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  1. Time sharing in working memory processing
    Barrouillet P, Camos V, Minamoto T, Nishiyama S, Chooi WT, Morita A, et al.
    J Exp Psychol Learn Mem Cogn, 2023 Oct;49(10):1539-1556.
    PMID: 37307321 DOI: 10.1037/xlm0001261
    Although working memory (WM) is usually defined as a cognitive system coordinating processing and storage in the short term, in most WM models, memory aspects have been developed more fully than processing systems, and many studies of WM tasks have tended to focus on memory performance. The present study investigated WM functioning without focusing exclusively on short-term memory performance by presenting participants with an n-back task on letters, n varying from 0 to 2, each letter being followed by a tone discrimination task involving from one to three tones. Predictions regarding the reciprocal effects of these tasks on each other were motivated by the time-based resource-sharing (TBRS) theoretical framework for WM that assumes the temporal sharing of attention between processing and memory. Although, as predicted, increasing the n value had a detrimental effect on tone discrimination in terms of accuracy and response times, and increasing the number of tones disrupted speed and accuracy on n-back performance, the overall pattern of results did not perfectly fit the TBRS predictions. Nonetheless, the main alternative models of WM do not seem to offer a complete account. The present findings point toward the need to use a larger range of tasks and situations in designing and testing models of WM. (PsycInfo Database Record (c) 2023 APA, all rights reserved).
    Matched MeSH terms: Attention/physiology
  2. Fulltext The effects of a distracting N-back task on recognition memory are reduced by negative emotional intensity
    Buratto LG, Pottage CL, Brown C, Morrison CM, Schaefer A
    PLoS One, 2014;9(10):e110211.
    PMID: 25330251 DOI: 10.1371/journal.pone.0110211
    Memory performance is usually impaired when participants have to encode information while performing a concurrent task. Recent studies using recall tasks have found that emotional items are more resistant to such cognitive depletion effects than non-emotional items. However, when recognition tasks are used, the same effect is more elusive as recent recognition studies have obtained contradictory results. In two experiments, we provide evidence that negative emotional content can reliably reduce the effects of cognitive depletion on recognition memory only if stimuli with high levels of emotional intensity are used. In particular, we found that recognition performance for realistic pictures was impaired by a secondary 3-back working memory task during encoding if stimuli were emotionally neutral or had moderate levels of negative emotionality. In contrast, when negative pictures with high levels of emotional intensity were used, the detrimental effects of the secondary task were significantly attenuated.
    Matched MeSH terms: Attention/physiology*
  3. Aggregated effects of combining daily milk consumption and aerobic exercise on short-term memory and sustained attention among female students
    Leong IT, Moghadam S, Hashim HA
    Percept Mot Skills, 2015 Feb;120(1):57-66.
    PMID: 25621523 DOI: 10.2466/22.06.PMS.120v11x3
    Regular aerobic exercise and milk consumption have been found to have positive effects on certain cognitive functions such as short-term memory and sustained attention. However, aggregated effects of combining these modalities have not been explored. This study examined the combined effects of milk supplementation and aerobic exercise on the short-term memory and sustained attention of female students aged 16 yr. (N = 81). The intervention involved serving of 250 ml of regular milk during school days and/or a 1-hr. aerobic exercise period twice per week for 6 weeks. The Digit Span Test and Digit Vigilance Test were used to measure short-term memory and sustained attention, respectively. The combination group (milk and exercise) and exercise group performed significantly better than did the milk and control groups in terms of short-term memory. No significant interaction or group differences were found for sustained attention. The results suggest benefits of regular exercise for students' short-term memory.
    Matched MeSH terms: Attention/physiology*
  4. Evaluation of attentional demands during motor learning: validity of a dual-task probe paradigm
    Goh HT, Gordon J, Sullivan KJ, Winstein CJ
    J Mot Behav, 2014;46(2):95-105.
