The distinction between different kinds or degrees of consciousness can also be approached by studying the way we experience things, which is known as a phenomenological or introspective approach to consciousness. A fairly simple account of this sort can be found in Searle (1992):

Consciousness can vary in degree even during our waking hours, as for example when we move from being wide awake and alert to sleepy or drowsy, or simply bored and inattentive. Some people introduce chemical substances into their brains for the purpose of producing altered states of consciousness, but even without chemical assistance, it is possible in ordinary life to distinguish different degrees and forms of consciousness. Consciousness is an on/off switch: a system is either conscious or not. But once conscious, the system is a rheostat: there are different degrees of consciousness (p. 83).

In the quote Searle distinguishes between the on/off sense of being conscious (instead of nonconscious), and different degrees under which consciousness may be experienced. From the perspective of the GWM, the first sense of consciousness occurs when automatic attentional systems ‘switch on’ the global workspace, letting perceptual representations reach the ‘stage’ of consciousness (Baars 2005). This happens automatically, as when one simply opens one’s eyes in front of a green leaf and sees it but can also be mediated by voluntary control as when one turns one’s attention to some particular part of the leaf or to something else according to one’s interests.

Now in the second sense mentioned in the previous paragraph, voluntary attention can also be used to explain degrees of consciousness in the sense that selective attention can amplify the sensory attributes of what is being perceived (Dehaene; Changeaux, 2011). In the case of vision, it is well known that attention is associated with higher spatial resolution and color sensibility. When I focus my attention on the patterns of the veins in the surface of a leaf, I become aware of more features and details of the leaf. Since voluntary attention requires frontal executive cortex (Baars 2005), the increase in awareness is to some extent an exercise of reflective consciousness. This is not to say, though, that reflective consciousness comprises all ways of being conscious. Consider the case of the ‘absent-driver’, which refers to the common situation that happens when, after driving long distances, one drifts one’s attention from the road and starts to wander into thoughts about past experiences, plans, etc. Again, Searle (1990) will serve us to illustrate the point:

I am not paying much attention to the details of the road and the traffic. But it is simply not true that I am totally unconscious of these phenomena. If I were, there would be a car crash. We need therefore to make a distinction between the center of my attention, the focus of my consciousness on the one hand, and the periphery on the other. […] There are lots of phenomena right now of which I am peripherally conscious, for example the feel of the shirt on my neck, the touch of the computer keys at my fingertips, and so on (p. 635).

What Searle calls “peripheral consciousness” corresponds to what phenomenological approaches to consciousness have described as an implicit, first-order form of awareness that permeates our conscious experiences without requiring introspection (Gallagher; Zahavi, 2016). Phenomenologists (e.g. Husserl, Sartre) argue that when one turns one’s conscious attention to-i.e. ‘posits’ the existence of-objects in the environment or parts of our own bodies, we must presuppose an underlying ‘non-positing’ consciousness, an inarticulate awareness of what lies in the unattended surroundings (Siewert 2009). Such implicit form of consciousness has been used to argue, on phenomenological grounds, against high-order theories of consciousness and to claim that animals can possess non-reflective self-awareness (Gallagher; Zahavi, 2016).

Conscious experience of unattended stimuli has also been studied in a famous experiment by Sperling (1960), who briefly presented an array of 12 letters to participants, asking them to focus on a particular row, immediately after the letters disappear. Participants were able to report about three items of the attended row, but it was quite clear to them that they saw an array of letters. When cued after stimulus offset to help prompt memories of the letters, participants could recall most items from the array. This suggest that while the attended letters where reflectively processed, and thus reportable, the unattended ones were still experienced consciously, though in a pre-reflective way. Unattended experiences, however, remain in sensory memory available for reflective report for just a few seconds or less.

This quick fading of unattended (pre-reflective) experiences might explain why such experiences are often not reported or remembered, and thus believed to be nonconscious, as high-order theorists do. In other words, unreportability of past experiences does not demonstrate that they were never conscious, given the possibility of memory failure (Jamieson; Bekoff, 1992; Simons, 2000). Furthermore, one may argue that some implicit representations of unattended objects could make their way into long term memory and be remembered. Returning to the absent driver, it is hard to rule out the possibility that he could recall some of his experiences of the road, especially after being cued about events that happened during the drive (e.g. do you recall seeing semi-trailer trucks? Of any color?).

