Human Cognitive Performance Research Articles

The effects of wearing respirators on human fine motor, visual, and cognitive performance

When selecting a respirator, it is important to understand how employees' motor, visual and cognitive abilities are impacted by the personal protective equipment. This study compares dust, powered-air-purifying and full-face, negative-pressure respirators. Thirty participants performed three varied tasks. Each participant performed each task without a respirator and while wearing the three respirator types. The tasks included a hand tool dexterity test, the Motor-Free Visual Perception Test and the Serial Sevens Test to evaluate fine motor, visual and cognitive performance, respectively. The time required for task completion and the errors made were measured. Analysis showed no significant effect due to respirator use on the task completion time. A significant increase was found in the error rate when participants performed the cognitive test wearing the full-face, negative-pressure respirator. Participants had varying respirator preferences. They indicated a potential for full-face, negative-pressure respirators to negatively affect jobs demanding high cognitive skills such as problem solving and decision-making. Practitioner summary: while respirators are life-saving personal protective equipment (PPE), they can unintentionally reduce human performance, especially if job characteristics are not considered during PPE selection. An experiment was conducted to compare three respirators (dust respirator, powered-air-purifying respirators and full-face respirator) for varying task types. The full-face respirator was found to affect human cognitive performance negatively.

Acute exposure to evening blue‐enriched light impacts on human sleep

Light in the short wavelength range (blue light: 446-483nm) elicits direct effects on human melatonin secretion, alertness and cognitive performance via non-image-forming photoreceptors. However, the impact of blue-enriched polychromatic light on human sleep architecture and sleep electroencephalographic activity remains fairly unknown. In this study we investigated sleep structure and sleep electroencephalographic characteristics of 30 healthy young participants (16 men, 14 women; age range 20-31years) following 2h of evening light exposure to polychromatic light at 6500K, 2500K and 3000K. Sleep structure across the first three non-rapid eye movement non-rapid eye movement - rapid eye movement sleep cycles did not differ significantly with respect to the light conditions. All-night non-rapid eye movement sleep electroencephalographic power density indicated that exposure to light at 6500K resulted in a tendency for less frontal non-rapid eye movement electroencephalographic power density, compared to light at 2500K and 3000K. The dynamics of non-rapid eye movement electroencephalographic slow wave activity (2.0-4.0Hz), a functional index of homeostatic sleep pressure, were such that slow wave activity was reduced significantly during the first sleep cycle after light at 6500K compared to light at 2500K and 3000K, particularly in the frontal derivation. Our data suggest that exposure to blue-enriched polychromatic light at relatively low room light levels impacts upon homeostatic sleep regulation, as indexed by reduction in frontal slow wave activity during the first non-rapid eye movement episode.

The largest human cognitive performance dataset reveals insights into the effects of lifestyle factors and aging

Making new breakthroughs in understanding the processes underlying human cognition may depend on the availability of very large datasets that have not historically existed in psychology and neuroscience. Lumosity is a web-based cognitive training platform that has grown to include over 600 million cognitive training task results from over 35 million individuals, comprising the largest existing dataset of human cognitive performance. As part of the Human Cognition Project, Lumosity's collaborative research program to understand the human mind, Lumos Labs researchers and external research collaborators have begun to explore this dataset in order uncover novel insights about the correlates of cognitive performance. This paper presents two preliminary demonstrations of some of the kinds of questions that can be examined with the dataset. The first example focuses on replicating known findings relating lifestyle factors to baseline cognitive performance in a demographically diverse, healthy population at a much larger scale than has previously been available. The second example examines a question that would likely be very difficult to study in laboratory-based and existing online experimental research approaches at a large scale: specifically, how learning ability for different types of cognitive tasks changes with age. We hope that these examples will provoke the imagination of researchers who are interested in collaborating to answer fundamental questions about human cognitive performance.

