Final answer:
The approximate capacity of short-term memory, according to George Miller's 1956 research, is 7 plus or minus 2 bits of information, which means the answer is 'a. 5-7 bits'.
Step-by-step explanation:
According to the research conducted by George Miller in the 1950s, he concluded that the capacity of short-term memory is approximately 7 plus or minus 2 bits of information. Therefore, the correct answer to the question is 'a. 5-7 bits'. This conclusion is based on his review of the research available at that time, indicating that people can typically retain between 5 and 9 items in their short-term memory.
However, modern studies such as Nelson Cowan's (2010) suggest that the working memory capacity may actually be closer to 4 plus or minus 1 items. Short-term memory holds information before it is either forgotten or stored in long-term memory, analogous to the way a document is either saved or discarded on a computer. The importance of rehearsal in transferring information from short-term to long-term memory implies a dynamic relationship between information retention and active use.