Regulation of cognitive resources during sustained attention and working memory in 10-year-olds and adults

The impact of intellectual disability and sport expertise on cognitive and executive functions

Our aim was to identify the suitability of three assessment tools (i.e., Flanker test, Updating Word Span, and Color Trails Test) for future inclusion in the classification process of elite Paralympic athletes with intellectual disability and to assess the strength of the relation between Executive function (EF) and intelligence. Cognitive and EF assessments were performed on 59 participants, divided into four groups according to their cognitive level (with versus without intellectual disability) and sport expertise (athlete versus novice). Inhibition and working memory update skills were implicated in people with intellectual disability. For set-shifting, a more nuanced picture was observed. Strong associations between EF and intelligence was found in people with intellectual disability. Working memory updating and set-shifting are relevant EF skills to assess in the context of elite sport; however, culture-free alternatives for the Updating Word Span test are needed, and alternatives to the Color Trails Test, less reliant on literacy skills are required.

Examining the role of attentional allocation in working memory precision with pupillometry in children and adults

Working memory (WM) precision, or the fidelity with which items can be remembered, is an important aspect of WM capacity that increases over childhood. Why individuals are more or less precise from moment to moment and why WM becomes more stable with age are not yet fully understood. Here, we examined the role of attentional allocation in visual WM precision in children aged 8 to 13 years and young adults aged 18 to 27 years, as measured by fluctuations in pupil dilation during stimulus encoding and maintenance. Using mixed models, we examined intraindividual links between change in pupil diameter and WM precision across trials and the role of developmental differences in these associations. Through probabilistic modeling of error distributions and the inclusion of a visuomotor control task, we isolated mnemonic precision from other cognitive processes. We found an age-related increase in mnemonic precision that was independent of guessing behavior, serial position effects, fatigue or loss of motivation across the experiment, and visuomotor processes. Trial-by-trial analyses showed that trials with smaller changes in pupil diameter during encoding and maintenance predicted more precise responses than trials with larger changes in pupil diameter within individuals. At encoding, this relationship was stronger for older participants. Furthermore, the pupil-performance coupling grew across the delay period-particularly or exclusively for adults. These results suggest a functional link between pupil fluctuations and WM precision that grows over development; visual details may be stored more faithfully when attention is allocated efficiently to a sequence of objects at encoding and throughout a delay period.

Pupillometry as a Window into Young Children's Sustained Attention

Sustained attention is critical to cognition, social competence, and academic success. Importantly, sustained attention undergoes significant development over the early childhood period. Yet, how sustained attention fluctuates over time on task has not been clearly outlined, particularly in young children. In this study, we provide a first test of whether the pupillary response can be used as an indicator of moment-to-moment sustained attention over time on task in young children. Children aged 5 to 7 years (N = 41) completed a psychomotor vigilance task, where they were asked to press a button as fast as possible at the onset of a target stimulus. We measured reaction times over the course of the task, pupil size prior to target onset (baseline pupil size), and pupil size in response to target onset (task-evoked pupil size). The results showed a stereotypical vigilance decrement in children's response times: as time on task increased, reaction times increased. Critically, children's task-evoked pupil size decreased over time on task, while no such change was present in baseline pupil size. These results suggest that young children's waning sustained attention may be linked to a decrease in alertness while overall arousal is maintained. We discuss the importance of leveraging pupillometry to understand the mechanisms of sustained attention over individuals and development.

Synergistic effects of disgust and anger on amygdala activation while recalling memories of interpersonal stress: An fMRI study

Occurrence of an unpleasant interpersonal event in daily life may cause an individual to experience unpleasant emotions and recall memories regarding it. These emotions, manifesting in daily social interactions, are often complex and mixed. In the laboratory, autobiographical recall is frequently used to induce emotions; however, it often involves recalling memories associated with a specific discrete emotion (e.g., sadness). To examine the neural activity of emotions similar to real-life experiences, we examined neural activity while recalling memories of stressful interpersonal events in daily life, without specifying a discrete emotion. Of the 23 university students recruited, 21 were analyzed and asked to freely recall memories and answer a series of questions on a monitor concerning their recalled memories while their neural activity was measured with functional magnetic resonance imaging. Amygdala activity increased while receiving the instructions, followed by a decrease in activity. This indicates that the participants' arousal and vigilance initially increased in response to a novel stimulus, and then decreased by habituation. Disgust and anger, which frequently occur as negative interpersonal feelings, were most prominently produced with strong associations with each other. More importantly, activation of the right amygdala while responding to questions regarding the recalled memories was positively correlated with disgust or anger only when not controlling for anger or disgust, respectively. These results indicate that responding to questions facilitated the generation of a mixed emotional response compared to during free recall alone. Furthermore, disgust and anger as a mixed emotion can synergistically activate amygdala.