    PMID: 24447033 DOI: 10.1080/00222895.2013.868337
    The aim of this study was to examine the validity of a 2-choice audio-vocal reaction time (RT) probe task for measuring the changes in attentional demand during practice and learning of a discrete motor task. Twenty participants practiced the motor task across 3 days and were probed with the RT task during either the preparation or execution phase of the primary task. As practice progressed, participants improved in the primary task performance and shortened the RTs to the probe task. This indicated that less attention was required to plan and execute the movement and suggested that the RT probe task was a sensitive and valid tool to measure changes in attentional demands across practice. The authors implemented several additional experimental controls to address possible confounders including unintentional learning of the probe task, primary-secondary task trade-off effects, and compliance with task priority instructions. These experimental controls further ensured the validity of the probe paradigm and interpretability of the dual-task cost findings. Our experimental methods provided confirmatory evidence for the validity of the 2-choice RT task as a means to assess attentional demands during motor learning.
    Matched MeSH terms: Attention/physiology*
  5. Fulltext Local context influences memory for emotional stimuli but not electrophysiological markers of emotion-dependent attention
    Barnacle GE, Tsivilis D, Schaefer A, Talmi D
    Psychophysiology, 2018 04;55(4).
    PMID: 29023754 DOI: 10.1111/psyp.13014
    Emotional enhancement of free recall can be context dependent. It is readily observed when emotional and neutral scenes are encoded and recalled together in a "mixed" list, but diminishes when these scenes are encoded separately in "pure" lists. We examined the hypothesis that this effect is due to differences in allocation of attention to neutral stimuli according to whether they are presented in mixed or pure lists, especially when encoding is intentional. Using picture stimuli that were controlled for semantic relatedness, our results contradicted this hypothesis. The amplitude of well-known electrophysiological markers of emotion-related attention-the early posterior negativity (EPN), the late positive potential (LPP), and the slow wave (SW)-was higher for emotional stimuli. Crucially, the emotional modulation of these ERPs was insensitive to list context, observed equally in pure and mixed lists. Although list context did not modulate neural markers of emotion-related attention, list context did modulate the effect of emotion on free recall. The apparent decoupling of the emotional effects on attention and memory, challenges existing hypotheses accounting for the emotional enhancement of memory. We close by discussing whether findings are more compatible with an alternative hypothesis, where the magnitude of emotional memory enhancement is, at least in part, a consequence of retrieval dynamics.
    Matched MeSH terms: Attention/physiology*
  6. Electroencephalography-detected neurophysiology of internet addiction disorder and internet gaming disorder in adolescents - A review
    Sharifat H, Suppiah S
    Med J Malaysia, 2021 05;76(3):401-413.
    PMID: 34031341
    INTRODUCTION: Internet Addiction Disorder (IAD) is an umbrella term for various types of Internet-based behavioural addiction, whereas Internet Gaming Disorder (IGD) addresses a specific type of IAD that is postulated to be due to a lack of control in impulse inhibition. IGD is an area of concern in the Diagnostic and Statistics Manual of Mental Disorders (DSM-5), which can be objectively assessed by dysfunctional behaviour and the increasing time of being online, particularly during the COVID-19 pandemic. Electroencephalography (EEG) identifies amplitude changes in the evoked response potential (ERP) among IGDs, correlated with underlying comorbidities.

    MATERIALS AND METHODS: A scoping review was performed to elaborate on the research regarding resting-state EEG and task-based EEG, particularly for Go/No-go paradigms pertaining to subjects with IAD or specifically IGD. The role of EEG was identified in its diagnostic capability to identify the salient changes that occurred in the response to reward network and the executive control network, using restingstate and task-based EEG. The implication of using EEG in monitoring the therapy for IAD and IGD was also reviewed.

