An inability to voluntarily conjure mental images, known in science as aphantasia, does not rule out vivid visual imagery during sleep. That is the conclusion of an international team of researchers led by Derek Arnold and Loren Bouyer of the University of Queensland in Australia, working with Merlin Monzel of the University of Bonn in Germany, according to infohub.kz.
The results of a large-scale survey and analysis of sensory perception mechanisms were published in the journal Scientific Reports. The scientists found that an inability to consciously picture faces and objects by day does not stop the brain from producing full-fledged visual and auditory imagery during nighttime sleep.
The researchers analyzed questionnaires from 205 volunteers, of whom 84 were placed in a group of people with pronounced visual aphantasia and 121 made up a control group. The scientists examined in detail not only the ability to picture scenes mentally but also other sensory modalities: sounds, smells, taste, touch, the sense of body movement and inner speech.
It turned out that 46% of respondents with aphantasia regularly have dreams with clear visual details, and only about 8% reported a complete absence of visual imagery in their dreams.
The link between daytime imagination and dreams proved uneven. For some volunteers, sensory experience while awake fully matches their dreams, while others easily hear voices or see the faces of loved ones in dreams — something they cannot reproduce while awake even with a strong effort of will.
The authors suggest the problem lies in the coordination of brain regions: by day, the voluntary launch of images is blocked, while at night unconscious neural networks activate sleeping imagery.