Memory-based Task Research Articles

Perception of Different Tone Contrasts at Sub-Lexical and Lexical Levels by Dutch Learners of Mandarin Chinese.

This study explores the difficulties in distinguishing different lexical tone contrasts at both sub-lexical and lexical levels for beginning and advanced Dutch learners of Mandarin, using a sequence-recall task and an auditory lexical decision task. In both tasks, the Tone 2-Tone 3 contrast is most prone to errors for both groups of learners. A significant improvement in the advanced group was found for this tone contrast in the sub-lexical sequence recall task, but not in the lexical decision task. This is taken as evidence that utilizing tones in on-line spoken word recognition is more complex and demanding for L2 learners than in a memory-based task. The results of the lexical decision task also revealed that advanced learners have developed a stronger sensitivity to Tone 1 compared to the other three tones, with Tone 4 showing the least sensitivity. These findings suggest different levels of robustness and distinctiveness for the representation of different lexical tones in L2 learners’ lexicon and consequently different levels of proficiency in integrating tones for lexical processing. The observed patterns of difficulty are potentially related to the acoustic characteristics of different lexical tone contrasts as well as to the interference of the suprasegmental features of learner’s native language (i.e., the tonal contrasts of Dutch intonation) on the acquisition of the Mandarin lexical tone contrasts.

The Effect of Bilingualism on Cue-Based vs. Memory-Based Task Switching in Older Adults

The Effect of Bilingualism on Cue-Based vs. Memory-Based Task Switching in Older Adults

The Effect of Bilingualism on Cue-Based vs. Memory-Based Task Switching in Older Adults.

Findings suggest a positive impact of bilingualism on cognition, including the later onset of dementia. However, it is not clear to what extent these effects are influenced by variations in attentional control demands in response to specific task requirements. In this study, 20 bilingual and 20 monolingual older adults performed a task-switching task under explicit task-cuing vs. memory-based switching conditions. In the cued condition, task switches occurred in random order and a visual cue signaled the next task to be performed. In the memory-based condition, the task alternated after every second trial in a predictable sequence without presenting a cue. The performance of bilinguals did not vary across experimental conditions, whereas monolinguals experienced a pronounced increase in response latencies and error rates in the cued condition. Both groups produced similar switch costs (difference in performance on switch trials as opposed to repeating trials within the mixed-task block) and mixing costs (difference in performance on repeat trials of a mixed-task block as opposed to trials of a single-task block), but bilinguals produced them with lower response latencies. The cognitive benefits of bilingualism seem not to apply to executive functions per se but to affect specific cognitive processes that involve task-relevant context processing. The present results suggest that lifelong bilingualism could promote in older adults a flexible adjustment to environmental cues, but only with increased task demands. However, due to the small sample size, the results should be interpreted with caution.

Response time models separate single- and dual-process accounts of memory-based decisions

Human decisions often deviate from economic rationality and are influenced by cognitive biases. One such bias is the memory bias according to which people prefer choice options they have a better memory of—even when the options’ utilities are comparatively low. Although this phenomenon is well supported empirically, its cognitive foundation remains elusive. Here we test two conceivable computational accounts of the memory bias against each other. On the one hand, a single-process account explains the memory bias by assuming a single biased evidence-accumulation process in favor of remembered options. On the contrary, a dual-process account posits that some decisions are driven by a purely memory-driven process and others by a utility-maximizing one. We show that both accounts are indistinguishable based on choices alone as they make similar predictions with respect to the memory bias. However, they make qualitatively different predictions about response times. We tested the qualitative and quantitative predictions of both accounts on behavioral data from a memory-based decision-making task. Our results show that a single-process account provides a better account of the data, both qualitatively and quantitatively. In addition to deepening our understanding of memory-based decision-making, our study provides an example of how to rigorously compare single- versus dual-process models using empirical data and hierarchical Bayesian parameter estimation methods.

Short-term Smartphone App-Based Focused Attention Meditation Diminishes Cognitive Flexibility.

