Visual deception: The historical connection between illusions and hallucinations from a Gestalt theoretical and cognitive neuroscience perspective

Abstract

This article describes illusions and hallucinations from a Gestalt psychological and cognitive neuroscientific point of view. Filling in the missing gaps, researchers hypothesize about the attempt of the brain to predict what has been seen as it compensates for the small delay between ocular and cortical processing. Whereas illusions are the result of the brain filling in wrong information and results in misperception of external stimuli, hallucinations arise independently of external stimuli and are therefore labeled as "false perceptions". Gestalt psychology held that illusions are the result of the brain's interference with what we actually see, offers several laws that describe certain principles. Cognitive neuroscience focusses more on explaining these principles, made possible due to brain imaging and the knowledge of the corresponding brain areas. The underlying mechanisms during hallucinations have not yet been completely clarified. Different theories assume they are caused by damage in specific areas of the brain and abnormal levels of neurotransmitters.