Some experimental evidence appears to support this possibility. In a study (Simons et al., 2002), one experimenter holding a basketball approaches a pedestrian to ask directions, while a group of students passes between them and surreptitiously take the basketball away from the experimenter. Afterwards, most pedestrians reported seeing nothing unusual, or anything changing, or anything different about the appearance of the experimenter. However, when asked specifically if the experimenter used to have a basketball, more than half recalled having seen the ball and were able to describe some of its atypical features (red and white stripes). Then it seems that the subjects were pre-reflectively conscious of the change, however lacked awareness of the change until they were prompted to reflect about it.

Neuroscientists use the term ‘primary consciousness’ to denote a kind of consciousness that is not reflective in the high-order sense explained above. Consider Feinberg and Mallatt’s definition of primary consciousness:

The basic ability to have subjective experiences including exteroceptive, interoceptive, or affective experiences. Primary consciousness includes the capacity to have any conscious mental images or affects and “something it is like to be” (Nagel, 1974). It is not reflective, nor is it higher consciousness or self-consciousness (2018, p. 131).

Thus, primary consciousness corresponds to basic sensory experiences, both from the external world or the inner body, as well as affective experiences. The latter correspond to experiences attached to a positive or negative valence (e.g., pleasure or pain, respectively), which motivate action more directly than non-affective experiences. Primary consciousness is often said to depend on the cortico-thalamic system (the core of the mammalian brain) which is evolutionary prior to reentrant pathways connecting this core region with the cortex responsible for high-order awareness (Seth, Baars & Edelman 2005, Panksepp 2005). Some neuroscientists also believe it possible that non-mammals and even non-vertebrates are capable of primary consciousness by virtue of different neural structures (Boly et al., 2013; Feinberg; Mallatt, 2018). In any case, my point here is that neuroscientists generally agree with the idea that primary consciousness is present in many animals and that it is, by definition, non-reflective.

On this view, animal consciousness would be implicit and non-reflective, like what phenomenologists have described as the pre-reflective consciousness of our bodies that lies ‘behind’ our reflective awareness. Non-reflective pain would then feel somewhat ‘peripheral’ or ‘dreamlike’ to animals, to use two concepts used earlier. For example, consider an ‘absent headache’: one has a persistent dull headache, but after getting distracted and ceasing to pay attention to the headache, it ceases to bother; some minutes later, we focus again on the headache and on how to get rid of it. Retrospectively, it might appear as if during the ‘absent’ period the headache had disappeared from consciousness. But, the argument goes, it just turned into pre-reflective mode, somewhat present but ‘behind our backs’ and easily forgettable.

The problem with this account of non-reflective pain is that it is, indeed, too deflationary. If animal pain is analogous to the absent driver’s experience of the road or the absent headache, then experiencing pain would be almost trivial for the animal. But this is certainly not the case. Animal pain is typically explicit enough to get the animal very upset, which makes sense insofar as the function of pain is to warn the animal of danger and trigger a rapid response. The deflationary account of non-reflective pain can also lead to the view that animal pain is virtually nonconscious. But, as shown in section 2, this is ill-founded; there is theoretical and empirical room for conceiving animal consciousness without resorting to the reflective awareness that characterizes human subjectivity (Jamieson; Bekoff, 1992; DeGrazia, 1996; Saidel, 1999).

The anthropocentric account of animal consciousness blurs the distinction between reflective and non-reflective experiences, so that the reflective component of human consciousness would not change first-order experiences substantively. Such a view is sometimes defended by some animal ethics theorists. Sapontzis, for example, claims that “there is no reason to believe that intellectually sophisticated beings have feelings to a quantitatively or qualitatively greater degree than do intellectually unsophisticated beings” (p. 272). Therefore, according to this view, animal pain would be just like pain in humans, or as Peter Singer has famously put it, “pain is pain” (1975, p. 23).

The anthropocentric account has the problem of ignoring that there is conceptual space for the claim that pains and other experiences can come in different kinds. In the words of the cognitive ethologist Donald Griffin, a pioneer in the field of animal consciousness: “the difference between the human and other brains is the content of conscious experience. This content of consciousness, what one is aware of, surely differs both qualitatively and quantitatively in astronomical magnitudes.” (2001, p. 18). If I have been successful in my presentation so far, it should be both conceptually and empirically plausible to believe that reflective and non-reflective experiences can be rather different. The fact that human consciousness is widely reflective and so gives us little chance to grasp what a non-reflective experience is like, should not lead us to overlook that non-reflective animals may inhabit a different kind of consciousness.

