Subjectivity and artificial sentience
The experience of consciousness is about feelings
Rather than the cerebral cortex, affective consciousness arises from more primitive parts of the brain that we share with other animals, namely the brainstem. Neuropsychologist Mark Solms presents cases of patients with major damage to the prefrontal cortex yet they have subjective experience. Even patients with no cortex at all respond emotionally to events because they still have a brainstem. In one patient, deep brain stimulation of their brainstem induced wild emotional changes, such as suicidal despair, within a minute of two of stimulation.
Feelings signal if biological things are going well or badly
Feelings differ from other sensations, such as sight and hearing, because they have valence- they feel good or bad- that represents the state of the biological need behind it. Hunger and thirst feel bad because they highlight that a physiological need is not being met. Good feelings convey that our biological needs are being met.
Different biological needs have a different quality- the feeling of suffocation feels different to hunger- since different actions are needed to meet these needs. Our biological needs, such as breathing, body temperature and blood glucose, are regulated autonomically beyond our voluntary control. We become conscious of them if they require us to act in some voluntary way and this stops once the underlying need has been met.
Feelings are rooted in homeostasis
Interoception involves our brains making predictions about our internal biological states and the resulting prediction errors drive homoeostasis necessary for survival; for example, to maintain our internal temperature, glucose and oxygen within a limited range.
The same process occurs for allostasis where this kind of control is anticipatory- our brains make predictions about anticipated biological states so that we can make changes to prepare for them. Think of the bear that puts on fat in anticipation of hibernation.
In both cases of homeostasis and allostasis, it feels bad when we deviate from expected states and feels good when we return to them.
Feelings help us make choices when there is uncertainty
Most homeostasis occurs unconsciously because we have evolved innate controls. For example, when we start heating up, we detect that our internal state is not in its equilibrium state, triggering an innate control algorithm- if the body heats up, then sweat and pant. This causes us to cool down and is turned off once our interoceptive error signals have been minimised, signalling that we’ve returned to equilibrium. In short, feelings provide positive or negative feedback, the emotional motivation of which guides us to act in the right direction for survival.
When situations arise where we lack innate control algorithms we need to explore the world to learn what to do. Feelings guide us if we are going in the right or wrong direction. For example, breathing is regulated beyond our conscious control. However, if we find ourselves inside a building that is on fire, then we explore the building to find the way out by feeling if going in this or that direction is leading us towards oxygen and coolness rather than smoke and heat.
Engineering artificial sentience?
If feelings serve a functional, affective purpose based in homeostasis, then subjectivity could be explained mechanically. To test this homeostatic hypothesis, Marks Solms’ research team is engineering an artificial sentience, although this will not be a living system: every living system is a homeostatic system but not every homeostatic system is a living system. Being alive is a not a necessary condition for feeling.