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Full-Text Articles in Psychology

Sentience In Decapod Crustaceans: A General Framework And Review Of The Evidence, Andrew Crump, Heather Browning, Alex Schnell, Charlotte Burn, Jonathan Birch Jan 2022

Sentience In Decapod Crustaceans: A General Framework And Review Of The Evidence, Andrew Crump, Heather Browning, Alex Schnell, Charlotte Burn, Jonathan Birch

Animal Sentience

We outline a framework for evaluating scientific evidence of sentience, focusing on pain experience. It includes eight neural and cognitive-behavioural criteria, with confidence levels for each criterion reflecting the reliability and quality of the evidence. We outline the rationale for each criterion and apply our framework to a controversial sentience candidate: decapod crustaceans. We have either high or very high confidence that true crabs (infraorder Brachyura) satisfy five criteria, amounting to strong evidence of sentience. Moreover, we have high confidence that both anomuran crabs (infraorder Anomura) and astacid lobsters/crayfish (infraorder Astacidea) meet three criteria—substantial evidence of sentience. The case is, …


Pain Sentience Criteria And Their Grading, Eva Jablonka, Simona Ginsburg Jan 2022

Pain Sentience Criteria And Their Grading, Eva Jablonka, Simona Ginsburg

Animal Sentience

On the basis of the target article by Crump and colleagues, we suggest a more parsimonious scheme for evaluating the evidence for sentience. Since some of the criteria used by Crump et al. are not independent and some are uninformative we exclude some criteria and amalgamate others. We propose that evidence of flexible learning and prioritization, in conjunction with relevant data on brain organization, is sufficient for assigning pain-sentience to an animal and we suggest a scoring scheme based on four criteria.


Emotional Component Of Pain Perception In The Medicinal Leech?, Brian D. Burrell Jan 2022

Emotional Component Of Pain Perception In The Medicinal Leech?, Brian D. Burrell

Animal Sentience

Crump et al. have provided a series of criteria to assess animal sentience that is focused on the perception of pain, which is known to have both sensory and emotional components. They also provide a qualitative scoring system to assess data that address the eight criteria and apply this paradigm to decapod crustaceans. The criteria laid out have the potential to be applied to other invertebrates typically thought to have sensory response to tissue damage, but no emotional component to pain perception.


A Framework For Evaluating Evidence Of Pain In Animals, Matilda Gibbons, Lars Chittka Jan 2022

A Framework For Evaluating Evidence Of Pain In Animals, Matilda Gibbons, Lars Chittka

Animal Sentience

Crump et al. define eight criteria indicating sentience in animals, with a focus on pain. Here, we point out the risk of false negative or false positive diagnoses of pain. Criteria of different levels of inclusivity are useful for using the precautionary principle in animal welfare considerations, and for more formal scientific evidence of pain. We suggest tightening the criteria -- from more general evidence of sentience to pain alone -- because crucial evidence for animal welfare decisions might otherwise be missed for animals subjected to invasive and injurious procedures.


Defending Human Difference By Raising The Bar, Joe Gough Jan 2022

Defending Human Difference By Raising The Bar, Joe Gough

Animal Sentience

Chapman & Huffman (C&H) offer a theory of why we humans want to believe that we are different: to justify our cruelty to animals. This commentary offers further supporting evidence of this and examines more closely what the claim that humans are ‘different’ amounts to. It also considers some methodological issues in animal psychology closely related to C&H ‘s theory. These problems result from a common strategy for defending hypotheses about human difference.


Inhibition Of Pain Or Response To Injury In Invertebrates And Vertebrates, Matilda Gibbons, Sajedeh Sarlak Jan 2020

Inhibition Of Pain Or Response To Injury In Invertebrates And Vertebrates, Matilda Gibbons, Sajedeh Sarlak

Animal Sentience

In certain situations, insects appear to lack a response to noxious stimuli that would cause pain in humans. For example, from the fact that male mantids continue to mate while being eaten by their partner it does not follow that insects do not feel pain; it could be the result of modulation of nociceptive inputs or behavioural outputs. When we try to infer the underlying mental state of an insect from its behaviour, it is important to consider the behavioural effects of the associated physiological and neurobiological mechanisms.


