Memory is essential for learning as it allows us to store information and draw on past experiences. Information is transferred between short and long-term memory, with long-term memory storing information permanently. The capacity of long-term memory is extremely large though unknown. Previous knowledge stored in long-term memory can improve critical thinking by allowing newer facts to build upon familiar concepts in complex and logical ways. Both positive examples like preparation and organization and negative examples like intrusive thoughts or poor recall can impact the ability to learn.