What type of hallucinations involves seeing things that are not present?

Visual hallucinations are characterized by seeing things that are not present in the environment. This type of hallucination can involve a variety of visual distortions, such as seeing objects, people, or even animals that do not exist. Individuals experiencing visual hallucinations may perceive these images as very real, leading to confusion and distress.

In contrast to visual hallucinations, the other types referenced—auditory, tactile, and olfactory—pertain to the senses of hearing, touch, and smell, respectively. Auditory hallucinations involve hearing sounds, voices, or noises that are not present, tactile hallucinations relate to the sensation of physical touch that isn't actually there, and olfactory hallucinations are associated with smelling odors that have no real source. Thus, visual hallucinations specifically focus on visual perception, making them the correct answer to the question.