Psychologist Andrew Neher has written that "there is no good evidence to support the notion that auras are, in any way, psychic in origin."[33] Studies in laboratory conditions have demonstrated that the aura is instead best explained as a visual illusion known as an afterimage.[34][35] Neurologists contend that people may perceive auras because of effects within the brain: epilepsy, migraines, or the influence of psychedelic drugs such as LSD.[36][37]

It has been suggested that auras may be the result of synaesthesia.[38] However, a 2012 study discovered no link between auras and synaesthesia, concluding "the discrepancies found suggest that both phenomena are phenomenological and behaviourally dissimilar."[39] Clinical neurologist Steven Novella has written "Given the weight of the evidence it seems that the connection between auras and synaesthesia is speculative and based on superficial similarities that are likely coincidental."[40]

Other causes may include disorders within the visual system provoking optical effects.[citation needed]

Bridgette Perez in a review for the Skeptical Inquirer has written "perceptual distortions, illusions, and hallucinations might promote belief in auras... Psychological factors, including absorption, fantasy proneness, vividness of visual imagery, and after-images, might also be responsible for the phenomena of the aura."[41]

Scientists have repeatedly concluded that the ability to see auras does not actually exist

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