One of the most controversial and debated problems regarding the nature of sentience, is how to integrate the biology and neurobiology of sentience with the problem of the "explanatory gaps" that are proposed to arise between the functions of the nervous system as objectively and scientifically explained and sentience-or more generally consciousness-as it is subjectively experienced. In this paper I discuss a theory I have called Neurobiological emergentism (NBE) that is based upon a biological-neurobiological-evolutionary model that explains both how sentience emerges from complex nervous systems as well as scientifically resolves the explanatory gaps. I propose a model in which the emergence of sentience occurs roughly in three stages: Emergent Stage 1 (ES1) single-celled sensing organisms without neurons or nervous systems that appeared approximately 3.5-3.4 billion years ago and are non-sentient; Emergent Stage 2 (ES2) presentient animals that appeared approximately 570 million years ago (mya) that have neurons and simple nervous systems and fall between ES1 and ES3 animals; and Emergent stage 3 (ES3) sentient animals that emerged along diverse evolutionary lines during the Cambrian period approximately 560-520 mya, a group that includes all vertebrates (fish, reptiles, birds, and mammals), arthropods (insects and crabs), onychophorans (velvet worms) and cephalopods such as the octopus and squid that possess neurobiologically complex central nervous systems. I describe how this model leads to a scientific resolution of two related "explanatory gaps" (the personal nature of sentience and the character of experience), both of which are created by the natural emergence of sentience. However, in place of the "explanatory gaps," I propose that there is an experiential gap that emerges between the objective brain and subjective experience, but that this "gap" can be fully scientifically explained and naturalized and can account for the personal subjective nature of sentience without completely "objectifying" it.

A new theory of Neurobiological Emergentism that explains how sentience emerges from the brain. Sentience is the feeling aspect of consciousness. In From Sensing to Sentience, Todd Feinberg develops a new theory called Neurobiological Emergentism (NBE) thatintegrates biological, neurobiological, evolutionary, and philosophical perspectives to explain how sentience naturally emerges from the brain. Emergent properties are broadly defined as features of a complex system that are not present in the parts of a system when they are considered in isolation but may emerge as a system feature of those parts and their interactions. Tracing a journey of billions of years of evolution from life to the basic sensing capabilities of single-celled organisms up to the sentience of animals with advanced nervous systems, including all vertebrates (for instance, fish, reptiles, birds, and mammals), arthropods (insects and crabs), and cephalopods (such as the octopus), Feinberg argues that sentience gradually but eventually emerged along diverse evolutionary lines with the evolution of sufficiently neurobiologically complex brains during the Cambrian period over 520 million years ago. Ultimately, Feinberg argues that viewing sentience as an emergent process can explain both its neurobiological basis as well its perplexing personal nature, thus solving the historical philosophical problem of the apparent “explanatory gap” between the brain and experience.

Strong points of the target article by Crump et al. are that it offers clear criteria for judging whether decapods are sentient, an effective semi-quantitative grading system for this purpose, and an astute, critical review of the literature. It concludes plausibly that major subgroups of decapods are sentient. A minor problem is that it includes classical, Pavlovian learning as a marker of sentience along with the more valid marker of complex (e.g., operant) learning. Another minor problem is that it does not distinguish results that are negative because of likely absence of sentience from results that are negative because they have not yet been gathered. Future studies should explore how decapods are sentient with so few neurons in their nervous system (

