One of the most influential models of memory was the two-process model by Atkinson and Schiffrin (1968); incoming information enters the short-term memory (STM) as a result of applying attention to a stimulus. The brain makes sense of the incoming sensory information by perception, and then in the rehearsal loop, the information is rehearsed before it is stored in the long-term memory (LTM). The rehearsal loop is an important part of this model as it is what enables information to be remembered more easily and stored in the LTM.
Peterson and Peterson (1959) made an experiment where they researched the capacity of the STM. The experiment was called ‘The Brown-Peterson technique’, which involved participants hearing various trigrams (such as XPJ). Only one trigram is presented on each trial. Immediately afterwards, the participants are instructed to recall what they heard or to count backwards, in threes, out loud, from some specified number for 3,6,9,12,15 or 18 seconds (the retention interval). The function of this interference task is to prevent rehearsal.
At the end of the time period, the participants try to recall the trigram. Peterson found that nearly 70 per cent was forgotten after only a nine-second delay, and 90 per cent after 18 seconds. The STM is believed to hold information for about 20 seconds without repeating it (rehearsal). If information is sufficiently rehearsed it will be transferred to the LTM and can be recalled. It is also said that unattended information may also enter the STM, and this may be due to not applying enough attention to the information that needs to be rehearsed and may affect recall.
In other words it may be due to interference and this experiment is to see if interference affects recall in STM. The two-process model assumes that incoming information enters the STM and it is rehearsed in the rehearsal loop before it is stored in the LTM. This is related to this study, because various objects are looked at by participants and then rehearsed. The objects being rehearsed is the sensory information entering the STM, and the participants must rehearse these objects in the rehearsal loop to store it in the LTM. The ‘Brown-Peterson technique’ experiment also relates to this study.
Participants are instructed to recall various trigrams of letters, such like the objects in this experiment, with and without interference, where participants have to count backwards in threes from a specified number. The interference task used in the present experiment is based on this, instead having to put books in alphabetical order. The ‘Brown-Peterson technique’ focused more on how the amount of time to rehearse affected recall, whereas in this study, the focus is purely on whether interference actually affects recall in the STM. The aim of this experiment is to see if interference affects recall in STM.
In one condition participants rehearse and in the other an interference task blocks rehearsal. Hypotheses Hi?? – The participants who rehearse the objects without interference will recall more of them than the participants who have an interference task blocking rehearsal. Hi?? – If there are any differences between the participants who rehearse the objects without interference and the participants who have an interference task blocking rehearsal, it will be because of chance. Method and Design The experiment is a laboratory experiment, therefore being in a controlled environment. Conditions must be controlled in order to make it a fair test.