[odyssey7]

If we take the behavior of matter as the observable signs of how it feels — this is true if sensation motivates action — then many rich states of sensation have been observed in subatomic particles.

The computational process of an organism is evolved to operate the organism, toward survival of the species. I don’t think these sensations would necessarily be more complex than those of subatomic particles, but they would need to be directed by the system to represent the state of the system and the observed environment, to link to actions the system could take, and to bias actions toward survival of the system.