Gymnastics is one of the most physically demanding activities imaginable, and you would assume it's a good idea to have complete use of your eyes while performing aerial somersaults. But science never got anywhere by taking assumptions at face value.
In this case, researchers from the University of Minnesota analyzed the performance of NCAA gymnasts in three different situations:
Experiments were designed to examine the visual contributions to performance of back aerial double somersaults by collegiate acrobats. Somersaults were performed on a trampoline under three visual conditions: (a) NORMAL acuity; (b) REDUCED acuity (subjects wore special contacts that blocked light reflected onto the central retina); and (c) NO VISION. Videotaped skill performances were rated by two NCAA judges and digitized for kinematic analyses.
So, would the gymnasts be able to perform blind as well as they could with normal vision? The answers may (not) surprise you:
Subjects' performance scores were similar in NORMAL and REDUCED conditions and lowest in the NO VISION condition. Control of body movement, indicated by time-to-contact, was most variable in the NO VISION condition. Profiles of angular head and neck velocity revealed that when subjects could see, they slowed their heads prior to touchdown in time to process optical flow information and prepare for landing. There was not always enough time to process vision associated with object identification and prepare for touchdown. It was concluded that collegiate acrobats do not need to identify objects for their best back aerial double somersault performance.
So wait...the gymnasts did better when they could see, but only because they thought they had more control over their surroundings? If I might willfully misinterpret the point of this study, I think it apparently just demonstrated that vision is a placebo effect. For some reason, this experiment was never repeated in other sports, such as long distance running or race car driving. Not sure why...