    RESULTS: EEG generally revealed reduced beta waves and increased theta waves in addicts. IGD with depression demonstrated increased theta and decreased alpha waves. Whereas increased P300, a late cognitive ERP component, was frequently associated with impaired excessive allocation of attentional resources of the IAD towards addiction-specific cues. IGD had increased whole brain delta waves at baseline, which showed significant reduction post therapy.

    CONCLUSION: EEG can identify distinct neurophysiological changes among Internet Addiction Disorder and Internet Gaming Disorder that are akin to substance abuse disorders.

    Matched MeSH terms: Attention/physiology*
  7. Sensory adaptation and inhibition of return: dissociating multiple inhibitory cueing effects
    Lim A, Eng V, Janssen SMJ, Satel J
    Exp Brain Res, 2018 05;236(5):1369-1382.
    PMID: 29520444 DOI: 10.1007/s00221-018-5225-3
    Inhibition of return (IOR) refers to an increase in reaction times to targets that appeared at a previously cued location relative to an uncued location, often investigated using a spatial cueing paradigm. Despite numerous studies that have examined many aspects of IOR, the neurophysiological mechanisms underlying IOR are still in dispute. The objective of the current research is to investigate the plausible mechanisms by manipulating the cue and target types between central and peripheral stimuli in a traditional cue-target paradigm with saccadic responses to targets. In peripheral-cueing conditions, we observed inhibitory cueing effects across all cue-target onset asynchronies (CTOAs) with peripheral targets, but IOR was smaller and arose later with central targets. No inhibition was observed in central-cueing conditions at any CTOAs. Empirical data were simulated using a two-dimensional dynamic neural field model. Our results and simulations support previous work demonstrating that, at short CTOAs, behavioral inhibition is only observed with repeated stimulation-an effect of sensory adaptation. With longer CTOAs, IOR is observed regardless of target type when peripheral cueing is used. Our findings suggest that behaviorally exhibited inhibitory cueing effects can be attributed to multiple mechanisms, including both attenuation of visual stimulation and local inhibition in the superior colliculus.
    Matched MeSH terms: Attention/physiology*
  8. Changes in emotional distress, short term memory, and sustained attention following 6 and 12 sessions of progressive muscle relaxation training in 10-11 years old primary school children
    Hashim HA, Zainol NA
    Psychol Health Med, 2015;20(5):623-8.
    PMID: 25603900 DOI: 10.1080/13548506.2014.1002851
    This study compared the effects of 6 and 12 sessions of relaxation training on emotional distress, short-term memory, and sustained attention in primary school children.
    Matched MeSH terms: Attention/physiology*
  9. Fulltext Can people guess what happened to others from their reactions?
    Pillai D, Sheppard E, Mitchell P
    PLoS One, 2012;7(11):e49859.
    PMID: 23226227 DOI: 10.1371/journal.pone.0049859
    Are we able to infer what happened to a person from a brief sample of his/her behaviour? It has been proposed that mentalising skills can be used to retrodict as well as predict behaviour, that is, to determine what mental states of a target have already occurred. The current study aimed to develop a paradigm to explore these processes, which takes into account the intricacies of real-life situations in which reasoning about mental states, as embodied in behaviour, may be utilised. A novel task was devised which involved observing subtle and naturalistic reactions of others in order to determine the event that had previously taken place. Thirty-five participants viewed videos of real individuals reacting to the researcher behaving in one of four possible ways, and were asked to judge which of the four 'scenarios' they thought the individual was responding to. Their eye movements were recorded to establish the visual strategies used. Participants were able to deduce successfully from a small sample of behaviour which scenario had previously occurred. Surprisingly, looking at the eye region was associated with poorer identification of the scenarios, and eye movement strategy varied depending on the event experienced by the person in the video. This suggests people flexibly deploy their attention using a retrodictive mindreading process to infer events.
    Matched MeSH terms: Attention/physiology
  10. Cognitive evoked potential (P300): a metric for cerebral concussion
    Pratap-Chand R, Sinniah M, Salem FA
    Acta Neurol. Scand., 1988 Sep;78(3):185-9.
