Hallucinations is a terrible term for this. We want models that can create new ideas and make up stories. The problem is that they will give false answers to questions with factual answers, and that they don't realize this.
In humans, this is known as confabulation, and it happens due to various forms of brain damage, especially with damage to orbitofrontal cortex (part of prefrontal cortex). David Rumelhart, who was the main person who came up with backpropagation in a paper co-authored with Geoff Hinton, actually got Pick's disease which specifically results in damage to prefrontal cortex and people with that disease exhibit a lot of the same problems we have with today's LLMs:
In humans, this is known as confabulation, and it happens due to various forms of brain damage, especially with damage to orbitofrontal cortex (part of prefrontal cortex). David Rumelhart, who was the main person who came up with backpropagation in a paper co-authored with Geoff Hinton, actually got Pick's disease which specifically results in damage to prefrontal cortex and people with that disease exhibit a lot of the same problems we have with today's LLMs: