Proactive Interference Effects Research Articles

Generic cognitive adaptations to task interference in task switching

The present study investigated how the activation of previous tasks interferes with the execution of future tasks as a result of temporal manipulations. Color and shape matching tasks were organized in runs of two trials each. The tasks were specified by a cue presented before a task run, cueing only the first trials of each run. Response times (RTs) and error rates were measured for task switching and task repetition conditions. Task interference was varied as a function of response-cue interval (RCI of 300 and 900 ms), that is, the interval between the task runs. Keeping the response–stimulus interval within the task runs constant at 300 ms allowed the disentangling of the direct effects of RCI manipulation on performance (first trials) from the general effects on performance (both trials in the run). The data showed similar performance improvement due to RCI increase on both trials in the task run. Furthermore, increasing RCI improved both switch and repetition performance to a similar extent. Together, our findings provide further evidence for accounts stressing generic effects of proactive task interference in task switching.

General proactive interference and the N450 response

Strategic repetition of verbal stimuli can effectively produce proactive interference (PI) effects in the Sternberg working memory task. Unique fronto-cortical activation to PI-eliciting letter probes has been interpreted as reflecting brain responses to PI. However, the use of only a small set of stimuli (e.g., letters and digits) requires constant repetition of stimuli in both PI and baseline trials, potentially creating a general PI effect in all conditions. We used event-related potentials to examine general PI effects by contrasting the interference-related frontal N450 response in two Sternberg tasks using a small versus large set size. We found that the N450 response differed significantly from baseline during the small set-size task only for response-conflict PI trials but not when PI was created solely from stimulus repetition. During the large set-size task N450 responses in both the familiarity-based and response-conflict PI conditions differed from baseline but not from each other. We conclude that the general stimulus repetition inherent in small set-size conditions can mask effects of familiarity-based PI and complicate the interpretation of any associated neural response.

The effects of ongoing activity on time estimation in prospective remembering

AbstractTwo experiments examined whether time‐based prospective memory performance is influenced by the continuous or discontinuous nature of an ongoing activity. The first experiment demonstrated that prospective memory performance was not influenced by the engagement in continuous or discontinuous ongoing activity. The second experiment demonstrated that a discontinuous ongoing activity negatively affected prospective memory performance when participants had to execute two time‐based tasks for which the retention intervals partially overlapped. The results suggest that when individuals are engaged in multiple time‐based tasks, a general timing disruption occurs, with a proactive interference effect resulting in costs that are detrimental to prospective timing. Copyright © 2009 John Wiley & Sons, Ltd.

Interference Effects on Commonly Used Memory Tasks

This paper reports two studies which investigated the effect of interference on delayed recall scores of the WMS-III and other commonly used memory measures. In Study 1, participants completed the immediate and delayed components of the WMS-III, with or without the introduction of conceptually similar memory tasks between the recall trials. In Study 2, this order of administration was reversed, with the WMS-III subtests used as the interference items. The results indicated that the introduction of interference items during the delay negatively affected delayed recall performance on almost all sub-tests. In addition, equal effects of proactive and retroactive interference were demonstrated. These findings raise concerns regarding the standardization process for memory tasks and highlight the need to consider interference effects in clinical practice, and stand as a caution in the use of memory-related materials during the delay interval in memory testing.

Variables Affecting Memory Deficits in Relapsing-Remitting Multiple Sclerosis

Memory impairment features prominently among the cognitive problems caused by Multiple Sclerosis (MS). In the present study 33 patients diagnosed with the relapsing-remitting form of MS and 30 controls matched on age, education, gender, and IQ were tested on measures of verbal learning (immediate and delayed recall of word lists and short stories), and lexical retrieval from long term memory (verbal fluency tests). MS patients demonstrated significant deficits in both immediate and delayed recall ability as well as in verbal fluency. Group differences in delayed verbal recall depended upon initial encoding ability of the same material, with the exception of delayed recall of the Wechsler Memory Scale Logical Memory story B. This finding may have been due to greater susceptibility of MS patients to the effects of proactive interference. Verbal fluency deficits appeared to depend upon a general impairment in the speed of information processing.

