Interferance Flashcards
Validity issues
Interference theory is based mostly on lab experiments.
On the plus side, researchers have tight control over variables. For example, McGeoch and McDonald controlled the type of material participants learned. Also, all studies control the amount of time between learning and recalling a list of words (even Baddeley and Hitch’s study of rugby players). As control helps researchers to avoid confounding variables, their findings can demonstrate clear links between interference and forgetting.
On the other hand, the majority of lab experiments tend to use artificial materials and unrealistic procedures, as we have seen elsewhere on this spread. For instance, in a typical lab study the time between learning and recalling a list of words is short (perhaps 10 or 20 minutes). This is very different from everyday life, in which we often learn something and then recall it a long time later. For example, a student might learn and revise a topic and then recall that material in an exam several weeks afterwards.
Therefore, because lab studies maximise the possibility of interference occurring, they may exaggerate its importance as a cause of forgetting.
Real-world interference
One strength is that there is evidence of interference effects in more everyday situations.
Alan Baddeley and Graham Hitch (1977) asked rugby players to recall the names of the teams they had played against during a rugby season. The players all played for the same time interval (over one season) but the number of intervening games varied because some players missed matches due to injury. Players who played the most games (most interference for memory) had the poorest recall.
This study shows that interference can operate in at least some real-world situations, increasing the validity of the theory.
Counterpoint
interference may cause some forgetting in everyday situations but it is unusual. This is because the conditions necessary for interference to occur are relatively rare. This is very unlike lab studies, where the high degree of control means a researcher can create ideal conditions for interference. For instance, as we have seen on this spread, two memories (or sets of learning) have to be fairly similar in order to interfere with each other.
This may happen occasionally in everyday life (e.g. if you were to revise similar subjects close in time), but not often.
This suggests that most forgetting may be better explained by other theories such as retrieval failure due to a lack of cues
Interference and cues
One limitation is that interference is temporary and can be overcome by using cues (hints or clues to help us remember something).
Endel Tulving and Joseph Psotka (1971) gave participants lists of words organised into categories, one list at a time (participants were not told what the categories were). Recall averaged about 70% for the first list, but became progressively worse as participants learned each additional list (proactive interference). But had the words really disappeared from LTM or were they still available? At the end of the procedure the participants were given a cued recall test - they were told the names of the categories. Recall rose again to about 70%.
This shows that interference causes a temporary loss of accessibility to material that is still in LTM, a finding not predicted by interference theory.
Support from drug studies
Another strength comes from evidence of retrograde facilitation.
Anton Coenen and Gilles van Luitelaar (1997) gave participants a list of words and later asked them to recall the list, assuming the intervening experiences would act as interference. They found that when a list of words was learned under the influence of the drug diazepam, recall one week later was poor (compared with a placebo control group). But when a list was learned before the drug was taken, later recall was better than placebo. So the drug actually improved (facilitated) recäll of material learned beforehand. John Wixted (2004) suggests that the drug prevents new information (i.e. experienced after taking the drug) reaching parts of the brain involved in processing memories, so it cannot interfere retroactively with information already stored.
This finding shows that forgetting can be due to interference - reduce the interference and you reduce the forgetting
