Data from magnetic resonance imaging, autopsy, endocranial measurements, and other techniques show that: brain size correlates 0.40 with cognitive ability; average brain size varies by race; and average cognitive ability varies by race. These results are as replicable as one will find in the social and behavioral sciences. They pose serious problems for Rose 's claim that reductionistic science is inadequate, inefficient, and/or unproductive.

Recently, Weisbecker and Goswami presented the first comprehensive comparative analysis of brain size, metabolic rate, and development periods in marsupial mammals. In this paper, a strictly energetic perspective is applied to identify general mammalian correlates of brain size evolution. In both marsupials and placentals, the duration or intensity of maternal investment is a key correlate of relative brain size, but here I show that allomaternal energy subsidies may also play a role. In marsupials, an (...) energetic constraint on brain size in adults is only revealed if we consider both metabolic and reproductive rates simultaneously, because a strong trade‐off between encephalization and offspring production masks the positive correlation between basal metabolic rate and brain size in a bivariate comparison. In conclusion, starting from an energetic perspective is warranted to elucidate relations between ecology, social systems, life history, and brain size in all mammals. (shrink)

What parameters determine brain size? This question is of particular interest for humans because our large brains confer outstanding cognitive abilities. The answer has long been sought in comparative analyses of brain size relative to body size (herein termed ‘brain size’) in our fellow homeothermic vertebrates – namely other mammals and birds. Unfortunately, brain size is an idiosyncratic trait corresponding to a seemingly miscellaneous collection of traits ranging from gestation length to (...) deception behaviour. Some order can be established by attributing brain size correlates to categories of constraint (‘what traits permit or limit increased brain sizes?’) and selection (‘what traits select for increased brain sizes?. Even so, the vast number of potential correlates has lead to a plethora of (frequently mutually exclusive) hypotheses regarding avian and mammalian brain size evolution. This confusion has recently prompted calls for better integration of brain size correlates. In this article we argue that the latest advances in the field of brain size constraints, combined with modern techniques for tracing brain development, put an integrated framework of brain size evolution within our reach. (shrink)

Recent brain imaging points to differences in brain structure that relate to intelligence, but how do we model their causal relationship within a coherent framework that circumvents classic dualist traps? A bottom-level nonlinear, dynamic, multifactor, multiplicative, multidimensional, molecular (ND4M) trait-covariance time-space model may accomplish this better than traditional approaches.

Using neoPiagetian theory of mental attention (or working memory), I task-analyze two complex performances of great apes and one symbolic performance (funeral burials) of early Homo sapiens. Relating results to brain size growth data, I derive estimates of mental attention for great apes, Homo erectus, Neanderthals, and modern Homo sapiens, and use children's cognitive development as reference. This heuristic model seems consistent with research.

As bridges or brains become bigger or smaller, the changes pose problems of design thatneed to be solved. Larger brains could have larger or more neurons, or both. With largerneurons, it becomes difficult to maintain conduction times over longer axons andelectrical cable properties over longer dendrites. With more neurons, it becomes difficultfor each neuron to maintain its proportion of connections with other neurons. Theseproblems are addressed by making brains more modular, thereby reducing the lengths ofmany connections, and by altering functions. (...) Smaller brains may not have enoughneurons for all circuits, and they may lose modules and functions. Mammals with moreneocortex tend to have more cortical areas and more columns and types of columnswithin the larger areas. (shrink)

Brain parts can scale independently of the whole brain, and an example is given to point out that the authors underestimate variation that can exist in brains of equal size.

Any account of “what is special about the human brain” (Passingham 2008) must specify the neural basis of our unique ability to produce speech and delineate how these remarkable motor capabilities could have emerged in our hominin ancestors. Clinical data suggest that the basal ganglia provide a platform for the integration of primate-general mechanisms of acoustic communication with the faculty of articulate speech in humans. Furthermore, neurobiological and paleoanthropological data point at a two-stage model of the phylogenetic evolution of (...) this crucial prerequisite of spoken language: (i) monosynaptic refinement of the projections of motor cortex to the brainstem nuclei that steer laryngeal muscles, presumably, as part of a “phylogenetic trend” associated with increasing brain size during hominin evolution; (ii) subsequent vocal-laryngeal elaboration of cortico-basal ganglia circuitries, driven by human-specificFOXP2mutations.;>This concept implies vocal continuity of spoken language evolution at the motor level, elucidating the deep entrenchment of articulate speech into a “nonverbal matrix” (Ingold 1994), which is not accounted for by gestural-origin theories. Moreover, it provides a solution to the question for the adaptive value of the “first word” (Bickerton 2009) since even the earliest and most simple verbal utterances must have increased the versatility of vocal displays afforded by the preceding elaboration of monosynaptic corticobulbar tracts, giving rise to enhanced social cooperation and prestige. At the ontogenetic level, the proposed model assumes age-dependent interactions between the basal ganglia and their cortical targets, similar to vocal learning in some songbirds. In this view, the emergence of articulate speech builds on the “renaissance” of an ancient organizational principle and, hence, may represent an example of “evolutionary tinkering” (Jacob 1977). (shrink)