If It Looks Like A Duck: Fish Fit The Criteria For Pain Perception, Julia E. Meyers-Manor Jan 2018

If It Looks Like A Duck: Fish Fit The Criteria For Pain Perception, Julia E. Meyers-Manor

Animal Sentience

Whereas we have denied the experience of pain to animals, including human babies, the evidence is becoming clearer that animals across a variety of species have the capacity to feel pain (Bellieni, 2012). As converging findings are collected from pain studies and the study of cognition, it is becoming harder to deny that fish are among the species that do feel pain.


Pain In Fish: Evidence From Peripheral Nociceptors To Pallial Processing, Michael L. Woodruff Jan 2018

Pain In Fish: Evidence From Peripheral Nociceptors To Pallial Processing, Michael L. Woodruff

Animal Sentience

The target article by Sneddon et al. (2018) presents convincing behavioral and pharmacological evidence that ray-finned fish consciously perceive noxious stimuli as painful. One objection to this interpretation of the evidence is that the fish nervous system is not complex enough to support the conscious experience of pain. Data that contradict this objection are presented in this commentary. The neuroanatomy and neurophysiology of the fish nervous system from the peripheral nerves to the pallium is able to support the sentient appreciation of pain.


Fish Sentience Denial: Muddying The Waters, Lynne U. Sneddon, Javier Lopez-Luna, David C.C. Wolfenden, Matthew C. Leach, Ana M. Valentim, Peter J. Steenbergen, Nabila Bardine, Amanda D. Currie, Donald M. Broom, Culum Brown Jan 2018

Fish Sentience Denial: Muddying The Waters, Lynne U. Sneddon, Javier Lopez-Luna, David C.C. Wolfenden, Matthew C. Leach, Ana M. Valentim, Peter J. Steenbergen, Nabila Bardine, Amanda D. Currie, Donald M. Broom, Culum Brown

Animal Sentience

Recent empirical studies have reported evidence that many aquatic species, including fish, cephalopods and crustaceans, have the capacity for nociception and pain, and that their welfare should be taken into consideration. Some sceptics, rejecting the precautionary principle, have denied that any study demonstrates pain or other aspects of sentience in fish. This target article discusses some of the scientific shortcomings of these critiques through a detailed analysis of a study exploring nociception and analgesia in larval zebrafish.


On Crabs And Statistics, Jonathan Birch Jan 2018

On Crabs And Statistics, Jonathan Birch

Animal Sentience

I respond to commentaries by Elwood and Seth & Dienes and to a recent critique by Diggles, discussing the link between avoidance learning and sentience, the relevance of the clash between frequentist and Bayesian statistics, the risks to decapod welfare in aquaculture, and the broader concerns one may have about a “precautionary” approach to protecting invertebrates.


Denialism And Muddying The Water Or Organized Skepticism And Clarity? That Is The Question, Ben Diggles, Howard I. Browman Jan 2018

Denialism And Muddying The Water Or Organized Skepticism And Clarity? That Is The Question, Ben Diggles, Howard I. Browman

Animal Sentience

The research being commented on here has been criticized and defended in journals. Sneddon et al. (2018) add nothing substantive. We have nothing further to add. Readers are referred to Diggles (2018) and to Browman et al. (2018) for a detailed assessment.


The “Precautionary Principle” – A Work In Progress, Shelley Adamo Jan 2017

The “Precautionary Principle” – A Work In Progress, Shelley Adamo

Animal Sentience

The target article by Birch illustrates the practical difficulties with the “Animal Sentience Precautionary Principle” (ASPP) while presenting potential solutions. However, the ASPP will be difficult to use without guidelines detailing how evidence of sentience should be assessed. Moreover, extrapolating conclusions found for a single species to all species within an Order is problematic. Finally, I recommend that Birch demonstrate his ASPP framework using a controversial test case to help show how it could be used in real-world situations.


