Prior-list Intrusions Research Articles

No position-specific interference from prior lists in cued recognition: A challenge for position coding (and other) theories of serial memory

Position-specific intrusions of items from prior lists are rare but important phenomena that distinguish broad classes of theory in serial memory. They are uniquely predicted by position coding theories, which assume items on all lists are associated with the same set of codes representing their positions. Activating a position code activates items associated with it in current and prior lists in proportion to their distance from the activated position. Thus, prior list intrusions are most likely to come from the coded position. Alternative “item dependent” theories based on associations between items and contexts built from items have difficulty accounting for the position specificity of prior list intrusions. We tested the position coding account with a position-cued recognition task designed to produce prior list interference. Cuing a position should activate a position code, which should activate items in nearby positions in the current and prior lists. We presented lures from the prior list to test for position-specific activation in response time and error rate; lures from nearby positions should interfere more. We found no evidence for such interference in 10 experiments, falsifying the position coding prediction. We ran two serial recall experiments with the same materials and found position-specific prior list intrusions. These results challenge all theories of serial memory: Position coding theories can explain the prior list intrusions in serial recall and but not the absence of prior list interference in cued recognition. Item dependent theories can explain the absence of prior list interference in cued recognition but cannot explain the occurrence of prior list intrusions in serial recall.

Serial order depends on item-dependent and item-independent contexts.

We address four issues in response to Osth and Hurlstone's (2022) commentary on the context retrieval and updating (CRU) theory of serial order (Logan, 2021). First, we clarify the relations between CRU, chains, and associations. We show that CRU is not equivalent to a chaining theory and uses similarity rather than association to retrieve contexts. Second, we fix an error Logan (2021) made in accounting for the tendency to recall ACB instead of ACD in recalling ABCDEF (fill-in vs. in-fill errors, respectively). When implemented correctly, the idea that subjects mix the current context with an initial list cue after the first order error correctly predicts that fill-in errors are more frequent than in-fill errors. Third, we address position-specific prior-list intrusions, suggesting modifications to CRU and introducing a position-coding model based on CRU representations to account for them. We suggest that position-specific prior-list intrusions are evidence for position coding on some proportion of the trials but are not evidence against item coding on other trials. Finally, we address position-specific between-group intrusions in structured lists, agreeing with Osth and Hurlstone that reasonable modifications to CRU cannot account for them. We suggest that such intrusions support position coding on some proportion of the trials but do not rule out CRU-like item-based codes. We conclude by suggesting that item-independent and item-dependent coding are alternative strategies for serial recall and we stress the importance of accounting for immediate performance. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Testing potential mechanisms underlying test-potentiated new learning.

An emerging body of studies demonstrates that practicing retrieval of studied information, by comparison with restudying or no treatment, can facilitate subsequent learning and retrieval of new information, a phenomenon termed the forward testing effect (FTE) or test-potentiated new learning. Several theoretical explanations have been proposed to account for the FTE. A release-from-PI theory proposes that interpolated testing induces context changes and enhances event segregation, which in turn protect new learning from proactive interference (PI). A strategy-change view hypothesizes that prior tests teach learners to adopt more effective/elaborative learning and retrieval strategies in subsequent study and test phases. Finally, a reset-of-encoding account proposes that interim testing on studied information reduces memory load, resets the subsequent encoding process, and enhances encoding of new information. The current study recruited a large sample (over 1,000 participants) and employed a multilist learning task and mediation analyses to test these theories. The results suggest that prior list intrusions (an index of PI) significantly mediated the FTE, supporting the release-from-PI theory. In addition, interim testing enhanced strategic processing of temporal information during new learning (reflected by increased clustering), and temporal clustering significantly mediated the FTE, supporting a role for strategy-change in the FTE. Lastly, a variety of indices were constructed to represent the benefit of reset-of-encoding, but none of them provided evidence supporting the reset-of-encoding view. The results shed new light on the complex mechanisms underlying the forward benefits of testing. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Direct brain recordings identify hippocampal and cortical networks that distinguish successful versus failed episodic memory retrieval