Applying functional near-infrared spectroscopy and eye-tracking in a naturalistic educational environment to investigate physiological aspects that underlie the cognitive effort of children during mental rotation tests

Spatial cognition is related to academic achievement in science, technology, engineering, and mathematics (STEM) domains. Neuroimaging studies suggest that brain regions' activation might be related to the general cognitive effort while solving mental rotation tasks (MRT). In this study, we evaluate the mental effort of children performing MRT tasks by measuring brain activation and pupil dilation. We use functional near-infrared spectroscopy (fNIRS) concurrently to collect brain hemodynamic responses from children's prefrontal cortex (PFC) and an Eye-tracking system to measure pupil dilation during MRT. Thirty-two healthy students aged 9-11 participated in this experiment. Behavioral measurements such as task performance on geometry problem-solving tests and MRT scores were also collected. The results were significant positive correlations between the children's MRT and geometry problem-solving test scores. There are also significant positive correlations between dorsolateral PFC (dlPFC) hemodynamic signals and visuospatial task performances (MRT and geometry problem-solving scores). Moreover, we found significant activation in the amplitude of deoxy-Hb variation on the dlPFC and that pupil diameter increased during the MRT, suggesting that both physiological responses are related to mental effort processes during the visuospatial task. Our findings indicate that children with more mental effort under the task performed better. The multimodal approach to monitoring students' mental effort can be of great interest in providing objective feedback on cognitive resource conditions and advancing our comprehension of the neural mechanisms that underlie cognitive effort. Hence, the ability to detect two distinct mental states of rest or activation of children during the MRT could eventually lead to an application for investigating the visuospatial skills of young students using naturalistic educational paradigms.

Age-dependent Upper Limb Myoelectric Control Capability in Typically Developing Children

Research in EMG-based control of prostheses has mainly utilized adult subjects who have fully developed neuromuscular control. Little is known about children's ability to generate consistent EMG signals necessary to control artificial limbs with multiple degrees of freedom. As a first step to address this gap, experiments were designed to validate and benchmark two experimental protocols that quantify the ability to coordinate forearm muscle contractions in typically developing children. Able-bodied, healthy adults and children participated in our experiments that aimed to measure an individual's ability to use myoelectric control interfaces. In the first experiment, participants performed 8 repetitions of 16 different hand/wrist movements. Using offline classification analysis based on Support Vector Machine, we quantified their ability to consistently produce distinguishable muscle contraction patterns. We demonstrated that children had a smaller number of highly independent movements (can be classified with >90% accuracy) than adults did. The second experiment measured participants' ability to control the position of a cursor on a 1-DoF virtual slide using proportional EMG control with three different visuomotor gain levels. We found that children had higher failure rates and slower average target acquisitions than adults did, primarily due to longer correction times that did not improve over repetitive practice. We also found that the performance in both experiments was age-dependent in children. The results of this study provide novel insights into the technical and empirical basis to better understand neuromuscular development in children with upper-limb loss.

Working memory development: A 50-year assessment of research and underlying theories

The author has thought about working memory, not always by that name, since 1969 and has conducted research on its infant and child development since the same year that the seminal work of Baddeley and Hitch (1974) was published. The present article assesses how the field of working memory development has been influenced since those years by major theoretical perspectives: empiricism (along with behaviorism), nativism (along with modularity), cognitivism (along with constructivism), and dynamic systems theory. The field has not fully discussed the point that these theoretical perspectives have helped to shape different kinds of proposed working memory systems, which in turn have deeply influenced what is researched and how it is researched. Here I discuss that mapping of theoretical viewpoints onto assumptions about working memory and trace the influence of this mapping on the field of working memory development. I illustrate where these influences have led in my own developmental research program over the years.

Emotional Distraction by Constant Finger Tapping

Abstract. This study examined the effects of emotional distraction in the context of recalling stressful interpersonal events in daily life. Previous studies have revealed that distraction decreases unpleasant emotions. In this study, we examined whether distraction tasks decrease unpleasant task-related thoughts in addition to unpleasant emotions. Furthermore, to investigate the implicit effects of emotional changes, we examined changes in pupil size in relation to unpleasant emotions and task-unrelated thoughts (TUT). The behavioral tasks were administered to 21 university students ( Mage = 21.24 ± 2.93 years; range: 18–30 years). After excluding participants for poor data quality, 16 (21.31 ± 3.34 years; 18–30 years) were included for further pupil data analysis. As an emotion induction procedure, participants were asked to freely recall memories of stressful interpersonal events in their daily lives and were given a series of questions about their recalled memories, which were presented on the monitor. In the following distraction experiment, questions during the emotion induction procedure were represented as emotional stimulation; a distraction task (non-constant or constant finger tapping) or rest condition was then performed; subsequently, ratings were given for attentional state, thought types conceived during the tasks, and emotional state. Upon analysis, differences in the ratings for unpleasant emotion and TUT were non-significant between all conditions. Nevertheless, pupil dilation in the non-constant and constant conditions was associated with decreased unpleasant emotions ( p < .05; p < .05 to .01). More importantly, pupil dilation was associated with decreased unpleasant TUT ( p < .05) only in the constant condition. Although the observed effects were subtle, we found that constant finger tapping decreased unpleasant emotions and TUT. It is expected for a future emotion regulation study to further investigate the effects in the relationships among emotions, thoughts, and physiological states, which can help in coping with unpleasant emotions.

