Interference theory

The interference theory is a theory regarding human memory. Interference occurs in learning. The notion is that memories encoded in long-term memory (LTM) are forgotten and cannot be retrieved into short-term memory (STM) because either memory could interfere with the other. There is an immense number of encoded memories within the storage of LTM. The challenge for memory retrieval is recalling the specific memory and working in the temporary workspace provided in STM. German psychologists continued in the field with Georg Elias Müller and Pilzecker in 1900 studying retroactive interference. To the confusion of Americans at a later date, Müller used "associative Hemmung" (inhibition) as a blanket term for retroactive and proactive inhibition.

In 1924, John G. Jenkins and Karl Dallenbach showed that everyday experiences can interfere with memory, employing an experiment that showed that retention was better throughout sleep than over the same amount of time devoted to the activity. The United States again made headway in 1932 with John A. McGeoch suggesting that decay theory should be replaced by an interference theory.

Proactive interference

Proactive interference is the interference of older memories with the retrieval of newer memories.

Context

Proactive interference build-up occurs with memories being learned in similar contexts. A common example is observing previous motor abilities from one skill interfering with a new set of motor abilities being learned in another skill from the initial. If the items or pairs to be learned are conceptually related to one another, then proactive interference has a greater effect. Delos Wickens discovered that proactive interference build-up is released when there is a change to the category of items being learned, leading to increased processing in STM. Presenting new skills later in practice can considerably reduce proactive interference desirable for participants to have the best opportunity to encode fresh new memories into LTM. Thus, using recent-probes task and fMRIs, the brain mechanisms involved in resolving proactive interference identify as the ventrolateral prefrontal cortex and the left anterior prefrontal cortex.

Research

With lists

Researchers have studied the joint influence of proactive and retroactive interference using a list of items to be remembered. As expected, the recall was hampered by increasing the number of items in a given list. Proactive interference also affected learning when dealing with multiple lists. Researchers had participants learn a list of ten paired adjectives. The experimenters would consider a list to be learned if the participant could correctly recall eight of the ten items. After two days, participants could recall close to 70% of the items. However, those asked to memorize a new list the day after learning the first one had a recall of only 40%. Those who learned a third list recalled 25% of the items. Therefore, proactive interference affected the correct recall of the last list learned, because of the previous one, or two. In terms of forgetting, the effect of proactive interference was supported by further studies using different methods. The effect of proactive interference was reduced when the test was immediate and when the new target list was different from the previously learned lists.

Span performance

Span performance refers to working memory capacity. It is hypothesized that span performance is limited in language comprehension, problem-solving, and memory. Proactive Interference affects susceptibility to span performance limitations, as span performance in later experimental trials were worse than performance in earlier trials. With single tasks, proactive interference had less effect on participants with high working memory spans than those with low ones. With dual tasks, both types were similarly susceptible.

To differ, others have tried to investigate the relation of proactive interference when cued to forget. Turvey and Wittlinger designed an experiment to examine the effects of cues such as "not to remember" and "not to recall" with currently learned material. While "not to remember" had a significant effect in reducing proactive interference, cued to "not to recall" previously encoded and stored information did not significantly reduce the effect. Therefore, these associated cues do not directly control the potential effect of proactive interference on short-term memory span.

Proactive interference has shown an effect during the learning phase in terms of stimuli at the acquisition and retrieval stages with behavioral tasks for humans, as found by Castro, Ortega, and Matute. With 106 participants, they investigated two main questions: if two cues are learned as predictors of the same outcome (one after the other), would the second-cue outcome association be retarded? And secondly, once the second association is fully learned, will there still be an effect on subsequent trials? The research, as predicted, showed retardation and impairment in associations, due to the effect of Proactive Interference.

Retroactive interference

Retroactive interference, also known as Retroactive inhibition, is the interference of newer memories with the retrieval of older memories. These memory research pioneers demonstrated that filling the retention interval (defined as the amount of time that occurs between the initial learning stage and the memory recall stage) with tasks and material caused significant interference effects with the primary learned items.

As compared to proactive interference, retroactive interference may have larger effects because there is not only competition involved but also unlearning.

Iconic research

Modified (free) recall

Briggs's (1954) study modeled McGeoch's work on interference by setting the stage for a classic design of retroactive interference. In his study, participants were asked to learn 12 paired associates to a criterion of 100%. To ensure parsimony, these pairs can be labeled as A₁-B₁-, A₂-B₂-...A_I-B_I (also called AB/AC paradigm). Briggs used a "modified free recall" technique by asking participants to recall an item when cued with B_I. Over multiple anticipation trials, participants learned B_I items through the prompt of B_I items. After perfecting A_I- B_I learning, participants were given a new list of paired associates to learn; however B_I items were replaced with C_I items (now given a list of A₁-C₁-, A₂-C₂-...A_I-C_I). As the learning of A_I-C_I pairs increased, the learning of A_I-B_I pairs decreased. Eventually recalling the C_I items exceeded the recall of the B_I items, representing the phenomenon of retroactive interference.

A significant part of Briggs's (1954) study was that once participants were tested after a delay of 24 hours the Bi responses spontaneously recovered and exceeded the recall of the Ci items. Briggs explained the spontaneous recovery illustration as an account of A_I-B_I items competing with A_I-C_I items or, as McGeoch would define it: "a resultant [of] momentary dominance".

