Interference can play a big role in determining the amount of forgetting between the information’s initial acquisition and the time of its attempted retrieval. It occurs when one set of learned information interferes with another set, and results to a retrieval failure or an alternation of the initial information (memory). Two kinds of interference exist, the retroactive referring to interference caused by the learning of later information with the recall of earlier ones, and the proactive referring to interference caused by the learning of earlier material with the recall of later ones.
Loftus and Palmer (1975) studied this kind of memory error in an experiment in which participants were asked to view a slide sequence showing an automobile. The experiment included three stages them being, the viewing of the event, a post event interview or narrative in which additional inferences by the witness occurred, and a final test of accuracy in remembering the original event. The results showed that witnesses often recalled their inferences or other information from the post-event session as though they were part of the original event, and that in many occasions they were not able to identify the source of their recall.
Loftus claimed that the reason for this was the way in which memory may be altered by subsequent information, clearly supporting the importance of retroactive interference. Alternation can also be observed by the reconstructive ‘nature’ of memory. Giving a big role on interpretation, Bartlett (1932) suggested that we reconstruct the past by trying to fit it into our existing schemata and the more difficult this is to do, the more likely it is that information is forgotten or distorted so that it fits.
Reconstructive memory theory was also supported by Loftus (1980) who has investigated it in relation to eyewitness testimony. She argued that the evidence given by witnesses in court cases are highly unreliable, for which she blames the form of questions that witnesses are asked, influencing their memories of what they have witnessed. (As cited in Gross, 1996) ‘Permastore’ theory provided a different picture of how certain memories function. Bahrick (1984) tested college graduates to see how much they remembered of Spanish language classes that they had taken in high school or college.
Most of them had made no use of the language after finishing the course, so this was recall without intervening practice. There was a difference between recall and recognition, but in both, retention seemed to have levelled out over very long periods of time. Bahrick suggested that some memory is retained in a ‘permastore’ which is unaffected by the passage of time. Those students who had learned better originally, remembered better over the years. A similar pattern is found for most procedural memory though procedures that are not learned through extensive practice can be lost very quickly.
The use of cues in remembering has also provided support for the permanence of memory traces which can be retrieved long after they have been ‘forgotten’. Many mnemonic techniques are based on developing memorable links between different bits of information, such as one item automatically leads on to the next. Tulving (1971) argued that forgetting might be due to the lack of appropriate retrieval cues, rather than the erasure or over-writing of the initial learning.
Throughout his studies he observed that not only were the subjects able to recognize more than they could recall, suggesting that they knew more than their recall indicated, but more importantly that the experimenter was able to use retrieval cues to manipulate the probability that an item would or would not be accessible to the subject. Retrieval cues are also used during studies on autobiographical memories. By autobiographical memories we mean people’s memories of their own experiences through life. Lindon (1975), recorded and recalled events in her own life in a systematic way during a period of seven years.
The recording of events was collected by means of short descriptions on cards, while the corresponding dates were written at the back of each card. During testing, she was reading the descriptions and was trying to recall the dates on which the event happened. Lindon found a steady loss of memory on these items, of about 6% a year. Also she showed that first events such as a first meeting of a series of following ones can be remembered much easier than later ones. A future replication of this study found life events to be much more slowly forgotten, where not a single instance of complete forgetting was found. (Wagenaar 1986).
This once again proved that memories leave permanent traces on the memory system, which can later be retrieved with the appropriate cues. Certain injuries to the brain, particularly to the hippocampus and surrounding regions, can produce disorders of memory. In anterograde amnesia, the patient’s ability to fix material in long-term memory is reduced. In retrograde amnesia, the loss is for memories prior to the injury and is sometimes attributed to a disruption of trace consolidation.
An important issue is that patients with severe anterograde amnesia can acquire certain long-term memories, clearly shown by the case of H. M. who after the removal of his hippocampus, was left with severe anterograde amnesia. H. M had near normal memory for anything which he had learned prior to the surgery but he had little memory of events which occurred after the surgery. His short term memory was normal while he could not transfer information into the long term memory and if he could, he was unable to retrieve it. A similar example is this of Clive Wearing who was an expert on music knowledge. After the destruction of his hippocampus by a virus he suffered severe anterograde amnesia.
Like H. M, he was unable to have memories of events which occurred after the destruction of the hippocampus, but he preserved his musical ability. The only difference with H. M was that his capacity for remembering events of his earlier life was extremely inconsistent. By outlying all these years of empirical studies, I wanted to emphasize the complexity of memory as a human cognition mechanism. What all these studies suggested, is that there is no certain answer to the question on whether memories are permanent as there has not yet been, a complete understanding of the function of memory.
This question may be unanswerable in principle, but I will favor the position which regards forgetting as a retrieval failure for the purpose of this essay. Throughout the essay I demonstrated that memories are permanently stored in our minds and can be recovered with several techniques. This cannot include all memories as a hole but certainly the majority of them. On the other hand memories may be altered with interference such as misleading information, as it was clearly shown by Loftus’ studies.