Memory Search Research Articles

Attending to items in working memory: evidence that refreshing and memory search are closely related.

Refreshing refers to the use of attention to reactivate items in working memory (WM). In the present study, we aimed to test the hypothesis that refreshing is closely related to memory search. The assumption is that refreshing and memory search both rely on a basic covert memory process that quickly retrieves the memory items into the focus of attention, thereby reactivating the information (Cowan, 1992; Vergauwe & Cowan, 2014). Consistent with the idea that people use their attention to prevent loss from WM, previous research has shown that increasing the proportion of time during which attention is occupied by concurrent processing, thereby preventing refreshing, results in poorer recall performance in complex span tasks (Barrouillet, Portrat, & Camos, Psychological Review, 118, 175-192, 2011). Here, we tested whether recall performance is differentially affected by prolonged attentional capture caused by memory search. If memory search and refreshing both rely on retrieval from WM, then prolonged attentional capture caused by memory search should not lead to forgetting, because memory items are assumed to be reactivated during memory search, in the same way that they would be if that period of time were used for refreshing. Consistent with this idea, prolonged attentional capture had a disruptive effect when it was caused by the need to retrieve knowledge from long-term memory, but not when it was caused by the need to search through the content of WM. The present results support the idea that refreshing operates through a process of retrieval of information into the focus of attention.

Induction of acetylation processes in animals with serotonergic neuron dysfunction reverses their capability of long-term memory formation

The major tasks of neurobiology include the understanding of mechanisms governing long-term memory formation and search for means to improve memory. Animals with dysfunction of the serotonergic system are a convenient model for investigation of memory processes. The ablation of serotonergic neurons by the neurotoxin 5,7-DOT leads to the inability of Helix snails to form an aversive food avoidance reflex. Previously we have found that epigenetic processes, such as histone methylation and acetylation, are involved in the formation of food aversion, and that disturbance of these processes leads to the inability to form long-term memory. The goal of this study was to investigate the possibility to reverse long-term memory in DOT-treated animals through the induction of acetylation processes. We found that treatment with histone deacetylase inhibitors NaB and Trichostatin A significantly increased the ability of DOT-treated animals to form the food aversion reflex. The results point to an important role of serotonin in the induction of the epigenetic processes mediating the formation of this type of long-term memory and to significantly improve its parameters by induction of acetylation processes. Our Neurodegeneration model, based on ablation of serotonergic neurons, can be useful in studies of the epigenetic mechanisms underlying long-term memory destruction and screening of compounds crucial for memory formation.

An exemplar-familiarity model predicts short-term and long-term probe recognition across diverse forms of memory search.

Experiments were conducted to test a modern exemplar-familiarity model on its ability to account for both short-term and long-term probe recognition within the same memory-search paradigm. Also, making connections to the literature on attention and visual search, the model was used to interpret differences in probe-recognition performance across diverse conditions that manipulated relations between targets and foils across trials. Subjects saw lists of from 1 to 16 items followed by a single item recognition probe. In a varied-mapping condition, targets and foils could switch roles across trials; in a consistent-mapping condition, targets and foils never switched roles; and in an all-new condition, on each trial a completely new set of items formed the memory set. In the varied-mapping and all-new conditions, mean correct response times (RTs) and error proportions were curvilinear increasing functions of memory set size, with the RT results closely resembling ones from hybrid visual-memory search experiments reported by Wolfe (2012). In the consistent-mapping condition, new-probe RTs were invariant with set size, whereas old-probe RTs increased slightly with increasing study-test lag. With appropriate choice of psychologically interpretable free parameters, the model accounted well for the complete set of results. The work provides support for the hypothesis that a common set of processes involving exemplar-based familiarity may govern long-term and short-term probe recognition across wide varieties of memory- search conditions.

Does the benefit of testing depend on lag, and if so, why? Evaluating the elaborative retrieval hypothesis.

