treatment Nest lasted longer and consisted of more notes than in the treatments Water and Dust. Schenk et al. 1983 found that the mean duration of a single gakel-call was longer when dustbathing was thwarted stronger by longer deprivation. However, from the present study, nothing decisive can be concluded about the relation between the number of gakel-calls and their temporal characteristics on the one hand, and the intensity of thwarting in the different treatments on the other
I understand and appreciate the thinking behind step in Ren’s argument. However, the ultimate result is this:
I experienced “disabling”-level pain for a couple of hours, by choice and with the freedom to stop whenever I want. This was a horrible experience that made everything else seem to not matter at all...
A single laying hen experiences hundreds of hours of this level of pain during their lifespan, which lasts perhaps a year and a half—and there are as many laying hens alive at any one time as there are humans. How would I feel if every single human were experiencing hundreds of hours of disabling pain?
My main takeaway is that the breadth and variety of experience that arguably falls under the umbrella of “disabling pain” is enormous, and we can only have low-moderate confidence in animal welfare pain metrics. As a result, I am updating toward increased skepticism in high-level summaries of animal welfare research.
The impact of nest deprivation on laying hen welfare may still be among the most pressing animal welfare issues. But, if tractability was held constant, I might prefer to focus on alleviating physical pain among a smaller number of birds.
Also, to disagreevoters, I’m genuinely curious about why you disagree! Were you already appropriately skeptical before? Do you think I am being too skeptical? Why or why not?
It was a very nice surprise to see the Cumulative Pain method used here to guide this debate. The ‘value tag’ that is already placed on different causes by resource allocation decisions is often based on personal experiences, specialist opinion, tradition or often even empathic guesses. Yet the criteria underlying these decisions are seldom explicit or open to scrutiny. This is one of the things we wanted to help change with the method: to help inform decisions based on an atomized process, where every assumption is explicit, and can help debate in a more objective way, based on estimates and evidence about the actual hedonic experiences of the subjects/targets of the interventions (as is the case here!). The sensitivity app (https://www.pain-track.org/hens) was also created to ensure that anyone disagreeing with our assumptions/estimates could use their own.
Re. the comments:
like Michael, for an experience that someone is desperate to stop immediately, similar to “slicing into my leg with a hot, sharp live wire”, we would attribute a higher likelihood of Excruciating pain (as this does not seem as something that can be tolerated for a long time). We have not yet estimated any mathematical equivalence between the intensity categories for the reasons we discuss in the FAQ (https://welfarefootprint.org/frequently-asked-questions/), but Excruciating pain is likely much much worse (something similar to an exponential—rather than linear—function) than Disabling pain (we are working on a draft on this issue that should be released at some point this year).
You are right that Disabling pain possibly accepts a range of intensities, all fitting the Disabling definition (continuously distressing/disruptive, cannot be ignored, prevents positive welfare, reduces attention to other ongoing stimuli). We have chosen not to create more categories to ensure both resolution and tractability (given the scarcity of evidence typically available from animal studies), but subdivision of the intensity categories is certainly possible and desirable should evidence be available that enables it.
It is true that distressed behaviors can be present in the absence of suffering, but this is unlikely to be the case when these behaviors are conditional and proportional to the degree of aversiveness of the situation, and observed along with various other independent indicators of distress. For example, pre-laying behavior is very different for hens with or without access to a proper nest and excessive pacing (seen in the latter case) is associated with other aversive situations. Other indicators include the observation of inelastic demand for a nest (hens paying increasingly higher costs to get to a nest), the overcoming of aversive obstacles (e.g., narrow gaps, long walking distances, dominant/unfamiliar birds), and vocalizations typically associated with frustration in other contexts. We also need to consider the evolutionary importance of psychological distress in the absence of important resources for survival and reproduction. In the case of physical pain, it is the unpleasantness of the pain experience that protects individuals from provoking further tissue damage when the eliciting stimuli is no longer present. Negative affective states of a more diffuse nature (psychological pain) are similarly strongly selected to ensure that individuals do not give up seeking important resources, as is the case of a nest, mates and offspring.