Human data collected using noninvasive imaging techniques have established the importance of parietal regions towards episodic memory retrieval, including the angular gyrus and posterior cingulate cortex. Such regions comprise part of a putative core episodic retrieval network. In free recall, comparisons between contextually appropriate and inappropriate recall events (i.e. prior list intrusions) provide the opportunity to study memory retrieval networks supporting veridical recall, and existing findings predict that differences in electrical activity in these brain regions should be identified according to the accuracy of recall. However, prior iEEG studies, utilizing principally subdural grid electrodes, have not fully characterized brain activity in parietal regions during memory retrieval and have not examined connectivity between core recollection areas and the hippocampus or prefrontal cortex. Here, we employed a data set obtained from 100 human patients implanted with stereo EEG electrodes for seizure mapping purposes as they performed a free recall task. This data set allowed us to separately analyze activity in midline versus lateral parietal brain regions, and in anterior versus posterior hippocampus, to identify areas in which retrieval-related activity predicted the recollection of a correct versus an incorrect memory. With the wide coverage afforded by the stereo EEG approach, we were also able to examine interregional connectivity. Our key findings were that differences in gamma band activity in the angular gyrus, precuneus, posterior temporal cortex, and posterior (more than anterior) hippocampus discriminated accurate versus inaccurate recall as well as active retrieval versus memory search. The left angular gyrus exhibited a significant power decrease preceding list intrusions as well as unique phase–amplitude coupling properties, whereas the prefrontal cortex was unique in exhibiting a power increase during list intrusions. Analysis of connectivity revealed significant hemispheric asymmetry, with relatively sparse left-sided functional connections compared to the right hemisphere. One exception to this finding was elevated connectivity between the prefrontal cortex and left angular gyrus. This finding is interpreted as evidence for the engagement of prefrontal cortex in memory monitoring and mnemonic decision-making.

Testing enhances subsequent learning in older adults.

Interference susceptibility has been suggested to be a major factor for episodic memory impairment in healthy older adults. Previous work has shown that retrieval practice can reduce proactive interference and thus enhance learning and memory in younger adults, a finding referred to as the forward effect of testing in the literature. This study examined the late developmental trajectory of the forward effect in middle-aged and older adults (40 to 79 years of age). Participants studied three lists of items in anticipation of a final cumulative recall test. In the testing condition, participants were tested immediately on Lists 1 and 2 after initial study, whereas in the restudy condition, they restudied Lists 1 and 2. In both conditions, participants were tested immediately on List 3. The results of the immediate List-3 recall test showed a reliable forward effect of testing, with interim testing of Lists 1 and 2 enhancing List-3 recall and reducing the number of prior-list intrusions. Notably, this effect of testing was found independent of participants' age. These results suggest that retrieval practice can reduce proactive interference in middle-aged and older adults. Together with recent findings on the presence of the backward effect of testing in older adults-that is, improved recall of studied material after retrieval versus restudy, these findings indicate that retrieval practice can be a very powerful tool to delimit memory impairment in older age. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Reduced interference from memory testing: A postretrieval monitoring account.

Initial learning can interfere with subsequent learning (proactive interference [PI]), but recent work indicates initial testing can reduce PI. Here, we tested 2 alternative hypotheses of this effect: Does testing reduce PI by constraining retrieval to the target list, or by facilitating a postretrieval monitoring process? Participants first studied 4 lists of unrelated words. The study-only group performed a distractor task following each list, whereas the tested group recalled each list. After these initial lists, both groups studied and were tested on a final list. Replicating prior work, the tested group recalled more of the final list items and had fewer prior-list intrusions than the study-only group (i.e., initial testing reduced subsequent PI). To test the 2-alternative hypotheses, Experiment 1 used a modified recall test for the final list, whereby participants were asked to recall the final list of words and also report any items from prior lists that inadvertently came to mind. Contrary to the constrained retrieval hypothesis, initial testing did not reduce the number of prior list items that came to mind, but consistent with the postretrieval monitoring hypothesis, testing increased the likelihood that the intrusions would be correctly attributed to prior lists. Experiments 2 and 3 further tested the postretrieval monitoring hypothesis by testing the final list twice. According to the hypothesis, testing all of the lists should render prior testing nondiagnostic of list membership, thereby impairing retrieval monitoring in the test group and minimizing its ability to reduce PI. This prediction was confirmed. (PsycINFO Database Record

Expanding the scope of memory search: Modeling intralist and interlist effects in free recall.

