Manipulated Task Difficulty Research Articles

Theories and hypotheses: The forgotten plane of the multiverse

Multiverse analyses—the systematic examination of the effects of decisions that researchers can take over the course of a research project—became more common in recent psychophysiological research. However, multiverse analyses in psychophysiology almost exclusively focus on methodological and statistical decisions that can have a considerable impact on the findings. The role of the conceptual multiverse regarding theory-related research decisions is largely ignored. We argue that the choice of a theory that guides hypotheses, study design, measurement methods, and statistical analyses is the first plane of the psychophysiological multiverse. Depending on the chosen theoretical framework, researchers will choose different methods, and statistical analyses will emphasize specific aspects. We illustrate this process with a research example studying the effects of task difficulty manipulations on cardiovascular effects reflecting effort. We argue in favor of an approach that explicitly acknowledges the various theoretical accounts that can constitute the background of a study and demonstrate how a comparative analytical approach can provide a comprehensive multiverse without increasing type I error due to mere exploration.

Developmental Changes in Executive Control: Investigating Dual-Task Interference During Motor and Central Cognitive Processing with the Overlapping Task Paradigm

ABSTRACT Previous studies demonstrated that dual-task impairments are higher in children than in young adults. A previous study systematically assessed the sources of these larger dual-task impairments by identifying age-related differences in capacity limitations during dual-task processing. Capacity limitations in central cognitive processes were present in both age groups, while perceptual capacity limitations were larger in children than in young adults. However, the literature lacks further confirmations and explanations for increased dual-task impairments in children. Moreover, this previous study was not informative regarding age-related differences in potential capacity limitations during central cognitive processing in relation to limitations during motor processing. Therefore, in a German context, the present study investigated children (N = 32) and young adults (N = 32) by combining visual (Task 1) and auditory (Task 2) sensorimotor tasks, separated by a varying stimulus onset asynchrony, in dual tasks of the psychological refractory period (PRP) type. Performance differences were assessed by manipulations of task difficulty in Task 1. The results replicated the finding of increased dual-task impairments in children compared with young adults. Furthermore, the manipulations in the PRP dual task resulted in similar effects in both age groups. Thus, these findings confirmed the presence of capacity limitations during central cognitive processing, while there were no processing limitations in motor processing between children and young adults.

Cross-frequency coupling in cortico-hippocampal networks supports the maintenance of sequential auditory information in short-term memory.

It has been suggested that cross-frequency coupling in cortico-hippocampal networks enables the maintenance of multiple visuo-spatial items in working memory. However, whether this mechanism acts as a global neural code for memory retention across sensory modalities remains to be demonstrated. Intracranial EEG data were recorded while drug-resistant patients with epilepsy performed a delayed matched-to-sample task with tone sequences. We manipulated task difficulty by varying the memory load and the duration of the silent retention period between the to-be-compared sequences. We show that the strength of theta-gamma phase amplitude coupling in the superior temporal sulcus, the inferior frontal gyrus, the inferior temporal gyrus, and the hippocampus (i) supports the short-term retention of auditory sequences; (ii) decodes correct and incorrect memory trials as revealed by machine learning analysis; and (iii) is positively correlated with individual short-term memory performance. Specifically, we show that successful task performance is associated with consistent phase coupling in these regions across participants, with gamma bursts restricted to specific theta phase ranges corresponding to higher levels of neural excitability. These findings highlight the role of cortico-hippocampal activity in auditory short-term memory and expand our knowledge about the role of cross-frequency coupling as a global biological mechanism for information processing, integration, and memory in the human brain.

Validation of a mobile fNIRS device for measuring working memory load in the prefrontal cortex

Functional near-infrared spectroscopy (fNIRS) is a neuroimaging technique that measures cortical blood flow to infer neural activation. Traditionally limited to laboratory settings due to high costs and complex operation, recent advancements have introduced mobile fNIRS devices, significantly broadening the scope of potential research participants. This study validates the use of the Mendi, a two-channel mobile fNIRS system, for measuring prefrontal oxyhemoglobin concentration changes during an n-back task. We manipulated task difficulty through different n-back levels (one-back versus three-back), revealing increased oxyhemoglobin concentrations in the prefrontal cortex during the more demanding three-back task compared to the one-back task. This finding demonstrates the Mendi's ability to distinguish between low and high cognitive task loads. Behavioural data, showing a decrease in accuracy under high load conditions, further corroborates these neuroimaging findings. Our study validates the Mendi mobile fNIRS system as an effective tool for assessing working memory load and underscores its potential in enhancing neuroscientific research accessibility. The user-friendly and cost-effective nature of mobile fNIRS systems like the Mendi opens up neuroscientific research to a diverse set of participants, enabling the investigation of neural processes in real-world environments across a variety of demographic groups.

