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Chapter 3 - Animal Emotions

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Appendix on Animal Emotions

3.0 Chapter Outline

The literature relating to the emotions is vast, and I shall not attempt to survey it in this chapter (de Sousa, 2003, provides an excellent overview). The aim of this chapter is a very specific one: namely, to show that a particular theory of the emotions - namely, Panksepp's neurophysiological-cum-evolutionary account (1998) - when combined with my account of intentional agency in chapter two, explains all of the defining features of emotions in non-human animals.

Panksepp's (1998) theory has generated a great deal of productive scientific research relating to the core emotions in animals, but makes no attempt to explain each and every human emotion. Thus there will be no discussion in this chapter of emotions (such as remorse or Schadenfreude) that presuppose a high level of cognitive sophistication, which few if any non-human animals possess. The emotions that I discuss here will be common ones, whose ascription to at least some non-human animals is relatively uncontroversial.

In this chapter, I refrain from discussing the philosophical question of whether emotions in animals are accompanied by phenomenal consciousness. The consensus view of most psychologists is that the very concept of an unconscious emotion is an oxymoron (Berridge, 2003c), but as we shall see in chapter 4, phenomenal consciousness is but one of many different varieties of consciousness, and for the time being, I shall ask the reader to keep an open mind as to which kind of consciousness is required for the basic animal emotions.

Panksepp's own personal view, that there is a "core consciousness" at the heart of every animal emotion which is purely affective and devoid of intrinsic cognitive content, is philosophically controversial, as it assumes that these emotions can be defined independently of their cognitive content. In any case, the rigorous scientific criteria which Panksepp (1998) has proposed for identifying emotions in animals are logically independent of his views on consciousness, which I discuss in chapter 4.


3.1 Methodological Considerations

Assumptions

3.1(a) Human Emotions cannot be defined apart from animal emotions

In this chapter, I shall take it as a "given" that at least some non-human animals have emotions. I maintain that any attempt to define human emotions in isolation from animal emotions is doomed to failure, for two reasons.

Animal emotions are a linguistic "given". Refusing to recognise emotions in non-human animals would do violence to the way we talk about emotions, because these animals often serve as primary referents for words describing emotions. If I were teaching a child the meaning of anger, I could do no better than to point to a hissing, snarling cat and say: "This is what anger looks like." Here, the angry cat functions as an exemplar.

Animal emotions are also an anthropological "given". Recent research into the effectiveness of pet therapy programs has established beyond reasonable doubt that humans and their companion animals are emotionally symbiotic, and that pet ownership is widespread in almost all cultures. Put simply, pet-owners' feelings feed off those of their pets, and the emotional well-being of these people can only be defined in relation to that of their companion animals (Midgley, 1993).

Our inability to define human emotions apart from those of animals in no way implies that they can experience the entire gamut of human emotions. Certain emotions (such as remorse) appear to be unique to human beings, because of their sophisticated cognitive component (Evans, 2001).

3.1(b) General Properties of Emotions

Emotions have been the subject of long-standing philosophical controversy. However, one recent positive development is that philosophers have come to agree on several key points:

A broad consensus has emerged on what we might call adequacy conditions on any theory of emotion. An acceptable philosophical theory of emotions should be able to account at least for the following nine characteristics...

  • emotions are typically conscious phenomena; yet
  • they typically involve more pervasive bodily manifestations than other conscious states;
  • they vary along a number of dimensions: intensity, type and range of intentional objects, etc;
  • they are reputed to be antagonists of rationality; but also
  • they play an indispensable role in determining the quality of life;
  • they contribute crucially to defining our ends and priorities;
  • they play a crucial role in the regulation of social life;
  • they protect us from an excessively slavish devotion to narrow conceptions of rationality;
  • they have a central place in moral education and the moral life (de Sousa, 2003, italics mine).
I argued above that human emotions could not be defined in isolation from animal emotions. On the other hand, the imputation of characteristics such as rationality, morality and language to non-human animals remains highly questionable at best (in the light of what we currently know) and downright anthropomorphic at worst. I shall therefore ignore any items on de Sousa's list which make explicit mention of rationality (i.e. the third and eighth items), morality (the last item) or language (the fourth item, which appears to rely on the subject's verbally reported "quality of life"). Although certain human emotions (e.g. remorse and pride) obviously require these features, they cannot be necessary features of emotions in non-human animals. (Arguments claiming that the attribution of any emotion to an individual presupposes that it is rational or can use language will be discussed in the Appendix.)