A Human Cognitive Performance Measure Based on Available Options for Adaptive Aiding

The concept of adaptive automation stipulates dynamically changing levels of automation as solution for the conflict between advantages offered by different static levels of automation. The use of a task performance measure to invoke adaptive automation enables adapting not only to the current situation but additionally to the specific needs of different operators. This paper presents an approach to measure the task performance by comparing the observed interaction behavior with the options available. This takes account of the fact that the achievable result strongly depends on the current situation and the available interaction options. The presented approach is based on a Coloured-Petri-Net (CPN) simulation environment and generates action sequences in the Petri Nets state space which represent the consequences of alternative options. Thus, evaluating operators' actions taking into account the available options becomes possible. This paper further discusses the advantages and disadvantages of the proposed approach regarding its application for adaptive automation. On the one hand, the method is sensitive to the environmental conditions and is able to measure the performance at any time. On the other hand, a drawback of the method is its high computational demand so that it has been used only for retrospective analyses up to now.

Sleep Locally, Act Globally

In most animals, sleep is considered a global brain and behavioral state. However, recent intracortical recordings have shown that aspects of non–rapid eye movement (NREM) sleep and wakefulness can occur simultaneously in different parts of the cortex in mammals, including humans. Paradoxically, however, NREM sleep still manifests as a global behavioral shutdown. In this review, the authors examine this paradox from an evolutionary perspective. On the basis of strategic modeling, they suggest that in animals with brains composed of heavily interconnected and functionally interdependent units, a global regulator of sleep maintains the behavioral shutdown that defines sleep and thereby ensures that local use-dependent functions are performed in a safe and efficient manner. This novel perspective has implications for understanding deficits in human cognitive performance resulting from sleep deprivation, sleep disorders such as sleepwalking, changes in consciousness that occur during sleep, and the function of sleep itself.

Age-related changes in sleep and circadian rhythms: impact on cognitive performance and underlying neuroanatomical networks.

Circadian and homeostatic sleep-wake regulatory processes interact in a fine tuned manner to modulate human cognitive performance. Dampening of the circadian alertness signal and attenuated deterioration of psychomotor vigilance in response to elevated sleep pressure with aging change this interaction pattern. As evidenced by neuroimaging studies, both homeostatic sleep pressure and circadian sleep-wake promotion impact on cognition-related cortical and arousal-promoting subcortical brain regions including the thalamus, the anterior hypothalamus, and the brainstem locus coeruleus (LC). However, how age-related changes in circadian and homeostatic processes impact on the cerebral activity subtending waking performance remains largely unexplored. Post-mortem studies point to neuronal degeneration in the SCN and age-related modifications in the arousal-promoting LC. Alongside, cortical frontal brain areas are particularly susceptible both to aging and misalignment between circadian and homeostatic processes. In this perspective, we summarize and discuss here the potential neuroanatomical networks underlying age-related changes in circadian and homeostatic modulation of waking performance, ranging from basic arousal to higher order cognitive behaviors.

Acute sleep deprivation: the effects of the AMPAKINE compound CX717 on human cognitive performance, alertness and recovery sleep

AMPA receptor modulation is a potential novel approach to enhance cognitive performance. CX717 is a positive allosteric modulator of the AMPA receptor that has shown efficacy in rodent and primate cognition models. CX717 (100 mg, 300 mg and 1000 mg) and placebo were studied in 16 healthy male volunteers (18-45 years) in a randomized, crossover study. Cognitive function, arousal and recovery sleep (by polysomnography) were assessed during the extended wakefulness protocol. Placebo condition was associated with significant decrements in cognition, particularly at the circadian nadir (between 03:00 and 05:00). Pre-specified primary and secondary analyses (general linear mixed modelling, GLMM) at each separate time point did not reveal consistent improvements in performance or objective alertness with any dose of CX717. Exploratory repeated measures analysis, a method used to take into account the influence of individual differences, demonstrated an improvement in attention-based task performance following the 1000 mg dose. Analysis of the recovery sleep showed that CX717 1000 mg significantly reduced stage 4 and slow-wave sleep (p ≤ 0.05) with evidence of reduced electroencephalogram (EEG) slow-wave and spindle activity. The study suggests that CX717 only at the 1000 mg dose may counteract effects of sleep deprivation on attention-based tasks and that it may interfere with subsequent recovery sleep.