Effects of task difficulty on performance and event-related bradycardia during preparation for action

The slowing of heart rate prior to movement onset has been presented as a marker of task-related cognitive processing and linked with performance accuracy. Here we examined this event-related bradycardia and task performance as a function of task difficulty. Forty experienced golfers completed a series of golf putting conditions that manipulated task difficulty by varying target distance, target size, and surface contour. Performance was measured by the number of holed putts and finishing distance from the hole. Physiological activity was recorded throughout. Analyses confirmed that performance varied as a function of task difficulty, worsening with longer distances to target, smaller targets, and sloping paths to target. Task difficulty also impacted the cardiac response, including the rate of heart rate deceleration, change in heart rate, and heart rate at impact. These heart rate metrics were found to correlate with performance strongly, moderately, and weakly, respectively. In conclusion, heart rate deceleration in the moments preceding movement onset was affected by task difficulty. Features of this cardiac deceleration pattern were characteristic of successful performance. Our findings are discussed in terms of the role of cognitive and motor processes during the execution of complex motor skills.

Eye-Tracking in Physical Human-Robot Interaction: Mental Workload and Performance Prediction.

In Physical Human-Robot Interaction (pHRI), the need to learn the robot's motor-control dynamics is associated with increased cognitive load. Eye-tracking metrics can help understand the dynamics of fluctuating mental workload over the course of learning. The aim of this study was to test eye-tracking measures' sensitivity and reliability to variations in task difficulty, as well as their performance-prediction capability, in physical human-robot collaboration tasks involving an industrial robot for object comanipulation. Participants (9M, 9F) learned to coperform a virtual pick-and-place task with a bimanual robot over multiple trials. Joint stiffness of the robot was manipulated to increase motor-coordination demands. The psychometric properties of eye-tracking measures and their ability to predict performance was investigated. Stationary Gaze Entropy and pupil diameter were the most reliable and sensitive measures of workload associated with changes in task difficulty and learning. Increased task difficulty was more likely to result in a robot-monitoring strategy. Eye-tracking measures were able to predict the occurrence of success or failure in each trial with 70% sensitivity and 71% accuracy. The sensitivity and reliability of eye-tracking measures was acceptable, although values were lower than those observed in cognitive domains. Measures of gaze behaviors indicative of visual monitoring strategies were most sensitive to task difficulty manipulations, and should be explored further for the pHRI domain where motor-control and internal-model formation will likely be strong contributors to workload. Future collaborative robots can adapt to human cognitive state and skill-level measured using eye-tracking measures of workload and visual attention.

Walking speed differentially affects lower extremity biomechanics in individuals with anterior cruciate ligament reconstruction compared to uninjured controls

BackgroundWalking biomechanics are commonly affected after anterior cruciate ligament reconstruction and differ compared to uninjured controls. Manipulating task difficulty has been shown to affect the magnitude of walking impairments in those early after knee surgery but it is unclear if patients in later phases post-op are similarly affected by differing task demands. Here, we evaluated the effects of manipulating walking speed on between-limb differences in ground reaction force and knee biomechanics in those with and without anterior cruciate ligament reconstruction. MethodsWe recruited 28 individuals with anterior cruciate ligament reconstruction and 20 uninjured control participants to undergo walking assessments at three speeds (self-selected, 120%, and 80% self-selected speed). Main outcomes included sagittal plane knee moments, angles, excursions, and ground reaction forces (vertical and anterior-posterior). FindingsWe observed walking speed differentially impacted force and knee-outcomes in those with anterior cruciate ligament reconstruction. Between-limb differences increased at fast and decreased at slow speeds in those with anterior cruciate ligament reconstruction while uninjured participants maintained between-limb differences regardless of speed (partial η2 = 0.13–0.33, p < 0.05). Anterior cruciate ligament reconstruction patients underloaded the surgical limb relative to both the contralateral, and uninjured controls in GRFs and sagittal plane knee moments (partial η2 range = 0.13–0.25, p < 0.05). InterpretationOverall, our findings highlight the persistence of walking impairments in those with anterior cruciate ligament reconstruction despite completing formal rehabilitation. Further research should consider determining if those displaying larger changes in gait asymmetries in response to fast walking also exhibit poorer strength and/or joint health outcomes.