    PMID: 3227804
    Cognitive impairment has been reported to occur in minor head injury (concussion). The value of the P300 evoked potential as a measure of cerebral concussion was studied in 20 patients with minor head injury and compared with the data from 20 normal subjects. Significant abnormalities of the P300 latency and amplitude were noted in these patients in the post-concussion period. The abnormalities improved completely on repeat testing. The correlation of the P300 to other parameters of head injury is discussed. The P300 constitutes a simple laboratory test that is sensitive measure of cerebral dysfunction in concussive head injuries.
    Matched MeSH terms: Attention/physiology
  11. Comparative study of trait emotional intelligence and executive functioning among youth
    Alavi M, Mehrinezhad SA, Amini D, Ninggal MT, Latif AA
    J Gen Psychol, 2019 01 07;146(1):50-67.
    PMID: 30612531 DOI: 10.1080/00221309.2018.1535484
    This study investigated the relationship between trait emotional intelligence (TEI) and executive skills (ESs), and the differences between TEI and ESs among Malaysian and Iranian youths. In this study, 226 Malaysians and 248 Iranians completed the TEIQue-SF and Executive Skills Questionnaire. Hypotheses were tested with Partial Least Squares-Structural Equation Modeling (PLS-SEM). Findings indicated that TEI had significant predictions on ESs, depending on cultural contexts. Significant differences were found in the effects of TEI on ESs, including emotional control, metacognition, goal-directed persistence, response inhibition, planning/prioritization, sustained attention, stress tolerance, task initiation, and working memory among Malaysian and Iranian youth. No significant difference was found in the effects of TEI on ESs, including flexibility, organization, and time management across both groups. This study makes a unique contribution to emotional intelligence and executive functioning research literature by considering several ESs at the same time for personal development and promoting healthier lives. Comparison of the effect of TEI on ESs in the Malaysian and Iranian contexts using advanced analysis methods is one of the most important methodological contributions of the study.
    Matched MeSH terms: Attention/physiology*
  12. The Time Course of Activity within the Dorsal and Rostral-Ventral Anterior Cingulate Cortex in the Emotional Stroop Task
    Feroz FS, Leicht G, Steinmann S, Andreou C, Mulert C
    Brain Topogr, 2017 Jan;30(1):30-45.
    PMID: 27659288 DOI: 10.1007/s10548-016-0521-3
    Growing evidence from neuroimaging studies suggest that emotional and cognitive processes are interrelated. Anatomical key structures in this context are the dorsal and rostral-ventral anterior cingulate cortex (dACC and rvACC). However, up to now, the time course of activations within these regions during emotion-cognition interactions has not been disentangled. In the present study, we used event-related potentials (ERP) and standardized low-resolution electromagnetic tomography (sLORETA) region of interest (ROI) source localization analyses to explore the time course of neural activations within the dACC and rvACC using a modified emotional Stroop paradigm. ERP components related to Stroop conflict (N200, N450 and late negativity) were analyzed. The time course of brain activations in the dACC and rvACC was strikingly different with more pronounced initial responses in the rvACC followed by increased dACC activity mainly at the late negativity window. Moreover, emotional valence modulated the earlier N450 stage within the rvACC region with higher neural activations in the positive compared to the negative and neutral conditions. Emotional arousal modulated the late negativity stage; firstly in the significant arousal × congruence ERP effect and then the significant higher current density in the low arousal condition within the dACC. Using sLORETA source localization, substantial differences in the activation time courses in the dACC and rvACC could be found during the emotional Stroop task. We suggest that during late negativity, within the dACC, emotional arousal modulated the processing of response conflict, reflected in the correlation between the ex-Gaussian µ and the current density in the dACC.
    Matched MeSH terms: Attention/physiology*
  13. Stimulus-response incompatibility eliminates inhibitory cueing effects with saccadic but not manual responses
    Eng V, Lim A, Kwon S, Gan SR, Jamaluddin SA, Janssen SMJ, et al.