I have argued against making consciousness a defining feature of animal emotions, in order to avoid possible methodological bias and lack of conceptual clarity. In place of de Sousa's first condition, I propose the following requirement: animal emotions may or may not be conscious, but at a minimum, they must be mental states which are amenable to scientific investigation. The reasonableness of this requirement can be argued for, not only on linguistic grounds (the word "emotion" is used in our language to denote a state which is psychological as well as physical) but also on scientific grounds - as shown by the fact that there are several well-established scientific disciplines that investigate emotions as mental events.

Citing Wittgenstein, Leahy (1994, p. 124) argues that the popular conviction that emotions and other feelings (such as pain) designate private sensations which are inaccessible to scientific investigation, arises from focusing exclusively on isolated feelings such as toothaches:

'A main cause of philosophical disease - a one-sided diet: one nourishes one's thinking with only one kind of example' (PI 593). The question we must ask is, 'How does a human being learn the meaning of the names of sensations? - of the word "pain" for example' (1994, p. 124).
Similar observations apply to animal emotions (Leahy, 1994, p. 128). The key point here is that if emotions were inherently private, it would be impossible for us to learn the meanings of the words used to designate them. But in fact, emotions are often defined ostensibly in a public context: "This is what anger looks like". We may even use animals as paradigm cases of these emotions.

The subjectivist account of emotions also fails to explain the other features of animal emotions listed above: how outward bodily states are able to manifest these allegedly private inner feelings, or why there should be different kinds of emotions, or what makes private inner states possess the property of "aboutness", or how such essentially private states can have an important social role.

At the other extreme, I reject any accounts of emotions which define them purely in terms of outward behavioural dispositions and thus fail to explain why emotions should be treated as mental states at all. Dispositions do not require a mentalistic explanation: as we saw in chapter two, a mind-neutral goal-centred intentional stance can be used instead.

That leaves five features of animal emotions that are of interest to us:

3.1(c) Animal emotions have intentional objects

Much of the argumentation in this chapter rests upon the assumption, which I defended in chapter two, that Daniel Dennett's intentional stance can be applied to all kinds of mental states, including emotions. In other words, emotions, like beliefs, desires and other mental states, have to be "about" something: they require intentional objects. As Leahy (1994) puts it:

The emotions, or most of them, are said to be directed, and to have objects ... A person should be able to say what they are afraid of, hoping for, or feeling guilty about (1994, p. 130).

Animals cannot tell us what the objects of their emotions are, but can still be said to have directed feelings:

The targets of an animal's fear or anger are usually clear enough and it is perfectly natural and necessary to speak of them (Leahy, 1994, p. 135).

There are, however, situations where we experience emotions without any apparent object - either because the brain registers it at a subconscious level, so that we are not consciously aware of what it is, or because the emotion lacks any kind of object whatsoever (e.g. an ill-defined feeling of depression).

De Sousa (2003) discusses three ways of dealing with object-less emotions: (a) differentiating them from emotions proper, and placing them in a separate category, e.g. "moods"; (b) assimilating object-less emotional states to emotions of the same kind that have an object, by virtue of the strong "family resemblance" between the former and the latter; and (c) distinguishing between particular instances of emotions and kinds of emotions. The former may lack an object; the latter cannot.

I shall adopt the third approach here. The first and second approaches both make the category of "emotions" a somewhat artificial one, and thus effectively deny that it designates a natural category, despite extensive neurological evidence (to be presented below) indicating that animals possess several different kinds of emotions, which are empirically well-defined.

Philosophers speak of each kind of emotion as having a formal object - that is, "a property implicitly ascribed by the emotion to its target, focus or propositional object, in virtue of which the emotion can be seen as intelligible" (de Sousa, 2003). For instance, my fear of a snake only makes sense because I construe certain properties of the snake as frightening or dangerous.

Although the formal object of an emotion renders intelligible its attribution to an individual, it fails to ground the emotion in the animal's intrinsic ends by telling us what it is for: i.e. how it helps the animal to survive and/or flourish. Many emotions - especially those we commonly attribute to non-human animals - have a teleology: we can think of each kind of animal emotion as being "for" responding appropriately to a certain kind of biologically significant event, which is what the emotion is about. I propose to call this kind of event the generic intentional object of the emotion. Fear, for instance, is "about" objects recognised as dangerous, and it is for responding appropriately to them. That is what makes it different from anger.