The notion that a hen under higher levels of feed deprivation would work less hard for access to food is a thoughtful one. However, the levels of feed restriction applied where unlikely to deprive the hens from the energy needed to access food. More importantly, evidence has shown the opposite: within the time periods of food deprivation used in experiments (e.g. up to 50-60 hours) hens deprived of food for a longer period work harder than hens deprived of food for a shorter period (e.g. https://www.sciencedirect.com/science/article/abs/pii/0168159190900156)
On the extent to which it is possible to compare physical and psychological pain, or use similar criteria to define their intensity, this is an interesting discussion and one that we would also like to work more on. For example, it may be hard to identify, in the short term, reliable biological markers of psychological suffering, and the same is true for humans. Consider for example the lack of changes in adrenocortical function in prisoners held 10 days in solitary confinement (“Adrenocortical function, as measured by plasma cortisol levels, indicated that solitary confinement was not more stressful than normal institutional life”, https://psycnet.apa.org/doiLanding?doi=10.1037%2Fh0081866), despite the severity of the experience as reported by those who have undergone it.
Based on your intro, I take it that you are one of the authors of the pain scale. It’s been a while since I thought about this post, but I appreciate your info-dense comment, and given your apparent background I will take some time to read and think about it over the next week. It might be a bit before I can offer a substantive reply, but thank you for chiming in!
I had more trouble understanding how nest deprivation could be equivalent to “**** me, make it stop. Like someone slicing into my leg with a hot, sharp live wire.” So I looked up the underpinnings of this metric, in Ch. 6 of the book they build their analysis on (pg. 6-9 is the key material).
They base this on the fact that chickens pace, preen, show aggressive competition for nests when availability is limited, and will work as hard to push open heavy doors to access nests as they will to access food after 4-28 hours of food deprivation. Based on this, the authors categorize nest deprivation as a disabling experience that each hen endures for an average of about 45 minutes per day.
This is a technically accurate definition, but I still had trouble intuiting this as equivalent to a daily experience of disabling physical pain equivalent to having your leg sliced open with a hot, sharp live wire.
Researchers are limited to showing that chickens exhibit distress during nest deprivation, or, in more sophisticated research, that they work as hard to access nest boxes as they do to access food after 4-28 hours of food deprivation.
I am suspicious of the claim that these methods are adequate to allow us to make comparisons of physical and emotional pain across species. This is especially true with the willingness-to-work metric they use to compare the severity of nest deprivation and starvation on chickens.
Willingness-to-work is probably mediated by energy. After starvation, chickens will be low-energy, and willingness-to-work probably underestimates their suffering. A starving person would like to do 100 pushups to access an all-you-can-eat buffet, but physically is unable to do so. If he’s also willing to do 100 pushups to join the football team, does that mean that keeping him off the team is as bad as starving him?
People show distressed behaviors in the absence of suffering. I bite my fingernails pretty severely. Sometimes, they even bleed. It’s not motivated by severe anxiety in those moments. It’s just force of habit. Chickens may be hardwired by evolution to work hard to access nests, without necessary suffering while they do so.
Our perceptions of how distressed a behavior is is culturally-specific, not to mention species-specific. I pace and walk around the neighborhood when I’m thinking hard. People get piercings and tattoos. People fight recreationally. We don’t assume that people are experiencing high emotional distress in the moments they choose to do these things. Why do we assume that about chickens?
I’ve spent too long writing this comment, so I’m going to just stop here.
Nest deprivation could be in the bottom half of the disabling pain intensity range. Ren put their tattoo experiences described as “**** me, make it stop. Like someone slicing into my leg with a hot, sharp live wire.” near the high end of disabling. Also, the latter just sounds excruciating to me personally, not merely disabling, but we discussed that here.
Besides the evidence you mention, they also mention vocalizations (gakel-calls), which seem generally indicative of frustration across contexts (dustbathing deprivation, food/water deprivation, nesting deprivation), and hens made more of them when nest deprived than when deprived of food, water or dustbathing in Zimmerman et al., 2000, although in that study, the authors discuss the possibility that nest deprivation gakel-calls are more specific and not necessarily indicative of frustration:
Thank you for contributing more information.
I understand and appreciate the thinking behind step in Ren’s argument. However, the ultimate result is this:
My main takeaway is that the breadth and variety of experience that arguably falls under the umbrella of “disabling pain” is enormous, and we can only have low-moderate confidence in animal welfare pain metrics. As a result, I am updating toward increased skepticism in high-level summaries of animal welfare research.