    Atten Percept Psychophys, 2017 May;79(4):1097-1106.
    PMID: 28229429 DOI: 10.3758/s13414-017-1295-8
    There are thought to be two forms of inhibition of return (IOR) depending on whether the oculomotor system is activated or suppressed. When saccades are allowed, output-based IOR is generated, whereas input-based IOR arises when saccades are prohibited. In a series of 4 experiments, we mixed or blocked compatible and incompatible trials with saccadic or manual responses to investigate whether cueing effects would follow the same pattern as those observed with more traditional peripheral onsets and central arrows. In all experiments, an uninformative cue was displayed, followed by a cue-back stimulus that was either red or green, indicating whether a compatible or incompatible response was required. The results showed that IOR was indeed observed for compatible responses in all tasks, whereas IOR was eliminated for incompatible trials-but only with saccadic responses. These findings indicate that the dissociation between input- and output-based forms of IOR depends on more than just oculomotor activation, providing further support for the existence of an inhibitory cueing effect that is distinct to the manual response modality.
    Matched MeSH terms: Attention/physiology
  14. Fulltext Neural signals of selective attention are modulated by subjective preferences and buying decisions in a virtual shopping task
    Goto N, Mushtaq F, Shee D, Lim XL, Mortazavi M, Watabe M, et al.
    Biol Psychol, 2017 09;128:11-20.
    PMID: 28666891 DOI: 10.1016/j.biopsycho.2017.06.004
    We investigated whether well-known neural markers of selective attention to motivationally-relevant stimuli were modulated by variations in subjective preference towards consumer goods in a virtual shopping task. Specifically, participants viewed and rated pictures of various goods on the extent to which they wanted each item, which they could potentially purchase afterwards. Using the event-related potentials (ERP) method, we found that variations in subjective preferences for consumer goods strongly modulated positive slow waves (PSW) from 800 to 3000 milliseconds after stimulus onset. We also found that subjective preferences modulated the N200 and the late positive potential (LPP). In addition, we found that both PSW and LPP were modulated by subsequent buying decisions. Overall, these findings show that well-known brain event-related potentials reflecting selective attention processes can reliably index preferences to consumer goods in a shopping environment. Based on a large body of previous research, we suggest that early ERPs (e.g. the N200) to consumer goods could be indicative of preferences driven by unconditional and automatic processes, whereas later ERPs such as the LPP and the PSW could reflect preferences built upon more elaborative and conscious cognitive processes.
    Matched MeSH terms: Attention/physiology*
  15. Effects of white noise on word recall performance and brain activity in healthy adolescents with normal and low auditory working memory
    Othman E, Yusoff AN, Mohamad M, Abdul Manan H, Abd Hamid AI, Giampietro V
    Exp Brain Res, 2020 Apr;238(4):945-956.
    PMID: 32179941 DOI: 10.1007/s00221-020-05765-3
    The present study examined the impact of white noise on word recall performance and brain activity in 40 healthy adolescents, split in two groups (normal and low) depending on their auditory working memory capacity (AWMC). Using functional magnetic resonance imaging, participants performed a backward recall task under four different signal-to-noise ratio (SNR) conditions: 15, 10, 5, and 0-dB SNR. Behaviorally, normal AWMC individuals scored significantly higher than low AWMC individuals across noise levels. Whole-brain analyses showed brain activation not to be statistically different between groups across noise levels. In the normal group, a significant positive relationship was found between performance and number of activated voxels in the right superior frontal gyrus. In the low group, significant positive correlations were found between performance and number of activated voxels in left superior frontal gyrus, left inferior frontal gyrus, and left anterior cingulate cortex. These findings suggest that the strategic structure involved in the enhancement of AWM performance may differ in normal and low AWMC individuals.
