What term describes a phenomenon where perceptions consistently differ from objective reality?

The term that best describes a phenomenon where perceptions consistently differ from objective reality is "illusion." Illusions are sensory experiences where the perceived reality diverges from what is actually present in the environment. This can include visual, auditory, or other sensory distortions that lead to misinterpretations of stimuli. For example, an illusion can occur when lines appear to be of different lengths due to contextual cues, even though they are actually the same.

While other terms, such as perceptual distortion, delusion, and hallucination, also relate to discrepancies between perception and reality, they have more specific meanings that do not fully encapsulate the general nature of consistent misperceptions as portrayed by illusions. Perceptual distortion tends to refer to broader alterations in perception but does not imply a consistent deviation. Delusions involve strongly held false beliefs that are resistant to reason and reality, while hallucinations pertain to sensory experiences that occur without external stimuli, such as hearing voices that are not there. Each of these concepts operates within different contexts in psychology and does not grasp the overarching phenomenon of routinely mistaken perceptions that the term "illusion" captures.