Object-less feelings are therefore derivative upon directed feelings. I propose that the ascription of object-less feelings to a non-human animal can only take place after we have identified:

(i) emotions of the same kind in that animal, that are "directed" at something;

(ii) the generic intentional object of the kind of emotion the animal is feeling; and

(iii) non-arbitrary, teleological criteria which allow us to identify the different kinds of emotions as natural categories.

We can now re-write the third of our five selected features of animal emotions as follows:

Animal emotions come in different kinds, and each kind of emotion has a range of intensities, and a generic intentional object. Emotions on specific occasions typically have intentional objects too.

Even with these revisions, our list of the features of animal emotions remains an incomplete characterisation. Although it stipulates that they are mental states, it fails to explain what makes them mental. The only feature it lists which is pertinent to mental states is their intentionality, but as we saw in chapter two, behaviour describable in intentional terms can occur even in the absence of mental states (e.g. goal-directed movement in bacteria). Something else is needed.


3.2 What are the cognitive pre-requisites of animal emotions?

The importance of intentional agency

That "something else", I claim, is intentional agency, which requires a minimal mind. My proposal is that the cognitive pre-requisites of animal emotions are identical with the requirements for intentional agency in animals. In chapter two, I argued that intentional agency presupposed the occurrence of relevant beliefs and motivations which I referred to as "desires". However, there is no reason why other emotions (e.g. fear or anger) could not motivate animal agents equally well.

We can now define an emotion in mentalistic terms, as a positive or negative internal state that is capable of motivating intentional agency in a species of animal. (This is not intended as a complete definition; extra, neurophysiological conditions will be added in section 4.)

(Cabanac (2000) speaks of emotions as having a positive or negative valence, by which he means subjective feelings of pleasure or displeasure, which are manifested in an animal's hedonic preference rankings. I shall avoid using Cabanac's term here, as my discussion of consciousness is deferred until chapter 4.)

One might object that emotions typically accompany reactions rather than actions, and that most emotional reactions in animals are innate and beyond their control. Attempting to identify animal emotions by focusing on intentional agency seems like searching in the wrong place.

However, it needs to be kept in mind that emotions are by definition mental states. We cannot identify these mental states in animals until we have located behaviours which are best understood by adopting either an agent-centred intentional stance or a first-person intentional stance.

Reactions, by definition, cannot be described in terms of an agent-centred intentional stance, as they are not actions. (Nor does it seem that reactions per se could require a first-person intentional stance to explain them. Animal reactions are either innate or acquired through conditioning. And as we saw in chapter two, both kinds of reactions can easily be explained by adopting a mind-neutral, third-person intentional stance which employs purely causal terminology.) The only kind of conditioning that manifests intentional agency is operant conditioning.

I conclude that while emotional reactions are bona fide mental states, they do not (taken by themselves) warrant the ascription of mental states to animals. Since emotions are mental states, we have to first identify their occurrence in animals within the context of intentional agency before we can legitimately speak of them as accompanying animals' reactions.

Are emotions possible in the absence of beliefs?


How fast one jumps away from a snake like this can make the difference between life and death

On the account I am proposing, emotions may sometimes occur in the absence of accompanying beliefs, but the ascription of emotions to animals is only warranted for those that are capable of holding beliefs. This distinction resolves our conflicting intuitions regarding the cognitive requirements for having emotions. It appears obvious that we can experience emotions such as fear, even in the absence of beliefs. However, the ability to experience an emotion (e.g. fear of a snake) seems to presuppose that one has certain beliefs about its intentional object (e.g. that the snake is dangerous).

If we are talking about an animal's emotional reactions (fear of a snake), then it is indeed possible that they will be felt before the animal has had time to form relevant beliefs ("This is a snake"). As LeDoux (1998, p. 166) points out, in such life-and-death situations, emotional reactions in humans and other animals have to be very fast - even if they turn out to be mistaken, as occurs when a hiker mis-identifies a thin curved stick in his path as a snake.

By contrast, intentional agency requires the occurrence of beliefs regarding the attainment or avoidance of the object. The animal forms and revises these beliefs in the process controlling and correcting its bodily movements in an effort to attain its goal.

Do animal beliefs have a propositional content?