Prefrontal activation and pupil dilation during n-back task performance: A combined fNIRS and pupillometry study

The n-back task is one of the most commonly used working memory (WM) paradigms in cognitive neuroscience. Converging evidence suggests activation in the lateral prefrontal cortex (PFC) and pupil dilation [a proxy for locus coeruleus (LC) activation] during this task. However, it remains unclear whether the lateral PFC and the LC are functionally associated during n-back task performance. This study's aim was to examine the relationship between changes in lateral PFC activity and the pupil diameter and to evaluate the effect of WM load on such relationship during the n-back task. Thirty-nine healthy young adults (10 males, 29 females) underwent a number n-back paradigm with 0- and 3-back conditions. Their prefrontal hemodynamics and changes in pupil size during task performance were simultaneously measured using a 16-channel functional near-infrared spectroscopy (fNIRS) device and a wearable eye tracker. Young adults exhibited significant activation in the bilateral lateral PFC and significant increases in pupil size when the WM load was high (i.e., 3-back) but not low (i.e., 0-back) compared with the resting period. Interestingly, significant positive correlations were found between changes in lateral PFC activity and pupil size during the 0-back task only. These correlations tended to be stronger during the 0-back than the 3-back condition. Thus, the functional relationship between the lateral PFC and the LC may vary at different load levels during the n-back task. Our findings have important implications for neuropsychiatric research and support concurrent fNIRS and pupillometric measurements for a better understanding of the mechanisms underlying WM processing.

Pupil Constrictions and Their Associations With Increased Negative Affect During Responses to Recalled Memories of Interpersonal Stress

Abstract. Pupil diameter change is indicative of emotional processing. Most previous findings regarding pupillary response and emotion have reported that the pupil enlarges in response to the presentation of emotional perceptual stimuli (e.g., visual images) within several seconds. It is considered that such stimuli activate the sympathetic nervous system, leading to pupil dilation. In order to examine the effects of emotions similar to daily emotional experiences of mood, the present study examined pupil diameter changes and their relationships with subjective emotional changes while recalling a topic of stressful interpersonal events in daily life. The data of 20 university students (11 males, Mage = 20.36 ± 2.38 years; 9 females, Mage = 22.33 ± 3.57) were analyzed. In the experimental task, participants were instructed to recall their memories concerning the topic through instructions and questions presented on a monitor, which proceeded at their own pace, through a key press. Subsequently, after baseline and instruction periods, participants were instructed to freely recall their memories. They were then asked to respond silently to a series of questions concerning the freely recalled memories. In the analysis, we compared the pupil diameters between these different periods and observed that pupil diameters significantly decreased during the response period relative to the free recall or baseline periods. Furthermore, pupil constrictions during the response period were negatively correlated with increases in negative affect scale scores. Pupil constriction, which is indicative of decreased arousal level and parasympathetic activation, was presumably caused by multiple factors including less cognitive difficulty and a relatively long experimental task period. As the result of a less tonic mode in the response period, the attention of participants might be more successfully focused on ongoing tasks, which might lead to optimal performance in recalling memories, possibly leading to correlations between pupil diameter and negative emotional changes.

Pupillary Dilations of Mice Performing a Vibrotactile Discrimination Task Reflect Task Engagement and Response Confidence

Pupillometry, the measure of pupil size and reactivity, has been widely used to assess cognitive processes. Changes in pupil size have been shown to correlate with various behavioral states, both externally and internally induced such as locomotion, arousal, cortical state, and decision-making processes. Besides, these pupillary responses have also been linked to the activity of neuromodulatory systems that modulate attention and perception such as the noradrenergic and cholinergic systems. Due to the extent of processes the pupil reflects, we aimed at further resolving pupillary responses in the context of behavioral state and task performance while recording pupillary transients of mice performing a vibrotactile two-alternative forced-choice task (2-AFC). We show that before the presentation of task-relevant information, pre-stimulus, pupil size differentiates between states of disengagement from task performance vs. engagement. Also, when subjects have to attend to task stimuli to attain a reward, post-stimulus, pupillary dilations exhibit a difference between correct and error responses with this difference reflecting an internal decision variable. We hypothesize that this internal decision variable relates to response confidence, the internal perception of the confidence the subject has in its choice. As opposed to this, we show that in a condition of passive performance, when the stimulus has no more task relevance due to reward being provided automatically, pupillary dilations reflect the occurrence of stimulation and reward provision but not decisional variables as under active performance. Our results provide evidence that in addition to reflecting attentiveness under task performance rather than arousal per se, pupil dilations also reflect the confidence of the subject in his ensuing response. This confidence coding is overlaid within a more pronounced pupil dilation that reflects post-decision components that are related to the response itself but not to the decision. We also provide evidence as to how different behavioral states, imposed by task demands, modulate what the pupil is reflecting, presumably showing what the underlying cognitive network is coding for.

Relationship Between Eye-Movement Patterns, Cognitive Load, and Reading Ability in Children with Reading Difficulties

Children with reading difficulties (RD) share challenges in executive functions (EF). Neurobiological correlates provide evidence for EF challenges during reading among these readers, but an online cognitive load detection mechanism has yet to be developed. Nevertheless, eye-movement tracking can provide online data of reading patterns (pupil dilation, fixations) and, indeed, atypical eye-movement patterns of children with RD during reading have been documented. To identify eye-movement patterns related to increased cognitive load during reading in children with RD compared to typical readers, eye movements of 8-12-year-old English-speaking children were recorded during their reading of sentences with increasing difficulty (sentences that make sense, then sentences that do not make sense) and comparing incorrect and correct responses. Children with RD demonstrated greater pupil dilation when reading sentences that make sense than when reading sentences that do not make sense and also when reading incorrectly, compared to typical readers. Increased pupil dilation in children with RD when reading sentences correctly was positively correlated with phonological awareness capabilities. Higher phonological awareness and reading abilities were related to increased pupil dilation only in children with RD during correct reading, which is related to a heavier cognitive load. Results suggest that in addition to traditional findings of altered fixation patterns in children with RD, increased pupil dilation during reading may reflect EF challenges among this population. These findings can potentially be used to adapt online written materials for children with RD based on their fixation and pupil dilation patterns.