Despite the voluminous literatures on testing effects and lag effects, surprisingly few studies have examined whether testing and lag effects interact, and no prior research has directly investigated why this might be the case. To this end, in the present research we evaluated the elaborative retrieval hypothesis (ERH) as a possible explanation for why testing effects depend on lag. Elaborative retrieval involves the activation of cue-related information during the long-term memory search for the target. If the target is successfully retrieved, this additional information is encoded with the cue-target pair to yield a more elaborated memory trace that enhances target access on a later memory test. The ERH states that the degree of elaborative retrieval during practice is greater when testing takes place after a long rather than a short lag (whereas elaborative retrieval during restudy is minimal at either lag). Across two experiments, final-test performance was greater following practice testing than following restudy only, and this memorial advantage was greater with long-lag than with short-lag practice. The final test also included novel cue conditions used to diagnose the degree of elaborative retrieval during practice. The overall pattern of performance in these conditions provided consistent evidence for the ERH, with more extensive elaborative retrieval during long- than during short-lag practice testing.

Ионно-молекулярная модель памяти. Механизмы поиска информации в библиотеке памяти

In the context of developed by the authors of the memory model, the mechanism of information search in the library memory were studied. The authors proposed consistent variants of such mechanisms from the positions of biophysics, chemistry and mathematical logic. As in the previous articles, the role of the spectrum of the activity of hydrogen ions was highlighted. Events (facts) are placed in the library memory on the time axis - stratigraphy memory (according to V.V. Nabokov) and are subject to internal chronotype (according to A.A. Ukhtomsky). The authors touched a question upon vectorization time in biological systems in relation to the functioning of mechanisms of information search in the library memory. The authors note that the vectorization time in biosystems is the basis of the "speed" work of all mechanisms of memory. The mechanism of memory functions; for example, sleep, even deep - its essence is the work of the subconscious, i.e. the reference to the images and content of memory. Even taking into account the principle of anthropomorphism in the design of technical devices memory by individual, don’t associate characteristic for these devices "compression" of information from the brain work: here the information is not "shrinks" and recoded, contributing to lower power consumption of the process and reducing the overall entropy. The authors argue that the geometry of the drive with inherent spectra of the activity of hydrogen ions it is logically to consider the characteristics of similarity. This characteristic has fractal dimension that gives some level of comfort to compare patterns, which were discussed in this work. Identical and similar items patterns contribute equally to the formation of fractal dimension.

The Neural Basis of Involuntary Episodic Memories

Voluntary episodic memories require an intentional memory search, whereas involuntary episodic memories come to mind spontaneously without conscious effort. Cognitive neuroscience has largely focused on voluntary memory, leaving the neural mechanisms of involuntary memory largely unknown. We hypothesized that, because the main difference between voluntary and involuntary memory is the controlled retrieval processes required by the former, there would be greater frontal activity for voluntary than involuntary memories. Conversely, we predicted that other components of the episodic retrieval network would be similarly engaged in the two types of memory. During encoding, all participants heard sounds, half paired with pictures of complex scenes and half presented alone. During retrieval, paired and unpaired sounds were presented, panned to the left or to the right. Participants in the involuntary group were instructed to indicate the spatial location of the sound, whereas participants in the voluntary group were asked to additionally recall the pictures that had been paired with the sounds. All participants reported the incidence of their memories in a postscan session. Consistent with our predictions, voluntary memories elicited greater activity in dorsal frontal regions than involuntary memories, whereas other components of the retrieval network, including medial-temporal, ventral occipitotemporal, and ventral parietal regions were similarly engaged by both types of memories. These results clarify the distinct role of dorsal frontal and ventral occipitotemporal regions in predicting strategic retrieval and recalled information, respectively, and suggest that, although there are neural differences in retrieval, involuntary memories share neural components with established voluntary memory systems.

The structure-sensitivity of memory access: evidence from Mandarin Chinese.

The present study examined the processing of the Mandarin Chinese long-distance reflexive ziji to evaluate the role that syntactic structure plays in the memory retrieval operations that support sentence comprehension. Using the multiple-response speed-accuracy tradeoff (MR-SAT) paradigm, we measured the speed with which comprehenders retrieve an antecedent for ziji. Our experimental materials contrasted sentences where ziji's antecedent was in the local clause with sentences where ziji's antecedent was in a distant clause. Time course results from MR-SAT suggest that ziji dependencies with syntactically distant antecedents are slower to process than syntactically local dependencies. To aid in interpreting the SAT data, we present a formal model of the antecedent retrieval process, and derive quantitative predictions about the time course of antecedent retrieval. The modeling results support the Local Search hypothesis: during syntactic retrieval, comprehenders initially limit memory search to the local syntactic domain. We argue that Local Search hypothesis has important implications for theories of locality effects in sentence comprehension. In particular, our results suggest that not all locality effects may be reduced to the effects of temporal decay and retrieval interference.

