Working memory training tasks are conducted on computers and are often paired with positive reinforcement, feedback of the individual's performance, and other motivational features such as displaying the individual's current score beside their personal best score. Practicing these tasks demands numerous processes such as encoding, inhibition, maintenance, manipulation, shifting and controlling attention, and the ability to manage two tasks simultaneously or dividing attention. Possible forms of the tasks include recalling a series of locations of items on the screen, recalling digits or letters in either the order presented or reverse order, or recalling specifically where a particular number or digit was in a sequence. Computers are additionally programmed to adjust the difficulty of the task to the individual's performance with each trial in order to maximize learning and overall improvement. If the individual does poorer on one trial, the difficulty will decrease. Similarly, if the individual excels on the next few trials, the difficulty will increase. Two ways of altering the difficulty are adjusting the number of stimuli to be remembered and adding visual distractions.