Researchers reported in a recent article in the Journal of Neuroscience, “We like increasingly anthropomorphic artificial agents, but feel uncomfortable if they become too human-like.” They found that an area of the brain, the VMPFC (ventromedial prefrontal cortex), was activated when the discomfort was sensed:

During decision-making, separate signals in VMPFC and DMPFC encoded subjects’ decision variable for choices involving humans or artificial agents, respectively. A distinct amygdala signal predicted rejection of artificial agents. Our data suggest that human reactions toward artificial agents are governed by a neural mechanism that generates a selective, nonlinear valuation in response to a specific feature combination (human-likeness in nonhuman agents). Thus, a basic principle known from sensory coding—neural feature selectivity from linear-nonlinear transformation—may also underlie human responses to artificial social partners.

A.M. Rosenthal-von der Putten et al. Neural mechanisms for accepting and rejecting artificial social partners in the uncanny valley. Journal of Neuroscience. Published online July 1, 2019. doi: 10.1523/JNEUROSCI.2956-18.2019. (open access)

They are saying that our dislike of almost-human bots is a “hardwired” natural reaction to something that doesn’t seem quite right.

Centuries ago, the Uncanny Valley was the stuff of finely crafted horror tales where dark secrets are only slowly revealed, for example in Jane Eyre or Wuthering Heights. Some sources think it best not to try to make robots look almost human, to avoid losing touch with the rest of us in the Uncanny Valley.

Further reading: Most people don’t live in Uncanny Valley: Consumers were not buying robots as friends this year. The market for drudgery busters remains strong. For robotic dogs and pals, not so much

and

I, Robot, Am Gathering Dust in the Sales Room … Why do robotics experts think that customers will warm to robots just because they look like people?

But then there’s Alita: Battle Angel. A Mind Matters News review. Sometimes, it actually works.