Our brain has done a pretty good job of protecting us, an example being our ancestors managing to avoid getting eaten by sabre-toothed tigers, but the human brain remains relatively easy to fool. Optical illusions, dreams, hallucinations, altered states of consciousness, and the placebo effect are just a handful of familiar cases where our brains perception of what is happening, doesn't correspond to whatever is actually occurring.
You can try and lesser these effects through mental exercises, for example video games can have a considerable effect on brain activity. Another example is a type of mental arithmetic practiced in Japan, counting devices relying on rows of beads are common in the country, but a valued skill is "anzan", which is very fast and accurate mental abacus in essence. Using these imagination-based calculating tools, the most skilled participants can sum fifteen three-digit decimals in less than two seconds. Contestants begin using the mental abacus so immediately that afterwards they cannot remember any of the individual three-digit numbers.
Skills that can rely on mental practice are also familiar to those who need to practice physical motions regularly, such as musicians and athletes. For instrumentalists, having an actual instrument to play is pretty handy, but it turns out that having a mental copy of one can be almost as good. The musical community in general has been aware of this for decades or more. These days, neuroscience is beginning to catch up to musicians who practice mentally. Although the details are still somewhat elusive, the key to the success of mental imagery as a rehearsal technique is that most of the same neurological regions are invoked by mental practice as by real practice.
As with rehearsing a piece on the piano, practicing a complex physical task in the mind alone is nearly as effective a learning strategy as actually physically doing it. But it doesn't stop there. In a 2004 study, a group of researchers from the Cleveland Clinic Foundation decided to find out whether mental practice of a minor exercise routine could actually result in physical changes to the target areas of the body. One group of subjects performed a regular exercise involving moving a finger sideways; a second group regularly imagined doing the same exercise but did not go through the physical motions; and a third (control) group did nothing unusual with their fingers at all. After 12 weeks of training, the physical finger-workout group showed an increase of 53% in finger strength; the control group did not show any changes in finger strength; and the mental-finger-stretching group showed an increase of 35%. In other words, the mental-exercise group physically increased the strength of one of their fingers by imagining, repeatedly, over the course of about three months, that they were exercising it. They didn't have to lift a finger in order to convince their brains that they were, in fact, lifting a finger.
Neuroscientists are still working on the enigma of why this might be. Clearly the brain has been tricked. Nonetheless, it is clear that the human imagination alone is capable of doing things that are certainly more than imaginary in their results.