Cognitive flexibility is an important aspect relevant to daily life situations, and there is an increasing public interest to optimize these functions, for example, using (brief) meditation practices. However, the underlying neurophysiological mechanisms remain poorly understood. On the basis of theoretical considerations, both improvements and deteriorations of cognitive flexibility are possible through focused attention meditation (FAM). We investigated the effect of a brief smartphone app-based FAM on task switching using EEG methods, temporal signal decomposition, and source localization techniques (standardized low-resolution electromagnetic brain tomography). The study was conducted using a crossover study design. We show that even 15 min of FAM practicing modulates memory-based task switching, on a behavioral level and a neurophysiological level. More specifically, FAM hampers response selection and conflict resolution processes and seem to reduce cognitive resources, which are necessary to rapidly adapt to changing conditions. These effects are represented in the N2 and P3 time windows and associated with ACC. It seems that FAM increases the attention to one specific aspect, which may help to focus but carries also the risk that behavior becomes too rigid. FAM thus seems to modulate both the stimulus- and response-related aspects of conflict monitoring in ACC. Motor-related processes were not affected. The results can be explained using a cognitive control dilemma framework, suggesting that particularly alterations in background monitoring may be important to consider when explaining the effects of FAM during task switching.

A memory-based task scheduling algorithm for grid computing based on heterogeneous platform and homogeneous tasks

A memory-based task scheduling algorithm for grid computing based on heterogeneous platform and homogeneous tasks

A memory-based task scheduling algorithm for grid computing based on heterogeneous platform and homogeneous tasks

Grid computing is a new computing mode in recent years, which focuses on parallel infrastructure and its comprehensive application ability to network computers and distributed processors. Grid computing has been fully applied in the field of modern information technology and computer. Task scheduling is the core of grid computing. The quality of task scheduling algorithm directly affects the response time of the whole computing system. For heterogeneous tasks on heterogeneous platforms, this paper proposes a task scheduling algorithm with memory function, and introduces the distributed particle swarm optimisation algorithm into this algorithm, which realises the combination of resource processing tasks in grid computing and the behaviour characteristics of intelligent groups, so as to better realise the dynamic and scalable scheduling of heterogeneous tasks on heterogeneous platforms to adapt to grid environment sex. Finally, the grid simulation software GridSim is used to simulate the algorithm proposed in this paper. At the same time, it is compared with the state stochastic scheduling algorithm. Experimental results show that the proposed algorithm has obvious advantages in scheduling quality in grid environment.

Human string-pulling with and without a string: movement, sensory control, and memory.

String-pulling is a behavior that is allied to many daily acts and is an easily performed action featuring hand-over-hand movements to reel in a string (or rope). String-pulling has been used as a test of perceptual and cognitive functions in many animal species, including human children, but its movements and sensory control have not been characterized. Male and female university students (n = 68) performed target-based or memory-based string-pulling in which they pulled down a string suspended on an overhead pulley and immediately afterwards attempted to make the same movement in a memory-based test. Frame-by-frame video scoring was used to describe movements, eye-tracking and visual occluding glasses were used to assess sensory control, and a Matlab video-analysis procedure was used to describe kinematics. The string was advanced using five arm/hand movements: with lift and advance comprising fast up movements, and grasp, pull and push comprising slow down movements. Fingers closed 5 (pinky) through 1 (thumb) to make a whole-hand grasp and release in target-based string pulling but moved in a reverse sequence for the memory-based task. Target-based string pulling was not visually guided unless participants were instructed to grasp at a cue, and then vision featured eye-tracking of the target and pupil dilation with the grasp, but there was no relation between eye events for memory-based string-pulling. For target-based string-pulling the left and right hands advanced the string with both independent and concurrent movement but only independent movements were featured in a more symmetrical memory-based movement. The results are discussed in relation to the sensory control of hand movements, contemporary theories of the neural control of hand movements, and species differences in string-pulling.

IS COMBINED TRAINING MORE EFFECTIVE THAN SINGLE-DOMAIN TRAINING: A RANDOMIZED CONTROLLED TRIAL WITH OLDER ADULTS

Previous research suggests that both cognitive training and physical exercise help to maintain brain health and cognitive functions that decline with age. The main objectives of this four-arms RCT are (1) to investigate the synergetic effects of a group-based multidomain training program that combines cognitive video-game training with physical exercise, in comparison to those produced by cognitive training combined with physical control activity, physical training combined with cognitive control activity, or a combination of both control activities; (2) to investigate in a memory-based task switching task whether event Related Potential (ERP) latencies of the P2 component are shorter, and N2 and P3b components are enhanced after training; and (3) to find out whether possible enhancements persist after a 3-month period without training. One hundred and twenty participants will be randomly assigned to one of the four combinations of cognitive training and physical exercise. The cognitive component will be either video-game training (cognitive intervention, CI) or video games not specifically designed to train cognition (cognitive control, CC). The physical exercise component will either emphasize endurance, strength, and music-movement coordination (exercise intervention, EI) or stretching, toning and relaxation (exercise control, EC). This RCT will investigate the short and long-term effects of combined multi-domain training compared to cognitive training and physical training alone, on executive control and memory functions of healthy older adults, in comparison with the performance of an active control group. This trial is an ongoing project started in 2018. Trial registration: Clinicaltrials.gov ID: NCT03823183; https://register.clinicaltrials.gov/

Wide sensory filters underlie performance in memory-based discrimination and generalization.