When Response Selection Becomes Gambling: Post-error Slowing and Speeding in Self-paced Colour Discrimination Tasks

People tend to slow down after committing an error in many tasks. However, some studies failed to observe such post-error slowing. Furthermore, recent work found speeding after another type of sub-optimal outcomes: people often speed up after losses in gambling situations. What features determine whether people slow down or speed up after sub-optimal outcomes (error vs. loss)? To answer this question, we focused on the role of task characteristics and control over the outcome, by making a task where we previously observed post-error slowing more like tasks where we previously observed post-loss speeding. First, we made a color-discrimination task completely self-paced (Experiment 1A) and added reward/punishment (Experiment 1B). In both experiments, post-error slowing was observed, without modulation by reward/punishment. We then manipulated task difficulty to investigate the influence of control over the outcome. Consistent with our predictions, control over the outcome modulated post-error adjustments, as participants slowed down after controllable errors, but sped up after uncontrollable errors (Experiment 3). Importantly, this effect was global as post-error speeding was observed when controllable and ’uncontrollable’ errors were intermixed (Experiment 2), suggesting an influence of overall task context. Thus, responses to sub-optimal outcomes might depend on the control over the outcome.

A comprehensive decoding of cognitive load

The extent of neurophysiological activation, such as brain activities, eye movement, and skin conductance, can vary as a joint function of cognitive load. These functions are the basis of models that describe human behavior and neural mechanisms for diagnosing and treating cognitive disorders, such as Alzheimer’s disease, mild cognitive impairment, and stroke-related cognitive dysfunction. Such models can enhance our understanding of the disease processes and enable crucial applications like predicting cognitive trajectories for early diagnosis. However, despite the success of these models in predicting early-stage cognitive impairment and decline, their practical use is limited in clinics because most of the models focus on utilizing one or two factors of the neurophysiological activation to achieve prediction. Still, little is known about the mechanisms through which the task difficulty and cognitive demands affect the expression of neurophysiological activation and whether there is an expression difference under cognitive task demands. The purpose of this paper is to provide a comprehensive examination of the neurophysiological expression difference and mechanisms under various cognitive loads. We designed an experimental protocol and developed a data processing framework to explicitly examine brain activity and eye movement under various levels of cognitive task difficulty and find that (1) eye movement is a readout of cognitive processes, but it is a joint function of task difficulty, brain activity, and skin conductance; (2) brain activity has specific patterns related to the various levels of cognitive load and exerts its influence on predicting the dynamics of cognitive processes. These findings suggest that neuroimaging studies comparing task-related neurophysiological activation must be examined and interpreted in a holistic view of neural mechanisms. • Manipulating task difficulty imposes dynamics of cognitive demands that sensing devices can capture and learn through machine learning models. • Eye movement is a readout of cognitive processes, but it is a joint function of task difficulty, brain activity, and skin conductance. • Brain activity has specific patterns related to the various levels of cognitive load and influences predicting the dynamics of cognitive processes. • The relationship between brain activity patterns, eye movement, and dynamics of cognitive processes provides evidence for further development of the early diagnosis of cognitive disorder diseases.

Unintended emotions in the laboratory: Emotions incidentally induced by a standard visual working memory task relate to task performance.

The ability to temporarily hold information in visual working memory (VWM) is among the most crucial and most extensively examined human cognitive functions. Here, we empirically confirm previous speculations (a) that a standard VWM task arouses emotions in participants and (b) that these task-induced emotions are related to VWM performance. In a first qualitative study (N = 19), by adapting a qualitative method of inquiry, the think-aloud technique, we found that the task induced different positive and negative emotions, such as joy and anger, which varied on the inter- as well as on the intraindividual level. The emotional experiences seemed to be tied to the implicit achievement requirement of the VWM task (getting it right vs. wrong). Encouraged by these findings, two quantitative studies (N = 45, and N = 44, respectively) revealed that VWM performance was positively linked to joy and pride, and negatively linked to anger, frustration, and boredom on the inter- and on the intraindividual level. Notably, these emotions were also affected by an experimental manipulation of task difficulty (set size 4 vs. 8). Further, the findings from Study 3 were replicated in a fourth high-powered online study (N = 110). This research is the first to demonstrate that a task designed to measure VWM in itself triggers emotions, specifically achievement emotions, which, in turn, are linked with VWM performance. Our findings suggest that these task-induced emotions should be considered as potential confounding variables in future research on VWM and in cognitive research in general. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Spontaneous discovery of novel task solutions in children.