Modified modified free recall

J.M. Barnes and B.J. Underwood (1959) expanded Briggs's (1954) study by implementing a similar procedure. The main difference in this study, however, was that, unlike Briggs's (1954) "modified free recall" (MFR) task where participants gave one-item responses, Barnes and Underwood asked participants to give both List 1 and List 2 responses to each cued recall task. Participants' ability to recall both items was termed the "modified modified free recall" (MMFR) technique. Equivocally to Briggs's (1954) results, RI occurred when C_I recalled responses gradually came to exceed B_I responses. Barnes and Underwood argued that because there was "unlimited recall time" to produce multiple-item responses, the fact that A_I-C_I responses still trumped A_I-B_I responses represented an account of unlearning.

Notable research concepts

Forgetting

Since German psychologist H. Ebbinghaus (1885, 1913) made the first scientific studies on forgetting in the late nineteenth century, further research on the rate of forgetting presented information was found to be steep. The study found that adults 55–67 years of age showed less magnetic activity in their prefrontal cortices than the control group. Executive control mechanisms are located in the frontal cortex and deficits in working memory show changes in the functioning of this brain area. The researcher found that the presentation of subsequent stimuli in succession causes a decrease in recalled accuracy. Researchers found that retroactive interference affects the performance of old motor movements when newly acquired motor movements are practiced.

Word tasks

Retroactive Interference increases when the items are similar, therefore increasing association between them as shown by spreading activation. Barnes and Underwood found that when participants in the experimental condition were presented with two similar word lists, the recollection of the first-word list decreased with the presentation of the second-word list. An example scenario in which Output Interference might occur would be if one had created a list of items to purchase at a grocery store, but then, neglected to take the list when leaving home. The act of remembering a couple of items on that list decreases the probability of remembering the other items on that list.

Research

Short-term memory

Henry L. Roediger III and Schmidt found that the act of retrieval can serve as the source of the failure to remember, using multiple experiments that tested the recall of categorized and paired associative lists. Three experiments were carried out where subjects were first presented with category lists, and then, asked to recall the items in the list after being shown the category name as a cue. He conducted multiple experiments to determine the input conditioned necessary to produce Output Interference. The results of recall performance revealed significant differences due to age where the older group recalled fewer items than the middle group who recalled fewer items than the youngest group. Although it was also indicated that older adults had an increased susceptibility to output interference compared to younger adults and the difference increased as additional items were recalled. This is to say that although you remember a specific detail, over time you may have greater difficulty retrieving the detail you encoded. It has been suggested that the time interval between encoding and retrieval determines the accuracy of recall.

A practical example of decay theory is seen in the financial sector. If you open a bank account and do not deposit or withdraw money from the account, after some time, the bank will render the account dormant. The owner of the account, then, has to reopen the account for it to remain active. The bank account (the memory) is rendered dormant (the memory weakened) over time if there is no activity on the account (if the memory is not retrieved after some time).

Similarities

Decay theory is similar to interference theory in the way that old memories are lost over time. Memories are lost in Decay Theory by the passing of time. In Interference Theory, memories are lost due to newly acquired memories. Both Decay and Interference Theories are involved in psychological theories of forgetting.

Differences

Decay and interference theory differ in that Interference Theory has a second stimulus that impedes the retrieval of the first stimulus. Decay Theory is caused by time itself. Decay Theory is a passive method of forgetting as no interference is produced. Interference Theory is an active process because the act of learning new information directly impedes the recollection of previously stored information.

Dual task interference

Dual-task interference is a kind of interference that occurs when two tasks are attempted simultaneously. Harold Pashler wrote a paper summing up the theoretical approaches to dual-task interference. The basis of his research looked at when one attempts two or more tasks at the same time, why in some cases is one successful in completing their task and in other cases not. This is the concept of Interference Theory. The thoughts, outputs, and side effects of one task either affect the previous or subsequent recall.

Neurobiology

thumb|right|alt=MRI brain|MRI of a human brain

Event-related fMRI studies

thumb|left|alt=Caudate Nucleus in red|[[Caudate Nucleus highlighted in red]]

Stroop and Simon task

The performance of Stroop and Simon tasks were monitored on 10 healthy young adults using magnetic resonance image (MRI) scanning. Functional images were acquired at specific time intervals during each subject's scan.

Reducing competitive ad interference

Repetition improves brand name recall when presented alone. When competitive advertising was presented, it was shown that repetition provided no improvement in brand name recall over a single exposure. The competitive ads interfered with the added learning from repetition. However, when the target brand name was shown using varying ad executions interference was reduced. Presenting ads in multi-modalities (visual, auditory) will reduce possible interference because there are more associations or paths to cue recall than if only one modality had been used. This is the principle of multimedia learning. Also, interference is increased when competing ads are presented in the same modality. Therefore, by presenting ads in multiple modalities, the chance that the target brand has unique cues is increased.

See also

• Neuroimaging
• Working memory
• Memory inhibition
• Memory conformity
• Einstellung effect
• Language transfer (interference between languages)
• Forgetting curve
• Between-systems memory interference model

References

• Bjork, R. A. (1992). Interference and memory. In L. R. Squire (Ed.), Encyclopedia of learning and memory (pp. 283–288). New York: Macmillan.