A growing number of studies have found that large brains may help animals survive by avoiding predation. These studies provide an alternative explanation for existing correlative evidence for one of the dominant hypotheses regarding the evolution of brain size in animals, the social brain hypothesis (SBH). The SBH proposes that social complexity is a major evolutionary driver of large brains. However, if predation both directly selects for large brains and higher levels of sociality, correlations between sociality and (...) brain size may be spurious. We argue that tests of the SBH should take direct effects of predation into account, either by explicitly including them in comparative analyses or by pin‐pointing the brain‐behavior‐fitness pathway through which the SBH operates. Existing data and theory on social behavior can then be used to identify precise candidate mechanisms and formulate new testable predictions. (shrink)

Many models have posited that the concomitant evolution of large brains and body sizes in hominins was constrained by metabolic costs. In such studies, the impact of body temperature has arguably not been sufficiently addressed despite the well-established fact that the rates of most physiological processes are manifestly temperature-dependent. Hence, the potential role of body temperature in regulating the number of neurons and body size is investigated by means of a heuristic quantitative model. It is suggested that modest deviations (...) in body temperature might allow for substantive changes in brain and body parameters. In particular, a higher body temperature may prove amenable to an increased number of neurons, a higher brain-to-body mass ratio and fewer hours expended on feeding activities, while the converse could apply when the temperature is lowered. Future studies should, therefore, endeavor to explore and incorporate the effects of body temperature in metabolic theories of hominin evolution, while also integrating other factors such as foraging efficiency, diet, and fire control in tandem. (shrink)

Although brain size and the concept of intelligence have been extensively used in comparative neuroscience to study cognition and its evolution, such coarse-grained traits may not be informative enough about important aspects of neurocognitive systems. By taking into account the different evolutionary trajectories and the selection pressures on neurophysiology across species, Logan and colleagues suggest that the cognitive abilities of an organism should be investigated by considering the fine-grained and species-specific phenotypic traits that characterize it. In such a (...) way, we would avoid adopting human-oriented, coarse-grained traits, typical of the standard approach in cognitive neuroscience. We argue that this standard approach can fail in some cases, but can, however, work in others, by discussing two major topics in contemporary neuroscience as examples: general intelligence and brain asymmetries. (shrink)

How does evolution grow bigger brains? It has been widely assumed that growth of individual structures and functional systems in response to niche-specific cognitive challenges is the most plausible mechanism for brain expansion in mammals. Comparison of multiple regressions on allometric data for 131 mammalian species, however, suggests that for 9 of 11 brain structures taxonomic and body size factors are less important than covariance of these major structures with each other. Which structure grows biggest is largely (...) predicted by a conserved order of neurogenesis that can be derived from the basic axial structure of the developing brain. This conserved order of neurogenesis predicts the relative scaling not only of gross brain regions like the isocortex or mesencephalon, but also the level of detail of individual thalamic nuclei. Special selection of particular areas for specific functions does occur, but it is a minor factor compared to the large-scale covariance of the whole brain. The idea that enlarged isocortex could be a a by-product of structural constraints later adapted for various behaviors, contrasts with approaches to selection of particular brain regions for cognitively advanced uses, as is commonly assumed in the case of hominid brain evolution. (shrink)