    Matched MeSH terms: Attention/physiology*
  16. Time course of inhibition of return in a spatial cueing paradigm with distractors
    Eng V, Lim A, Janssen SMJ, Satel J
    Acta Psychol (Amst), 2018 Feb;183:51-57.
    PMID: 29328938 DOI: 10.1016/j.actpsy.2017.12.011
    Studies of endogenous and exogenous attentional orienting in spatial cueing paradigms have been used to investigate inhibition of return, a behavioral phenomenon characterized by delayed reaction time in response to recently attended locations. When eye movements are suppressed, attention is covertly oriented to central or peripheral stimuli. Overt orienting, on the other hand, requires explicit eye movements to the stimuli. The present study examined the time course of slowed reaction times to previously attended locations when distractors are introduced into overt and covert orienting tasks. In a series of experiments, manual responses were required to targets following central and peripheral cues at three different cue-target intervals, with and without activated oculomotor systems. The results demonstrate that, when eye movements are suppressed, behavioral inhibition is reduced or delayed in magnitude by the presence of a distractor relative to conditions without distractors. However, the time course of behavioral inhibition when eye movements are required remains similar with or without distractors.
    Matched MeSH terms: Attention/physiology
  17. Fulltext Repetition Is the Feature Behind the Attentional Bias for Recognizing Threatening Patterns
    Shabbir M, Zon AMY, Thuppil V
    Evol Psychol, 2018;16(1):1474704918754782.
    PMID: 29455569 DOI: 10.1177/1474704918754782
    Animals attend to what is relevant in order to behave in an effective manner and succeed in their environments. In several nonhuman species, there is an evolved bias for attending to patterns indicative of threats in the natural environment such as dangerous animals. Because skins of many dangerous animals are typically repetitive, we propose that repetition is the key feature enabling recognition of evolutionarily important threats. The current study consists of two experiments where we measured participants' reactions to pictures of male and female models wearing clothing of various repeating (leopard skin, snakeskin, and floral print) and nonrepeating (camouflage, shiny, and plain) patterns. In Experiment 1, when models wearing patterns were presented side by side with total fixation duration as the measure, the repeating floral pattern was the most provocative, with total fixation duration significantly longer than all other patterns. Leopard and snakeskin patterns had total fixation durations that were significantly longer than the plain pattern. In Experiment 2, we employed a visual-search task where participants were required to find models wearing the various patterns in a setting of a crowded airport terminal. Participants detected leopard skin pattern and repetitive floral pattern significantly faster than two of the nonpatterned clothing styles. Our experimental findings support the hypothesis that repetition of specific visual features might facilitate target detection, especially those characterizing evolutionary important threats. Our findings that intricate, but nonthreatening repeating patterns can have similar attention-grabbing properties to animal skin patterns have important implications for the fashion industry and wildlife trade.
    Matched MeSH terms: Attention/physiology
  18. Fulltext In search of a reliable electrophysiological marker of oculomotor inhibition of return
    Satel J, Hilchey MD, Wang Z, Reiss CS, Klein RM
    Psychophysiology, 2014 Oct;51(10):1037-45.
    PMID: 24976355 DOI: 10.1111/psyp.12245
    Inhibition of return (IOR) operationalizes a behavioral phenomenon characterized by slower responding to cued, relative to uncued, targets. Two independent forms of IOR have been theorized: input-based IOR occurs when the oculomotor system is quiescent, while output-based IOR occurs when the oculomotor system is engaged. EEG studies forbidding eye movements have demonstrated that reductions of target-elicited P1 components are correlated with IOR magnitude, but when eye movements occur, P1 effects bear no relationship to behavior. We expand on this work by adapting the cueing paradigm and recording event-related potentials: IOR is caused by oculomotor responses to central arrows or peripheral onsets and measured by key presses to peripheral targets. Behavioral IOR is observed in both conditions, but P1 reductions are absent in the central arrow condition. By contrast, arrow and peripheral cues enhance Nd, especially over contralateral electrode sites.