We appreciate the goals of Mikhalevich & Powell (M&P) and largely agree with their conclusions but we differ on some of their definitions and terms. Affects (emotional feelings) should be part of sentience. Although the evidence presented for insect sentience is strong, we list some of the counterevidence that should be considered. Our own research supports M&P’s choice of arthropods, cephalopods, and vertebrates as the only sentient organisms with moral status. Jon Mallatt, Clinical Associate Professor, WWAMI Medical Education Program, University of Idaho, does research on the origin of the major animal groups, especially vertebrates, and on the evolution and nature of consciousness. Website Todd E. Feinberg, Clinical Professor of Psychiatry and Neurology, Icahn School of Medicine at Mount Sinai does research on how the neurobiology of the brain creates consciousness and the individual’s sense of identity. Website Mikhalevich & Powell (2020) (M&P) make a good argument that, for consistency, the same standards should be used to judge sentience and moral worth in vertebrates and invertebrates. Also valuable is how M&P assemble a large amount of literature on invertebrate (mostly insect) sentience and cognition. We especially appreciate their pointing out that a capacity for pain is used too often as the sole standard for judging whether an animal is sentient, when many other affective states are possible (e.g., stress, starvation, pleasure) and should all be considered. Two of the commentaries to date, however, have centered on pain despite M&P’s plea against it (Elwood, 2020; Veit & Huebner, 2020). Although we agree with many of M&P’s proposals and conclusions, we suggest that some of their positions should be further clarified. 1. Terminology and definitions. M&P do not always make it clear on what basis they judge an animal to deserve moral status. In various places in the target article, the basis is said to be having mental states, cognition, sentience, cognition plus sentience, flexible behaviors, or affective states along with cognition. Most of these traits overlap, but some are fairly distinct (e.g., sentience and cognition), so it is difficult to know what the authors mean. Later in the text, Animal Sentience 2020.343: Mallatt & Feinberg on Mikhalevich & Powell on Invertebrate Minds 2 however, they definitively settle on sentience as their basis for moral status, eliminating cognition because computers have cognitive functions. Sentience is the correct choice, and most of the other commentators understood that M&P were using it (Balcombe, 2020; Browning and Veit, 2020; Cammaerts, 2020; Elwood, 2020; Figdor, 2020; Levy, 2020; Soryl, 2020). We just wish M&P had established their sentience standard at the start of the target article. Many different terms besides “sentience” are used to designate the most basic, minimal form of “consciousness” (yet another term). M&P sometimes use these multiple terms in confusing ways. Table 1 is our version of the best usage, developed from our work on consciousness (Feinberg and Mallatt, 2018, 2019, 2020). Most other sources agree with us, especially that the basic type is called phenomenal consciousness and that this includes both images and affects (Block, 1995; Mellor, 2019), but M&P do not. Table 1. Proposed terminology for basic, minimal consciousness *We assume all affects are conscious. For another view, see Adolphs and Anderson (2018). A large part of the confusion comes from the way M&P use the term “phenomenal consciousness.” They point out that it is a difficult and controversial term. Then they say it is doubly “inadequate.” From this, the reader might infer that they are rejecting it; but instead of rejecting it, they use phenomenal consciousness repeatedly without explicitly stating what they take it to mean (although the context implies that what they mean is “being capable of experience”). What is going on here? The only thing that is clear is that M&P do not believe that phenomenal consciousness includes affect — that it is only a “precondition” for affect. According to other authors, however, when phenomenal consciousness is stripped of its philosophical complications, it includes experiencing affects as well as sensations (Block, 1995). Even Carruthers’s deeply philosophical and elaborated analysis (to which M&P refer) states that affect (valence) is in phenomenal consciousness (Carruthers, 2018, p. 676), not a separate thing that is glossed onto it, as M&P seem to think. We would accordingly recommend that M&P include affect in their definition of phenomenal consciousness. This will avoid errors and confusion; then they can say that phenomenal consciousness, sentience, and experiencing are all equivalent (Table 1) and that that is what imparts moral worth. M&P also use the key term “sentience” inconsistently. They first define it as the capacity for subjective experience, but later define it differently, as affect: "Phenomenal consciousness alone is not an adequate basis by which to establish the existence of a welfare ... if things are to matter to an organism, it must be capable of experiencing states of affairs as pleasurable or aversive.... We think this affective glossing of conscious experience is better captured by the term sentience." Sentience ≡ phenomenal consciousness ≡ having experiences and consists of two kinds of experiences: A. sensory experiences (including “images”) B. affective experiences (emotions and moods)* Animal Sentience 2020.343: Mallatt & Feinberg on Mikhalevich & Powell on Invertebrate Minds 3 The context of the target article indicates that M&P only believe in the first definition, but the inconsistency adds to the reader’s confusion. As M&P’s argument now stands, the semantics lead to a logical incoherence: Their current claims are that sentience is experience, that phenomenal consciousness is experience, that affects are different from phenomenal consciousness, and that sentience includes or even is affect. Sentience and phenomenal consciousness cannot both be experience if phenomenal consciousness excludes affect but sentience includes affect, as claimed. Again, the solution to this logical contradiction is to adopt the standard terminology of Table 1. 2. Counterevidence. Although M&P present considerable convincing evidence that insects have both sentience and sophisticated cognition and learning, they do not include the experimental evidence against these abilities. This counterevidence was presented in the article by Abramson & Wells (2018), “An inconvenient truth: Some neglected issues in invertebrate learning,” which M&P only cite in passing. Abramson & Wells report that the learning abilities of bees — neurobiologically and behaviorally among the most complex insects — are sometimes more specific and less flexible than those of vertebrates. Bees can become confused when either the spatial location or the target cue for a learned food source is changed experimentally, even modestly (cap-pushing test of Abramson et al., 2016; moved reward site of Sanderson et al., 2013; changed target of Abramson, 1990). These findings are relevant because M&P urge against using deflationary (simpler) cognitive explanations of invertebrate behaviors when more complex explanations are applied to vertebrates who perform the same behaviors. It is therefore potentially devastating when an invertebrate performs worse, opening the door for deflationary accounts that claim bees are not sentient but just take unconscious shortcuts to solve problems. Our point is that this valid counterevidence should not be ignored. We do not deny that the preponderance of the evidence suggests that insects are conscious. We found two studies that showed insect consciousness to be especially convincing (Feinberg and Mallatt, 2018, pp. 6062): first, the study by Fauria et al. (2000) where bees learned a complex two-part target, indicating that they form and recall mental images; and second, the study by Perry et al. (2016) where a pre-taste of a sugar reward made bees more likely to interpret ambiguous cues as leading to the reward — a form of optimism. These bees passed the judgement-bias test, a standard way of evaluating whether vertebrates have affective consciousness. 3. Why just arthropods and cephalopods? A strength of M&P’s analysis is that they attribute sentience and moral status only to arthropods and cephalopods among the non-vertebrates. Recognizing which organisms are sentient is difficult. Levy (2020) acknowledges this difficulty, suggesting that we should not even try but should instead assign moral status to cognition, which is easier to recognize. (This is rejected by M&P and Vonk, 2020.) More relevantly, Figdor (2020) and Veit & Huebner (2020) acknowledge the difficulty by asking why M&P draw the sentient line at these particular invertebrates rather than considering whether plants, bacteria, and all living things are sentient. Our own work on which organisms have consciousness (Feinberg and Mallatt, 2016, 2018, 2019, 2020) suggests that M&P drew the line at the right place. We derived which organisms are conscious from two logical (and ultimately testable) assumptions. To identify the organisms with affective consciousness (Table 1), we assumed that emotions are revealed by the capacity for global operant learning (extensive learning from experience). We assumed this because this kind of learning provides double evidence of Animal Sentience 2020.343: Mallatt & Feinberg on Mikhalevich & Powell on Invertebrate Minds 4 emotions: (1) the initial attraction to a reward (or aversion to a punishment); and (2) the recall of the learned reward (or punishment) to motivate behaviors. Our criterion of global operant learning is similar to the Unlimited Associative Learning idea of Bronfman et al. (2016) and Ginsburg and Jablonka (2019). To identify the organisms with image-based consciousness (Table 1) — mental simulations of the sensed world — w