The human memory system is remarkable in its capacity to focus its search on items learned in a given context. This capacity can be so precise that many leading models of human memory assume that only those items learned in the context of a recently studied list compete for recall. We sought to extend the explanatory scope of these models to include not only intralist phenomena, such as primacy and recency effects, but also interlist phenomena such as proactive and retroactive interference. Building on retrieved temporal context models of memory search (e.g., Polyn, Norman, & Kahana, 2009), we present a substantially revised theory in which memory accumulates across multiple experimental lists, and temporal context is used both to focus retrieval on a target list, and to censor retrieved information when its match to the current context indicates that it was learned in a nontarget list. We show how the resulting model can simultaneously account for a wide range of intralist and interlist phenomena, including the pattern of prior-list intrusions observed in free recall, build-up of and release from proactive interference, and the ability to selectively target retrieval of items on specific prior lists (Jang & Huber, 2008; Shiffrin, 1970). In a new experiment, we verify that subjects' error monitoring processes are consistent with those predicted by the model.

Prior-list intrusions in serial recall are positional.

Henson (1996) provided a number of demonstrations of error patterns in serial recall that contradict chaining models. One such error pattern concerned when participants make intrusions from prior lists: Rather than originating from random positions in the prior list, intrusions tend to be recalled in the same position as their position in the prior list, a finding which led to the endorsement of positional models of serial recall. However, all of the demonstrations of positional intrusions occurred in designs in which relatively small sets of items were repeatedly employed as stimuli. In recent years, a number of investigations have found evidence for chaining in designs in which large sets of items are employed and items are never reused across trials (open sets). We conducted 2 experiments using open sets of items to test whether a pure chaining model is a viable model for open-set conditions. Both experiments revealed that intrusions from the immediately preceding list exhibited a strong tendency to be output in the same position as their position in the prior list, suggesting the usage of positional representations in open-set designs. A chaining model that lacks positional representations provides an inadequate account of serial recall in open-set conditions.

The role of test expectancy in the build-up of proactive interference in long-term memory.

We examined the hypothesis that interpolated testing in a multiple list paradigm protects against proactive interference by sustaining test expectancy during encoding. In both experiments, recall on the last of 5 word lists was compared between 4 conditions: a tested group who had taken tests on all previous lists, an untested group who had not taken any tests on previous lists, and 2 other groups (one tested and the other untested) who were warned about the upcoming test prior to study of the fifth list. In both experiments, the untested/warned group performed significantly better than the untested/unwarned group on both correct recall and prior list intrusions but did not achieve the same recall accuracy as tested groups. In Experiment 2, an instruction manipulation check further narrowed the gap between the untested/warned group and the tested groups. In addition, we verified that a reduction in test expectancy indeed occurred in the untested group compared with the tested group by asking participants to indicate how likely they believed they were to receive a test on each studied list. These findings suggest that testing protects against proactive interference largely via attentional processes and/or more effective encoding.

Recall termination in free recall.

Although much is known about the dynamics of memory search in the free recall task, relatively little is known about the factors related to recall termination. Reanalyzing individual trial data from 14 prior studies (1,079 participants in 28,015 trials) and defining termination as occurring when a final response is followed by a long nonresponse interval, we observed that termination probability increased throughout the recall period and that retrieval was more likely to terminate following an error than following a correct response. Among errors, termination probability was higher following prior-list intrusions and repetitions than following extralist intrusions. To verify that this pattern of results can be seen in a single study, we report a new experiment in which 80 participants contributed recall data from a total of 9,122 trials. This experiment replicated the pattern observed in the aggregate analysis of the prior studies.

PyParse: A semiautomated system for scoring spoken recall data

Studies of human memory often generate data on the sequence and timing of recalled items, but scoring such data using conventional methods is difficult or impossible. We describe a Python-based semiautomated system that greatly simplifies this task. This software, called PyParse, can easily be used in conjunction with many common experiment authoring systems. Scored data is output in a simple ASCII format and can be accessed with the programming language of choice, allowing for the identification of features such as correct responses, prior-list intrusions, extra-list intrusions, and repetitions.

The fSAM model of false recall.

The authors report a new theory of false memory building upon existing associative memory models and implemented in fSAM, the first fully specified quantitative model of false recall. Participants frequently intrude unstudied critical words while recalling lists comprising their strongest semantic associates but infrequently produce other extralist and prior-list intrusions. The authors developed the theory by simulating recall of such lists, using factorial combinations of semantic mechanisms operating at encoding, retrieval, or both stages. During encoding, unstudied words' associations to list context were strengthened in proportion to their strength of semantic association either to each studied word or to all co-rehearsed words. During retrieval, words received preference in proportion to their strength of semantic association to the most recently recalled single word or multiple words. The authors simulated all intrusion types and veridical recall for lists varying in semantic association strength among studied and critical words from the same and different lists. Multiplicative semantic encoding and retrieval mechanisms performed well in combination. Using such combined mechanisms, the authors also simulated several core findings from the Deese-Roediger-McDermott paradigm literature, including developmental patterns, specific list effects, association strength effects, and true-false correlations. These results challenge existing false-memory theories.