Cognitivist philosophers (e.g. Frey, 1980) have argued that emotions necessarily involve having propositional attitudes towards certain statements: for instance, one cannot be angry with someone without believing that she is guilty of doing something bad. Frey (1980, p. 90) argues that beliefs (unlike states of affairs) are capable of being true or false: to believe that P is to believe that the sentence "P" is true. Animals which lack language cannot formulate propositions and are therefore incapable of either having beliefs or experiencing emotions. Infants and severely cognitively impaired human beings would likewise be excluded.

Regan (1988, p. 42) argues that this conclusion is absurd. He offers the counter-example of an intellectually impaired man who is incapable of learning a language, reacting in terror to the sight of a rubber snake. Our "common sense" intuition is that the man is afraid because he believes the snake is pursuing him and will harm him. If a non-human animal reacted similarly, we would say it was afraid too, and impute the same belief to it.

Regan puts forward the notion of a preference-belief (1988, p. 58) as a way of rendering intelligible the attribution of beliefs to animals. He suggests that a dog which desires a bone also has a preference-belief that there is a connection between its choosing a bone and satisfying its desire for a certain flavour. Likewise, we might say that a man who flees a rubber snake has a preference-belief that there is a connection between his running away and satisfying his desire to avoid the snake.

It is certainly true that an individual's preferences can tell us a lot about his/her feelings, and animal researchers in recent years have done a lot of valuable research relating to weighing-up processes, conflicts of motivation, trade-offs and relative rankings of desires in animals such as lizards (Cabanac, 2003), chickens (Marian Dawkins, 1994; see also Vines, 1994) and rats (Berridge, 2003). However, I maintain that the existence of complex preference behaviour, by itself, cannot warrant the ascription of emotions to animals, as this kind of behaviour can be described using a third-person, goal-centred intentional stance and therefore does not require the ascription of mental states. In the case of the dog and the bone, the dog chooses the bone, but does not do anything to get the bone. As there is no genuine means-end behaviour, a goal-centred account is adequate. We can discover much more complex behaviour in organisms that lack desires. For instance, if E. coli's sensors detect an attractant (e.g. galactose), and later sense another compound (e.g. glucose) that is more attractive than the first one, a "weighing" of the relative quality of the nutrients occurs, resulting in a chain of reactions whereby the bacteria change the direction of their motion. This looks like "conflict resolution", but as Kilian and Muller (2001, p. 3) point out, the way in which bacteria react to a chemical is utterly inflexible, and the behaviour exhibited here is merely the resultant of two fixed patterns of behaviour.

If preference behaviour is an inadequate basis for the ascription of desires and their attendant beliefs to animals, then what might the missing ingredient be? My suggestion is that the attribution of beliefs and desires to an animal simply requires it to be an intentional agent that is capable of self-correcting behaviour, which enables it to modify its strategies for attaining its goals. For example, if an animal learns that doing F will not help it attain its goal, but that doing G will do so, then we can meaningfully attribute to it a change of belief about the appropriate way of attaining its goal. Or to borrow one of Regan's own cases (1988, p. 70), a dog digging in the garden to retrieve an old bone it has buried exhibits the kind of behaviour that manifests a strategic belief. No bacterium could do that.

Does my account warrant the ascription of belief to the man looking at the rubber snake, in Regan's example? At first sight, there appears to be a problem, as the belief ("There is a snake") is not one which can be cashed out in strategic terms. To make matters worse, we would require language in order to convince someone that the object was not a real snake ("See? It's made of rubber").

The reason why the attribution of belief makes sense here, I suggest, is that an intentional agent that lacks linguistic ability is still capable of modifying its strategic behaviour towards what it construes as a dangerous object - e.g. learning a better way of avoiding it. In that case, we can meaningfully attribute to it beliefs about how to avoid the object. Since any belief about how to avoid X presupposes the background belief that X is present, then we can say that such an agent implicitly possesses this belief.

To make this clearer, let us modify Regan's case a little, and suppose that the snake is not a rubber snake but a very life-like mechanical snake with a built-in thermal sensor and a movement detector, programmed to pursue the nearest moving warm object: in this case, the man in Regan's story. At first, the man tries to run away from the snake, acting on the apparent belief that the best way to avoid the snake is to get as far away from it as possible, but this strategy proves unsuccessful, as long as the man is the nearest moving warm object. There are two happy endings to our story which both illustrate my point on strategic beliefs:

(1) Exhausted, the man stops running - and discovers that the snake stops pursuing it. The man realises that standing still keeps the snake at bay.

(2) Luckily, there happen to be other people around. The man learns that he can avoid the snake by positioning himself behind someone when approached.