Focused attention predicts visual working memory performance in 13-month-old infants: A pupillometric study

Attention turns looking, into seeing. Yet, little developmental research has examined the interface of attention and visual working memory (VWM), where what is seen is maintained for use in ongoing visual tasks. Using the task-evoked pupil response - a sensitive, real-time, involuntary measure of focused attention that has been shown to correlate with VWM performance in adults and older children - we examined the relationship between focused attention and VWM in 13-month-olds. We used a Delayed Match Retrieval paradigm, to test infants' VWM for object-location bindings - what went where - while recording anticipatory gaze responses and pupil dilation. We found that infants with greater focused attention during memory encoding showed significantly better memory performance. As well, trials that ended in a correct response had significantly greater pupil response during memory encoding than incorrect trials. Taken together, this shows that pupillometry can be used as a measure of focused attention in infants, and a means to identify those individuals, or moments, where cognitive effort is maximized.

Pupil dilation as an index of effort in cognitive control tasks: A review

Pupillometry research has experienced an enormous revival in the last two decades. Here we briefly review the surge of recent studies on task-evoked pupil dilation in the context of cognitive control tasks with the primary aim being to evaluate the feasibility of using pupil dilation as an index of effort exertion, rather than task demand or difficulty. Our review shows that across the three cognitive control domains of updating, switching, and inhibition, increases in task demands typically leads to increases in pupil dilation. Studies show a diverging pattern with respect to the relationship between pupil dilation and performance and we show how an effort account of pupil dilation can provide an explanation of these findings. We also discuss future directions to further corroborate this account in the context of recent theories on cognitive control and effort and their potential neurobiological substrates.

Unity and diversity in working memory load: Evidence for the separability of the executive functions updating and inhibition using machine learning

OBJECTIVE

According to current theoretical models of working memory (WM), executive functions (EFs) like updating, inhibition and shifting play an important role in WM functioning. The models state that EFs highly correlate with each other but also have some individual variance which makes them separable processes. Since this theory has mostly been substantiated with behavioral data like reaction time and the ability to execute a task correctly, the aim of this paper is to find evidence for diversity (unique properties) of the EFs updating and inhibition in neural correlates of EEG data by means of using brain-computer interface (BCI) methods as a research tool. To highlight the benefit of this approach we compare this new methodology to classical analysis approaches.

METHODS

An existing study has been reinvestigated by applying neurophysiological analysis in combination with support vector machine (SVM) classification on recorded electroencephalography (EEG) data to determine the separability and variety of the two EFs updating and inhibition on a single trial basis.

RESULTS

The SVM weights reveal a set of distinct features as well as a set of shared features for the two EFs updating and inhibition in the theta and the alpha band power.

SIGNIFICANCE

In this paper we find evidence that correlates for unity and diversity of EFs can be found in neurophysiological data. Machine learning approaches reveal shared but also distinct properties for the EFs. This study shows that using methods from brain-computer interface (BCI) research, like machine learning, as a tool for the validation of psychological models and theoretical constructs is a new approach that is highly versatile and could lead to many new insights.

Auditory noise increases the allocation of attention to the mouth, and the eyes pay the price: An eye-tracking study

We investigated the effect of auditory noise added to speech on patterns of looking at faces in 40 toddlers. We hypothesised that noise would increase the difficulty of processing speech, making children allocate more attention to the mouth of the speaker to gain visual speech cues from mouth movements. We also hypothesised that this shift would cause a decrease in fixation time to the eyes, potentially decreasing the ability to monitor gaze. We found that adding noise increased the number of fixations to the mouth area, at the price of a decreased number of fixations to the eyes. Thus, to our knowledge, this is the first study demonstrating a mouth-eyes trade-off between attention allocated to social cues coming from the eyes and linguistic cues coming from the mouth. We also found that children with higher word recognition proficiency and higher average pupil response had an increased likelihood of fixating the mouth, compared to the eyes and the rest of the screen, indicating stronger motivation to decode the speech.

Beyond eye gaze: What else can eyetracking reveal about cognition and cognitive development?

This review provides an introduction to two eyetracking measures that can be used to study cognitive development and plasticity: pupil dilation and spontaneous blink rate. We begin by outlining the rich history of gaze analysis, which can reveal the current focus of attention as well as cognitive strategies. We then turn to the two lesser-utilized ocular measures. Pupil dilation is modulated by the brain's locus coeruleus-norepinephrine system, which controls physiological arousal and attention, and has been used as a measure of subjective task difficulty, mental effort, and neural gain. Spontaneous eyeblink rate correlates with levels of dopamine in the central nervous system, and can reveal processes underlying learning and goal-directed behavior. Taken together, gaze, pupil dilation, and blink rate are three non-invasive and complementary measures of cognition with high temporal resolution and well-understood neural foundations. Here we review the neural foundations of pupil dilation and blink rate, provide examples of their usage, describe analytic methods and methodological considerations, and discuss their potential for research on learning, cognitive development, and plasticity.