Familiarity and categorization processes in memory search

A fundamental distinction in tasks of memory search is whether items receive varied mappings (targets and distractors switch roles across trials) or consistent mappings (targets and distractors never switch roles). The type of mapping often produces markedly different performance patterns, but formal memory-based models that account quantitatively for detailed aspects of the results have not yet been developed and evaluated. Experiments were conducted to test a modern exemplar-retrieval model on its ability to account for memory-search performance involving a wide range of memory-set sizes in both varied-mapping (VM) and consistent-mapping (CM) probe-recognition tasks. The model formalized the idea that both familiarity-based and categorization-based processes operate. The model was required to fit detailed response-time (RT) distributions of individual, highly practiced subjects. A key manipulation involved the repetition of negative probes across trials. This manipulation produced a dramatic dissociation: False-alarm rates increased and correct-rejection RTs got longer in VM, but not in CM. The qualitative pattern of results and modeling analyses provided evidence for a strong form of categorization-based processing in CM, in which observers made use of the membership of negative probes in the “new” category to make old–new recognition decisions.

Crossword expertise as recognitional decision making: an artificial intelligence approach.

The skills required to solve crossword puzzles involve two important aspects of lexical memory: semantic information in the form of clues that indicate the meaning of the answer, and orthographic patterns that constrain the possibilities but may also provide hints to possible answers. Mueller and Thanasuan (2013) proposed a model accounting for the simple memory access processes involved in solving individual crossword clues, but expert solvers also bring additional skills and strategies to bear on solving complete puzzles. In this paper, we developed an computational model of crossword solving that incorporates strategic and other factors, and is capable of solving crossword puzzles in a human-like fashion, in order to understand the complete set of skills needed to solve a crossword puzzle. We compare our models to human expert and novice solvers to investigate how different strategic and structural factors in crossword play impact overall performance. Results reveal that expert crossword solving relies heavily on fluent semantic memory search and retrieval, which appear to allow experts to take better advantage of orthographic-route solutions, and experts employ strategies that enable them to use orthographic information. Furthermore, other processes central to traditional AI models (error correction and backtracking) appear to be of less importance for human players.

Bivalent task switching and memory load: Similar costs on reaction times, different costs on concurrent timing.

Some studies suggest that time estimation involves executive control resources. This proposition was challenged recently, however, by results showing simultaneous performance of executive and timing tasks with no cost. The present study examined whether bivalent switching, in which targets may be relevant in more than one task, would interfere with timing. In Experiment 1, the effect of switching between memory search and a classification task was compared with the effect of varying load in memory search. Effects of task switching and of increasing load were similar on reaction times (RTs) in an RT control condition, but drastically different on concurrent timing: Time productions were affected by memory search only. In Experiment 2, the effect of task switching preparation, which involves advance reconfiguration in the switching paradigm, was examined. Preparation to a switch and timing could be performed simultaneously with no cost. These results reveal a fundamental difference between memory search and task switching in terms of dual-task costs, and show that timing and some executive control tasks do not share cognitive resources.

Set-relevance Determines the Impact of Distractors on Episodic Memory Retrieval

We investigated the interplay between stimulus-driven attention and memory retrieval with a novel interference paradigm that engaged both systems concurrently on each trial. Participants encoded a 45-min movie on Day 1 and, on Day 2, performed a temporal order judgment task during fMRI. Each retrieval trial comprised three images presented sequentially, and the task required participants to judge the temporal order of the first and the last images ("memory probes") while ignoring the second image, which was task irrelevant ("attention distractor"). We manipulated the content relatedness and the temporal proximity between the distractor and the memory probes, as well as the temporal distance between two probes. Behaviorally, short temporal distances between the probes led to reduced retrieval performance. Distractors that at encoding were temporally close to the first probe image reduced these costs, specifically when the distractor was content unrelated to the memory probes. The imaging results associated the distractor probe temporal proximity with activation of the right ventral attention network. By contrast, the precuneus was activated for high-content relatedness between distractors and probes and in trials including a short distance between the two memory probes. The engagement of the right ventral attention network by specific types of distractors suggests a link between stimulus-driven attention control and episodic memory retrieval, whereas the activation pattern of the precuneus implicates this region in memory search within knowledge/content-based hierarchies.