Despite tremendous advances in neuroscience, the topic “brain, sex and gender” remains a matter of misleading interpretations, that go well beyond the bounds of science. In the 19th century, the difference in brain sizes was a major argument to explain the hierarchy between men and women, and was supposed to reflect innate differences in mental capacity. Nowadays, our understanding of the human brain has progressed dramatically with the demonstration of cerebral plasticity. The new brain imaging techniques (...) have revealed the role of the environment in continually re-shaping our brain all along our lifetimes as it goes through new experiences and acquires new knowledge. However, the idea that biology is a major determining factor for cognition and behavioral gender differentiation, is still very much alive. The media are far from being the only guilty party. Some scientific circles actively promote the idea of an innate origin of a gender difference in mental capacities. Experimental data from brain imaging, cognitive tests or genetics are often distorted to serve deterministic ideas. Such abuse of “scientific discourses” have to be counteracted by effective communication of clear and unbiased information to the citizens. This paper presents a critical analysis of selected examples which emphasize sex differences in three fields e.g. skills in language and mathematics, testosterone and financial risk-taking behavior, moral cognition. To shed light on the data and the methods used in some papers, we can now—with today’s knowledge on cerebral plasticity—challenge even more strongly, many false interpretations. Our goal here is double: we want to provide evidence against archaic beliefs about the biological determinism of sex differences but also promote a positive image of scientific research. (shrink)

Sex dimorphism occurs when group means differ by four or more standard deviations. However, the average size of the corpus callosum is greater in males by about one standard deviation in rats, 0.2 standard deviation in humans, and virtually zero in mice. Furthermore, variations in corpus callosum size are related to brain size and are not sex specific.

Brain evolution is a complex weave of species similarities and differences, bound by diverse rules and principles. This book is a detailed examination of these principles, using data from a wide array of vertebrates but minimizing technical details and terminology. It is written for advanced undergraduates, graduate students, and more senior scientists who already know something about “the brain,” but want a deeper understanding of how diverse brains evolved. The book's central theme is that evolutionary changes in absolute (...) brain size tend to correlate with many other aspects of brain structure and function, including the proportional size of individual brain regions, their complexity, and their neuronal connections. To explain these correlations, the book delves into rules of brain development and asks how changes in brain structure impact function and behavior. Two chapters focus specifically on how mammal brains diverged from other brains and how Homo sapiens evolved a very large and “special” brain. Key Words: basal ganglia; cladistics; development; hippocampus; homology; lamination; mammal; neocortex; neuromere; parcellation; primate. (shrink)

Group size is a function of relative neocortical volume in nonhuman primates. Extrapolation from this regression equation yields a predicted group size for modern humans very similar to that of certain hunter-gatherer and traditional horticulturalist societies. Groups of similar size are also found in other large-scale forms of contemporary and historical society. Among primates, the cohesion of groups is maintained by social grooming; the time devoted to social grooming is linearly related to group size among the (...) Old World monkeys and apes. To maintain the stability of the large groups characteristic of humans by grooming alone would place intolerable demands on time budgets. It is suggested that (1) the evolution of large groups in the human lineage depended on the development of a more efficient method for time-sharing the processes of social bonding and that (2) language uniquely fulfills this requirement. Data on the size of conversational and other small interacting groups of humans are in line with the predictions for the relative efficiency of conversation compared to grooming as a bonding process. Analysis of a sample of human conversations shows that about 60% of time is spent gossiping about relationships and personal experiences. It is suggested that language evolved to allow individuals to learn about the behavioural characteristics of other group members more rapidly than is possible by direct observation alone. (shrink)

The phenomenon of size constancy is defined as the apparent perceptual invariance of the linear dimensions of a seen object as this approaches the eye or recedes from it. It has been interpreted as resulting from the application by the brain of a size correction, made possible by the subject's apprehension of distance cues present in the image. We present several observations which, by dissociating accommodation from distance of the seen object and by suppressing the optic effects (...) of accommodation on the visual image itself, show that this interpretation is incorrect, and that in fact the size correction of the visual image is a function of the central effort of accommodation, not of the distance of the seen object. (shrink)

Finlay et al. address the importance of developmental constraints in brain size evolution. I discuss some aspects of this view such as the relation of brain size with processing capacity. In particular, I argue that in human evolution there must have been specific selection for increased processing capacity, and as a consequence for increased brain size.

