Peterson and peterson studied how well participants can remember groups of three letters (like brt, qsd) after various delays. they found that participants remembered an average of 80 percent of the groups after 3 seconds but only 10 percent after 18 seconds. they hypothesized that this decrease in performance was due to but later research showed that it was actually due to

decay, interference

Explanation:

Peterson and Peterson studied how well participants can remember groups of three letters (like BRT, QSD) after various delays. They found that participants remembered an average of 80 percent of the groups after 3 seconds but only 10 percent after 18 seconds. They hypothesized that this decrease in performance was due to decay, but later research showed that it was actually due to interference.