Because you don’t seem to understand the difference between learning avoidance and reducing sensitivity. (If you notice my first comment I specifically referred to learned avoidance not simply any kind of learning.)
Reflexive behavior is a predefined response to a stimulus over some predefined limit and thus on it’s own it’s reactive not predictive. In a purely neutral context there is no reason to increase the response based on the external stimulus.
Avoidance requires the ability to predict before a negative response occurs. Without the negative association there is no impetus to increase avoidance.
Aka, don’t put your hand in fire is inherently different than how quickly you remove your hand from fire.
PS: Reducing sensitivity with exposure is a rather different thing as it helps deal with edge cases. At a meta level, strong constant uncontrollable spasms is extremely unlikely to be an ideal response to a given stimulus.
I see the distinction you're going for, but ultimately it doesn't work.
>Avoidance requires the ability to predict before a negative response occurs
The article discusses the mechanism by which the "avoidance behavior" they describe is learned. It mentions that the downregulation of inhibitory neurons causes heightened sensitivity to stimuli. But downregulation of inhibitory neurons is the same species of process involved in desensitizaion of reflex arcs, i.e. make a certain set of neurons require a higher threshold for activation. Your assumption that "avoidance behavior" requires something beyond reflex activation doesn't follow.
And lets be clear, all learning is predictive. A reflex being upregulated or downregulated is a mechanism of prediction by which an organism's response is modified to more closely correlate with the environment. What you seem to be going for when you use prediction is an organism's mental model of the environment that is detailed enough to associate certain states with negative valence, and behavior planning to avoid entering into such states. In organisms with that level of processing, I agree that an experience of pain is required. But it doesn't follow that any behavior that can be described as predictive requires such mental models.
I think you are making an arbitrary distinction between levels of response.
“more closely correlate with the environment” that’s leaning.
A tree that grows to light will physically reflect information in learned about the environment. It’s encoded in it’s physical form rather than neurons, but it’s still encoding information. In that case lack of sunlight is clearly not what we would associate as pain and I would not say it has ethical implications, but it is a negative stimulus from a tree’s perspective.
Anyway, avoidance is assumed to already happen as a separate system. “it’s already been shown in lots of different invertebrate animals that they can sense and avoid dangerous stimuli that we perceive as painful.“ Fruit fly’s have 250,000 neurons they can encode quite a bit to their mental model. This is simply changing the thresholds before learning occurs, or updating the system that updates their mental model.
As to the encoding, I think physical damage as a negative stimulus is kind of obvious.
>I think you are making an arbitrary distinction between levels of response.
I don't think the distinction between behavior carried out by reflex networks and behavior carried out by planning involving mental models is arbitrary. We have no reason to think reflex networks involve experience whereas we do have reason to think behavior involving mental models does. So it seems like this distinction is the critical distinction in terms of determining if some organism experiences pain.
>Anyway, avoidance is assumed to already happen as a separate system.
You're projecting more onto the term "avoidance" than is warranted, and you haven't defended your reading of the term. I take something like the withdraw reflex as an example of an avoidance behavior. Clearly you don't, but since your argument rests on your different understanding of the term, and your assumption that the authors of the article intend your reading of the term, its the key disagreement and deserves more attention.
Continuing the quote from the article you started "...In non-humans, we call this sense ‘nociception’, the sense that detects potentially harmful stimuli like heat, cold, or physical injury". So it doesn't seem like the authors are intending to reference predictive behavior, but simply protective behavior in response to noxious sensory perceptions, what you called reactive behavior.
Learned avoidance is in the literature ex: “A Drosophila larva essentially lives to eat. If one odour is repeatedly paired with a sugar substrate, and another is not, it will start to preferentially approach the first odour. If the pairing is with a quinine or high salt substrate, it will start to avoid the odour.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3427554/#!po=27...
Which is why I am saying learn avoidance behavior is simply not the topic of this research.
PS: That also includes some examples of complex behaviors.
Reflexive behavior is a predefined response to a stimulus over some predefined limit and thus on it’s own it’s reactive not predictive. In a purely neutral context there is no reason to increase the response based on the external stimulus.
Avoidance requires the ability to predict before a negative response occurs. Without the negative association there is no impetus to increase avoidance.
Aka, don’t put your hand in fire is inherently different than how quickly you remove your hand from fire.
PS: Reducing sensitivity with exposure is a rather different thing as it helps deal with edge cases. At a meta level, strong constant uncontrollable spasms is extremely unlikely to be an ideal response to a given stimulus.