Children often perform worse than adults on tasks that require focused attention. While this is commonly regarded as a sign of incomplete cognitive development, a broader attentional focus could also endow children with the ability to find novel solutions to a given task. To test this idea, we investigated children's ability to discover and use novel aspects of the environment that allowed them to improve their decision-making strategy. Participants were given a simple choice task in which the possibility of strategy improvement was neither mentioned by instructions nor encouraged by explicit error feedback. Among 47 children (8-10 years of age) who were instructed to perform the choice task across two experiments, 27.5% showed a full strategy change. This closely matched the proportion of adults who had the same insight (28.2% of n = 39). The amount of erroneous choices, working memory capacity and inhibitory control, in contrast, indicated substantial disadvantages of children in task execution and cognitive control. A task difficulty manipulation did not affect the results. The stark contrast between age-differences in different aspects of cognitive performance might offer a unique opportunity for educators in fostering learning in children.

Imposed load versus voluntary investment: Executive control and attention management in dual-task performance

Dual task performance is one of the most frequently used paradigm in the evaluation of coping with concurrent task demands. The Breakfast Task experimented in this paper, was originally developed as a general indicator of coping ability with high demand executive control and attention management requirements. It is a computer-based simulation, in which the performer is required to cook several food items while concurrently setting table for guests.The task was employed in different studies, to compare young to old adults, monolinguals to bilinguals, influence of Parkinson disease and brain injury. However, in a closer examination, it is a dual task setting, in which cooking reflects coping with imposed load while table setting is an indicator of strategy free, voluntary invested effort. Models of workload did not examine the impact of such asymmetric flexibility on concurrent performance. Three experiments with elaborated versions of the breakfast task, show that the difference between the tasks affects concurrent performance formats in response to manipulations of task difficulty, priority change and practice. These results and their implications are discussed in reference to limited capacity, resource and executive control models of multitasking and task load.

A method to assess response inhibition during a balance recovery step

BackgroundCorrelations between falls and individual differences in inhibitory control, suggest the ability to suppress automatic, but unwanted, action is important in fall prevention. Response inhibition has been a topic of considerable interest in the cognitive neuroscience community for many decades, bringing a wealth of techniques that could potentially inform assessment of reactive balance. For example, the stop signal task is a popular method to quantify inhibitory control ability. Research questionCan we apply the stop signal task to measure response inhibition in a balance recovery task? MethodsTwenty healthy, young adults completed a novel reactive balance test that required occasional suppression of a balance recovery step. Participants were released from a supported lean (‘Go’ cue) requiring them to quickly step forward to regain balance. On some trials, a tone (‘Stop’ cue) instructed participants to suppress a step and relax into a harness. Step trials were more frequent (80%) than stop trials (20%) to bias a rapid stepping response. The stop tone was presented at various delays following cable release, to manipulate task difficulty (i.e., longer delays make step suppression difficult). Individual differences in inhibitory control were determined using lift off times from force plates, and by contrasting muscle activation in failed compared to successful stop trials. ResultsMost participants were able to successfully suppress a balance recovery step on occasion, allowing for accurate estimation of individual differences in inhibitory control. The successful suppression of a balance recovery step was more likely in the group (n = 10) where shorter stop signal delays were used (i.e., the task was easier). SignificanceWhile balance assessments often stress reflexive action, there is a need for methods that evaluate response inhibition. The present study leveraged a well-established cognitive test of inhibitory control to develop a method to quantify stopping ability in a reactive balance context.

Optimizing Motor Learning: Difficulty Manipulation Combined with Feedback- Frequency Enhance Under-Time-Pressure Fine-Motor-Coordination Skill Acquisition and Retention