The moderate account seeks a middle way between anthropocentric and deflationary accounts of animal consciousness. On this view, the basic neurophysiology that gives rise to primary consciousness, including pain experiences, is shared by humans and other animals. However, our reflective capacities would allow us to transform pain experiences into something more intense and significant. This turns reflective pain into a different kind of conscious experience when compared to non-reflective pain. Here I present some cognitive mechanisms that can help us fleshing out this idea: attention and narrative identity.

Both high-order and first-order theories are consistent with the idea that consciousness always involves some form of attention, however attention and consciousness may be dissociated (Pitts, Lutsyshyna & Hillyard 2018). What seems clear, is that selective attention increases the baseline neuronal activity, amplifies the neuronal response to the selected location, and suppresses the neuronal response to objects that are not selected (Tsuchiya; Koch, 2016). This results in a more vivid and salient phenomenal experience, that is more accessible and likely to transit from iconic to working memory (Lamme 2003). Given the crucial involvement of selective attention and working memory in high-order processing of representations (which in turn is largely based on the fronto-parietal cortex, Lamy et al. 2013), it seems plausible to say that when first-order pain experiences undergo reflection they become more vivid and more likely to be consolidated in memory. Indeed, research shows that directing one’s attention to painful stimuli correlates with a more intense painful experience (Arntz et al., 1991).

Reflective animals may also amplify the cognitive significance of their experiences thanks to their narrative capacities. Recall that one of the main functions of consciousness is to integrate information from different brain regions, including providing perceptual information access to meta-representational systems, which function as contextual and executive interpreters. Thanks to these interpreters, reflective animals can generate a narrative that meta-represents the pain experience (in the case of humans, through linguistic representational vehicles). As has been suggested by Gazzaniga (1995), these interpreter mechanisms waive together autobiographical facts to produce a self-narrative that maintains a sense of continuous self. Along with sensory experiences, the satisfaction of narrative-relevant desires “reflect the lived, self-caring perspective of a conscious subject” (DeGrazia; Millum, 2021, p. 226). Arguably, as the satisfaction of these narrative-relevant desires is prudentially good for the animal, their frustration is prudentially bad. Therefore, the capacity for self-narrative can result in more potential for worsening the overall state of negative affective valence the animal is immersed in.

Affective experiences-conscious experiences attached to a positive or negative emotional valence-are relevant for moral status since those experiences appear to entail a welfare interest in having or not having them. Negative affective experiences are generally avoided, whereas positive affective experiences are generally desirable. Violation of a creature’s welfare interests by imposing negative affective experiences is presumed as morally problematic.

Non-human animals have welfare of their own, in the sense that when something bad happens to them, it is bad for them (Feinberg 1980). This contrasts with an instrumental interpretation of welfare, according to which the welfare of non-human animals is only valuable as a means to some other end. Consequently, animals that have welfare for their own sake can have legitimate moral claims on others. Most theories that take welfare as a fundamental ground of moral status, confer similar consideration to the interests of all entities that have comparable welfare interests (DeGrazia, 1996; Garner, 2005; Regan, 2003; Sapontzis, 1987). So, one would expect that, irrespective of whether we are dealing with reflective or non-reflective animals, insofar as their welfare interests are comparable, they should be on a par with respect to the moral obligations owed to them-at least with respect to obligations arising from moral status.

It should be noted that even under the rule of equal consideration of comparable interests, considerations of magnitude matter. Different animals (including humans) can have different interests and quantities of interests. These interests can also have different moral weight (DeGrazia & Millum 2021). For example, consider two different animal species, A and B, who are exposed to a certain stimulus X. Let us suppose that A’s interests in not experiencing X is greater than B’s, or that B simply lacks interests relative to X. All else being equal, the moral obligations owed to A would be stronger³. This view is generally accepted by animal ethicists. Quoting Peter Singer (1993), “we must take care when we compare the interests of different species. In some circumstances a member of one species will suffer more than a member of another species. In this case we should still apply the principle of equal consideration of interests but the result of so doing is, of course, to give priority to relieving the greater suffering.” (p. 58).