The way animals respond to a stimulus depends largely on an internal comparison between the current sensation and the memory of previous stimuli and outcomes. We know little about the accuracy with which the physical properties of the stimuli influence this type of memory-based discriminative decisions. Research has focused largely on discriminations between stimuli presented in quick succession, where animals can make relative inferences (same or different; higher or lower) from trial to trial. In the current study we used a memory-based task to explore how the stimulus’ physical properties, in this case tone frequency, affect auditory discrimination and generalization in mice. Mice performed ad libitum while living in groups in their home quarters. We found that the frequency distance between safe and conditioned sounds had a constraining effect on discrimination. As the safe-to-conditioned distance decreased across groups, performance deteriorated rapidly, even for frequency differences significantly larger than reported discrimination thresholds. Generalization width was influenced both by the physical distance and the previous experience of the mice, and was not accompanied by a decrease in sensory acuity. In conclusion, memory-based discriminations along a single stimulus dimension are inherently hard, reflecting a high overlap between the memory traces of the relevant stimuli. Memory-based discriminations rely therefore on wide sensory filters.

What’s in Your Wallet? Psychophysical Biases in the Estimation of Money

AbstractThe denomination effect (Raghubir and Srivastava 2009) suggests that individuals are less likely to spend when money is in the form of a single large denomination (e.g., a $10 bill) relative to many smaller denominations (e.g., ten $1 bills). We explore the idea that consumers are reluctant to break large bills because smaller denominations are less easy to monitor and keep track of relative to larger denominations. This increases the likelihood of spending with smaller denominations. In estimating the contents of one’s wallet, money is more difficult to recall, and recalled less accurately the smaller the denomination, and the more the number of units of any denomination. Study 1 demonstrates the biases in a memory-based task, study 2 adds a stimulus-based task, study 3 explores the effect of accuracy motivation and task difficulty, and study 4 links the biases to actual spending. We develop a descriptive psychophysical model of how individuals estimate contents of their wallet and fit the model ...

Behavioral and neurophysiological evidence for increased cognitive flexibility in late childhood.

Executive functions, like the capacity to control and organize thoughts and behavior, develop from childhood to young adulthood. Although task switching and working memory processes are known to undergo strong developmental changes from childhood to adulthood, it is currently unknown how task switching processes are modulated between childhood and adulthood given that working memory processes are central to task switching. The aim of the current study is therefore to examine this question using a combined cue- and memory-based task switching paradigm in children (N = 25) and young adults (N = 25) in combination with neurophysiological (EEG) methods. We obtained an unexpected paradoxical effect suggesting that memory-based task switching is better in late childhood than in young adulthood. No group differences were observed in cue-based task switching. The neurophysiological data suggest that this effect is not due to altered attentional selection (P1, N1) or processes related to the updating, organization, and implementation of the new task-set (P3). Instead, alterations were found in the resolution of task-set conflict and the selection of an appropriate response (N2) when a task has to be switched. Our observation contrasts findings showing that cognitive control mechanisms reach their optimal functioning in early adulthood.

Take-the-best and the influence of decision-inconsistent attributes on decision confidence and choices in memory-based decisions

ABSTRACTTake-the-best (TTB) is a decision strategy according to which attributes about choice options are sequentially processed in descending order of validity, and attribute processing is stopped once an attribute discriminates between options. Consequently, TTB-decisions rely on only one, the best discriminating, attribute, and lower-valid attributes need not be processed because they are TTB-irrelevant. Recent research suggests, however, that when attribute information is visually present during decision-making, TTB-irrelevant attributes are processed and integrated into decisions nonetheless. To examine whether TTB-irrelevant attributes are retrieved and integrated when decisions are made memory-based, we tested whether the consistency of a TTB-irrelevant attribute affects TTB-users’ decision behaviour in a memory-based decision task. Participants first learned attribute configurations of several options. Afterwards, they made several decisions between two of the options, and we manipulated conflict between the second-best attribute and the TTB-decision. We assessed participants’ decision confidence and the proportion of TTB-inconsistent choices. According to TTB, TTB-irrelevant attributes should not affect confidence and choices, because these attributes should not be retrieved. Results showed, however, that TTB-users were less confident and made more TTB-inconsistent choices when TTB-irrelevant information was in conflict with the TTB-decision than when it was not, suggesting that TTB-users retrieved and integrated TTB-irrelevant information.