Because the man was capable of adjusting his strategy for avoiding the snake, we can justifiably say that he acquired a new belief concerning the appropriate way to avoid the snake. Since this new belief presupposes the background beliefs that there is a snake, that it is dangerous and must be avoided, and (in case 2) that other people are present, we can say that the man implicitly believes all these things. The attribution of the emotion of fear to the man is also warranted in this case, as he is using the content of his new beliefs to avoid the snake more effectively. Finally, we can attribute the emotion of fear to the man even in cases (such as Regan's case of the rubber snake) where the man acquires no new strategic beliefs, because the man possesses the capability of forming such beliefs and would do so if an effective strategy could be found.

There is absolutely no reason why we could not attribute similar beliefs to a dog that was capable of the relevant strategic behaviour, as well as the emotion of fear.

One might object that even a fruit-fly can acquire beliefs (and discard old ones) about the best way to avoid a dangerous heat beam, yet the attribution of "fear" seems odd in this case, if (as is generally supposed) the fly does not experience the subjective feeling of fear. However, one might argue that while the fly's strategic behaviour shows that it satisfies the cognitive requirements for having an emotion such as fear, there could be other, non-cognitive requirements for having an emotion that it fails to satisfy.

I conclude that the attribution an emotion to an animal does not require it to have propositional attitudes. Strategic attitudes - "This works; that doesn't" - are what counts. The content of an animal's strategic beliefs relates to how it can pursue or avoid the intentional object of the emotion. The content of the animal's accompanying implicit beliefs consists of those propositions entailed by the strategic beliefs it forms.

My account implies that any animal that is capable of desiring ends (e.g. food or sex) must also be capable of desiring means to these ends. I would thus agree with Frey (1980, p. 104) in rejecting the possibility of an animal that only has simple desires, such as a dog's desire for a bone.

Finally, the examples cited by Frey (1980) to establish the inherent ambiguity of animal behaviour - notably the case of his dog, which wagged its tail in the same way when its master was outside the door, when lunch was imminent and when the sun was eclipsed by the moon - are not convincing, as they do not include the kind of strategic behaviour discussed above.


3.3 What are animal emotions "about", and what is each basic kind of animal emotion about?

Below, I argue that Panksepp's (1998) brain-based, neurophysiological approach to animal emotions explains their intentionality, or what they are "about". (I critically evaluate rival, body-based accounts of emotion in the Appendix.) I am certainly not proposing that the meaning of an emotion can be reduced to its neurophysiology - that would be a Rylean "category mistake". Even so, the notion that the "aboutness" of animal emotions can be explained in terms of their underlying brain states looks unpromising at first sight, as brain states do not seem to be "about" anything.

I suggested above that each kind of animal emotion has its own generic intentional object that explains its "aboutness" and makes it what it is. One merit of Panksepp's (1998) neurological approach to the emotions is that it allows us to identify the generic object of each emotion in a straightforward way: the basic kinds of emotions in animals arose in response to different kinds of environmental challenges their ancestors encountered. Meeting that challenge is what each kind of emotion is "about". An animal's response to each of these challenges is mediated by several emotion systems within its brain, easily identifiable to specialists, that give each kind of emotion its characteristic neurological "key signature". Each emotion system evolved in response to a different environmental challenge.

I claim that Panksepp's approach can explain on a generic level how a physical state of affairs such as a brain state can be "about" something. I propose that there are two robust senses - one non-mentalistic and the other mentalistic - in which the various kinds of emotions are "about" the environmental challenges they evolved to meet. First, each environmental challenge has caused the evolution of a distinctive suite of emotional responses which are directed at it. This has been accomplished through natural selection over millions of years: an animal's emotional response to a challenge (e.g. jumping back at the sight of a snake) promotes its survival. Second, as emotions are capable of motivating intentional actions as well as reactions, we can say that each environmental challenge has caused the evolution of a kind of mental capacity which is specifically directed at it. (For instance, an animal's emotion of fear can motivates it to not only react, but also act intentionally, in a way that saves its life.) Thus the environmental challenges facing animals are not only the ultimate causes, but also the objects, of the different kinds of emotions in animals.

Bacteria and plants have many organismic traits that possess the first kind of "aboutness", as they have evolved to meet environmental challenges.

Searle's (1999) criticism of causal accounts of intentionality, on the grounds that "[y]ou can always get the causal relations without the intentionality" (1999, p. 91), does not undermine the account defended here, for two reasons.

