Why is information forgotten from so easily from short-term memory (STM)? Two prominent theories are:
- Trace decay theory - the idea that information simply fades over time. It has been suggested STM has a duration of 30 seconds without rehearsal (Peterson and Peterson, 1959).
- Displacement interference theory - the idea that old information is pushed out by new information. This fits with the observation that STM can only hold a very limited amount of information - around seven items (Miller, 1956).
To address this problem, Reitman used a task involving tones. As these didn't use verbal memory, it distracted attention from the target items without displacment. Previous studies had shown that participants were not able to do the task at the same time as rehearsing the target words.
Early versions of her tone-distraction studies showed STM lasting longer than expected - could it be that there is no STM decay at all, and STM forgetting is just due to displacement?
|Tones provide distraction without verbal displacement.|
Ultimately, Reitman concluded that both play a role - displacement is important, but even with a tone-only task, decay still occurs.
Reitman, J.S. (1974). Without surreptitious rehearsal, information in short-term memory decays. Journal of Verbal Learning and Verbal Behaviour, 13, 365-377.