Dual-Brain Psychology is a theory and its clinical applications that come out of the author's clinical observations and from the Split-brain Studies. The theory posits, based on decades of rigorous, peer-reviewed experiments and clinical reports, that, in most patients, one brain's cerebral hemisphere when stimulated by simple lateral visual field stimulation, or unilateral transcranial photobiomodulation, reveals a dramatic change in personality such that stimulating one hemisphere evokes, as a trait, a personality that is more childlike and more (...) presently affected by childhood maltreatments that are usually not presently appreciated but are the proximal cause of the patient's symptoms. The personality associated with the other hemisphere is much more mature, less affected by the traumas, and less symptomatic. The theory can be applied to in-depth psychotherapy in which the focus is on helping the troubled side to bear and process the traumas with the help of the therapist and the healthier personality. A person's symptoms can be evoked to aid the psychotherapy with hemispheric stimulation and the relationship between the dual personalities can be transformed from conflicted and sabotaging to cooperating toward overall health. Stimulating the positive hemisphere in most therapy patients rapidly relieves symptoms such as anxiety, depression, or substance cravings. Two randomized controlled trials used unilateral transcranial photobiomodulation to the positive hemisphere as a stand-alone treatment for opioid cravings and both revealed high effect sizes. The theory is supported by brain imaging and rTMS studies. It is the first psychological theory and application that comes out of and is supported by rigorous peer-reviewed experimentation. (shrink)

Environmental policy has a size bias. Small organisms, such as microorganisms, command less attention from environmentalists than larger organisms, such as birds and large mammals. A simple thought experiment involving microscopic polar bears and giant microorganisms illustrates the importance of size in environmental ethics. Given the positive correlation between body size and brain size, there is probably a basis for a size bias in environmental ethics using ethical frameworks based on conations. This paper examines (...) the relevance of the size of organisms in environmental ethics. It emphasizes the need to understand the theoretical reasons for the importance of size, and not to base a size bias merely on a subjective anthropocentric prejudice favouring large organisms. (shrink)

Given the discovery of a distributed language and motor functional network, surprisingly few studies have explored whether language processing is related to motor skill training. To address this issue, the present study used functional magnetic resonance imaging to compare whole-brain activation between nonexperts and experts in table tennis, an open skill sport in which players make rapid decisions in response to an ever-changing environment. Whole-brain activation was assessed in 30 expert table tennis players with more than 7 years’ (...) experience and 35 age-matched nonexpert college students while they performed both a size and a semantic judgment task of words presented on a monitor. Compared with nonexperts, expert table tennis players showed greater activation in the left middle occipital gyrus and right precuneus while judging the size of the words versus during baseline fixation. They also showed greater activation in the left lingual gyrus during the semantic judgment task versus during baseline fixation. Our findings indicate that the visual regions engaged in language processing are associated with open motor skill training. (shrink)

I discuss Fitch & Denenberg's argument that no correction for brain size is needed when assessing callosal size. Morphometric criteria may not be sufficient to determine whether corrections are needed. Functional studies of callosal transfer will ultimately specify whether corrections for size are necessary in each case.

Research by neuroscientists suggests there is a distinction in the BSTc area of the brain between males and females. In transsexual females, those considered male at birth, but who had a strong conviction that they were female, the BSTc region appears to be similar in size to the female BSTc and transsexuals considered female at birth, but who were certain they were male, had a BSTc similar to the male BSTc. This distinction leads to the conclusion that in (...) addition to the recognised markers for gender - genitalia, gonads and chromosomes - we may need to also include the BSTc, given that this current research seems to substantiate what transsexuals are saying about their gender. This paper sets out to challenge our current reliance on the standard gender indicators alone and seeks to address some issues faced by transsexuals. (shrink)

In my target article, I argued (1) that the relationship between neocortical size and group size in primates implies that there is a cognitive limit on the size of human groups, and (2) that time constraints forced the evolution of language as a more efficient means of bonding the large groups that humans evolved. The doubts about these claims raised by these additional commentaries largely reflect misinterpretation of my original claims.

Data do exist to support the fact that the corpus callosum is relatively larger in women than in men. The corpus callosum is an integral part of the brain, and contrary to Fitch & Denenberg's examples of “pseudostatistics,” is not an extrinsic structure when determining its relative size.

The development of theories of global cortical dynamics, using linear wave theory, owes much to the pioneering work of Nunez. His work leads to clear predictions on relations of brain size, axonal conduction velocity, and the frequencies of the cerebral rhythms. These predictions do not appear to be fulfilled, but their falsification constrains the range of parameters applicable in further formulations.