First, the causal relationships described here are very strong ones, as (i) the features of animals' emotion systems have been shaped directly, by the very properties of the environmental challenges they have evolved to meet, and (ii) animals' emotion systems promote survival in virtue of their intrinsic properties. There is no room for wayward causal chains here.

Second, the environmental challenges that shaped the evolution of animals' emotion systems are not only their causes, but also their objects, insofar as animals' emotion systems are directed at them.

Searle invokes the causal self-referentiality of intentions to explain their "aboutness": if I drink some water to satisfy my desire for water, then my desire causes it to be the case that I drink the water. I find nothing to disagree with in Searle's account of the intentionality of particular emotions. However, Searle's account is not designed to answer the question of what each kind of emotion is about. The chief merit of a neurophysiological account of emotion, is that it tells us what the generic object of each kind of emotion is (a distinctive kind of environmental challenge), and where to look for it (in animals' brains, where the emotion systems that regulate their emotional responses are located).

Animal brains also have a history. Each neurologically distinct "emotion system" in an animal's brain which regulates its response to an environmental challenge reflects the way in which its brain evolved to meet this challenge. Studies of animals' brains can thus reveal the proper taxonomy of the basic animal emotions.

The adequacy of a neurophysiological account of emotions

Panksepp's neurophysiological account can also explain all of the key features of animal emotions we identified above.

It explains why emotions are mental states, since an animal's representational and behavioural capacity for intentional agency (which is what makes its emotions mental states) is grounded in its neurophysiology.

Moreover, since it is the brain which generates the body's response to emotions (LeDoux, 1998, pp. 292-295), Panksepp's brain-centred approach is capable of encompassing the second feature of animals' emotions: their bodily manifestations in animals' physical responses and intentional behaviour.

Neurophysiology accounts for the third feature of animal emotions very well, as it explains the different kinds of feelings animals have, the range in their intensities, and the variety of their intentional objects, in terms of the environmental context in which the "emotion systems" in animals' brains originally evolved.

Neurophysiology also sheds light on the fourth and fifth features. Since animals' emotions arose in response to different kinds of environmental challenges their ancestors encountered, we can say that these challenges motivate animals to seek, fight or avoid them, and thereby determine their ends. Emotions also play a role in animals' social lives, because they can motivate them to seek the company of others, to play and to care for their young.

A final objection to a neurophysiogical account of emotion is that the same emotion could have multiple physical realisations in different groups of animals, but if we identify emotions with brain states we will have to say that this is impossible. This objection rests on a misunderstanding. It is entirely possible that two lineages of animals (say, mammals and birds) evolved very different neurological systems (call them A and B) for coping with the same kind of environmental challenge. On the neurophysiological account being defended here, systems A and B mediate the same emotion, as they arose in response to the same generic challenge.


3.4 How do we identify basic emotions in animals, what are they and which animals can be said to have them?

I explain in the Appendix why two methodologies that are commonly used for distinguishing human emotions are unsuitable for other animals.

The merits of distinguishing emotions according to their generic intentional objects

It might be tempting to think that we can distinguish emotions according to their intentional objects. Such a proposal is too simplistic for three reasons. First, it is possible for an animal to have different emotions towards the same object on separate occasions. Second, the proposal does not account for emotions that have no intentional object, such as an ill-defined feeling of depression or the undirected emotional states that can be induced by removing parts of animals' brains. Finally, the proposal fails to explain emotions that have an intentional object which is real but inappropriate, such as when one fears mice or the number 13.

Fortunately, these difficulties can all be overcome by a neurophysiological account which distinguishes different kinds of emotions according to their generic intentional objects.

An animal may indeed experience two different emotions towards the same physical object on separate occasions, because it may instantiate two different kinds of environmental challenge, and thus two distinct generic intentional objects. Thus a primate may fear an individual it knows, while (s)he is exhibiting a sudden burst of rage, but on other occasions enjoy playing with the same animal.

On a neurophysiological account, particular cases where an animal feels an emotion that is about nothing at all (an object-less emotion) or nothing that merits the kind of response shown (inappropriate emotions) still qualify as bona fide instances of their kind, because they are accompanied by the same internal brain states as appropriate expressions of these emotions, and generate similar bodily responses. In these anomalous cases, the emotions felt by the animal are genuine, but the challenge they originally evolved to meet is absent.

What kinds of emotions do animals have?