Assessing Negative And Positive Evidence For Animal Pain, Robert W. Elwood Jan 2017

Assessing Negative And Positive Evidence For Animal Pain, Robert W. Elwood

Animal Sentience

Jonathan Birch suggests that we should take one well-conducted study that produces results consistent with the idea of pain as being sufficient to invoke the animal sentience precautionary principle. Here, I consider how to balance negative and positive results from such studies using examples from my own work. I also consider which criteria of pain might provide strong inference about pain and which may prove to be weaker.


The Potential For Sentience In Fishes, Jay R. Stauffer Jr. Jan 2017

The Potential For Sentience In Fishes, Jay R. Stauffer Jr.

Animal Sentience

Balcombe’s book is filled with information on the biology, behavior, and life history of fishes. I do not agree with all his premises. I am still somewhat perplexed about the discussion of whether fish feel pain; I am not sure whether the distinction between nociception and pain makes any difference. Overall, however, his treatment of the principles of both natural and sexual selection is comprehensive and accurate, and has greatly increased my knowledge and awareness of the biology, ethology, and potential for sentience in fishes. In summary, this work has exposed me to new ideas about how to examine fishes …


Insect Consciousness: Commitments, Conflicts And Consequences, Colin Klein, Andrew B. Barron Nov 2016

Insect Consciousness: Commitments, Conflicts And Consequences, Colin Klein, Andrew B. Barron

Animal Sentience

Our target article, “Insects have the capacity for subjective experience,” has provoked a diverse range of commentaries. In this response we have collated what we see as the major themes of the discussion. It is clear that we differ from some commentators in our commitments to what subjective experience is and what the midbrain is capable of. Here we clarify where we stand on those points and how our view differs from some other influential perspectives. The commentaries have highlighted the most lively areas of disagreement. We revisit here the debates surrounding whether the cortex is essential for any form …


Subjective Experience In Insects: Definitions And Other Difficulties, Shelley Adamo Aug 2016

Subjective Experience In Insects: Definitions And Other Difficulties, Shelley Adamo

Animal Sentience

Whether insects have the potential for subjective experiences depends on the definition of subjective experience. The definition used by Klein & Barron (2016) is an unusually liberal one and could be used to argue that some modern robots have subjective experiences. From an evolutionary perspective, the additional neurons needed to produce subjective experiences will be proportionately more expensive for insects than for mammals because of the small size of the insect brain. This greater cost could weaken selection for such traits. Minimally, it may be premature to assume that small neuronal number is unimportant in determining the capacity for consciousness.


Fish Pain's Burden Of Proof, Carl Safina Feb 2016

Fish Pain's Burden Of Proof, Carl Safina

Animal Sentience

A hypothesis like Key’s, that fish cannot feel pain, should really be stated as a null hypothesis — an assumption that there is no difference in the things being compared. Then evidence — including anecdotal evidence — for and against rejecting the null hypothesis can be examined and weighed. Key (2016a) has proven only that fish lack mammalian brains.


Brain Processes For “Good” And “Bad” Feelings: How Far Back In Evolution?, Jaak Panksepp Jan 2016

Brain Processes For “Good” And “Bad” Feelings: How Far Back In Evolution?, Jaak Panksepp

Animal Sentience

The question of whether fish can experience pain or any other feelings can only be resolved by neurobiologically targeted experiments. This commentary summarizes why this is essential for resolving scientific debates about consciousness in other animals, and offers specific experiments that need to be done: (i) those that evaluate the rewarding and punishing effects of specific brain regions and systems (for instance, with deep-brain stimulation); (ii) those that evaluate the capacity of animals to regulate their affective states; and (iii) those that have direct implications for human affective feelings, with specific predictions — for instance, the development of new treatments …