High Working Memory Load Impairs Language Processing during a Simulated Piloting Task: An ERP and Pupillometry Study

Given the important amount of visual and auditory linguistic information that pilots have to process, operating an aircraft generates a high working-memory load (WML). In this context, the ability to focus attention on relevant information and to remain responsive to concurrent stimuli might be altered. Consequently, understanding the effects of WML on the processing of both linguistic targets and distractors is of particular interest in the study of pilot performance. In the present work, participants performed a simplified piloting task in which they had to follow one of three colored aircraft, according to specific written instructions (i.e., the written word for the color corresponding to the color of one of the aircraft) and to ignore either congruent or incongruent concurrent auditory distractors (i.e., a spoken name of color). The WML was manipulated with an n-back sub-task. Participants were instructed to apply the current written instruction in the low WML condition, and the 2-back written instruction in the high WML condition. Electrophysiological results revealed a major effect of WML at behavioral (i.e., decline of piloting performance), electrophysiological, and autonomic levels (i.e., greater pupil diameter). Increased WML consumed resources that could not be allocated to the processing of the linguistic stimuli, as indexed by lower P300/P600 amplitudes. Also, significantly, lower P600 responses were measured in incongruent vs. congruent trials in the low WML condition, showing a higher difficulty reorienting attention toward the written instruction, but this effect was canceled in the high WML condition. This suppression of interference in the high load condition is in line with the engagement/distraction trade-off model. We propose that P300/P600 components could be reliable indicators of WML and that they allow an estimation of its impact on the processing of linguistic stimuli.

Infant and adult pupil dilation in response to unexpected sounds

Surprisingly occurring sounds outside the focus of attention can involuntarily capture attention. This study focuses on the impact of deviant sounds on the pupil size as a marker of auditory involuntary attention in infants. We presented an oddball paradigm including four types of deviant sounds within a sequence of repeated standard sounds to 14-month-old infants and to adults. Environmental and noise deviant sounds elicited a strong pupil dilation response (PDR) in both age groups. In contrast, moderate frequency deviants elicited a significant PDR in adults only. Moreover, a principal component analysis revealed two components underlying the PDR. Component scores differ, depending on deviant types, between age groups. Results indicate age effects of parasympathetic inhibition and sympathetic activation of the pupil size caused by deviant sounds with a high arousing potential. Results demonstrate that the PDR is a sensitive tool for the investigation of involuntary attention to sounds in preverbal children.

A Novel Pupillometric Method for Indexing Word Difficulty in Individuals With and Without Aphasia

PURPOSE

Cognitive effort is a clinically important facet of linguistic processing that is often overlooked in the assessment and treatment of people with aphasia (PWA). Furthermore, there is a paucity of valid ways to index cognitive effort in PWA. The construct of cognitive effort has been indexed for decades via pupillometry (measurement of pupil dilation and constriction during a cognitive task), yet pupillometry has not been implemented in studies including PWA. In the present study, we tested a novel method for indexing cognitive effort during linguistic processing in people with and without aphasia.

METHOD

Forty control participants and 39 PWA listened to semantically easy and difficult single nouns and looked at images while their pupillary responses were monitored. Mean pupil dilation in response to easy versus difficult nouns was calculated to index cognitive effort.

RESULTS

Larger mean pupil dilation values were obtained for difficult compared with easy nouns for both groups.

CONCLUSION

Results provide preliminary evidence that pupillometry can be used to index cognitive effort during linguistic processing of single nouns in people with and without aphasia. Methods for indexing cognitive effort will be a valuable addition to existing assessment methods. Suggestions for further research are offered.

A closer look at cognitive control: differences in resource allocation during updating, inhibition and switching as revealed by pupillometry

The present study investigated resource allocation, as measured by pupil dilation, in tasks measuring updating (2-Back task), inhibition (Stroop task) and switching (Number Switch task). Because each cognitive control component has unique characteristics, differences in patterns of resource allocation were expected. Pupil and behavioral data from 35 participants were analyzed. In the 2-Back task (requiring correct matching of current stimulus identity at trial p with the stimulus two trials back, p −2) we found that better performance (low total of errors made in the task) was positively correlated to the mean pupil dilation during correctly responding to targets. In the Stroop task, pupil dilation on incongruent trials was higher than those on congruent trials. Incongruent vs. congruent trial pupil dilation differences were positively related to reaction time differences between incongruent and congruent trials. Furthermore, on congruent Stroop trials, pupil dilation was negatively related to reaction times, presumably because more effort allocation paid off in terms of faster responses. In addition, pupil dilation on correctly-responded-to congruent trials predicted a weaker Stroop interference effect in terms of errors, probably because pupil dilation on congruent trials were diagnostic of task motivation, resulting in better performance. In the Number Switch task we found higher pupil dilation in switch as compared to non-switch trials. On the Number Switch task, pupil dilation was not related to performance. We also explored error-related pupil dilation in all tasks. The results provide new insights in the diversity of the cognitive control components in terms of resource allocation as a function of individual differences, task difficulty and error processing.