The multiple realizability thesis (MRT) is an important philosophical and psychological concept. It says any mental state can be constructed by multiple realizability (MR), meaning in many distinct ways from different physical parts. The goal of our study is to find if the MRT applies to the mental state of consciousness among animals. Many things have been written about MRT but the ones most applicable to animal consciousness are by Shapiro in a 2004 book called The Mind Incarnate and by Polger and Shapiro in their 2016 work, The Multiple Realization Book. Standard, classical MRT has been around since 1967 and it says that a mental state can have very many different physical realizations, in a nearly unlimited manner. To the contrary, Shapiro’s book reasoned that physical, physiological, and historical constraints force mental traits to evolve in just a few, limited directions, which is seen as convergent evolution of the associated neural traits in different animal lineages. This is his mental constraint thesis (MCT). We examined the evolution of consciousness in animals and found that it arose independently in just three animal clades—vertebrates, arthropods, and cephalopod mollusks—all of which share many consciousness-associated traits: elaborate sensory organs and brains, high capacity for memory, directed mobility, etc. These three constrained, convergently evolved routes to consciousness fit Shapiro’s original MCT. More recently, Polger and Shapiro’s book presented much the same thesis but changed its name from MCT to a “modest identity thesis.” Furthermore, they argued against almost all the classically offered instances of MR in animal evolution, especially against the evidence of neural plasticity and the differently expanded cerebrums of mammals and birds. In contrast, we argue that some of these classical examples of MR are indeed valid and that Shapiro’s original MCT correction of MRT is the better account of the evolution of consciousness in animal clades. And we still agree that constraints and convergence refute the standard, nearly unconstrained, MRT.