Temporal associations and prior-list intrusions in free recall.

When asked to recall the words from a just-presented target list, subjects occasionally recall words that were not on the list. These intrusions either appeared on earlier lists (prior-list intrusions, or PLIs) or had not appeared over the course of the experiment (extra-list intrusions). The authors examined the factors that elicit PLIs in free recall. A reanalysis of earlier studies revealed that PLIs tend to come from semantic associates as well as from recently studied lists, with the rate of PLIs decreasing sharply with list recency. The authors report 3 new experiments in which some items in a given list also appeared on earlier lists. Although repetition enhanced recall of list items, subjects were significantly more likely to make PLIs following the recall of repeated items, suggesting that temporal associations formed in earlier lists can induce recall errors. The authors interpret this finding as evidence for the interacting roles of associative and contextual retrieval processes in recall. Although contextual information helps to focus recall on words in the target list, it does not form an impermeable boundary between current- and prior-list experiences.

Pattern of intrusions in verbal recall: Comparison of Alzheimer's disease, Parkinson's disease, and frontal lobe dementia

Although some researchers have suggested that intrusions in word list learning are more frequent in Alzheimer's disease, recent studies have shown that this might not be true. In fact, intrusions are common in many neurological degenerative diseases. The goal of the present study was to examine the types of intrusions made by three groups of patients, namely patients with Parkinson's disease (PD), Alzheimer's disease (AD), and dementia with prominent frontal lobe semiology (FD). Although PD patients learned more words (trials 1 to 5 on the RAVLT) than the two other groups, there was no significant difference in the total number of intrusions. However, significant differences between groups were observed for nonrelated intrusions, the proportion of PD patients (15.4%) being lower than the proportion of AD (45.5%) and FD (45.8%) patients with this type of intrusions. No other type of intrusions (same category, recurring, phonemic) significantly differentiated between the three groups. The proactive interference effect (PI), measured as the difference between first recall of list A and list B recall, was stronger in PD than in the two other groups, reflecting the strong positive correlation between total number of words recalled on the RAVLT and severity of the PI effect. Prior list intrusions (intrusions from list A while recalling list B items) were significantly more pronounced in FD than in the two other groups. Finally, free associations (series of intrusions related to one another but not to the target items) were observed almost exclusively in FD patients. These findings illustrate some qualitative differences between various neurological degenerative diseases. They also stress the marked similarities between AD and FD with regards to verbal learning.

Response competition and interference effects in paired-associate learning by Korsakoff amnesics

Five Korsakoff amnesics and five non-amnesic alcoholics were compared in two studies in which they learnt semantically related paired-associate words in a negative transfer paradigm. The incidence of prior list intrusions was manipulated to determine the effect of response competition on new list learning. The results showed that impaired learning by amnesics was due to the effects of interference independent of response competition. It was suggested that amnesic patients suffer an exaggerated tendency to remain under the control of persistent mental sets and stimulus elements that could affect encoding and retrieval mechanisms.

The role of response confusion in proactive interference

In two experiments using the Brown-Peterson memory paradigm, various instructions to guess had small effects on recall, but sizeable effects on the incidence of prior list intrusions. Subjective confidence ratings indicated that prior list intrusions were generally known to be incorrect. In Experiment III, 24 subjects, who were required to recall items from the present and immediately preceding trial on each of 16 trials, recalled present trial items at the same level as subjects under normal conditions. Correlation analyses, intrusion analyses, and confidence rating analyses indicated no relation between recall of present and previous trial items. These results indicate that proactive interference is primarily the result of inability to generate correct items, rather than confusion between present and previous items.

Further evidence for a negative recency effect in free recall

The results of a previous experiment had indicated that the final words in a free-recall list were retrieved least well in a second recall session. This “negative recency effect” was found to hold for reminiscence items and, to some extent, for prior list intrusions in recall. Two further experiments showed that words retrieved in free recall were subsequently recognized less well if they had been presented late in their original input list. There was some evidence that a pattern of primacy and negative recency also held for the recognition of words not retrieved in free recall. It was concluded that terminal words in a free-recall list, although best recalled immediately, are thereafter least available in memory.