Episodic memory and semantic memory are completely independent systems. Discuss.

Episodic memory refers to memories of particular episodes in one’s life, and is definable with respect to time and place. For example, if someone was asked to give an account of everything they had eaten the day before, they would use episodic memory to recall this information. Semantic memory refers to all the facts we know and to our general knowledge of the world. Questions such as “Who is the British Prime Minister?” and “In which city would you find the Statue of Liberty?” would be answered using semantic memory. Unlike episodic memories, semantic memories are not tied to the particular time and place of learning. For instance, in order to remember that Tony Blair is the British Prime Minister, it is not necessary to remember the time and place that this information was first learnt. It was proposed by Tulving (1980) that episodic and semantic memory should be ‘regarded as separate’ (Tulving 1980, p. 32). But to what extent are episodic memory and semantic memory completely independent systems? This essay will examine some of the empirical evidence for and against the proposal of an episodic-semantic distinction, and highlight some of the ways in which much of this research is flawed.

One piece of evidence in support of a semantic-episodic distinction has been provided by Kihlstrom (1980), who demonstrated dissociations between episodic memory and semantic memory by using hypnosis to create different brain states in his participants. In the experiment, the participants were first classified in terms of the degree to which they were susceptible to hypnosis. Under hypnosis, the participants repeatedly learnt a list of 16 words. They were then administered with a post hypnotic suggestion that when they awakened from hypnosis they would not remember the list of words until given a reversibility cue by the experimenter. On being awakened from hypnosis, the participants completed an episodic and semantic memory task connected to the list of words they had just learnt. Kihlstrom (1980) found that the participants in the very high hypnotisability group performed very poorly on the episodic memory task, recalling almost none of the words, whereas those in the low hypnotisability group recalled 86% of them. However, all the participants performed equally well on the semantic memory task. It was also found that the episodic memories blocked by the post hypnotic suggestion became accessible once the participants had been given the reversibility cue. The fact that episodic memories were blocked through the use of hypnosis, but semantic memories were unaffected would therefore appear to suggest that episodic and semantic memory are independent systems. However, there have also been other studies which have demonstrated that hypnosis has no significant affect on episodic memory performance. For instance, Graham and Patton (1968) carried out a study in which the participants were asked to learn two list of adjectives, with some of them learning the second list whilst under hypnosis. It was found that the participants in the hypnosis condition showed a similar level of retroactive inhibition from the second list of adjectives to those in the control condition. Therefore, there appears to be an inconsistency between the findings of studies using hypnosis to demonstrate that episodic memory and semantic memory are independent systems.

This is a preview of the whole essay

A second type of evidence supporting the distinction between episodic and semantic memory comes from studies which compare the brain activity of participants while they complete different memory tasks. For instance, Wood, Taylor, Penny and Stump (1980) carried out a study in which they asked participants to inhale a low concentration of a radioactive isotope so as to measure their cerebral blood flow. The participants’ blood flow was then recorded while they completed either an episodic or semantic memory task, with Wood et al. (1980) finding a difference in blood flow depending on which memory task the participants were completing. They claimed that these findings should therefore be considered to ‘support an anatomical basis for the distinction between episodic and semantic memory’ (Wood et al. 1980, p. 113). However, there are other possible expatiations as to why a difference in the participants’ blood flow was observed. For example, perhaps Wood et al’s findings were a reflection of the differing levels of difficulty between the episodic memory and semantic memory tasks rather than evidence that episodic and semantic memory are independent systems. Further criticism of this study has been provided by McKoon, Ratcliff and Dell (1986), who argue that findings of this study must been seen as ‘intriguing rather than as strong evidence’ for a distinction between episodic and semantic memory until an extensive study of the blood flow method has been carried out, as little is currently known about this expensive research method.