The role of emergence in the creation of consciousness has been debated for over a century, but it remains unresolved. In particular there is controversy over the claim that a "strong" or radical form of emergence is required to explain phenomenal consciousness. In this paper we use some ideas of complex system theory to trace the emergent features of life and then of complex brains through three progressive stages or levels: Level 1 (life), Level 2 (nervous systems), and Level 3 (special neurobiological features), each representing increasing biological and neurobiological complexity and ultimately leading to the emergence of phenomenal consciousness, all in physical systems. Along the way we show that consciousness fits the criteria of an emergent property---albeit one with extreme complexity. The formulation Life + Special neurobiological features → Phenomenal consciousness expresses these relationships. Then we consider the implications of our findings for some of the philosophical conundrums entailed by the apparent "explanatory gap" between the brain and phenomenal consciousness. We conclude that consciousness stems from the personal life of an organism with the addition of a complex nervous system that is ideally suited to maximize emergent neurobiological features and that it is an example of standard ("weak") emergence without a scientific explanatory gap. An "experiential" or epistemic gap remains, although this is ontologically untroubling.

We appreciate the goals of Mikhalevich & Powell (M&P) and largely agree with their conclusions but we differ on some of their definitions and terms. Affects (emotional feelings) should be part of sentience. Although the evidence presented for insect sentience is strong, we list some of the counterevidence that should be considered. Our own research supports M&P’s choice of arthropods, cephalopods, and vertebrates as the only sentient organisms with moral status.

While life in general can be explained by the mechanisms of physics, chemistry, and biology, to many scientists and philosophers, it appears that when it comes to explaining consciousness, there is what the philosopher Joseph Levine called an "explanatory gap" between the physical brain and subjective experiences. Here, we deduce the living and neural features behind primary consciousness within a naturalistic biological framework, identify which animal taxa have these features (the vertebrates, arthropods, and cephalopod molluscs), then reconstruct when consciousness first evolved and consider its adaptive value. We theorize that consciousness is based on all the complex system features of life, plus even more complex features of elaborate brains. We argue that the main reason why the explanatory gap between the brain and experience has been so refractory to scientific explanation is that it arises from both life and from varied and diverse brains and brain regions, so bridging the gap requires a complex, multifactorial account that includes the great diversity of consciousness, its personal nature that stems from embodied life, and the special neural features that make consciousness unique in nature.

Purpose of Review Delusional misidentification syndromes (DMS) include conditions in which a false belief about the identity of a person, place, or object occurs in the context of psychiatric or neurological disorders. One form of DMS involves the delusion that the patient's mirror image is a separate individual. This review of reported cases characterizes the psychiatric, neuropathological, and neuropsychological aspects of DMS for the mirror image. An individual case presentation highlights the patient's subjective experience. Finally, the impact of this syndrome on the sense of self is considered. Recent Findings Mirror DMS is a persistent delusion that occurs in the context of neurological illness. It is associated with right hemisphere impairment and a variety of neuropsychological and neuroimaging abnormalities. This phenomenon contributes to our understanding of a range of neurobehavioral syndromes that can be classified as neuropathologies of the self (NPS). Summary DMS for the mirror image is a neurobehavioral syndrome in which the inability to recognize oneself in the mirror entails neurological, neuropsychological, as well as psychiatric aspects of the sense of self.