No effects of short‐term exposure to mobile phone electromagnetic fields on human cognitive performance: A meta‐analysis

During recent years, a large number of studies on the effects of electromagnetic fields emitted by cellular mobile phones on human cognitive performance have been carried out. However, the results have been ambiguous. We carried out the current meta-analysis in order to investigate the impact of electromagnetic fields emitted by mobile phones on human cognition. Seventeen studies were included in the meta-analysis as they fulfill several requirements such as single- or double-blind experimental study design, and documentation of means and standard deviations of dependent variables. The meta-analysis was carried out as a group comparison between exposed and non-exposed subjects. No significant effects of electromagnetic fields emitted by Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS) mobile phones were found. Cognitive abilities seem to be neither impaired nor facilitated. Results of the meta-analysis suggest that a substantial short-term impact of high frequency electromagnetic fields emitted by mobile phones on cognitive performance can essentially be ruled out.

DNA base excision repair gene polymorphisms modulate human cognitive performance and decline during normal life span

To test the hypothesis that single nucleotide polymorphisms (SNPs) in DNA repair genes are associated with cognitive performance during normal aging, the relationship between SNPs in selected exons in DNA base excision repair (BER) genes and cognitive performance was examined in 712 healthy Norwegian individuals aged 20–75 years. SNPs examined included PolB Pro242Arg, hOGG1 Ser326Cys, MutYH Met22Val, MutYH His324Gln, APE1 Gln51His, APE1 Glu148Asp, XRCC1 Lys298Asn, XRCC1 Arg7Leu, NEIL1 Asp252Asn, and NEIL2 Arg257Leu. XRCC1 Arg7Leu and PolB Pro242Arg were characterized by single nucleotide variations (≤0.1% homozygote SNPs). hOGG1 Ser326Cys (Ser/Cys 40.8%/Cys/Cys 5.7%), MutYH His324Gln (His/Gln37%/Gln/Gln 6.0%) and APE1 Glu148Asp (Glu/Asp 51.3%/Asp/Asp 23.0%) were characterized by higher SNP frequencies. MutYH Met22Val, APE1 Gln51His and NEIL2 Arg257Leu occurred at intermediate SNP frequencies of 11.5, 7.6 and 5.3%, respectively. Interestingly, hOGG1 Ser326Cys and APE1 Gln51His had genotype by age interactions with general cognitive function, reasoning, control and speed of processing in cross-sectional analysis and a significant effect on longitudinal decline. Dispersed association effects involving MutYH His324Gln, MutYH Met22Val, PolB Pro242Arg and NEIL2 Arg257Leu were also detected when APOE or CHRNA4, were included in the statistical model, a result consistent with proposed involvement of the latter markers in human cognitive decline and/or function. In summary, the results support the notion that polymorphisms in BER genes modulate cognitive performance in healthy elderly individuals.

A Framework-Based Approach to Identifying and Organizing the Complexity Factors of Human-System Interaction

As the nature of human interaction with modernized socio-technical systems is increasingly cognitive and complex, many studies have been devoted to examine a range of complexity factors influencing human cognitive performance. However, there is a lack of theoretical basis of discerning and categorizing those factors. It is thus inevitable to establish a conceptual framework that can be used to identify and organize the complexity factors in an analytical way. In this paper, we regard the world of complexity factors as an abstract system and propose a new framework consisting of five views, each of which is concerned with certain aspects of the abstract system. To develop the framework more systematically, we conducted a comprehensive literature review and applied a system thinking approach to deriving a set of requirements to be satisfied by the framework. Of those five views, we particularly emphasize the roles of knowledge view. Thus a complexity factor model based on the knowledge view is also proposed. We describe two possible uses of the framework and the complexity factor model, which are the analytical identification of the complexity factors and the systematic assessment of the complexity factors identified by earlier studies.

Human cognitive performance in a 3 mT power-line frequency magnetic field

Extremely low frequency (ELF, <300 Hz) magnetic fields (MF) have been reported to modulate cognitive performance in humans. However, little research exists with MF exposures comparable to the highest levels experienced in occupations like power line workers and industrial welders. This research aims to evaluate the impact of a 60 Hz, 3 mT MF on human cognitive performance. Ninety-nine participants completed the double-blind protocol, performing a selection of psychometric tests under two consecutive MF exposure conditions dictated by assignment to one of three groups (sham/sham, MF exposure/sham, or sham/MF exposure). Data were analyzed using a 3 × 2 mixed model analysis of variance. Performance between repetitions improved in 11 of 15 psychometric parameters (practice effect). A significant interaction effect on the digit span forward test (F = 5.21, P < 0.05) revealed an absence of practice effects for both exposure groups but not the control group. This memory test indicates MF-induced abolition of the improvement associated with practice. Overall, this study does not establish any clear MF effect on human cognition. It is speculated that an ELF MF may interfere with the neuropsychological processes responsible for this short-term learning effect supported by brain synaptic plasticity.

