To detect a presence, a real brain takes in sensory input and compares it to expectations, and stays calm or registers surprise, and from time to time issues predictions to guide the organism.

To detect an absence, the brain cannot rely on sensory input, by definition. To be surprised if sensory evidence is _not_ there requires a model of the world strong enough to register surprise if the expectation is not there, without a sensory prompt.

It seems to me detecting an absence is a strictly higher-order neurological task than processing sensory input.

If LLMs can't do this strictly higher-order neurological task, is that not a capability currently unique to living things?