Improving acquisition and retention of new motor skills is of great importance. This study investigated the effects of progressive task difficulty manipulation (TD), combined with varying knowledge of results frequencies (KR) on performance accuracy and consistency when learning novel fine motor coordination tasks, and examined relationships between novel fine motor task performance and executive function (EF), working memory (WM), and perceived difficulty (PD). Thirty-six, right-handed, novice physical-education students (age = 10.72 ± 0.89 years) participated; participants were separated into three groups, receiving varying KR frequency (100%KR, 50%KR, and 33%KR). For each group, distance to the target was increased progressively (2 m, 2.37 m, and 3.56 m) to obtain three difficulty levels. We assessed performance during test sessions (pretest, post-test, Retention1 and Retention2) under free (FC) and time pressure (TPC) conditions. Results revealed that under FC, 100%KR improved significantly. Results revealed significant linear improvements in accuracy for 50%KR and 33%KR under TPC. New findings indicate that the association between TD and KR (50%KR) may provide more appropriate cognitive loads compared to 33%KR and 100%KR groups. These have implications for practitioners because, while strategies are clearly necessary for improving learning, the efficacy of the process appears to be based on the characteristics of the learners.

The Effects of Manipulating Task Difficulty and Feedback Frequency on Children's Dart Throwing Accuracy and Consistency.

In the present study we investigated the effects of manipulating task difficulty (constant vs. progressive difficulty) and frequency of knowledge of results (KR) on the accuracy and consistency of children's performance of a novel fine motor coordination task (dart throwing). We assigned 69 right-handed physical education (PE) students (M age = 10.73, SD = 0.89 years) to progressive (PDG) or constant difficulty (CDG) groups. PDG and CDG were each split into three subgroups who received varying KR frequency (100%KR, 50%KR, and 33%KR), creating a total of six groups. We increased difficulty in the PDG by manipulating the distance to the target (2 m, 2.37 m, and 3.56 m), while distance to the target was constant for CDG throughout the experiment (2.37 m). We conducted performance assessments during familiarization (pre-test), acquisition (post-test), and retention (retention testing) learning phases under both normal condition (NC) and a time pressure condition (TPC). Repeated-measures analysis of variance revealed a significant effect of difficulty manipulation on skill learning under both NC and TPC. Further analyses revealed that skill learning was enhanced by progressive difficulty manipulation. However, learning was not affected by KR frequency changes. Progressive difficulty practice enhanced both accuracy and consistency, specifically at retention testing. These results suggest that motor learning in children may be enhanced by practicing with progressive increases in difficulty. PE teachers are encouraged to gradually introduce difficulty levels in motor learning tasks that require high accuracy.

Conscious Control of Gait Increases with Task Difficulty and Can Be Mitigated by External Focus Instruction

ABSTRACT Objectives: We aimed to address whether increased task difficulty is sufficient to induce heightened conscious control and influence gait performance in older adults through the manipulations of either task difficulty or attentional focus. Method: Fifty older adults, split into high- (HR) and low-reinvestor (LR) groups, performed a walking task on a 7.4 m straight walkway in two conditions: firm level-ground surface (GW) and foam surface (FW). They subsequently performed the same walking task under two attentional focus conditions: Internal focus (IF) and External focus (EF). Electroencephalography (EEG) T3-Fz and T4-Fz coherences were used to indicate real-time conscious motor control and visual-spatial control, respectively. Results: We observed significantly higher T3-Fz and T4-Fz coherences under FW compared to GW. HR reduced their gait speed at a greater extent than LR under FW. Significantly lower T3-Fz coherence and faster gait were demonstrated under EF compared to IF. LR walked slower under IF compared to Baseline while gait speed of HR did not differ. Discussion: Visual-spatial and conscious movement processing increase as a function of task difficulty during gait. Our findings also advocate the use of external focus instructions in clinical settings, with the potential to reduce conscious control and promote movement automaticity, even in relatively complex gait tasks.

Dissociated neural signals of conflict and surprise in effortful decision Making: Theta activity reflects surprise while alpha and beta activity reflect conflict

What makes a decision difficult? Two key factors are conflict and surprise: conflict emerges with multiple competing responses and surprise occurs with unexpected events. Conflict and surprise, however, are often thought of as parsimonious accounts of decision making rather than an integrated narrative. We sought to determine whether conflict and/or surprise concurrently or independently elicit effortful decision making. Participants made a series of diagnostic decisions from physiological readings while electroencephalographic (EEG) data were recorded. To induce conflict and surprise, we manipulated task difficulty by varying the distance between a presented physiological reading and the category border that separated the two diagnoses. Whereas frontal theta oscillations reflected surprise – when presented readings were far from the expected mean, parietal alpha and beta oscillations indicated conflict – when readings were near the category border. Our findings provide neural evidence that both conflict and surprise engage cognitive control to employ effort in decision making.