The impact of nest deprivation on laying hen welfare may still be among the most pressing animal welfare issues. But, if tractability was held constant, I might prefer to focus on alleviating physical pain among a smaller number of birds.
Also, to disagreevoters, I’m genuinely curious about why you disagree! Were you already appropriately skeptical before? Do you think I am being too skeptical? Why or why not?
It was a very nice surprise to see the Cumulative Pain method used here to guide this debate. The ‘value tag’ that is already placed on different causes by resource allocation decisions is often based on personal experiences, specialist opinion, tradition or often even empathic guesses. Yet the criteria underlying these decisions are seldom explicit or open to scrutiny. This is one of the things we wanted to help change with the method: to help inform decisions based on an atomized process, where every assumption is explicit, and can help debate in a more objective way, based on estimates and evidence about the actual hedonic experiences of the subjects/targets of the interventions (as is the case here!). The sensitivity app (https://www.pain-track.org/hens) was also created to ensure that anyone disagreeing with our assumptions/estimates could use their own.
Re. the comments:
like Michael, for an experience that someone is desperate to stop immediately, similar to “slicing into my leg with a hot, sharp live wire”, we would attribute a higher likelihood of Excruciating pain (as this does not seem as something that can be tolerated for a long time). We have not yet estimated any mathematical equivalence between the intensity categories for the reasons we discuss in the FAQ (https://welfarefootprint.org/frequently-asked-questions/), but Excruciating pain is likely much much worse (something similar to an exponential—rather than linear—function) than Disabling pain (we are working on a draft on this issue that should be released at some point this year).
You are right that Disabling pain possibly accepts a range of intensities, all fitting the Disabling definition (continuously distressing/disruptive, cannot be ignored, prevents positive welfare, reduces attention to other ongoing stimuli). We have chosen not to create more categories to ensure both resolution and tractability (given the scarcity of evidence typically available from animal studies), but subdivision of the intensity categories is certainly possible and desirable should evidence be available that enables it.
It is true that distressed behaviors can be present in the absence of suffering, but this is unlikely to be the case when these behaviors are conditional and proportional to the degree of aversiveness of the situation, and observed along with various other independent indicators of distress. For example, pre-laying behavior is very different for hens with or without access to a proper nest and excessive pacing (seen in the latter case) is associated with other aversive situations. Other indicators include the observation of inelastic demand for a nest (hens paying increasingly higher costs to get to a nest), the overcoming of aversive obstacles (e.g., narrow gaps, long walking distances, dominant/unfamiliar birds), and vocalizations typically associated with frustration in other contexts. We also need to consider the evolutionary importance of psychological distress in the absence of important resources for survival and reproduction. In the case of physical pain, it is the unpleasantness of the pain experience that protects individuals from provoking further tissue damage when the eliciting stimuli is no longer present. Negative affective states of a more diffuse nature (psychological pain) are similarly strongly selected to ensure that individuals do not give up seeking important resources, as is the case of a nest, mates and offspring.
The notion that a hen under higher levels of feed deprivation would work less hard for access to food is a thoughtful one. However, the levels of feed restriction applied where unlikely to deprive the hens from the energy needed to access food. More importantly, evidence has shown the opposite: within the time periods of food deprivation used in experiments (e.g. up to 50-60 hours) hens deprived of food for a longer period work harder than hens deprived of food for a shorter period (e.g. https://www.sciencedirect.com/science/article/abs/pii/0168159190900156)
On the extent to which it is possible to compare physical and psychological pain, or use similar criteria to define their intensity, this is an interesting discussion and one that we would also like to work more on. For example, it may be hard to identify, in the short term, reliable biological markers of psychological suffering, and the same is true for humans. Consider for example the lack of changes in adrenocortical function in prisoners held 10 days in solitary confinement (“Adrenocortical function, as measured by plasma cortisol levels, indicated that solitary confinement was not more stressful than normal institutional life”, https://psycnet.apa.org/doiLanding?doi=10.1037%2Fh0081866), despite the severity of the experience as reported by those who have undergone it.
Thanks for the interesting discussion!
Based on your intro, I take it that you are one of the authors of the pain scale. It’s been a while since I thought about this post, but I appreciate your info-dense comment, and given your apparent background I will take some time to read and think about it over the next week. It might be a bit before I can offer a substantive reply, but thank you for chiming in!