It is difficult to imagine what life would be like without memory . The meanings of thousands of everyday perceptions , the bases for the decisions we make , and the roots of our habits and skills are to be found in our past experiences , which are brought into the present by memory .

Memory can be defined as the capacity to keep information available for latter for later use . It not only includes “remembering ” things like arithmetic or historical facts but also involves any change in the way an animal typically behaves . Memory is involved when a rat gives up eating grain because he has sniffed something suspicious in the grain pile . Memory is also involved when a six-year-old child learns to swing a baseball bat .

Memory exists not only in humans and animals but also in some physical objects and machines . Computers , for example , contain devices for storing data for later use . It is interesting to compare the memory-storage capacity of a computer with that of a human being . The instant-access memory of a large computer may hold up to 100,000 “words” —ready for instant use . An average American teenager probably recognizes the meaning of about 100,000 words of English . However , this is but a fraction of the total amount of information which the teenager has stored . Consider , for example , the number of faces and places that the teenager can recognize on sight .

The use of words is the basis of the advanced problem solving intelligence of human beings . A large part of a person’s memory is in terms of words and combinations of words .