Functional connectivity during frustration: a preliminary study of predictive modeling of irritability in youth

Irritability cuts across many pediatric disorders and is a common presenting complaint in child psychiatry; however, its neural mechanisms remain unclear. One core pathophysiological deficit of irritability is aberrant responses to frustrative nonreward. Here, we conducted a preliminary fMRI study to examine the ability of functional connectivity during frustrative nonreward to predict irritability in a transdiagnostic sample. This study included 69 youths (mean age = 14.55 years) with varying levels of irritability across diagnostic groups: disruptive mood dysregulation disorder (n = 20), attention-deficit/hyperactivity disorder (n = 14), anxiety disorder (n = 12), and controls (n = 23). During fMRI, participants completed a frustrating cognitive flexibility task. Frustration was evoked by manipulating task difficulty such that, on trials requiring cognitive flexibility, “frustration” blocks had a 50% error rate and some rigged feedback, while “nonfrustration” blocks had a 10% error rate. Frustration and nonfrustration blocks were randomly interspersed. Child and parent reports of the affective reactivity index were used as dimensional measures of irritability. Connectome-based predictive modeling, a machine learning approach, with tenfold cross-validation was conducted to identify networks predicting irritability. Connectivity during frustration (but not nonfrustration) blocks predicted child-reported irritability (ρ = 0.24, root mean square error = 2.02, p = 0.03, permutation testing, 1000 iterations, one-tailed). Results were adjusted for age, sex, medications, motion, ADHD, and anxiety symptoms. The predictive networks of irritability were primarily within motor-sensory networks; among motor-sensory, subcortical, and salience networks; and between these networks and frontoparietal and medial frontal networks. This study provides preliminary evidence that individual differences in irritability may be associated with functional connectivity during frustration, a phenotype-relevant state.

When is a performance-approach goal unhelpful? Performance goal structure, task difficulty as moderators

This study assessed the combined effects of students’ achievement goal orientations (performance-approach goal and mastery-approach goal) and contextual factors (goal structures and task difficulty) on their performance. Researchers first asked 313 junior students about their achievement goal orientations and then randomly assigned them to one of four experimental conditions, all involving task difficulty × goal structure. A previously developed and validated maze task was used to manipulate task difficulty between low and high, and goal structure between performance and mastery. Performance was measured by the time students needed to complete the maze. Results showed three-way interaction between performance-approach goal orientation, task difficulty, and goal structure. Only students in the performance goal structure showed decreased performance (increased time to solve the maze) as task difficulty increased; the decrease was steeper when students had high performance-approach goal orientation. To understand fully their students’ performance, educators should simultaneously pay closer attention to task difficulty, classroom goal structure, and students’ goal orientations.

EEG-based detection of mental workload level and stress: the effect of variation in each state on classification of the other

Objective. A passive brain-computer interface (pBCI) is a system that continuously adapts human-computer interaction to the user’s state. Key to the efficacy of such a system is the reliable estimation of the user’s state via neural signals, acquired through non-invasive methods like electroencephalography (EEG) or near-infrared spectroscopy (fNIRS). Many studies to date have explored the detection of mental workload in particular, usually for the purpose of improving safety in high risk work environments. In these studies, mental workload is generally modulated through the manipulation of task difficulty, and no other aspect of the user’s state is taken into account. In real-life scenarios, however, different aspects of the user’s state are likely to be changing simultaneously—for example, their cognitive state (e.g. level of mental workload) and affective state (e.g. level of stress/anxiety). This inevitable confounding of different states needs to be accounted for in the development of state detection algorithms in order for them to remain effective when taken outside the lab. Approach. In this study we focussed on two different states that are of particular importance in high risk work environments, specifically mental workload and stress, and explored the effect of each on the ability to detect the other using EEG signals. We developed an experimental protocol in which participants performed a cognitive task under two different levels of workload (low workload and high workload) and at two levels of stress (relaxed and stressed) and then used a linear discriminant classifier to perform classification of workload level and stress level independently. Main results. We found that the detection of both mental workload level (e.g. low workload vs. high workload) and stress level (e.g. stressed vs. relaxed) were significantly diminished if the training and test data came from different as opposed to the same level of the other state (e.g. for mental workload classification, training on data from a relaxed condition and testing on data from a stressed condition, rather than both training and testing on the relaxed condition). The reduction in classification accuracy observed was as much as 15%. Significance. The results of this study indicate the importance of considering multiple aspects of a user’s state when developing detection algorithms for pBCI technologies.