The brain of every species of mammal contains various basic emotional systems. Panksepp (1998, pp. 48-49) defines these emotion systems in terms of the following features:

The first, second and fifth features are particularly relevant to my proposed method for classifying emotions according to their kinds. A suite of sensory stimuli that trigger identical unconditional responses in one of the emotion systems in an animal's brain all instantiate the same kind of environmental challenge that the animal has to deal with - i.e. its generic intentional object. The instinctive motor outputs triggered by the inputs are the animal's first line of defence. The fact that they can be subsequently modulated by cognitive inputs, means that provided the system satisfies the cognitive requirements for intentional agency (specified in chapter two), the system's response can be described as genuinely emotional and not merely reflexive.

Panksepp (1998) summarises the research to date on these systems:

There is good biological evidence for at least seven innate emotional systems ingrained within the mammalian brain (1998, p. 47).

"In the vernacular", writes Panksepp, the seven emotional systems include "fear, anger, sorrow, anticipatory eagerness, play, sexual lust, and maternal nurturance" (1998, p. 47). The first four systems are "evident in all mammals soon after birth" (1998, p. 54, italics mine), because the relevant neural circuits lie below the cortex, at a deeper level where the similarities between mammals are most profound. The neural circuits for our emotional systems are actually very ancient, since they arose in response to persistent external environmental challenges. The three special purpose systems - sexual LUST, maternal CARE and PLAY - are engaged only at certain times in mammals' life-cycles, and are not as clearly understood.

The classification of eagerness, play and nurturance as emotional states will strike many readers as odd. However, it makes good sense to do so if they motivate us to act as other emotions do. Panksepp also acknowledges the existence of many more affective feelings (e.g. pain, hunger), but argues that they do not qualify as basic emotional systems because they do not meet all the above criteria (1998, p. 47).

The seven emotion systems are summarised in the table below. (The capitals are Panksepp's.) More detailed information relating to accompanying bodily states and brain circuitry can be found in an Appendix.


Table 3.1 - Emotion Systems identified to date in Mammals (based on Panksepp, 1998)
Emotion System: FEAR system.

Animal Emotions corresponding to this system: Fear, anxiety, alarm and foreboding

Corresponding Environmental Challenge (generic intentional object): Pain and the threat of destruction

Motivation: Avoiding the threat of bodily harm

Characteristic behaviour: Freezing (mild intensity); flight (high intensity); scanning and vigilance

Notes:

  • Contrary to earlier ideas that fear was a learned, conditioned response to cues that predict pain., FEAR is now known to be affectively distinct from pain: electrical stimulation of the brain's pain systems does not produce fear in humans, and electrical activation of the FEAR system in the brain does not appear to evoke the sensation of pain in either humans or animals (Panksepp, 1998, p. 215). Although animals fear painful stimuli, fear and pain are neurologically distinct.
  • FEAR is also distinct from PANIC. PANIC is thought to be linked with an animal's distress when separated from a socially significant other (e.g. its mother).

Emotion System: RAGE system

Animal Emotions corresponding to this system: Rage, anger

Corresponding Environmental Challenge (generic intentional object): Events that restrict the animal's freedom (physical restraint or irritation of the animal's body surface) or access to resources (e.g. an invasion of the animal's territory)

Motivation: The need to compete effectively for environmental resources.

Characteristic behaviour: Tendency to strike out at, attack, bite or fight the offending agent (a living creature).

Notes:

  • Not all aggressive behaviour can be classified as RAGE. Of the three kinds of aggression circuits identified in the brain - corresponding to predatory aggression, intermale aggression and affective attack - only the last has the distinctive pattern of the RAGE system described above.

Emotion System: PANIC system

Animal Emotions corresponding to this system: Loneliness, panic, grief

Corresponding Environmental Challenge (generic intentional object): Social loss

Motivation: The urge to be reunited with companions after separation, which helps to create social bonding

Characteristic behaviour: Cries of distress when separated from caregiver

Notes:

  • PANIC is distinct from FEAR. PANIC is thought to be linked with an animal's distress when separated from a socially significant other (e.g. its mother).

Emotion System: Exploratory, appetitive SEEKING system

Animal Emotions corresponding to this system: Anticipatory eagerness

Corresponding Environmental Challenge (generic intentional object): Positive environmental incentives such as food, water, sex and warmth.

Motivation: The need for food, water, sex and warmth.

