Interference

Understanding Why Interference Occurs and Overcoming It

When information is very similar to other information that was previously learned or stored in memory, interference is more likely to occur.

There are two basic types of interference:

1. Proactive interference, and
2. Retroactive interference.

1. Proactive interference

Proactive interference Opens in new window occurs when an old memory or something which you have already learned interferes with later learning and makes it more difficult or impossible to remember that learning (or new memory) later on in the future.

If you have already learned French, and you are now trying to learn German, you find that, instead of a German word you are trying to remember, the equivalent French word comes to mind. That would be proactive interference.

2. Retroactive interference

Retroactive interference Opens in new window occurs when new information interferes with your ability to remember previously learned information.

In other words, retroactive interference involves new learning interfering with the recall of previously learned information.

If, for instance, you learned French first, and then German later, you might find that when you think back and try to remember the French words which you used to know, only the more recent German ones come to mind instead. This would be an example of retroactive interference.

Findings About Interference

McGeoch (1942) showed that in general, interference is most likely to occur with information that is similar. Research participants were asked to learn lists of different items, like numbers, nouns Opens in new window or adjectives Opens in new window, and later asked to recall them.

McGeoch found that there was very little interference between, say, a list of numbers and a list of adjectives; but that when participants had to learn two lists which were similar, such as two lists of adjectives, then interference was very strong.

This means that you would be more likely to categorize the information as being different, so interference is less likely to happen!

During the 1960s, interference was an extremely popular explanation for a number of memory phenomena. Hunter (1964) showed how the concept of interference could be applied as an explanation for primacy Opens in new window and recency effects Opens in new window, for the way that some information appears to transfer from short-term Opens in new window to long-term memory Opens in new window storage while other information does not, and, most importantly, for forgetting.

Many psychologists of the time believed that new information either interfered with, or was interfered by, existing information, was the source of most forgetting Opens in new window.

The traditional view of interference, as we saw earlier, was that it mainly occurs with very similar material, and is unlikely therefore to affect information which is very different.

But other researchers used the idea of interference more broadly. For example, Holmes (1974) argued that the reason why the emotions of worry and anxiety do not help people to remember work for exams is mainly because they bring in all sorts of extra thoughts, like ‘I’m going to fail’, or ‘I’ll never remember all this’.

These thoughts, Holmes argued, produce interference, so all that the student actually remembers is the anxiety, rather than the material.

In the early 1960s several psychologists believed that interference occurred because there was only a finite capacity for human memory Opens in new window. New information would be bound to interfere with existing information because otherwise there would not be enough room to store it all.

But there does not seem to be any real evidence for a limited-capacity model of memory: we seem to be able to remember any amount of meaningful information—although we are certainly limited in how much meaningless information we can take in.

Even if one does accept a limited-capacity model, there are other explanations for forgetting, like the idea that information is displaced, or pushed out altogether.

Nowadays interference, although it might occur, is not really regarded as the complete explanation for forgetting that many researchers considered it to be in the past. There was empirical evidence too, which challenged the idea that forgetting Opens in new window mainly occurred as a result of interference.

Tulving (1972) gave research participants a list of words to learn. Then they were given three different trials, in which they were asked to remember the words on the original list.

If people forget because existing material interferes with recall or storage, then those words which survive the interference should be available for recall, and those which do not should be completely forgotten.

But Tulving found that it was not as simple as that. When they were asked to remember what was on their list, the participants in the research tended to remember different words on each trial.

They generally remembered roughly the same number of words on each occasion, but the words varied — only about half of the recalled words came up on all three trials. So it was clear that interference, in itself, was not an adequate explanation for forgetting.