The ties to unbind: age-related differences in feature (un)binding in working memory for emotional faces

In the present study, we investigated age-related differences in the processing of emotional stimuli. Specifically, we were interested in whether older adults would show deficits in unbinding emotional expression (i.e., either no emotion, happiness, anger, or disgust) from bound stimuli (i.e., photographs of faces expressing these emotions), as a hyper-binding account of age-related differences in working memory would predict. Younger and older adults completed different N-Back tasks (side-by-side 0-Back, 1-Back, 2-Back) under three conditions: match/mismatch judgments based on either the identity of the face (identity condition), the face’s emotional expression (expression condition), or both identity and expression of the face (both condition). The two age groups performed more slowly and with lower accuracy in the expression condition than in the both condition, indicating the presence of an unbinding process. This unbinding effect was more pronounced in older adults than in younger adults, but only in the 2-Back task. Thus, older adults seemed to have a specific deficit in unbinding in working memory. Additionally, no age-related differences were found in accuracy in the 0-Back task, but such differences emerged in the 1-Back task, and were further magnified in the 2-Back task, indicating independent age-related differences in attention/STM and working memory. Pupil dilation data confirmed that the attention/STM version of the task (1-Back) is more effortful for older adults than younger adults.

Measuring perceived mental workload in children

Little is known about the mental workload, or psychological costs, associated with information processing tasks in children. We adapted the highly regarded NASA Task Load Index (NASA-TLX) multidimensional workload scale (Hart & Staveland, 1988) to test its efficacy for use with elementary school children. We developed 2 types of tasks, each with 2 levels of demand, to draw differentially on resources from the separate subscales of workload. In Experiment 1, our participants were both typical and school-labeled gifted children recruited from 4th and 5th grades. Results revealed that task type elicited different workload profiles, and task demand directly affected the children's experience of workload. In general, gifted children experienced less workload than typical children. Objective response time and accuracy measures provide evidence for the criterion validity of the workload ratings. In Experiment 2, we applied the same method with 1st- and 2nd-grade children. Findings from Experiment 2 paralleled those of Experiment 1 and support the use of NASA-TLX with even the youngest elementary school children. These findings contribute to the fledgling field of educational ergonomics and attest to the innovative application of workload research. Such research may optimize instructional techniques and identify children at risk for experiencing overload.

Task-evoked pupillometry provides a window into the development of short-term memory capacity

The capacity to keep multiple items in short-term memory (STM) improves over childhood and provides the foundation for the development of multiple cognitive abilities. The goal of this study was to measure the extent to which age differences in STM capacity are related to differences in task engagement during encoding. Children (n = 69, mean age = 10.6 years) and adults (n = 54, mean age = 27.5 years) performed two STM tasks: the forward digit span test from the Wechsler Intelligence Scale for Children (WISC) and a novel eyetracking digit span task designed to overload STM capacity. Building on prior research showing that task-evoked pupil dilation can be used as a real-time index of task engagement, we measured changes in pupil dilation while participants encoded long sequences of digits for subsequent recall. As expected, adults outperformed children on both STM tasks. We found similar patterns of pupil dilation while children and adults listened to the first six digits on our STM overload task, after which the adults' pupils continued to dilate and the children's began to constrict, suggesting that the children had reached their cognitive limits and that they had begun to disengage from the task. Indeed, the point at which pupil dilation peaked at encoding was a significant predictor of WISC forward span, and this relationship held even after partialing out recall performance on the STM overload task. These findings indicate that sustained task engagement at encoding is an important component of the development of STM.

Motor learning in children with hemiplegic cerebral palsy: feedback effects on skill acquisition

AIM

Motor learning is enhanced with practice and feedback. This cohort control study investigated the effect of different relative feedback frequencies during skill acquisition in children with cerebral palsy (CP) and children with typical development.

METHOD

Nineteen children with spastic hemiplegic CP (nine males, 10 females; mean age 11 y 7 mo; range 8-16 y) and 20 children with typical development (12 males, eight females; mean age 10 y 8 mo; range 8-14 y) were assigned to 100% or reduced (62%) feedback subgroups as they practised 200 trials of a discrete arm movement with specific spatiotemporal parameters. Children with CP used their less involved hand. Learning was inferred by delayed (24 h) retention and reacquisition tests.

RESULTS

All children improved in accuracy and consistency. Children with typical development demonstrated significantly greater accuracy than children with CP during acquisition (p=0.001), retention (p=0.031), and reacquisition (p=0.001), and greater consistency during retention (p=0.038). The typically developing group who received 100% feedback performed with significantly less error than the 62% feedback group during acquisition (p=0.001), and with greater retention (p=0.017). No statistically significant difference was found between feedback subgroups of children with CP, although the 100% feedback group consistently demonstrated less error.

INTERPRETATION

Children with CP use feedback in a manner similar to children with typical development when learning new skills with their less involved hand, but demonstrate less accuracy and consistency.