Fish Pain: An Inconvenient Truth, Culum Brown Jan 2016

Fish Pain: An Inconvenient Truth, Culum Brown

Animal Sentience

Whether fish feel pain is a hot political topic. The consequences of our denial are huge given the billions of fish that are slaughtered annually for human consumption. The economic costs of changing our commercial fishery harvest practices are also likely to be great. Key outlines a structure-function analogy of pain in humans, tries to force that template on the rest of the vertebrate kingdom, and fails. His target article has so far elicited 34 commentaries from scientific experts from a broad range of disciplines; only three of these support his position. The broad consensus from the scientific community is …


Why Fish Do Not Feel Pain, Brian Key Jan 2016

Why Fish Do Not Feel Pain, Brian Key

Animal Sentience

Only humans can report feeling pain. In contrast, pain in animals is typically inferred on the basis of nonverbal behaviour. Unfortunately, these behavioural data can be problematic when the reliability and validity of the behavioural tests are questionable. The thesis proposed here is based on the bioengineering principle that structure determines function. Basic functional homologies can be mapped to structural homologies across a broad spectrum of vertebrate species. For example, olfaction depends on olfactory glomeruli in the olfactory bulbs of the forebrain, visual orientation responses depend on the laminated optic tectum in the midbrain, and locomotion depends on pattern generators …


Should Fish Feel Pain? A Plant Perspective, František Baluška Jan 2016

Should Fish Feel Pain? A Plant Perspective, František Baluška

Animal Sentience

Key (2016) claims fish that fish do not feel pain because they lack the necessary neuronal architecture: their responses to noxious stimuli, according to Key, are executed automatically without any feelings. However, as pointed out by many of his commentators, this conclusion is not convincing. Plants might provide some clues. Plants are not usually thought to be very active behaviorally, but the evidence suggests otherwise. Moreover, in stressful situations, plants produce numerous chemicals that have painkilling and anesthetic properties. Finally, plants, when treated with anesthetics, cannot execute active behaviors such as touch-induced leaf movements or rapid trap closures after localizing …


What Would The Babel Fish Say?, Monica Gagliano Jan 2016

What Would The Babel Fish Say?, Monica Gagliano

Animal Sentience

Starting with its title, Key’s (2016) target article advocates the view that fish do not feel pain. The author describes the neuroanatomical, physiological and behavioural conditions involved in the experience of pain in humans and rodents and confidently applies analogical arguments as though they were established facts in support of the negative conclusion about the inability of fish to feel pain. The logical reasoning, unfortunately, becomes somewhat incoherent, with the arbitrary application of the designated human criteria for an analogical argument to one animal species (e.g., rodents) but not another (fish). Research findings are reported selectively, and questionable interpretations are …


Pain In Fish: Weighing The Evidence, James D. Rose Jan 2016

Pain In Fish: Weighing The Evidence, James D. Rose

Animal Sentience

The target article by Key (2016) examines whether fish have brain structures capable of mediating pain perception and consciousness, functions known to depend on the neocortex in humans. He concludes, as others have concluded (Rose 2002, 2007; Rose et al. 2014), that such functions are impossible for fish brains. This conclusion has been met with hypothetical assertions by others to the effect that functions of pain and consciousness may well be possible through unknown alternate neural processes. Key's argument would be bolstered by consideration of other neurological as well as behavioral evidence, which shows that sharks and ray are fishes …


Cortex Necessary For Pain — But Not In Sense That Matters, Adam J. Shriver Jan 2016

Cortex Necessary For Pain — But Not In Sense That Matters, Adam J. Shriver

Animal Sentience

Certain cortical regions are necessary for pain in humans in the sense that, at particular times, they play a direct role in pain. However, it is not true that they are necessary in the more important sense that pain is never possible in humans without them. There are additional details from human lesion studies concerning functional plasticity that undermine Key’s (2016) interpretation. Moreover, no one has yet identified any specific behaviors that mammalian cortical pain regions make possible that are absent in fish.


