The concept you're describing is known as "negative hallucination." While hallucinations involve perceiving something that is not present, negative hallucinations involve failing to perceive something that is actually present. In other words, it's the opposite of a regular hallucination, where you don't see or hear something that is physically there.
Negative hallucinations are less commonly discussed than regular hallucinations, but they have been explored in the context of certain psychological and neurological conditions. For example, some studies have suggested that negative hallucinations may occur in people with schizophrenia. In these cases, individuals might fail to perceive certain objects or people that are actually present in their environment, leading to apparent "absences" or gaps in their perception.
However, it's important to note that negative hallucinations are relatively rare and complex phenomena. If you're experiencing any unusual perceptual disturbances, it's crucial to seek professional medical advice from a qualified healthcare provider or a mental health professional. They can properly assess your situation and provide appropriate guidance or treatment. Self-diagnosis and assumptions about psychological experiences can be misleading and potentially harmful.