Long-Term and Short-Term Memory
Chunking involves combining small pieces of information to form larger units. Short-term memory can hold about five to nine units of information. Chunking stretches this limit to accommodate more information. For example, strings of numbers ("03251967") can be better remembered if they are interpreted as dates ("03-25-1967"). People use chunking to remember phone numbers, Social Security numbers, and combinations. It often occurs naturally and outside conscious awareness.A mnemonic is a technique that enhances learning and retrieval. One powerful mnemonic, called the method of loci, involves imagining items to remember as if they were in the rooms of a familiar building. People retrieve the items by mentally walking through the building and looking in each room. Chunking can also serve as a mnemonic. For example, it is difficult to simply memorize the correct order of operations for solving equations: parentheses, exponents, multiplication, division, addition, and subtraction. The order is easier to remember if the first letter of each operation (PEMDAS) is converted to a simple sentence, such as "Please Excuse My Dear Aunt Sally" or "Purple Elephants May Destroy A School." Memorizing material depends on more than just the total time spent studying that material. Distributed practice involves learning sessions spread out over time, usually with significant breaks between sessions. Massed practice involves continuous learning sessions with no rest breaks. Spreading study sessions over a semester is an example of distributed practice. Cramming for exams is an example of massed practice. Numerous studies show that distributed practice leads to longer-lasting memories than massed practice, even when students invest the same number of hours in each strategy. Distributed practice provides more opportunities for attempted memory retrieval. Multiple successful memory retrievals make people less likely to forget that memory. In addition, sleeping between study sessions helps with memory storage and studying in multiple settings makes memories easier to retrieve. Those events are more likely with distributed practice.