Nonverbal Indicators Of Pain, Simon Van Rysewyk Jan 2016

Nonverbal Indicators Of Pain, Simon Van Rysewyk

Animal Sentience

In discussing fish pain, Key (2016) privileges pain in humans — “the only species able to directly report on its feelings.” Human experience of pain is not necessarily best reflected by verbal self-report, however. Neural responses to noxious stimuli are influenced by individual differences and by context. Nonverbal pain displays such as facial expressions reflect part of the neural response to noxious stimuli. Most mammals have a specific facial grimace reflecting pain. If fish have a somatic expression of pain, the development of a reliable and accurate somatic pain scale specific to fish could make a contribution to the debate …


Fish Pain: Would It Change Current Best Practice In The Real World?, B. K. Diggles Jan 2016

Fish Pain: Would It Change Current Best Practice In The Real World?, B. K. Diggles

Animal Sentience

Much of the “fish pain debate” relates to how high the bar for pain should be set. The close phylogenetic affinities of teleosts with cartilaginous fishes which appear to lack nociceptors suggests caution should be applied by those who seek to lower the bar, especially given the equivocal and conflicting nature of the experimental data currently available for teleosts. Nevertheless, even if we assume fish “feel pain,” it is difficult to see how current best practice in aquaculture would change. This is because of the need to avoid stress at all stages of the rearing process to optimize health, growth …


Fish Pain: A Painful Topic, Carl Safina Jan 2016

Fish Pain: A Painful Topic, Carl Safina

Animal Sentience

If fish cannot feel pain, why do stingrays have purely defensive tail spines that deliver venom? Stingrays’ ancestral predators are fish. And why do many fishes possess defensive fin spines, some also with venom that produces pain in humans? These things did not evolve just in case sentient humans would evolve millions of years later and then invent scuba. If fish react purely unconsciously to “noxious” stimuli, why aren’t sharp jabbing spines enough? Why also stinging venom?


Devaluation As A Strategy To Address Behaviourally Whether Fish Feel, Robert Ian Bowers Jan 2016

Devaluation As A Strategy To Address Behaviourally Whether Fish Feel, Robert Ian Bowers

Animal Sentience

Failures of behavioural studies to address the question of whether fish feel pain have left scientists arguing on the basis of other criteria, including anatomy. I draw an analogy with a debate concerning the breadth of stimulus-response learning among nonhuman animals and propose an experiment that harks back to one solution to that debate: the devaluation paradigm. By changing the value of a noxious stimulus after training, one can differentiate a directly evoked response from a response to an intermediate representation, the pain.


Anthropomorphic Denial Of Fish Pain, Lynne U. Sneddon, Matthew C. Leach Jan 2016

Anthropomorphic Denial Of Fish Pain, Lynne U. Sneddon, Matthew C. Leach

Animal Sentience

Key (2016) affirms that we do not know how the fish brain processes pain but denies — because fish lack a human-like cortex — that fish can feel pain. He affirms that birds, like fish, have a singly-laminated cortex and that the structure of the bird brain is quite different from that of the human brain, yet he does not deny that birds can feel pain. In this commentary we describe how Key cites studies that substantiate mammalian pain but discounts the same kind of data as evidence of fish pain. We suggest that Key's interpretations are illogical, do not …


Fish Intelligence, Sentience And Ethics, Culum Brown Jan 2015

Fish Intelligence, Sentience And Ethics, Culum Brown

Sentience Collection

Fish are one of the most highly utilised vertebrate taxa by humans; they are harvested from wild stocks as part of global fishing industries, grown under intensive aquaculture conditions, are the most common pet and are widely used for scientific research. But fish are seldom afforded the same level of compassion or welfare as warm-blooded vertebrates. Part of the problem is the large gap between people’s perception of fish intelligence and the scientific reality. This is an important issue because public perception guides government policy. The perception of an animal’s intelligence often drives our decision whether or not to include …