The role of working memory capacity in visual search and search of visual short term memory

The role of working memory capacity in visual search and search of visual short term memory

Individual differences in visual working memory capacity and search efficiency may predict distinct strategic processes for dot arrays by numerosity comparison sensitivity

Individual differences in visual working memory capacity and search efficiency may predict distinct strategic processes for dot arrays by numerosity comparison sensitivity

Searching for the right word: Hybrid visual and memory search for words

In Bhybrid search^ (Wolfe Psychological Science, 23(7), 698-703, 2012), observers search through visual space for anyofmultipletargetsheldinmemory.Withphotorealistic objects as the stimuli, response times (RTs) increase linearly with the visual set size and logarithmically with the memory set size, even when over 100 items are committed to memory. It is well-established that pictures of objects are particularly easy to memorize (Brady, Konkle, Alvarez, & Oliva Proceed- ings of the National Academy of Sciences,105,14325-14329, 2008). Would hybrid-search performance be similar if the tar- gets were words or phrases, in which word order can be im- portant, so that the processes of memorization might be dif- ferent? In Experiment 1, observers memorized 2, 4, 8, or 16 words in four different blocks. After passing a memory test, confirming their memorization of the list, the observers searched for these words in visual displays containing two to 16 words. Replicating Wolfe (Psychological Science, 23(7), 698-703, 2012), the RTs increased linearly with the visual set size and logarithmically with the length of the word list. The word lists of Experiment 1 were random. In Experiment 2, wordsweredrawnfromphrasesthatobserversreportedknow- ing by heart (e.g., BLondon Bridge is falling down^). Ob- servers were asked to provide four phrases, ranging in length from two words to no less than 20 words (range 21-86). All words longer than two characters from the phrase, constituted the target list. Distractor words were matched for length and frequency. Even with these strongly ordered lists, the results again replicated the curvilinear function of memory set size seen in hybrid search. One might expect to find serial position effects, perhaps reducing the RTs for the first (primacy) and/or the last (recency) members of a list (Atkinson & Shiffrin, 1968 ;M urdockJournal of Experimental Psychology, 64, 482-488, 1962). Surprisingly, we showed no reliable effects of word order. Thus, in BLondon Bridge is falling down,^ BLondon^ and Bdown^ were found no faster than Bfalling.^

Individual differences in memory search and their relation to intelligence.

Attempts to understand why memory predicts intelligence have not fully leveraged state-of-the-art measures of recall dynamics. Using data from a multisession free recall study, we examine individual differences in measures of recall initiation and postinitiation transitions. We identify 4 sources of variation: a recency factor reflecting variation in the tendency to initiate recall from an item near the end of the list, a primacy factor reflecting a tendency to initiate from the beginning of the list, a temporal factor corresponding to transitions mediated by temporal associations, and a semantic factor corresponding to semantically mediated transitions. Together, these 4 factors account for 83% of the variability in overall recall accuracy, suggesting they provide a nearly complete picture of recall dynamics. We also show that these sources of variability account for over 80% of the variance shared between memory and intelligence. The temporal association factor was the most influential in predicting both recall accuracy and intelligence. We outline a theory of how controlled drift of temporal context may be critical across a range of cognitive activities.

Saccadic eye movement rate as a cue to deceit

In the present experiment we considered a cue that has not been examined in nonverbal deception research before, non-visual saccadic eye movement rate. The psychological process as to why saccadic eye movements could be related to deception is also new for nonverbal deception research: memory retrieval. Non-visual saccadic eye movement rate has been shown to be related to memory search, with searching information in long-term memory generating increased saccadic activity (Ehrlichman & Micic, 2012). According to fMRI research lying is associated with more long-term memory search than truth telling (Ganis et al., 2003), which leads to our hypothesis that liars display more saccadic eye movements than truth tellers. Thirty participants expressed a true opinion and lied about another opinion (within-subjects design) and the number of saccades per second of speech was measured. As predicted, participants displayed fewer saccades when they told the truth than when they told a spontaneous lie. The implications for this finding are discussed.

