A stroke can have all kinds of strange and unusual effects on people’s perceptions, from changing their sense of smell to hallucinations. In a particularly curious instance of this perception-twisting effect, a man suffered from a stroke and developed micropsia, a visual disorder in which objects are perceived to be smaller than they actually are, like a shrunken-down miniature.
Whatever he looked at – whether it was an item in the grocery store, a corridor, or even himself in the mirror – it appeared to be a fraction of its actual size.
As reported in a new case study published in the journal Neurocase, a 64-year-old man was admitted to a hospital in the Netherlands with weakness in his left arm. He also said that he had experienced a temporary loss of vision 11 days prior. A CT-scan of his brain revealed he had experienced a stroke in the occipito-parietal region, a chunk of the brain that deals with visual processing. Shortly after this incident, the man reported looking in the mirror and perceiving himself as 70 percent of his actual size.
As another example, he told doctors that he thought his clothes would not fit him anymore because they appeared to be too small. Despite typically wearing medium-size clothes, he started to buy extra-large shirts because his usual size didn’t look big enough. The effect was so severe he often worried whether certain corridors were too small for him to fit through.
With an undoubtedly interesting case on their hands, the doctors set about snooping into what was going on. In one part of their extensive investigation, the team used a computer to asses how he responded to visual stimuli. They also gave practical tests using different-sized cubes to gauge his size estimations. These tests highlighted that the man struggled with his left visual field. For example, if two cubes of differing sizes were placed next to each other, he consistently believed the left cube was smaller than the right one.
The researchers still aren’t certain why this man acquired such an acute form of micropsia, as the condition can be sparked by a number of different things, from drugs to epilepsy. However, based on their experiments, they concluded that the man sustained damage to his brain’s visual processing hub during his stroke. In an attempt to rectify the damage and maintain some constancy in his perception, the visual system over-compensated and created this effect.
“In sum, we suggest that the unilateral occipito-parietal infarction in our patient has caused contra-lesional visual sensory impairments, for which an unconscious, higher-order process tries to compensate at the price of creating a “shrunken” world,” concluded the researchers in their study.
[H/T: New Scientist]