“Doctor, Would You Prescribe a Pill to Help Me … ?” A National Survey of Physicians on Using Medicine for Human Enhancement

Using medical advances to enhance human athletic, aesthetic, and cognitive performance, rather than to treat disease, has been controversial. Little is known about physicians’ experiences, views, and attitudes in this regard. We surveyed a national sample of physicians to determine how often they prescribe enhancements, their views on using medicine for enhancement, and whether they would be willing to prescribe a series of potential interventions that might be considered enhancements. We find that many physicians occasionally prescribe enhancements, but doctors hold nuanced and ambiguous views of these issues. Most express concerns about the potential effects of enhancements on social equity, yet many also believe specific enhancements that are safe and effective should be available but not covered by insurance. These apparently contradictory views might reflect inherent tensions between the values of equity and liberty, which could make crafting coherent social policies on medical enhancements challenging. [Supplementary materials are available for this article. Go to the publisher's online edition of American Journal of Bioethics for the following free supplemental resource(s): An additional table (Table 5) referred to on p. 5]

Three Billion Years of Fatty Acid Metabolism Shape Human Cognitive Performance

Animal evolutionary history has progressed, in fits and starts, over several billions of years of changing environmental conditions on this planet. Ancient environments were strikingly different from modern conditions, and, in some cases, have left a permanent stamp on animal (including human) anatomy and physiology. Recently Lassek and Gaulin (2011) assessed the role which dietary fatty acids may play in shaping human cognitive performance, and in doing so, provide an intriguing glimpse into the evolution of animal nervous systems. Using a large sample of American children aged 6–16 from the Third National Health and Nutrition Examination Survey [Center for Disease Control (CDC), 1988–1994], Lassek and Gaulin explored the statistical relationships between human cognitive performance (assessed via standardized math and reading tests) and dietary components, while controlling for other measures of subjects’ social and environmental backgrounds (including lead exposure, family size and income, ethnicity). They found that dietary fatty acids, particularly n − 3 (“omega-3”) and n − 6 forms, were positively and negatively related, respectively, to cognition scores in both male and female children. The benefits of dietary n − 3 fatty acids were especially important for cognition in female children (Lassek and Gaulin, 2011). Both n − 3 and n − 6 fatty acids are essential nutrients that must be obtained from dietary sources, and our Western diets are known to have relatively low n − 3:n − 6 ratios (Blasbalg et al., 2011). Why their opposite utility? And why of differential importance for males and females? Lassek and Gaulin (2011) suggest explanations which are rooted in our evolutionary past. Our nervous systems contain a predominance of n − 3 fatty acids, which Lassek and Gaulin (2011) hypothesize is due to the fact that animal neurons first evolved in an environment rich in n − 3 fatty acids but limiting in n − 6 fatty acids. Under these conditions, n − 3 fatty acids became, and remain, critical for complete nervous development. Lassek and Gaulin cite corroborative evidence for the ability of n − 6 fatty acids to compete with n − 3 fatty acids for enzymatic access, suggesting that this competition is a direct mechanism for the differential utility of dietary n − 3 and n − 6 forms. Dietary intake of n − 3 fatty acids is shown by Lassek and Gaulin to be especially important for females, which they suggest is due to the fact that female children must partition their dietary intake of these essential nutrients for both their own use as well as toward fat stores for later use as a nutritive source for the provisioning of developing offspring. Here, too, an ancient evolutionary shaping of our animal parental roles continues to represent itself in our utilization of dietary components, with implications for cognitive performance. It is well understood that n − 3 fatty acids are profoundly bio-active in neural as well as other tissues, with influence on cell membrane fluidity (Fernstrom, 1999; Schmitz and Ecker, 2008, and others), oxidative capacity (example in Maillet and Weber, 2007), and gene expression (recently reviewed in Bordoni et al., 2006). Their direct effects on the genesis, viability, and connectivity of neural tissues have also been demonstrated repeatedly in animal studies (as cited by Lassek and Gaulin, 2011), and their dietary importance to the neural development of human infants is also known (Hoffman et al., 2009; Leung et al., 2011; Muhlhausler et al., 2011; Salvig and Lamont, 2011). Lassek and Gaulin (2011) now add to this body of knowledge by demonstrating the importance of dietary n − 3 fatty acids beyond infancy into childhood and adolescence, and also provide evidence and explanation for the differential importance of dietary fatty acids for female children. In doing so, they highlight the need for more stringent consideration of n − 3 dietary requirements during childhood as well as the need for more specific research on the mechanisms by which these essential nutrients influence human cognition. In using their evolutionary perspective, they also provide an important reminder of the need to consider evolutionary constraint in the shaping of our marvelously complex, yet very biologically, nervous systems – in many ways, we (still) are what we eat.