Neural correlates of ankle movements during different motor tasks: A feasibility study.

This ongoing study investigates the neural correlates of ankle dorsi-plantar flexion in active, passive, and proprioceptive tasks. Specifically, we investigated two proprioceptive matching tasks that required a simple combination of active and passive ankle movements: (1) a memory-based ipsilateral matching task and (2) a contralateral concurrent matching task. As expected, during the passive tasks, subjects recruited the same brain areas involved in the correspondent active movements (primary motor cortex (M1), premotor cortex (PM) supplementary motor cortex (SMA) and primary somatosensory cortex (S1)), but the activations were lower. Instead, in both the proprioceptive matching tasks, subjects recruited more motor and sensory-motor areas of the brain and the activations were greater.

Age Differences in Memory-Based Task Switching With and Without Cues

The study investigated the neuronal mechanisms of age-related changes in mixing costs during memory-based task switching with two levels of working memory (WM) load. Forty-eight healthy younger and 45 healthy older participants performed a memory based (high WM load) and a memory plus cue based (low WM load) switching task while event-related brain potentials (ERPs) were registered. Older adults revealed larger mixing costs in both reaction time (RT) and accuracy at higher WM loads than younger adults. The presence of explicit cues substantially reduced age differences in mixing costs for accuracy but not for RT. Similarly, no age differences regarding local switch costs were found at lower WM load. Surprisingly, larger RT local costs in younger adults than in older adults were found in the memory-based block. The CNV was reduced under high WM load and positively correlated with accuracy mixing costs in older adults. The target-locked occipital N1 and fronto-central P2 were larger in older adults relative to younger adults irrespective of WM load. The P2 latency reflected the pattern of switch costs observed in behavioral data. Moreover, P2 latency positively correlated with RT mixing costs in older adults. Elderly also showed a delayed N2 and a delayed and reduced P3b. The results suggest that age-related differences in mixing costs may be partially due to a less efficient task preparation and task set maintenance (CNV) in elderly. However, elderly attempted to compensate for these deficits by permanent activation of mechanisms relating to stimulus encoding (N1) and task-set retrieval (P2). Finally, the delayed fronto-central N2 as well as the delayed and reduced parietal P3b strongly suggest delays of response selection and working memory updating in elderly due to an increase in selection threshold or in response selection variability constituting the performance decline.

Normal aging affects movement execution but not visual motion working memory and decision-making delay during cue-dependent memory-based smooth-pursuit.

Aging affects virtually all functions including sensory/motor and cognitive activities. While retinal image motion is the primary input for smooth-pursuit, its efficiency/accuracy depends on cognitive processes. Elderly subjects exhibit gain decrease during initial and steady-state pursuit, but reports on latencies are conflicting. Using a cue-dependent memory-based smooth-pursuit task, we identified important extra-retinal mechanisms for initial pursuit in young adults including cue information priming and extra-retinal drive components (Ito et al. in Exp Brain Res 229:23-35, 2013). We examined aging effects on parameters for smooth-pursuit using the same tasks. Elderly subjects were tested during three task conditions as previously described: memory-based pursuit, simple ramp-pursuit just to follow motion of a single spot, and popping-out of the correct spot during memory-based pursuit to enhance retinal image motion. Simple ramp-pursuit was used as a task that did not require visual motion working memory. To clarify aging effects, we then compared the results with the previous young subject data. During memory-based pursuit, elderly subjects exhibited normal working memory of cue information. Most movement-parameters including pursuit latencies differed significantly between memory-based pursuit and simple ramp-pursuit and also between young and elderly subjects. Popping-out of the correct spot motion was ineffective for enhancing initial pursuit in elderly subjects. However, the latency difference between memory-based pursuit and simple ramp-pursuit in individual subjects, which includes decision-making delay in the memory task, was similar between the two groups. Our results suggest that smooth-pursuit latencies depend on task conditions and that, although the extra-retinal mechanisms were functional for initial pursuit in elderly subjects, they were less effective.

