Interference theory

• According to interference theory forgetting occurs when there are two competing memories that disrupt each other. This is particularly bad when two memories are similar in nature. They can become confused to the point that one (or both!) of the memories is forgotten. This is mainly an explanation for forgetting long-term memories as, whilst this is an almost permanent store, new or older memories can make it difficult to access the one we are trying to remember. There are two types of interference: Proactive and retroactive
• Proactive - This is when an old memory interferes with the recall of a newer memory. An example of this is buying a new car which has the lights and screen wash on opposite sides to the old car. When trying to flash your lights in the new car you may end up spraying your window with screen wash! In this case older learning (information about the old car) is interfering with new learning (information about the new car).
• Retroactive - This is when a new memory interferes with recall of an old memory, leading to the older memory being forgotten. For example, you've had your new car for a little while now that you have forgotten which side the controls were for windscreen wash and lights on the old car.
• Limitation - interference theory may only be an explanation of temporarily forgetting information. Iif a cue is provided, we can almost always retrieve the information that is required from LTM. If you were asked what you had for dinner on the 1st January this year, you have had many dinners after this to interfere with this information. However, if you were given a cue that indicated it was when you went for food with all of your family, this information is likely to be recalled. This limits this theory as this is not something that can be explained by the theory here.
• 1 - a limitation is that the research that helped to develop this theory does not accurately reflect the length of time before recall of memories is needed in everyday life. Baddeley (1990) noted that a lot of the research into this theory involved learning material but then recalling something almost straight after.
• 1.2 - Outside of this research context, we often don't need to recall an older memory for weeks, months or even years afterwards. For example, you revise for your exams a while before you sit them, yet acquire new memories along the way. The fact that you can still recall some/all of this information suggests that this theory may not apply to everyday life scenarios. This is a limitation as it questions the validity of this theory.
• Underwood (1957) found evidence to support proactive interference. He reviewed studies which had looked at forgetting of lists of words. He found that when participants had been given 15 or more lists to learn, they were only able to remember 15% of the last list, compared to 80% recall when they just had one list to learn. This supports the idea that earlier learning (the first 14 word lists) affects the recall of later material (the final list) which is an example of proactive interference.
• Waugh and Norman (1965) provide evidence to support the existence of retroactive interference. They gave participants 16 digits to remember. They were then given one of these digits (known as the 'probe) and asked to recall the digit that was immediately before. They found that recall was better when the probe was towards the end of the list. This can be explained by there being less 'new' information (more recent digits) to interfere with the recall of the older information. This therefore supports the theory of new information interfering with old which causes forgetting.