In a few decades, intelligent and sentient humanoid robots will wander the streets alongside humans, work with humans, socialize with humans, and perhaps one day will be considered individuals in their own right. In an article he wrote in 2014, Belgian researcher Maciano Hay discusses the question wether a machine or an AI could ever feel human-like emotions.
The "Human Brain Project" is aiming to create a functional computer simulation of the whole human brain before 2016. Does that mean that computers will finally experience feelings and emotions like us? Surely if an AI can simulate a whole human brain, and machine learning enables it to display emotion in ways that seem empathetic or emotionally intelligent, then it becomes a sort of virtual human, doesn't it? Not quite.
In theory, any neural process can be reproduced digitally in a computer, even though the brain is mostly analog. While sensory feelings like heat, cold or pain could easily be felt from the environment if the machine is equipped with the appropriate sensors, this is not the case for other physiological feelings like thirst, hunger, and sleepiness. These feelings alert us of the state of our body and are normally triggered by hormones such as vasopressin, ghrelin, or melatonin. Obviously, machines do not have a digestive system nor hormones.
An intelligent computer could of course prompt some emotions based on its own thought processes, just like the joy or satisfaction experienced by, for example, solving a mathematical problem. This emotion could be said to have arisen spontaneously from an internalized thought process that took place in the neocortex. In fact, as long as it is allowed to communicate with the outside world, there is no major obstacle to computers feeling true emotions of its own like joy, sadness, disappointment, fear, anger, etc. These are all emotions that can be produced by interactions through language with no need for physiological feedback.
What really distinguishes intelligent machines from humans, cyborgs or animals, however, is that the former do not have a biological body. This is essentially why they could not experience the same range of feelings and emotions as we do, since many of them inform us about the state of our biological body. Machines cannot reasonably feel hunger because they do not eat. They cannot get sick and don't need to worry about passing on its genes to posterity, and therefore a machine will have no reason to feel that complex emotion of “well being” the way humans do.
Thus, replicating emotions on machines with no biological body, no hormones, and no physiological needs can be very tricky. This is the case with social emotions like attachment, sexual emotions, the sense of taste, or the effects of alcohol. An intelligent robot with sensors could easily see, hear, detect smells, feel an object's texture, shape and consistency, feel pleasure and pain, heat and cold, and the like. But since machines do not eat, drink and digest, they wouldn't be able to experience these or other emotions originating from evolutionary mechanisms.
But the biggest obstacle to simulating physical feelings in a machine comes from the vagus nerve, a part of the autonomic nervous system that controls such varied things as digestion, heart rate and sweating. When we are scared or disgusted, we feel it in our guts. When we are in love we feel butterflies in our stomach. That's because of the way our nervous system is designed.
Humans are social animals. They typically seek to belong to a group, make friends, share feelings and experiences with others, gossip, seek approval or respect from others, and so on. Interestingly, a person's sociability depends on a variety of factors not found in machines, including gender, age, level of confidence, health, well being, genetic predispositions, and hormonal variations.
The expression of one's emotions is also heavily regulated by culture and taboos. That's why speakers of Roman languages will generally express their feelings and affection more freely than, say, Dutch or Finnish. Recent research indicates that people living in self-oriented cultures who are less appreciative of mixed feelings also tend to be less emotionally complex than people living in cultures with a greater emphasis on feelings of duty and familial bonds, like in various parts of Asia and Africa.
Some transhumanists would wish to one day upload their mind onto a computer and transfer their consciousness. However, the loss of our biological body would also deprive us of our capacity to experience feelings and emotions bound to our physiology. We may be able to keep those already stored in our memory, but we may never dream, enjoy food, or fall in love again.