According to Cindy Lustig, a psychology professor at the University of Michigan, children can only focus on one thing at a time, until about the age of nine, when they can hold more than one idea at a time. High school students and college students are very efficient at organizing and using information, coordinating processes, prioritizing non-linear dynamic interactions with information and tasks.
How does age affect multitasking skills? Older adults have more trouble with task switching because, according to Lustig, seniors have more chatter or multidimensional tasks on their minds. They have problems with limiting the scope of their attention. In other words, they are paying attention to too many things, whereas the child can only pay attention to one thing. In the above tiger example, the senior human might have the whole family's welfare on their mind and thus be slower to get the spear when needed.