Characteristic behaviour: Stimulus-bound appetitive behaviour: forward locomotion, sniffing, and investigating, mouthing and manipulating objects in the animal's environment. Also self-stimulation - a tendency to engage in events that increase the animal's arousal.

Notes:

  • Predatory aggression belongs to the mammalian brain's SEEKING system, not the RAGE system.
  • The SEEKING system mediates wanting as opposed to liking. It is not a pleasure system but an appetitive system.
  • The SEEKING system is a single emotion system, despite the diversity of targets (e.g. food, sex). Guided by regulatory imbalances in the animal's body, the SEEKING system triggers non-specific search behaviour that helps the animal obtain what it wants.

Emotion System: PLAY (special purpose system)

Animal Emotions corresponding to this system: Play

Corresponding Environmental Challenge (generic intentional object): Opportunity for rough-and-tumble play with conspecifics

Motivation: The need for social interaction

Characteristic behaviour: Rough-and-tumble (RAT) play between juveniles or between parent (usually the mother) and offspring. RAT play includes pinning and dorsal contacts, but varies widely among mammals. Solitary running, jumping, prancing and rolling in herbivores may also represent a form of play. Also laughter (humans) or very high-frequency chirping (rats).

Notes:

  • The mammalian brain also contains one or more pleasure systems that correspond to the alleviation of bodily imbalances and a return to an optimal level of functioning. The location and number of the brain's pleasure systems remains unknown.
  • PLAY is quite distinct from aggression as well as SEEKING. It roughly corresponds to "joy". It may not represent a single system.

Emotion System: LUST (special purpose system)

Animal Emotions corresponding to this system: Sexual desire

Corresponding Environmental Challenge (generic intentional object): Opportunity to procreate

Motivation: The need to procreate

Characteristic behaviour:
Males: courting, territorial marking and mounting.
Females: decrease in aggression towards aroused males. Active tendency to solicit male attention. Receptive posture indicating readiness to be mounted (lordosis reflex).

Emotion System: Maternal CARE (special purpose system)

Animal Emotions corresponding to this system: Nurturance (parental love)

Corresponding Environmental Challenge (generic intentional object): Offspring requiring maternal care

Motivation: The need to care for one's offspring

Characteristic behaviour: Responsiveness to distress signals by offspring. Nursing offspring and providing them with warmth and shelter (e.g. a nest). Gathering offspring together.


There may be several other animal emotions corresponding to natural kinds, as the above list of emotion systems reflects only our current knowledge.

It should also be stressed that neurological criteria alone cannot establish the presence of mental states such as emotions. To show this, it has to be demonstrated that each of the emotion systems described above can motivate intentional agency.

Which Animals Have Emotions?

Since mammals (a) possess the emotion systems listed in the table above, and (b) are certainly capable of intentional agency, we can provisionally assume that they all possess the seven-plus kinds of emotions described by Panksepp.

Some of the brain's emotional architecture appears to be very old. Panksepp (1998, pp. 42-43, 48-51, 70-79) uses a refined version of Maclean's model of the triune brain for illustrative purposes. The deepest layer of the forebrain, known as the basal ganglia, is where behavioural responses related to seeking, fear, anger and sexual lust originate. This region is well-defined in all vertebrates.

The next, loosely defined layer is commonly called the limbic system - a term attacked as outdated by LeDoux (1998, pp. 98-103) but defended as a useful heuristic concept by Panksepp (1998, pp. 57, 71, 353). (Both authors agree that certain specific structures in the limbic system serve important functions relating to the emotions.) This region of the brain contains neural programs relating to social emotions such as maternal care, social bonding (companionship), separation distress, and playfulness (Panksepp, 1998, p. 71). The limbic system is of similar relative size across all mammals, but is much smaller in reptiles.

Surrounding the limbic system is the neocortex, which Panksepp describes as the "storehouse of our cognitive skills". This region is most developed in human beings, but is not where feelings originate: "We cannot precipitate emotional feelings by artificially activating the neocortex either electrically or neurochemically" (1998, p. 43). I conclude that the only emotions that are specific to human beings are those whose cognitive requirements are beyond the capacities of other animals.

It is hard to draw conclusions at present for invertebrates, as their brains have a very different layout (see Appendix).

In the Appendix, I outline a general strategy for identifying occurrences of basic emotions in animals, in the context of the four different kinds of intentional agency identified in chapter two. I also propose and ethically evaluate different kinds of experiments that could be carried out for verifying these emotions in animals.