Our ability to perform several tasks simultaneously is limited by the sequential mode in which human brain processes information and, in particular, how a decision is made. Although decisions cannot be made in parallel, through training, it can be can reduced the time needed for decisions making.
In the Neuroscience Group, at Vanderbilt University, they have carried out several experiments in this direction. Using an equipment of functional magnetic resonance imaging (fMRI), they have made more records of individuals who were placed in a position to perform several tasks simultaneously. The data analysis found that part of the brain that enabled the greatest is the pre-frontal cortex one.
Subsequently, a group of volunteers was trained to perform a set of activities simultaneously (recognition of images and sounds and their classification through touch and voice actions). At the beginning of the training, they made the activities much slower, when the activities had to be carried out in parallel, than when they were done separately.After the training trial period, subjects gave the impression that the activities were carried out simultaneously.
Yes , with practice we can improve our ability to do several things. On very common example this is the way we learn to drive. When we drive we have to manipulate to the steering wheel to keep car on its course, at the same time we must depress the accelerator by just the right amount to keep the desired speed. We also need need to look out for route we need to take, the traffic condition, we need to judge the behavior of other vehicles on the road adjust our driving accordingly. From time to time we need to change the gears when we do this our one foot is operating the accelerator and the other foot operates clutch, one hand shifts the gear and the other hand continues to be on the steering wheel, keeping the car on course.
Initially when we are learning to drive, we find it very difficult to do all these things simultaneously, but as we practice, we are able to perform all these task with increasing ease. Finally, we become so good at handling these different operations simultaneously that we don't even realize that we have to make any special effort to do so.