Visual Working Memory Capacity and Proactive Interference

BackgroundVisual working memory capacity is extremely limited and appears to be relatively immune to practice effects or the use of explicit strategies. The recent discovery that visual working memory tasks, like verbal working memory tasks, are subject to proactive interference, coupled with the fact that typical visual working memory tasks are particularly conducive to proactive interference, suggests that visual working memory capacity may be systematically under-estimated.Methodology/Principal FindingsWorking memory capacity was probed behaviorally in adult humans both in laboratory settings and via the Internet. Several experiments show that although the effect of proactive interference on visual working memory is significant and can last over several trials, it only changes the capacity estimate by about 15%.Conclusions/SignificanceThis study further confirms the sharp limitations on visual working memory capacity, both in absolute terms and relative to verbal working memory. It is suggested that future research take these limitations into account in understanding differences across a variety of tasks between human adults, prelinguistic infants and nonlinguistic animals.

Scopolamine infused into perirhinal cortex improves object recognition memory by blocking the acquisition of interfering object information.

In a previous study, we reported apparently paradoxical facilitation of object recognition memory following infusions of the cholinergic muscarinic receptor antagonist scopolamine into the perirhinal cortex (PRh) of rats. We attributed these effects to the blockade by scopolamine of the acquisition of interfering information. The present study tested this possibility directly by modifying the spontaneous object recognition memory task to allow the presentation of a potentially interfering object either before the sample phase or in the retention delay between the sample and choice phases. Presentation of an object between the sample and choice phases disrupted subsequent recognition of the sample object (retroactive interference), and intra-PRh infusions of scopolamine prior to the presentation of the irrelevant object prevented this retroactive interference effect. Moreover, presentation of an irrelevant object prior to the sample phase interfered proactively with sample object recognition, and intra-PRh infusions of scopolamine prior to the presentation of the pre-sample object prevented this proactive interference effect. These results suggest that blocking muscarinic cholinergic receptors in PRh can disrupt the acquisition of potentially interfering object information, thereby facilitating object recognition memory. This finding provides further, strong evidence that acetylcholine is important for the acquisition of object information in PRh.

Control processes in verbal working memory: An event-related potential study

Event-related potentials (ERPs) were recorded using a large electrode array while subjects engaged in tasks designed to dissociate control from storage/maintenance processes in verbal working memory (WM). Increased ERP negativity (450–900 ms post-stimulus onset) over left frontal regions emerged only when required dynamic updating/revision of WM stores was initiated, with augmentation of right frontal negativity in the same epoch relative to more general overall task demands. Increased ERP positivity in a similar time window over parietal regions reflected initiation of required rehearsal/maintenance of memory set contents, with progressive amplitude increases with repeated dynamic updating/revision of memory stores, suggesting increased effortful activity to resist proactive interference effects. These findings are consistent with a left frontal-parietal network for process control in verbal working memory.

Direct evidence for a prefrontal contribution to the control of proactive interference in verbal working memory

Controlling the effects of proactive interference (PI), the deleterious effect of prior mental activity on current memory representations, is believed to be a key function of the prefrontal cortex. This view is supported by neuroimaging evidence for a correlation between the longer reaction times caused by high PI conditions of a working memory task and increased activity in left inferior frontal gyrus (IFG) of the prefrontal cortex. An alternative that has never been ruled out, however, is that this left IFG effect may merely reflect sensitivity to such nonspecific factors as difficulty and/or time on task. To resolve this confound, we applied the interference methodology of repetitive transcranial magnetic stimulation (rTMS) to the left IFG and two control regions while subjects performed delayed letter recognition. rTMS was guided with high-resolution magnetic resonance images and was time-locked to the onset of the memory probe. The effect of rTMS, a disruption of accuracy restricted to high-PI probes, was specific to the left IFG. These results demonstrate that unpredictable, phasic disruption of the left IFG selectively disrupts control of responses to high-conflict verbal working memory probes, and they conclusively reject nonspecific alternative accounts.

New Scores for the Category Test: Measures of Interference for Subtests 5 and 6

The Category Test is a well-known neuropsychological instrument used to assess concept formation and higher executive abilities. The present study investigated the utility of additional scores for the Category Test. We used principles developed in cognitive psychology to create several new measures for subtests 5 and 6 of this test. These scores were primarily designed to be sensitive to interference effects of learning decision rules from subtest 2, subtest 3, and subtest 4. The new scores as well as the total error scores from subtests 5 and 6 were used to discriminate subjects with documented brain injury from subjects who were neurologically normal based on neuroimaging and neurologic evaluation. The Category Test was given following Reitan's (1979) instructions, with the exception that no additional prompting was given to participants who struggled early with the test in order to reduce the “executive” guidance of the examiner. Because any “interference” from earlier subtests on performance of subtest 5 and subtest 6 should be related to mastery of these earlier subtests, the normal group was matched to the brain-impaired group on which subtest(s) they learned. This resulted in four learning groups: (a) learned subtests 3 and 4; (b) learned subtest 4 but not 3; (c) learned subtest 3 but not 4; and (d) failed to learn either subtest. ANOVA analyses revealed that the three measures of interference were significantly greater in the brain-damaged group than in the normal controls. Also, specific interference measures were related to specific prior subtest mastery, thus providing support for a proactive interference effect. In addition, we have evidence that our new measures may be selectively sensitive to frontal system dysfunction.