As well as there being problems with the existing research in support of independence, studies such as that carried out by Anderson and Ross (1980) have also provided evidence to suggest that episodic and semantic memory are not completely independent. In Anderson and Ross’s (1980) experiment, the participants were required to complete an episodic and semantic memory task. In the episodic task, the participants learnt a series of sentences such as ‘A spaniel is a dog’ and ‘A spaniel retrieves a ball.’ In the semantic test phase, the participants were shown a series of word pairs and then asked to indicate as fast as they could whether or not the first word was an example of the second word. For example, it the word pair was SPANIEL-DOG, then the correct response would be yes, but if the word pair was BEE-FLOWER, then the correct answer would be no. Anderson and Ross (1980) then observed whether the time taken by the participants to verify whether or not the word pairs were correct or incorrect was affected by the newly learned information in the episodic task. If episodic memory and semantic memory are independent systems, the learning of the new episodic information should not have an affect on semantic memory. However, Anderson and Ross (1980) found that the newly learned information influenced the verification time of the word pairs in the semantic task. The findings of this experiment are also supported by a study carried by Lewis and Anderson (1976), in which it was found that learning new facts about well known people led to a decrease in the time taken by participants to verify facts previously know about them. Thus, empirical evidence also exists that is not in accordance with the proposal that episodic memory and semantic memory are completely independent systems.

In conclusion, though some studies appear to support the notion that episodic and semantic memory are independent systems, there are questions concerning the validity and interpretation of their findings. In addition, the findings reported by Anderson and Ross (1980) and Lewis and Anderson (1968) seem to suggest that Tulving’s (1980) claim that the current research on the episodic-semantic distinction ‘favors the hypothesis of a functional separation between the episodic and semantic memory systems’ (Tulving, 1980, p.66) its not wholly supported. Therefore, it could be argued that the proposal that episodic memory and semantic memory are completely independent systems appears to be quite weak. However, the problem highlighted by the Wood et al.’s study that differences observed between episodic and semantic memory may actually be due to other factors, such as the differing levels of difficulty between the tasks, is applicable to both the evidence for and against an episodic-semantic distinction. Also, the fact that there is such a close relationship between episodic and semantic memory, means that it is difficult to develop tasks which measure only episodic memory or only semantic memory ability. Therefore, it could be argued that it is difficult to draw sound conclusions from any of the findings of research in this area, as it may not be valid to make assumptions about the relationship between these two memory systems by comparing the participants’ performance on tasks which are not exclusively measuring their episodic or semantic memory, but in some cases aspects of both. Until the development of pure episodic memory and semantic memory tasks, which are equal it terms of their level of difficulty, the findings of research in this area can not be accepted with a great degree of confidence. Thus the extent to which episodic memory and semantic memory are independent systems appears to be inconclusive.

REFERENCES

Anderson, J., & Ross. B. (1980). Evidence against a semantic-episodic distinction.

Journal of Experimental Psychology: Human, Learning and Memory, 5, 441-446

Graham, K. R., & Patton, A. (1968). Retroactive inhibition, hypnosis, and hypnotic

amnesia. International Journal of Clinical Experimental Hypnosis, 16, 68-74

Kihlstrom, J. F. (1980). Post-hypnotic amnesia for recently learned material: Interactions

with ‘episodic’ and ‘semantic’ memory. Cognitive Psychology, 12, 227-251

Lewis, C., & Anderson, J. (1976). Interference with real-world knowledge. Cognitive

Psychology, 8, 311-335

McKoon, G., Ratcliff, R., & Dell, G, S. (1986). A critical evaluation of the semantic-

episodic distinction. Journal of Experimental Psychology: Learning, Memory and Cognition, 12, 295-306

Tulving, E. (1983). Elements of Episodic Memory. Oxford: Oxford University Press

Wood, F., Taylor, B., Penny, R., & Stump, D. (1980). Regional cerebral blood flow

response to recognition memory versus semantic classification tasks. Brain and Language, 9, 113-122

Episodic memory and semantic memory are completely independent systems. Discuss.

This is a preview of the whole essay

Document Details

Related Essays

Episodic and Semantic Memory Distinction.

Semantic Memory and Language production.

Memory is not like a tape recording". Discuss. Memory is an essential feat...

Controlled Laboratory studies are widely used in memory research. Evaluate...