Functional cerebral lateralization and dual-task efficiency—Testing the function of human brain lateralization using fTCD

It has been hypothesized that functional cerebral lateralization enhances cognitive performance. Evidence was found in birds and fish. Our study aimed to test this hypothesis by analyzing the relationship between cerebral lateralization and both single-task performance and dual-task efficiency in humans. We combined a dynamic Landmark task which is assumed to be primarily processed in the right hemisphere and a frequently used word generation task which is assumed to be primarily processed in the left hemisphere. For each task individual strength and direction of hemispheric lateralization was assessed using functional transcranial Doppler sonography (fTCD). For each subject (15 women, 11 men), performance was measured in the two single-tasks and in the dual-task condition.Performance was not related to strength or direction of lateralization in single-tasks. With regard to dual-task efficiency, we found the expected advantage of having a typical lateralization pattern. Moreover, the results showed a slight negative, rather than a positive, relationship between strength of lateralization and dual-task efficiency. Further analysis showed that this negative relationship may only be present in subjects showing non-significant lateralization for one or both tasks. Therefore, the hypothesis that cerebral lateralization enhances human cognitive performance is too general: having two functions significantly lateralized to different hemispheres enhances dual-task efficiency, in this group strength of lateralized does not matter. However, if one or both functions are not significantly lateralized overall performance is worse and in this group, performance is negatively related to increased strength of lateralization.

Genome‐wide association study of theta band event‐related oscillations identifies serotonin receptor gene HTR7 influencing risk of alcohol dependence

Event-related brain oscillations (EROs) represent highly heritable neuroelectrical correlates of human perception and cognitive performance that exhibit marked deficits in patients with various psychiatric disorders. We report the results of the first genome-wide association study (GWAS) of an ERO endophenotype-frontal theta ERO evoked by visual oddball targets during P300 response in 1,064 unrelated individuals drawn from a study of alcohol dependence. Forty-two SNPs of the Illumina HumanHap 1 M microarray were selected from the theta ERO GWAS for replication in family-based samples (N = 1,095), with four markers revealing nominally significant association. The most significant marker from the two-stage study is rs4907240 located within ARID protein 5A gene (ARID5A) on chromosome 2q11 (unadjusted, Fisher's combined P = 3.68 × 10⁻⁶). However, the most intriguing association to emerge is with rs7916403 in serotonin receptor gene HTR7 on chromosome 10q23 (combined P = 1.53 × 10⁻⁴), implicating the serotonergic system in the neurophysiological underpinnings of theta EROs. Moreover, promising SNPs were tested for association with diagnoses of alcohol dependence (DSM-IV), revealing a significant relationship with the HTR7 polymorphism among GWAS case-controls (P = 0.008). Significant recessive genetic effects were also detected for alcohol dependence in both case-control and family-based samples (P = 0.031 and 0.042, respectively), with the HTR7 risk allele corresponding to theta ERO reductions among homozygotes. These results suggest a role of the serotonergic system in the biological basis of alcohol dependence and underscore the utility of analyzing brain oscillations as a powerful approach to understanding complex genetic psychiatric disorders.