Proactive interference and cuing effects in short-term cued recall: Does foil context matter?

Tehan and Humphreys's (1995, 1996) short-term cued recall paradigm showed that recall in short-term memory is cue driven. In critical trials, the participants studied two blocks of four words each and were required to forget the first block while remembering the second block. A foil in the first block (e.g., orange) was related to a target (e.g., carrot) in the second block. Proactive interference (PI) was evident when a retrieval cue was used that subsumed the foil and the target (e.g., type of juice), but not when a cue was used that subsumed only the target (e.g., type of vegetable). Four experiments were performed to examine the extent to which contextual organization in the foil block would enhance or diminish the foil's efficacy in creating PI. A novel condition was included in which the words in the foil block were studied in a phonologically related context but the target was cued semantically, and vice versa with a semantic context and phonological cue. There were no differences in recall accuracy between conditions with and without contextual organization, but reliable increases in foil intrusions were observed when contextual organization was present. Contextual organization enhanced the foil, rather than diminished it, but the strengthened foil generated PI only when the cue subsumed the foil and the target and had no effect when the cue subsumed only the target. The results are consistent with a cue-driven retrieval interpretation of short-term recall.

The role of proactive interference in mnemonic techniques

The success of many mnemonic techniques, such as the method of loci, is based on the use of specific well-known anchors, which are mentally combined with to-be-learned items and subsequently facilitate their retrieval. In our studies we intended to answer the question of whether the repeated application of the method of loci may result in proactive interference effects, as might be expected due to the applied association of items with the same loci each time the method is used. To this end, we manipulated list similarity in a typical proactive interference design and compared the method of loci with the link method and the rehearsal method, which do not involve the use of a specified set of anchors. Our results replicate those from other studies, which have shown that the use of a mnemonic technique leads to superior recall of list items compared to a simple rehearsal strategy. We were further able to show that the repeated learning of items from different categories results in moderate practice effects over three list-learning trials, whereas this effect is superimposed by an effect of proactive interference if different lists are composed of items from the same category. However, this effect of proactive interference was not increased for the method of loci, and we discuss this finding with regard to its practical implications.

When East meets West: the effect of cultural tone congruity in ad music and message on consumer ad memory and attitude

Research on the effect of congruity between an ad’s message and its background music on consumer memory indicates that ad music that is congruent with an ad’s message can enhance the consumer’s memory of the ad. Based on Heckler and Childers’ (1992) study on the nature of incongruity, we suggest that cultural tone incongruity between an ad’s message and its music can also lead to better ad memory. We demonstrate that East/West cultural tone incongruity between an ad’s message and its music does increase the consumer’s memory for the target ad, but it can also have an adverse effect on consumers’ attitudes towards the ad. This memory enhancement effect is stronger for high-attention respondents than for low-attention respondents. Moreover, the incongruity also leads to retroactive memory interference for the ad that immediately precedes the target ad. However, the predicted effect of proactive memory interference for the ad following the target ad was not found. Finally, the academic and managerial implications of the study for global product advertising are discussed.

Memory hazard functions: A vehicle for theory development and test.

A framework is developed to rigorously test an entire class of memory retention functions by examining hazard properties. Evidence is provided that the memory hazard function is not monotonically decreasing. Yet most of the proposals for retention functions, which have emerged from the psychological literature, imply that memory hazard is monotonically decreasing over the entire temporal range. Furthermore, the few remaining proposals, that do not have monotonically decreasing hazard, have difficulty fitting data over both short-term and long-term intervals. A new 2-trace hazard model is developed that successfully circumvents these difficulties. This new model is used to account for the size of memory span and the time course of proactive and retroactive interference effects. The model can fit the retention characteristics of H. M., the famous amnesic patient, as well as normal experimental participants. The model is also used to account for the time course of the misinformation effect.

Memory interference in multiple sclerosis

To explore verbal memory impairments associated with multiple sclerosis (MS), we compared proactive and retroactive interference effects on the California Verbal Learning Test (CVLT; Delis et al., 1987) in a sample of 83 community-residing individuals with MS and 80 healthy participants. Individuals with MS demonstrated normal accumulation of proactive interference (PI), but attenuated release from PI relative to healthy individuals. Furthermore, accumulation of retroactive interference (RI) at short-delay free recall (SDFR) was intensified for those with MS as compared to healthy participants. Interestingly, accumulation of RI predicted long-term memory (LTM) only for participants with MS. These findings suggest that individuals with MS may experience particular difficulty when required to use semantic properties of information flexibly to facilitate verbal LTM.

