What are emotions and why would we put them in AI?

In 2003 I started looking at the science of emotion in order to determine if it would be useful for robots.

But what are emotions?

Emotions may include bodily changes such as a glow and smile of happiness, the pounding heart of anxiety, the clenched fist of anger. Indeed, William James [the “father of American psychology” circa 1884] argued that an emotion is the perception of any such bodily change.1Oatley, K. (2004). Emotions: A Brief History.

So we’re talking appraisals of events. That definition doesn’t do enough for me. Not enough to create a robot with emotions.

Speaking of creating intelligent beings, in Mayan mythology, humans were created as a result of several experiments by the gods. The gods got it right on the fourth try, but the humans were too god-like, all-seeing and all-knowing, so they were “blinded”—perhaps a blinding by emotions.1Oatley, K. (2004). Emotions: A Brief History.

Ray Kurzweil, who I met once in Boston, wrote a book a while back called The Age of Spiritual Machines in which he says artificial intelligence will get so advanced that it will claim to have emotions but it will be difficult or impossible for us to evaluate that subjective experience scientifically. He also goes further and says AI will have “spiritual” experiences, also subjective in nature. And there’s not much difference between those two things categorically, aside from what neural correlates they have in humans.

Just being—experiencing, being conscious—is spiritual, and reflects the essence of spirituality. Machines, derived from human thinking and surpassing humans in their capacity for experience, will claim to be conscious, and thus to be spiritual.2Kurzweil, R. (1998). The Age of Spiritual Machines: When Computers Exceed Human Intelligence.

Emotion and Spirituality

When I had to do an English paper in 2003 (“middler year writing” at Northeastern University) I decided it would be something about emotions—but I wasn’t sure at first what the specific theme would be. One question I had was, why do people often associate emotion with souls and/or spirituality? Or do they? Did I just make up a straw man?

Is it simply that some never bother to consider how emotion works, so it gets classified with other mysterious phenomena like spirits? Or is it because religion has laid claims to human emotion?

A quick search finds this explanation:

Spiritual and Emotional are two types of mental behavioral changes in man that show some differences between them. Emotions are nothing but feelings related to worldly life. On the other hand, spiritual are feelings related to unearthly or unworldly life.3https://www.differencebetween.com/difference-between-spiritual-and-vs-emotional/

Oh they’re both feelings, alright. But that’s basically the same idea as in the aforementioned Age of Spiritual Machines.

I figured it wouldn’t hurt to talk to a religious leader to get the theological point of view of emotion (this is still back in 2003). I had a meeting with the minister of the Unitarian Universalist church of Harvard Square, who at that time was Dr. Thomas J.S. Mikelson. I didn’t record the meeting unfortunately (I couldn’t afford recording devices back then). Mikelson told me that the word “spiritual” is actually relatively new. Or perhaps the modern usage and popularity of it are new—according to the Oxford English Dictionary (OED)4Oxford English Dictionary, Second edition, 1989; online version March 2011., “spiritual” has been used in most of its current senses since at least the 1300s.

As an aside, it’s too bad that the usage of “spiritual” to mean “Of transcendent beauty or charm” is obsolete (according to OED):

1481 Myrrour of Worlde (Caxton) ii. iv. 69 Ther ben yet plente of other places so delectable, so swete, and so spyrytuel that yf a man were therin, he shold saye, that it were a very paradys.

So maybe “spiritual” isn’t the word I should be using. But it’s not a straw man, at least it wasn’t in the past. Emotion was in fact tied into religion:

of the history of the concept of emotion, he argues that the term ‘emotion’ was coined in the early 19th century, by psychologists impressed with physics, as a secular replacement for the morally, religiously, and metaphysically freighted distinction between ‘passion’ and ‘affection.5Roberts, Robert, “Emotions in the Christian Tradition”, The Stanford Encyclopedia of Philosophy (Spring 2021 Edition), Edward N. Zalta (ed.), URL = <https://plato.stanford.edu/archives/spr2021/entries/emotion-Christian-tradition/>

Passion would be the lesser emotion shared with animals. Affection would be the human-only emotion that humans share with angels and God in the Christian tradition.5Roberts, Robert, “Emotions in the Christian Tradition”, The Stanford Encyclopedia of Philosophy (Spring 2021 Edition), Edward N. Zalta (ed.), URL = <https://plato.stanford.edu/archives/spr2021/entries/emotion-Christian-tradition/>

The Word “Emotion”

The word “emotion” actually cropped up before the 19th century, back in 1579. First we see these now-obsolete usages:

  1. “A moving out, migration, transference from one place to another.” (1600s)
  2. “A moving, stirring, agitation, perturbation (in physical sense).” (1600s-1800s)
  3. “A political or social agitation; a tumult, popular disturbance.” (1500s-1700s)

Then we get to a modern usage starting in the 1600s:

Any agitation or disturbance of mind, feeling, passion; any vehement or excited mental state.

