Eligibility traces, overshadowing, latent inhibition, and blocking are ubiquitous across Bilateria. Pavlov identified these in the conditional reflexes of his salivating dogs; they are found in the involuntary reflexes of humans; and they are seen in the associative learning of flatworms, nematodes, slugs, fish, lizards, birds, rats, and most every bilaterian in the animal kingdom. These tricks for navigating the credit assignment problem evolved as far back as the very first brains to make associative learning work.