Parallel effects of memory set activation and search on timing and working memory capacity.

Accurately estimating a time interval is required in everyday activities such as driving or cooking. Estimating time is relatively easy, provided a person attends to it. But a brief shift of attention to another task usually interferes with timing. Most processes carried out concurrently with timing interfere with it. Curiously, some do not. Literature on a few processes suggests a general proposition, the Timing and Complex-Span Hypothesis: A process interferes with concurrent timing if and only if process performance is related to complex span. Complex-span is the number of items correctly recalled in order, when each item presented for study is followed by a brief activity. Literature on task switching, visual search, memory search, word generation and mental time travel supports the hypothesis. Previous work found that another process, activation of a memory set in long term memory, is not related to complex-span. If the Timing and Complex-Span Hypothesis is true, activation should not interfere with concurrent timing in dual-task conditions. We tested such activation in single-task memory search task conditions and in dual-task conditions where memory search was executed with concurrent timing. In Experiment 1, activating a memory set increased reaction time, with no significant effect on time production. In Experiment 2, set size and memory set activation were manipulated. Activation and set size had a puzzling interaction for time productions, perhaps due to difficult conditions, leading us to use a related but easier task in Experiment 3. In Experiment 3 increasing set size lengthened time production, but memory activation had no significant effect. Results here and in previous literature on the whole support the Timing and Complex-Span Hypotheses. Results also support a sequential organization of activation and search of memory. This organization predicts activation and set size have additive effects on reaction time and multiplicative effects on percent correct, which was found.

Multifractal analyses of human response time: potential pitfalls in the interpretation of results.

Analyses of response time series haveprovided insight into mental organiza-tionandcognitiveprocessesusedinawide variety of tasks such as simple reac-tion time, word naming, choice decision,visual search, memory search, and lexi-cal decision (Gilden, 2001). One of thenew and frequently used sets of analy-ses is the numerical definition of scaleinvariantstructureofresponsetimeseries,also called 1/

A two-stage search of visual working memory: investigating speed in the change-detection paradigm.

A popular procedure for investigating working memory processes has been the visual change-detection procedure. Models of performance based on that procedure, however, tend to be based on performance accuracy and treat working memory search as a one-step process, in which memory representations are compared to a test probe to determine if a match is present. To gain a clearer understanding of how search of these representations operate in the change-detection task, we examined reaction time in two experiments, with a single-item probe either located centrally or at the location of an array item. Contrary to current models of visual working memory capacity, our data point to a two-stage search process: a fast first step to check for the novelty of the probe and, in the absence of such novelty, a second, slower step to search exhaustively for a match between the test probe and a memory representation. In addition to these results, we found that participants tended not to use location information provided by the probe that theoretically could have abbreviated the search process. We suggest some basic revisions of current models of processing in this type of visual working memory task.

Memory search for the first target modulates the magnitude of the attentional blink.

The resolution of temporal attention is limited in a manner that makes it difficult to identify two targets in short succession. This limitation produces the phenomenon known as the attentional blink (AB), in which processing of a first target (T1) impairs identification of a second target (T2). In the AB literature, there is broad agreement that increasing the time it takes to process T1 leads to a larger AB. One might, therefore, predict that increasing the number of possible T1 identities, or target set, from 1 to 16 would lead to a larger AB. We were surprised to find that this manipulation of T1 difficulty had no influence on AB magnitude. In subsequent experiments, we found that AB magnitude interacts with T1 processing time only under certain circumstances. Specifically, when the T1 task was either well masked or had to be completed online, we found a reliable interaction between AB magnitude and the target set size. When neither of these conditions was fulfilled, there was no interaction between target set size and the AB. Previous research found that when the target set changes from trial to trial, trials with more possible targets elicited a larger AB. In the present study, the target set is held constant, reducing the demands on working memory. Nevertheless, AB magnitude still interacts with target set size, as long as the T1 task cannot be processed offline. Thus, the act of searching memory delays subsequent processing, even when the role of working memory has been minimized.