No effect of TETRA hand portable transmission signals on human cognitive function and symptoms

Current radio frequency radiation exposure guidelines rest on well-established thermal effects. However, recent research into analogue and digital transmission fields at levels covered by the exposure guidelines has indicated possible detrimental effects on human cognitive performance. To investigate this, we conducted a controlled climate chamber study of possible changes in cognitive performance in healthy volunteers exposed to transmission signals from TETRA hand portables (TETRA handsets). The trial deployed a balanced, randomized, double-blinded cross-over design. Performance on different paper-and-pencil, auditory and computer-based cognitive tasks was monitored in 53 male volunteers (mean age 36.41 years, SD 8.35) during 45-min exposure to a TETRA handset and sham control signals remotely controlled from a laboratory more than 100 km away. The main cognitive outcome was the Trail Making B (TMB) test. In addition, the participants completed a computer-based questionnaire measuring self-reported psychological and physical symptoms. No statistically significant differences (P < 0.05) between the TETRA and sham conditions were found for either TMB (estimated difference 3.8%, confidence interval (CI) -1.6% to 9.2%) or any of the remaining cognitive tasks or symptoms. In conclusion, we found no evidence that brief exposure to hand-held TETRA transmitters' affects human cognitive function or subjective symptoms.

Begging the Question: Presupposing That TMS Can Be Shown to Enhance Eyewitness Testimony

There is a common weakness in many analyses of the ethics of using neurotechnologies to enhance human cognitive performance: the assumption that these technologies have either in fact been shown to...

Effects of microgravity on cognition: The case of mental imagery

Human cognitive performance is an important factor for the successful and safe outcome of commercial and non-commercial manned space missions. This article aims to provide a systematic review of studies investigating the effects of microgravity on the cognitive abilities of parabolic or space flight participants due to the absence of the gravito-inertial force. We will focus on mental imagery: one of the best studied cognitive functions. Mental imagery is closely connected to perception and motor behavior. It aids important processes such as perceptual anticipation, problem solving and motor simulation, all of which are critical for space travel. Thirteen studies were identified and classified into the following topics: spatial representations, mental image transformations and motor imagery. While research on spatial representation and mental image transformation continues to grow and specific differences in cognitive functioning between 1 g and 0 g have been observed, motor imagery has thus far received little attention.

Sleep deprivation: implications for obstetric practice in the United States

Recent advances in basic science have expanded our understanding of the function of sleep and of the effects of sleep deprivation on human cognitive and psychomotor performance. In addition, a growing volume of data documents potential detrimental effects of sleep deprivation on medical practice. Such data have special implications for a specialty in which sleep deprivation is sometimes the norm. A review of this evidence suggests the pressing need for a reassessment of individual and small group obstetric practice, particularly as it relates to labor and delivery care; the current model of care in which each woman is delivered by the same provider who delivers prenatal care is generally not tenable in a culture increasingly focused on patient safety.

Domain-specific and domain-general learning factors are expressed in genetically heterogeneous CD-1 mice

It has been established that both domain-specific (e.g. spatial) as well as domain-general (general intelligence) factors influence human cognition. However, the separation of these processes has rarely been attempted in studies using laboratory animals. Previously, we have found that the performances of outbred mice across a wide range of learning tasks correlate in such a way that a single factor can explain 30–44% of the variance between animals. This general learning factor is in some ways qualitatively and quantitatively analogous to general intelligence in humans. The complete structure of cognition in mice, however, has not been explored due to the limited sample sizes of our previous analyses. Here we report a combined analysis from 241 CD-1 mice tested in five primary learning tasks, and a subset of mice tested in two additional learning tasks. At least two (possibly three) of the seven learning tasks placed explicit demands on spatial and/or hippocampus-dependent processing abilities. Consistent with previous findings, we report a robust general factor influencing learning in mice that accounted for 38% of the variance across tasks. In addition, a domain-specific factor was found to account for performance on that subset of tasks that shared a dependence on hippocampal and/or spatial processing. These results provide further evidence for a general learning/cognitive factor in genetically heterogeneous mice. Furthermore (and similar to human cognitive performance), these results suggest a hierarchical structure to cognitive processes in this genetically heterogeneous species.