Now I turn to discuss whether the fact that animals have reflective or non-reflective consciousness makes a difference in our moral obligations towards not inflicting pain to them. Consider the deflationary account of non-reflective pain discussed above. On this account, non-reflective pain would be such an implicit and faint experience, that it would hardly be comparable with the pain of a reflective creature. This could lead to justifying extremely unequal consideration towards the pain-interests of reflective and non-reflective animals, which may indeed be another reason for being suspicious about the deflationary account. On the other hand, the anthropocentric account of non-reflective pain also leads to controversial conclusions. Take Regan’s argument that "animals probably enjoy sexual congress as much as we do, and it is for this reason that I support vasectomies for male pet animals, rather than castration, and the development of effective contraceptives" (2003, p. 227). I am inclined to think that Regan is underestimating the depth, quality, richness and significance that reflective capacities add to human sexual experiences. This is not to say that non-reflective animals cannot enjoy of sexual congress, but that the range of positive affective states available to them is in many ways more modest than what is available to reflective animals.

To assess the welfare interests associated with non-reflective pain, let us now focus on the moderate account of non-reflective pain, which I have been defending as the most plausible. As argued previously, the capacity of conscious reflection can make reflective pain more intense and significant, than it would have been for a non-reflective animal. Both reflective and non-reflective pain would still be a comparable pain experience-a sensory and affective experience associated with a negative valence-but reflective pain would have a greater potential to compromise welfare than non-reflective pain. If this is so, the welfare interests associated with reflective pain would generally entail stronger moral obligations than those of non-reflective pain.

With respect to the intensity of stimulus, attentional enhancement of the pain stimulus can explain why reflective animals are susceptible to a more intense pain experience. It is well known that top-down mechanisms can modulate pain intensity, which in turn is highly influenced by emotional and contextual factors (Price 2017). We may compare the top-down mechanisms that modulate pain with the top-down mechanisms that, in visual perception, ‘fill-in’ unattended regions of our visual field. These mechanisms allow us to see more than the information that is actually been processed by first-order processes (Panksepp et al., 2017). Similarly, such reflective processing of a pain stimulus can make us experience more pain, as suggested earlier. It should be noted, however, that top-down modulation can cut-both ways. For example, viewing either fear or disgust photographic slides prior to pain stimulation reduces pain intensity and unpleasantness (Meagher et al., 2001).

So reflective animals would be capable of both amplifying or decreasing the intensity of their pain experiences (though not always voluntarily). This may confer reflective animals (like us) an advantage over non-reflective animals. For example, knowing that the vaccine we are about to get will imply just a brief shot and that it will prevent us from getting a harmful disease, might allow us to tolerate the injection better. But the point remains that, all else being equal, a reflective creature is susceptible to more intense pain experiences than a non-reflective counterpart.

A similar point can be made with respect to how significant pain is or how much suffering it involves. As mentioned in the previous section, reflective animals have the capacity to generate a self-narrative that engenders narrative-related desires relevant to one’s life. This allows the animal to generate more complex appraisals of their pain experiences, with the potential to amplify their overall negative experience. As DeGrazia notes, experiences with negative valence involve an evaluative appraisal of the subject’s overall situation that results in representations like “this is terrible” or “this is terrible for me”, which affect the subject’s welfare (DeGrazia, 2014). Arguably, evaluative appraisals in reflective animals can be more complex, for example including how pain impacts one’s plans or personal relationships in a meaningful manner, and in this way amplify the suffering caused by pain.

In sum, reflective and non-reflective consciousness can be considered two different kinds of consciousness because there are substantive phenomenological, cognitive, and neuroscientific differences between them. Furthermore, this distinction in kinds of consciousness has important implications for moral status. Granting that conscious animals in general can undergo intense pain and suffering, animals that possess reflective consciousness can experience pain and suffering to a greater extent, at least under certain circumstances. They have more at stake than animals with just primary, non-reflective, forms of consciousness. Therefore, there should be a prima facie presumption that harmful actions towards reflective animals are, ceteris paribus, more detrimental to their welfare, compared to non-reflective animals.

Finally, it is worth noticing that this claim is consistent with the principle of equal consideration of interests, insofar as reflective and non-reflective animals have comparable interests in not experiencing pain and suffering. The point is that we are justified in presuming that reflective animals’ interests in this respect are generally stronger and thus carry stronger moral weight, when compared with the interests of non-reflective animals. This should not translate into a disregard of animal welfare but serve as a justification for providing more stringent protections to reflective animals. Some may see this as grounding a difference in degrees of moral status between reflective and non-reflective animals, an issue concerning the concept of moral status that goes beyond the purposes of this paper. But the present proposal is also consistent with the claim that reflective and non-reflective animals have the same moral status, however the moral duties entailed by moral status are generally stronger when they arise from reflective animals.