While the term "reverse hallucination" is not commonly used in psychology or psychiatry, there are certain psychological phenomena where a person fails to perceive or recognize something that is actually present. This can happen for various reasons, and fear can indeed be one of them.
One relevant phenomenon is called "inattentional blindness." Inattentional blindness occurs when a person fails to notice a fully visible object or event because their attention is focused on something else. This can happen even if the object or event is right in front of them. It's not that they are hallucinating or seeing something that isn't there; instead, they simply fail to process the information due to their attention being directed elsewhere.
Fear or anxiety can play a role in inattentional blindness. When someone is fearful or anxious, their attention may become more narrowly focused on perceived threats or concerns, leading to a decreased ability to notice other details in their environment.
Another related phenomenon is "selective attention," which is the process of focusing on a specific aspect of the environment while ignoring others. In situations where fear is present, a person may selectively attend to potential threats or negative stimuli, causing them to overlook other information.
It's important to note that these phenomena are not hallucinations in the traditional sense, where someone perceives something that isn't there at all. Instead, they involve a failure to perceive or recognize something that is present due to cognitive or attentional factors.
If you find yourself experiencing such difficulties, it might be beneficial to explore the underlying emotions, fears, or anxieties that could be influencing your perception. In some cases, talking to a mental health professional can help you gain a better understanding of these processes and find ways to cope with them effectively. They can also help rule out any potential underlying conditions if you have concerns about your perception or cognition.