This article examines the anatomy and circuitry of skills that, like reading, calculating, recognizing, or remembering, are common abilities of humans. While the anatomical areas active are unique to each skill there are features common to all tasks. For example, all skills produce activation of a small number of widely separated neural areas that appear necessary to perform the task. These neural areas relate to internal codes that may not be observed by any external behavior nor be reportable by the (...) performer. There is considerable plasticity to the performance of skills. Task components can be given priority through attention, which serves to increase activation of the relevant brain areas. Attention can also cause reactivation of sensory areas driven by input, but usually only after a delay. The threshold for activation for any area may be temporarily reduced by prior activation . Skill components requiring attention tend to cause interference resulting in the dual tasks effects and unified focus of attention described in many cognitive studies. Practice may change the size or number of brain areas involved and alter the pathways used by the skill. By combining cognitive and anatomical analyses, a more general picture of the nature of skill emerges. (shrink)

Increases of absolute brain size during evolution reinforced stronger structuring of brain connectivity. One consequence is the hierarchical cluster structure of neural systems that combines predominantly short, but not strictly minimal, wiring with short processing pathways. Principles of “large equals well-connected” and “minimal wiring” do not completely account for observed patterns of brain connectivity. A structural model promises better predictions.

The human brain is an extraordinary organ. It has allowed us to walk on the moon, *to discover the of matter and life,* and to play chess almost as well as a computer. But this virtuosity raises a puzzle. The brain of Homo sapiens achieved its modern form and size between fifty and a hundred thousand years ago, well before the invention of agriculture, civilizations, and writing in the last ten thousand years. Our foraging ancestors had no (...) occasions to do astrophysics or play chess, and natural selection would not have rewarded them with more babies if they had. How, then, did our outsize, *science-ready* brain evolve? (shrink)

Hypotheses regarding the selective pressures driving the threefold increase in the size of the hominid brain since Homo habilis include climatic conditions, ecological demands, and social competition. We provide a multivariate analysis that enables the simultaneous assessment of variables representing each of these potential selective forces. Data were collated for latitude, prevalence of harmful parasites, mean annual temperature, and variation in annual temperature for the location of 175 hominid crania dating from 1.9 million to 10 thousand years ago. (...) We also included a proxy for population density and two indexes of paleoclimatic variability for the time at which each cranium was discovered. Results revealed independent contributions of population density, variation in paleoclimate, and temperature variation to the prediction of change in hominid cranial capacity (CC). Although the effects of paleoclimatic variability and temperature variation provide support for climatic hypotheses, the proxy for population density predicted more unique variance in CC than all other variables. The pattern suggests multiple pressures drove hominid brain evolution and that the core selective force was social competition. (shrink)

One of the major adaptations during the evolution of Homo sapiens was an increase in brain size. Here we present evidence that a significant and substantial proportion of variation in brain size may be related to changes in temperature. Based on a sample of 109 fossilized hominid skulls, we found that cranial capacities were highly correlated with paleoclimatic changes in temperature, as indexed by oxygen isotope data and sea-surface temperature. Indeed, as much as 52% of the (...) variance in the cranial capacity of these skulls could be accounted for by temperature variation at 100 ka intervals. As an index of more short-term seasonal fluctuations in temperature, we examined the latitude of the sites from which the crania originated. More than 22% of the variance in cranial capacity of these skulls could be accounted for by variation in equatorial distance. (shrink)

This article explores the implications of the social brain and the endorphin-based bonding mechanism that underpins it for the evolution of religion. I argue that religion evolved as one of the behavioural mechanisms designed to facilitate community bonding when humans first evolved the larger social groups of ~150 that now characterise our species. This is not a matter of facilitating cooperation, but of engineering social cohesion – a very different problem. Analysis of the size of C19th utopian communities (...) suggests that a religious basis both allowed larger groups to form and greatly enhanced their longevity. I suggest that religion evolved in two stages: an early immersive form with no formal structure based on trance-dancing (a form still evident in the rituals and practices of many hunter-gatherers) and a later form which had more formal structures and gave rise to our modern doctrinal religions. I argue that the modern doctrinal religions did not replace ancestral immersive religions but rather that the doctrinal component was overlaid on the ancient immersive form, thereby giving rise to the mystical stance that underlies all world religions. I suggest that it is this mystical stance that causes the constant upwelling of cults and sects within world religions. (shrink)