Cue-dependent memory-based smooth-pursuit in normal human subjects: importance of extra-retinal mechanisms for initial pursuit

Using a cue-dependent memory-based smooth-pursuit task previously applied to monkeys, we examined the effects of visual motion-memory on smooth-pursuit eye movements in normal human subjects and compared the results with those of the trained monkeys. These results were also compared with those during simple ramp-pursuit that did not require visual motion-memory. During memory-based pursuit, all subjects exhibited virtually no errors in either pursuit-direction or go/no-go selection. Tracking eye movements of humans and monkeys were similar in the two tasks, but tracking eye movements were different between the two tasks; latencies of the pursuit and corrective saccades were prolonged, initial pursuit eye velocity and acceleration were lower, peak velocities were lower, and time to reach peak velocities lengthened during memory-based pursuit. These characteristics were similar to anticipatory pursuit initiated by extra-retinal components during the initial extinction task of Barnes and Collins (J Neurophysiol 100:1135-1146, 2008b). We suggest that the differences between the two tasks reflect differences between the contribution of extra-retinal and retinal components. This interpretation is supported by two further studies: (1) during popping out of the correct spot to enhance retinal image-motion inputs during memory-based pursuit, pursuit eye velocities approached those during simple ramp-pursuit, and (2) during initial blanking of spot motion during memory-based pursuit, pursuit components appeared in the correct direction. Our results showed the importance of extra-retinal mechanisms for initial pursuit during memory-based pursuit, which include priming effects and extra-retinal drive components. Comparison with monkey studies on neuronal responses and model analysis suggested possible pathways for the extra-retinal mechanisms.

Cognitive processes involved in smooth pursuit eye movements: behavioral evidence, neural substrate and clinical correlation

Smooth-pursuit eye movements allow primates to track moving objects. Efficient pursuit requires appropriate target selection and predictive compensation for inherent processing delays. Prediction depends on expectation of future object motion, storage of motion information and use of extra-retinal mechanisms in addition to visual feedback. We present behavioral evidence of how cognitive processes are involved in predictive pursuit in normal humans and then describe neuronal responses in monkeys and behavioral responses in patients using a new technique to test these cognitive controls. The new technique examines the neural substrate of working memory and movement preparation for predictive pursuit by using a memory-based task in macaque monkeys trained to pursue (go) or not pursue (no-go) according to a go/no-go cue, in a direction based on memory of a previously presented visual motion display. Single-unit task-related neuronal activity was examined in medial superior temporal cortex (MST), supplementary eye fields (SEF), caudal frontal eye fields (FEF), cerebellar dorsal vermis lobules VI–VII, caudal fastigial nuclei (cFN), and floccular region. Neuronal activity reflecting working memory of visual motion direction and go/no-go selection was found predominantly in SEF, cerebellar dorsal vermis and cFN, whereas movement preparation related signals were found predominantly in caudal FEF and the same cerebellar areas. Chemical inactivation produced effects consistent with differences in signals represented in each area. When applied to patients with Parkinson's disease (PD), the task revealed deficits in movement preparation but not working memory. In contrast, patients with frontal cortical or cerebellar dysfunction had high error rates, suggesting impaired working memory. We show how neuronal activity may be explained by models of retinal and extra-retinal interaction in target selection and predictive control and thus aid understanding of underlying pathophysiology.

Effects of deviant trials on precue-based versus memory-based switching among two or four tasks

In two experiments, the effects of an introduction of deviant trials on precue-based and memory-based task switching were investigated. Deviant trials were trials that deviated from task foreknowledge as induced either by precues or memory of the task sequence. The experiments differed with respect to the number of tasks to be switched among (two in Experiment 1, four in Experiment 2). In Experiment 1, the introduction of deviant trials had a detrimental effect on precue-based task preparation, but had little impact on memory-based preparation. The latter observation was due to the fact that there was little evidence for memory-based preparation at the outset. In Experiment 2, introducing deviant trials had little effect on either precue-based or memory-based preparation. In contrast to Experiment 1, in Experiment 2 memory-based preparation was as effective as precue-based preparation.

The Met-allele of the BDNF Val66Met polymorphism enhances task switching in elderly

In this study we examined the relevance of the functional brain-derived neurotrophic factor (BDNF) Val66Met polymorphism as a modulator of task-switching performance in healthy elderly by using behavioral and event-related potential (ERP) measures. Task switching was examined in a cue-based and a memory-based paradigm. Val/Val carriers were generally slower, showed enhanced reaction time variability and higher error rates, particularly during memory-based task switching than the Met-allele individuals. On a neurophysiological level these dissociative effects were reflected by variations in the N2 and P3 ERP components. The task switch-related N2 was increased while the P3 was decreased in Met-allele carriers, while the Val/Val genotype group revealed the opposite pattern of results. In cue-based task-switching no behavioral and ERP differences were seen between the genotypes. These data suggest that superior memory-based task-switching performance in elderly Met-allele carriers may emerge due to more efficient response selection processes. The results implicate that under special circumstances the Met-allele renders cognitive processes more efficient than the Val/Val genotype in healthy elderly, corroborating recent findings in young subjects.