Here are some word usage quotes:

1660 Bp. J. Taylor Dvctor Dvbitantivm (R.), The emotions of humanity..the meltings of a worthy disposition.

1762 Ld. Kames Elem. Crit. ii. §2. (1833) 37 The joy of gratification is properly called an emotion.

Then we get to an even more modern usage from psychology:

A mental ‘feeling’ or ‘affection’ (e.g. of pleasure or pain, desire or aversion, surprise, hope or fear, etc.), as distinguished from cognitive or volitional states of consciousness. Also abstr. ‘feeling’ as distinguished from the other classes of mental phenomena.

The quotes for that start in the 1800s:

1808 Med. Jrnl. XIX. 422 Sea-sickness..is greatly under the dominion of emotion.

1841–4 R. W. Emerson Friendship in Wks. (1906) I. 81 In poetry..the emotions of benevolence and complacency..are likened to the material effects of fire.

1842 C. Kingsley Lett. (1878) I. 61 The intellect is stilled, and the Emotions alone perform their..involuntary functions.

1871 J. Tyndall Fragm. Sci. (ed. 6) II. xi. 231 He..almost denounces me..for referring Religion to the region of Emotion.

(Religion as emotion?)

1875 B. Jowett tr. Plato Dialogues (ed. 2) I. 249 The..emotions of pity, wonder, sternness, stamped upon their countenances.

It’s interesting to see how the concept of emotion seemed to come from movement and disturbance, changed into personal mental disturbances, and then became distinguished from conscious cognition.

Emotional AI?

I suppose the other frail connection that might exist in people’s minds between emotion and spirituality is due to the never-ending attempt to preserve something special or divine about humanity. Some will always grasp for lifeboats supposedly unique to humans such as “emotion” or “feeling” or “intelligence” or “winning at Jeopardy”…

Have I actually defined emotion enough yet? Well it’s actually a bit complicated.

emotion is one of those suitcaselike words that we use to conceal the complexity of very large ranges of different things whose relationships we don’t yet comprehend.6Minsky, M. (2006). The Emotion Machine: Commonsense Thinking, Artificial Intelligence, and the Future of the Human Mind.

A subset of that suitcase, which could be a useful start here, would be to think of emotions as mental states which help or hinder whatever goals your mind is trying to accomplish in the world at any given time.

the concept of Rational Thinking is incomplete—because logic can only help us to draw conclusions from the assumptions that we happen to make—but logic, alone, says nothing about which assumptions we ought to make.6Minsky, M. (2006). The Emotion Machine: Commonsense Thinking, Artificial Intelligence, and the Future of the Human Mind.

the need to cope with a changing and partly unpredictable world makes it very likely that any intelligent system with multiple motives and limited powers will have emotions. So the belief that emotions and intellect are somehow quite separate is mistaken7Sloman, A. and M. Croucher, ‘Why robots will have emotions’ in Proc. IJCAI Vancouver 1981

Emotion could be useful for artificial intelligence and robots. It’s a decision-making apparatus. Yes, you heard that right—decision making. More specifically, decision making in the kind of body-world system human minds control or are part of. A system which is full of limitations.

the interruptions, disturbances and departures from rationality which characterise emotions are a natural consequence of the sorts of mechanisms required by the constraints on the design of intelligent systems7Sloman, A. and M. Croucher, ‘Why robots will have emotions’ in Proc. IJCAI Vancouver 1981

damage to the ventromedial frontal cortex help answer this question, since their lesion renders their choices in the real world irrational, i.e., not in their best interest…this group of patients is defective in an essential and specific component of reasoning, the ability to guide choice by feeling.8Adolphs, R., Tranel, D., Bechara, A., Damasio, H., & Damasio, A.R. (1996). Neuropsychological Approaches to Reasoning and Decision-Making.

But there’s more to the interest in emotional AI beyond decision-making. Emotions may be a critical part of the evolution of human minds, and how individual minds develop from baby to adult. How critical? Like critical to basic thinking, knowledge, language abilities and consciousness. So for some who pursue the old goal of “Strong AI” that is human-like, emotional architectures might have to be a big part of that approach. More on this in future essays…


  • 1
    Oatley, K. (2004). Emotions: A Brief History.
  • 2
    Kurzweil, R. (1998). The Age of Spiritual Machines: When Computers Exceed Human Intelligence.
  • 3
    https://www.differencebetween.com/difference-between-spiritual-and-vs-emotional/
  • 4
    Oxford English Dictionary, Second edition, 1989; online version March 2011.
  • 5
    Roberts, Robert, “Emotions in the Christian Tradition”, The Stanford Encyclopedia of Philosophy (Spring 2021 Edition), Edward N. Zalta (ed.), URL = <https://plato.stanford.edu/archives/spr2021/entries/emotion-Christian-tradition/>
  • 6
    Minsky, M. (2006). The Emotion Machine: Commonsense Thinking, Artificial Intelligence, and the Future of the Human Mind.
  • 7
    Sloman, A. and M. Croucher, ‘Why robots will have emotions’ in Proc. IJCAI Vancouver 1981
  • 8
    Adolphs, R., Tranel, D., Bechara, A., Damasio, H., & Damasio, A.R. (1996). Neuropsychological Approaches to Reasoning and Decision-Making.

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