Functional brain imaging across development

The developmental cognitive neuroscience literature has grown exponentially over the last decade. This paper reviews the functional magnetic resonance imaging (fMRI) literature on brain function development of typically late developing functions of cognitive and motivation control, timing and attention as well as of resting state neural networks. Evidence shows that between childhood and adulthood, concomitant with cognitive maturation, there is progressively increased functional activation in task-relevant lateral and medial frontal, striatal and parieto-temporal brain regions that mediate these higher level control functions. This is accompanied by progressively stronger functional inter-regional connectivity within task-relevant fronto-striatal and fronto-parieto-temporal networks. Negative age associations are observed in earlier developing posterior and limbic regions, suggesting a shift with age from the recruitment of "bottom-up" processing regions towards "top-down" fronto-cortical and fronto-subcortical connections, leading to a more mature, supervised cognition. The resting state fMRI literature further complements this evidence by showing progressively stronger deactivation with age in anti-correlated task-negative resting state networks, which is associated with better task performance. Furthermore, connectivity analyses during the resting state show that with development increasingly stronger long-range connections are being formed, for example, between fronto-parietal and fronto-cerebellar connections, in both task-positive networks and in task-negative default mode networks, together with progressively lesser short-range connections, suggesting progressive functional integration and segregation with age. Overall, evidence suggests that throughout development between childhood and adulthood, there is progressive refinement and integration of both task-positive fronto-cortical and fronto-subcortical activation and task-negative deactivation, leading to a more mature and controlled cognition.

Children's verbal working memory: relative importance of storage, general processing speed, and domain-general controlled attention

This study evaluated multiple constraints of verbal working memory in typically developing 7- to 11-year-olds. Multiple measures of verbal working memory and the predictors-short-term memory storage, general speed, and domain-general controlled attention were used. General linear modeling (GLM) showed that storage and the efficiency of controlled attention (i.e., speed of updating information during attention switching) contributed to significant variance in children's verbal working memory. In a secondary analysis verbal storage and domain-general attention (focus switching accuracy and speed of updating on switch) emerged as significant predictors. Results suggest domain-general attention and verbal storage mechanisms to be independent constraints of verbal working memory.

Pupillometry

The measurement of pupil diameter in psychology (in short, “pupillometry”) has just celebrated 50 years. The method established itself after the appearance of three seminal studies ( Hess & Polt, 1960 , 1964 ; Kahneman & Beatty, 1966 ). Since then, the method has continued to play a significant role within the field, and pupillary responses have been successfully used to provide an estimate of the “intensity” of mental activity and of changes in mental states, particularly changes in the allocation of attention and the consolidation of perception. Remarkably, pupillary responses provide a continuous measure regardless of whether the participant is aware of such changes. More recently, research in neuroscience has revealed a tight correlation between the activity of the locus coeruleus (i.e., the “hub” of the noradrenergic system) and pupillary dilation. As we discuss in this short review, these neurophysiological findings provide new important insights to the meaning of pupillary responses for mental activity. Finally, given that pupillary responses can be easily measured in a noninvasive manner, occur from birth, and can occur in the absence of voluntary, conscious processes, they constitute a very promising tool for the study of preverbal (e.g., infants) or nonverbal participants (e.g., animals, neurological patients).

Pupillary Stroop effects

We recorded the pupil diameters of participants performing the words' color-naming Stroop task (i.e., naming the color of a word that names a color). Non-color words were used as baseline to firmly establish the effects of semantic relatedness induced by color word distractors. We replicated the classic Stroop effects of color congruency and color incongruency with pupillary diameter recordings: relative to non-color words, pupil diameters increased for color distractors that differed from color responses, while they reduced for color distractors that were identical to color responses. Analyses of the time courses of pupil responses revealed further differences between color-congruent and color-incongruent distractors, with the latter inducing a steep increase of pupil size and the former a relatively lower increase. Consistent with previous findings that have demonstrated that pupil size increases as task demands rise, the present results indicate that pupillometry is a robust measure of Stroop interference, and it represents a valuable addition to the cognitive scientist's toolbox.

Developmental Changes in Natural Viewing Behavior: Bottom-Up and Top-Down Differences between Children, Young Adults and Older Adults

Despite the growing interest in fixation selection under natural conditions, there is a major gap in the literature concerning its developmental aspects. Early in life, bottom-up processes, such as local image feature – color, luminance contrast etc. – guided viewing, might be prominent but later overshadowed by more top-down processing. Moreover, with decline in visual functioning in old age, bottom-up processing is known to suffer. Here we recorded eye movements of 7- to 9-year-old children, 19- to 27-year-old adults, and older adults above 72 years of age while they viewed natural and complex images before performing a patch-recognition task. Task performance displayed the classical inverted U-shape, with young adults outperforming the other age groups. Fixation discrimination performance of local feature values dropped with age. Whereas children displayed the highest feature values at fixated points, suggesting a bottom-up mechanism, older adult viewing behavior was less feature-dependent, reminiscent of a top-down strategy. Importantly, we observed a double dissociation between children and elderly regarding the effects of active viewing on feature-related viewing: Explorativeness correlated with feature-related viewing negatively in young age, and positively in older adults. The results indicate that, with age, bottom-up fixation selection loses strength and/or the role of top-down processes becomes more important. Older adults who increase their feature-related viewing by being more explorative make use of this low-level information and perform better in the task. The present study thus reveals an important developmental change in natural and task-guided viewing.

Oculomotor and pupillometric indices of pro- and antisaccade performance in youth-onset psychosis and attention deficit/hyperactivity disorder

The goals of the study were to examine inhibitory deficits on the antisaccade task in 8- to 20-year olds with youth-onset psychosis or attention deficit/hyperactivity disorder (ADHD) and healthy controls and to examine if age-related changes in performance differed across groups. In addition to the conventional measures of performance, pupillary dilations were used to obtain estimates of phasic and tonic level of arousal. Results showed that the psychosis, but not the ADHD, group had elevated antisaccade error rates; however, variability of error rates was high in all groups. These inhibitory failures were accompanied by a lower level of momentary cognitive effort (as indexed by pupillary dilations). The largest differences between the control and clinical groups were found not in the expected indices of inhibition but in the probability of correcting inhibitory errors and in variability of antisaccade response times, which were correlated with each other. These findings did not appear to be attributable to a deficit in maintaining task instructions in mind in either disorder or lack of motivation in ADHD. Instead, results point to impairments in both clinical groups in sustaining attention on a trial-by-trial basis, resulting in deficits in self-monitoring. Thus, results show inhibitory deficits in the context of more general attentional impairments in both disorders.

