Interference theory argues that forgetting occurs when two pieces of information/memories
conflict/interfere with each other causing one or both to be forgotten or distorted. It is
assumed memory can be disrupted or interfered by what we have previously learned or by
what we will learn in the future. Interference is proposed mainly as an explanation for
forgetting in the LTM and the theory suggests forgetting occurs in the LTM due to
information in LTM combining and interfering with other information during encoding.
There are two way in which interference can cause forgetting, proactive interference and
retroactive interference.
Proactive interference occurs when older memory interferes with a newer one. For
instance, when your teacher has learned so many name in the past she has difficult learning
the new names of her current class. An example of proactive interference is Underwood’s
(1957) study which required participants to learn a series of wordlists. His study found that
participants who memorised 10 or more list after 24hrs only remembered 20% of what they
learned. Whereas if they learned only 1 list recall was 70%. Thus, this suggest the more lists
a participant must learn the worse their recall, explained by proactive interference.
Retroactive interference occurs when a newer memory interferes with an older one. For
instance, when your teacher has learned so many new names this year she has difficulty
remembering the names of student from last year. An example of retroactive interference is
Muller (1900) study which got participants to learn a list of syllables and they were given an
intervening task between describing paintings. This study produced retroactive interference
as participants struggled to recall their lists.
A strength of the interference theory is that studies are done in lab settings. For example,
many of the studies are done in high controlled environments with strict control over
extraneous/ irrelevant influences giving us confidence that interference explanation for
forgetting is valid. However, findings from lab studies lack mundane realism and eco logical
validity as studies are done in artificial setting using artificial stimuli like wordlists and tasks
participants experience are not true to real life. Moreover Anderson (2000) believed
interference did play a role in forgetting but how much is attributed remain unclear.
Therefore, findings from interference theory are difficult to generalise to real life everyday
forgetting as they are studied in lab setting and how much is credited due to interference is
uncertain.
Another strength of the interference theory is real life application. For example, Danaher
(2008) found when people are exposed to rival adverting brands in a short time interval
recall and recognition of advertiser’s message are confused. This is a genuine problem
considering the amount of money spent on advertisement only to be diluted by inference.
However, there is a strategy to overcome this, by running adverts on a specific day and by
ensuring they are significantly spaced apart from rival brands can help prevent adverts from
dilution. Thus, the interference theory is useful for real life situations as it helps advertisers
as they attempt to build brands.