The nature of the relationship between mind and body is one of the greatest remaining mysteries. As such, the historical origin of the current dominant belief that mind is a function of the brain takes on especial significance. In this article I aim to explore and explain how and why this belief emerged in early 19th-century Britain. Between 1815 and 1819 two brain-based physiologies of mind were the subject of controversy and debate in Britain: the system of phrenology (...) devised by Franz Joseph Gall, and William Lawrence’s lectures at the Royal College of Surgeons. Both owed a profound intellectual debt to continental comparative anatomy. In the final quarter of the 18th-century, Johann Friedrich Blumenbach, Petrus Camper and Johann Gottfried von Herder had broken away from the traditional doctrine of the Great Chain of Being by allowing for a clear anatomical distinction between ‘man’ and beast based on the morphology of the skull. This reconceptualization of man as an anatomically distinct being gave Gall and Lawrence grounds to propose that the peculiarities of the human mind were dependent on mankind’s unique cerebral size and structure. (shrink)

The philosopher Ludwig Wittgenstein chose as his prime exemplar of certainty the fact that the skulls of normal people are filled with neural tissue, not sawdust. In 1980 the British pediatrician John Lorber reported that some normal adults, apparently cured of childhood hydrocephaly, had no more than 5 % of the volume of normal brain tissue. While initially disbelieved, Lorber’s observations have since been independently confirmed by clinicians in France and Brazil. Thus Wittgenstein’s certainty has become uncertain. Furthermore, the (...) paradox that the human brain’s information content appears to exceed the storage capacity of even normal-sized brains, requires resolution. This article is one of a series on disparities between brain size and its assumed information content, as seen in cases of savant syndrome, microcephaly, and hydrocephaly, and with special reference to the Victorian era views of Conan Doyle, Samuel Butler, and Darwin’s research associate, George Romanes. The articles argue that, albeit unlikely, the scope of explanations must not exclude extracorporeal information storage. (shrink)

Clarke and Beck propose that the approximate number system (ANS) represents rational numbers. The evidence cited supports only the view that it represents ratios (and positive integers). Rational numbers are extensive magnitudes (i.e., sizes), whereas ratios are intensities. It is also argued that WHAT a system represents and HOW it does so are not as independent of one another as the authors assume.

In this commentary we discuss a predictive sensorimotor illusion, the size-weight illusion, in which the smaller of two objects of equal weight is perceived as heavier. We suggest that Grush's emulation theory can explain this illusion as a mismatch between predicted and actual sensorimotor feedback, and present preliminary data suggesting that the cerebellum may be critical for implementing the emulator.

Brain-computer interfaces (BCIs) are being investigated as an access pathway to communication for individuals with physical disabilities, as the technology obviates the need for voluntary motor control. However, to date, minimal research has investigated the use of BCIs for children. Traditional BCI communication paradigms may be suboptimal given that children with physical disabilities may face delays in cognitive development and acquisition of literacy skills. Instead, in this study we explored emotional state as an alternative access pathway to communication. We (...) developed a pediatric BCI to identify positive and negative emotional states from changes in hemodynamic activity of the prefrontal cortex (PFC). To train and test the BCI, 10 neurotypical children aged 8–14 underwent a series of emotion-induction trials over four experimental sessions (one offline, three online) while their brain activity was measured with functional near-infrared spectroscopy (fNIRS). Visual neurofeedback was used to assist participants in regulating their emotional states and modulating their hemodynamic activity in response to the affective stimuli. Child-specific linear discriminant classifiers were trained on cumulatively available data from previous sessions and adaptively updated throughout each session. Average online valence classification exceeded chance across participants by the last two online sessions (with 7 and 8 of the 10 participants performing better than chance, respectively, in Sessions 3 and 4). There was a small significant positive correlation with online BCI performance and age, suggesting older participants were more successful at regulating their emotional state and/or brain activity. Variability was seen across participants in regards to BCI performance, hemodynamic response, and discriminatory features and channels. Retrospective offline analyses yielded accuracies comparable to those reported in adult affective BCI studies using fNIRS. Affective fNIRS-BCIs appear to be feasible for school-aged children, but to further gauge the practical potential of this type of BCI, replication with more training sessions, larger sample sizes, and end-users with disabilities is necessary. (shrink)