The neural bases of the effects of item-nonspecific proactive interference in working memory.

We reanalyzed the behavioral and fMRI data from seven previously published studies of working memory in order to assess the behavioral and neural effects of item-nonspecific proactive interference (PI; attributable to the accrual of antecedent information independent of the repetition of particular items). We hypothesized that item-nonspecific PI, implicated in age-related declines in working memory performance, is mediated by the same mechanism(s) that mediate item-specific PI (occurring when an invalid memory probe matches a memorandum from the previous trial). Reaction time increased across trials as a function of position within the block, a trend that reversed across the duration of each multiblock experiment. The fMRI analyses revealed sensitivity to item-nonspecific PI during the probe epoch in the left anterior inferior frontal gyrus and the left dorsolateral prefrontal cortex(PFC). They also revealed a negative trend, across trials, in the transient probe-evoked component of the global signal. A common PFC-based mechanism may mediate many forms of PI.

Asymmetric Interference Effects in Fragment Completion: The Consequences of Recognition Failures and Successes

We examined the extent to which implicit and explicit memory performance is susceptible to the effects of proactive and retroactive interference produced by orthographic similarity. Participants studied target and nontarget words that were orthographically similar or dissimilar. At test, they were given fragments of the target words intermixed with fragments of nonstudied words. Participants' initial task was to determine whether each fragment was a studied word. If they recognized it, they were to complete the fragment with the studied word; if not, they were to complete the fragment with the first word that came to mind. Completion rates including both recognized and nonrecognized target fragments provided evidence of proactive but not retroactive interference. The implicit processing engaged by the nonrecognized target fragments was found to be the primary source of the proactive interference effect.

Semantic Interference in Mild Alzheimer Disease: Preliminary Findings

<h3>OBJECTIVE</h3> The authors evaluated the usefulness and psychometric properties of the Semantic Interference Test (SIT) in patients with mild Alzheimer disease (AD). <h3>METHODS</h3> Subjects were first presented with 10 common objects to be learned over three trials. Proactive interference was assessed by having subjects recall 10 new objects that were semantically related to the previous ones. Retroactive interference was assessed by having subjects recall the original 10 objects. <h3>RESULTS</h3> Controlling for overall memory impairment, very mildly impaired AD patients demonstrated significantly greater proactive and retroactive interference effects than the normal, community-dwelling comparison group. The proactive score alone and the combined proactive-plus-retroactive score index were more effective than traditional neuropsychological measures of delayed recall in distinguishing between the very mildly impaired AD group and the normal-comparison group. <h3>CONCLUSION</h3> The authors discuss the potential usefulness of the SIT in identifying vulnerability to semantic interference in early AD.

Semantic Interference in Mild Alzheimer Disease: Preliminary Findings

The authors evaluated the usefulness and psychometric properties of the Semantic Interference Test (SIT) in patients with mild Alzheimer disease (AD). Subjects were first presented with 10 common objects to be learned over three trials. Proactive interference was assessed by having subjects recall 10 new objects that were semantically related to the previous ones. Retroactive interference was assessed by having subjects recall the original 10 objects. Controlling for overall memory impairment, very mildly impaired AD patients demonstrated significantly greater proactive and retroactive interference effects than the normal, community-dwelling comparison group. The proactive score alone and the combined proactive-plus-retroactive score index were more effective than traditional neuropsychological measures of delayed recall in distinguishing between the very mildly impaired AD group and the normal-comparison group. The authors discuss the potential usefulness of the SIT in identifying vulnerability to semantic interference in early AD.

Proactive interference effects on sentence production.

Proactive interference refers to recall difficulties caused by prior similar memory-related processing. Information-processing approaches to sentence production predict that retrievability affects sentence form: Speakers may word sentences so that material that is difficult to retrieve is spoken later. In this experiment, speakers produced sentence structures that could include an optional that, thereby delaying the mention of a subsequent noun phrase. This subsequent noun phrase was either (1) conceptually similar to three previous noun phrases in the same sentence, leading to greater proactive interference, or (2) conceptually dissimilar, leading to less proactive interference. Speakers produced more thats (and were more disfluencies) before conceptually similar noun phrases, suggesting that retrieval difficulties during sentence production affect the syntactic structures of sentences that speakers produce.