    Matched MeSH terms: Attention/physiology*
  19. Fulltext Motor dexterity and strength depend upon integrity of the attention-control system
    Rinne P, Hassan M, Fernandes C, Han E, Hennessy E, Waldman A, et al.
    Proc Natl Acad Sci U S A, 2018 01 16;115(3):E536-E545.
    PMID: 29284747 DOI: 10.1073/pnas.1715617115
    Attention control (or executive control) is a higher cognitive function involved in response selection and inhibition, through close interactions with the motor system. Here, we tested whether influences of attention control are also seen on lower level motor functions of dexterity and strength-by examining relationships between attention control and motor performance in healthy-aged and hemiparetic-stroke subjects (n = 93 and 167, respectively). Subjects undertook simple-tracking, precision-hold, and maximum force-generation tasks, with each hand. Performance across all tasks correlated strongly with attention control (measured as distractor resistance), independently of factors such as baseline performance, hand use, lesion size, mood, fatigue, or whether distraction was tested during motor or nonmotor cognitive tasks. Critically, asymmetric dissociations occurred in all tasks, in that severe motor impairment coexisted with normal (or impaired) attention control whereas normal motor performance was never associated with impaired attention control (below a task-dependent threshold). This implies that dexterity and force generation require intact attention control. Subsequently, we examined how motor and attention-control performance mapped to lesion location and cerebral functional connectivity. One component of motor performance (common to both arms), as well as attention control, correlated with the anatomical and functional integrity of a cingulo-opercular "salience" network. Independently of this, motor performance difference between arms correlated negatively with the integrity of the primary sensorimotor network and corticospinal tract. These results suggest that the salience network, and its attention-control function, are necessary for virtually all volitional motor acts while its damage contributes significantly to the cardinal motor deficits of stroke.
    Matched MeSH terms: Attention/physiology*
  20. Removal of BCG artefact from concurrent fMRI-EEG recordings based on EMD and PCA
    Javed E, Faye I, Malik AS, Abdullah JM
    J Neurosci Methods, 2017 11 01;291:150-165.
    PMID: 28842191 DOI: 10.1016/j.jneumeth.2017.08.020
    BACKGROUND: Simultaneous electroencephalography (EEG) and functional magnetic resonance image (fMRI) acquisitions provide better insight into brain dynamics. Some artefacts due to simultaneous acquisition pose a threat to the quality of the data. One such problematic artefact is the ballistocardiogram (BCG) artefact.

    METHODS: We developed a hybrid algorithm that combines features of empirical mode decomposition (EMD) with principal component analysis (PCA) to reduce the BCG artefact. The algorithm does not require extra electrocardiogram (ECG) or electrooculogram (EOG) recordings to extract the BCG artefact.

    RESULTS: The method was tested with both simulated and real EEG data of 11 participants. From the simulated data, the similarity index between the extracted BCG and the simulated BCG showed the effectiveness of the proposed method in BCG removal. On the other hand, real data were recorded with two conditions, i.e. resting state (eyes closed dataset) and task influenced (event-related potentials (ERPs) dataset). Using qualitative (visual inspection) and quantitative (similarity index, improved normalized power spectrum (INPS) ratio, power spectrum, sample entropy (SE)) evaluation parameters, the assessment results showed that the proposed method can efficiently reduce the BCG artefact while preserving the neuronal signals.

    COMPARISON WITH EXISTING METHODS: Compared with conventional methods, namely, average artefact subtraction (AAS), optimal basis set (OBS) and combined independent component analysis and principal component analysis (ICA-PCA), the statistical analyses of the results showed that the proposed method has better performance, and the differences were significant for all quantitative parameters except for the power and sample entropy.

    CONCLUSIONS: The proposed method does not require any reference signal, prior information or assumption to extract the BCG artefact. It will be very useful in circumstances where the reference signal is not available.

    Matched MeSH terms: Attention/physiology
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