Short Term Memory Limits in Performance

The present experiment showed that people can remember six letters for subsequent ordered recall and simultaneously process digits in memory during the retention interval for the letters. This lack of mutual interference was observed when the digits but not their order of presentation must be retained. When the order of the digits was also required, mutual interference between the letter and digit tasks occurred. These results were interpreted as evidence against the common assumption of a unitary working memory (short-term memory) which is limited to about seven items and which is required in cognitive operations such as decision making.