Pupillary dilation as an index of task demands

To analyze how pupillary responses reflect mental effort and allocation of processing resources under several load conditions, the pupil diameter of 18 participants was recorded during an auditory digit-span recall task under three load conditions: Low (5 digits), Moderate (8 digits), and Overload (11 digits). In previous research, under all load conditions a significant linear enlargement in pupil diameter was observed as each digit was presented. Significant dilations from the end of the presentation phase to the beginning of the recall phase were also observed but only under low and moderate loads. Contrary to previous research, under the Overload condition, no reduction in pupil diameter was observed when resource limits were exceeded; however, a plateau was observed when the ninth digit was presented until the beginning of the recall phase. Overall, pupillometric data seem to indicate that participants may keep processing actively even though resources are exceeded.

Regulation of cognitive resources during an n-back task in youth-onset psychosis and attention-deficit/hyperactivity disorder (ADHD)

The goals of the current study were to use behavioral and pupillary measures to examine working memory on a spatial n-back task in 8-20-year-olds with youth-onset psychosis or ADHD (Combined subtype) and healthy controls to determine the contribution of different attentional factors to spatial working memory impairments, and to examine if age-related changes in performance differed across groups. Although both clinical groups had lower perceptual sensitivity on both 0- and 1-back, there was no evidence of an impairment in spatial working memory or differential order effects on the 0-back. Instead, results suggest that both clinical groups had difficulty encoding the stimuli. They also appeared to have difficulty maintaining attention and/or readiness to respond, and, to a lesser extent, recruiting resources on a trial-to-trial basis. It is likely that these attentional problems prevented the clinical groups from encoding the stimuli effectively and contributed to their general performance deficits.

Pupillometric and behavioral markers of a developmental shift in the temporal dynamics of cognitive control

The capacity to anticipate and prepare for future events is thought to be critical for cognitive control. Dominant accounts of cognitive control treat the developing system as merely a weaker version of the adult system, progressively strengthening over time. Using the AX Continuous Performance Task (AX-CPT) in combination with high-resolution pupillometry, we find that whereas 8-year-old children resemble adults in their proactive use of cognitive control, 3.5-year-old children exhibit a qualitatively different, reactive form of cognitive control, responding to events only as they unfold and retrieving information from memory as needed in the moment. These results demonstrate the need to reconsider the origins of cognitive control and the basis for children's behaviors across domains.

Sex differences in a virtual water maze: an eye tracking and pupillometry study

Sex differences in human spatial navigation are well known. However, the exact strategies that males and females employ in order to navigate successfully around the environment are unclear. While some researchers propose that males prefer environment-centred (allocentric) and females prefer self-centred (egocentric) navigation, these findings have proved difficult to replicate. In the present study we examined eye movements and physiological measures of memory (pupillometry) in order to compare visual scanning of spatial orientation using a human virtual analogue of the Morris Water Maze task. Twelve women and twelve men (average age=24 years) were trained on a visible platform and had to locate an invisible platform over a series of trials. On all but the first trial, participants' eye movements were recorded for 3s and they were asked to orient themselves in the environment. While the behavioural data replicated previous findings of improved spatial performance for males relative to females, distinct sex differences in eye movements were found. Males tended to explore consistently more space early on while females demonstrated initially longer fixation durations and increases in pupil diameter usually associated with memory processing. The eye movement data provides novel insight into differences in navigational strategies between the sexes.

Motor learning in children: feedback effects on skill acquisition

BACKGROUND AND PURPOSE

Reduced feedback during motor skill practice benefits motor learning. However, it is unknown whether these findings can be applied to motor learning in children, given that children have different information-processing capabilities than adults. The purpose of this study was to determine the effect of different relative frequencies of feedback on skill acquisition in children compared with young adults.

SUBJECTS

The participants were 20 young adults and 20 children.

METHODS

All participants practiced 200 trials of a discrete arm movement with specific spatiotemporal parameters. Participants from each group (adults and children) were randomly assigned to either a 100% feedback group or a reduced (62% faded) feedback group. Learning was inferred from the performance on the delayed (24-hour) retention and reacquisition tests.

RESULTS

All participants improved accuracy and consistency across practice trials. During practice, the adults performed with significantly less error than the children. Adults who practiced with reduced feedback performed with increased consistency during the retention test compared with those who practiced with 100% feedback. In contrast, children who received reduced feedback during practice performed with less accuracy and consistency during the retention test than those who received 100% feedback. However, when feedback was reintroduced during the reacquisition test, the children in the reduced feedback group were able to improve their performance comparable to those in the 100% feedback group.

DISCUSSION AND CONCLUSION

During motor learning, children use feedback in a manner different from that of adults. To optimize motor learning, children may require longer periods of practice, with feedback reduced more gradually, compared with young adults.