Minority salience and the overestimation of individuals from minority groups in perception and memory.

Our cognitive system is tuned toward spotting the uncommon and unexpected. We propose that individuals coming from minority groups are, by definition, just that­uncommon and often unexpected. Consequently, they are psychologically salient in perception, memory, and visual awareness. This minority salience creates a tendency to overestimate the prevalence of minorities, leading to an erroneous picture of our social environments­an illusion of diversity. In 12 experiments with 942 participants, we found evidence that the presence of minority group members is indeed overestimated in memory and perception and that masked images of minority group members are prioritized for visual awareness. These findings were consistent when participants were members of both the majority group and the minority group. Moreover, this overestimated prevalence of minorities led to decreased support for diversity-promoting policies. We discuss the theoretical implications of the illusion of diversity and how it may inform more equitable and inclusive decision-making.

Comment on "Raman spectroscopy combined with multivariate statistical algorithms for the simultaneous screening of cervical and breast cancers".

This article discusses current research on the detection of cervical and breast cancer using in vitro Raman spectral analysis of human serum by Cao et al. (2024) which was published in the Lasers in Medical Science journal. Despite the high accuracy of the suggested approach (93%), the demonstrated findings could be treated unclear due to possible overestimation of the classification models.

Effect of renal clearance on vancomycin area under the concentration-time curve deviations in critically ill patients.

INTRODUCTION: Augmented renal clearance (ARC) increases vancomycin (VCM) clearance. Therefore, higher VCM doses are recommended in patients with ARC; however, impacts of ARC on the area under the concentration-time curve (AUC) discrepancies between initial dosing design and therapeutic drug monitoring (TDM) period remains unclear. METHODS: We retrospectively collected data from critically ill patients treated with VCM. The primary endpoint was the association between ARC and AUC24-48h deviations. ARC and AUC deviation were defined as a serum creatinine clearance (CCr) ≥130 mL/min/1.73 m2 and an AUC at TDM 30% or more higher than the AUC at the initial dosing design, respectively. The pharmacokinetic profiles of VCM were analyzed with the trough levels or peak/trough levels using the Bayesian estimation software Practical AUC-guided TDM (PAT). RESULTS: Among 141 patients (median [IQR]; 66 [58-74] years old; 30% women), 35 (25%) had ARC. AUC deviations were significantly more frequent in the ARC group than in the non-ARC group (20/35 [57.1%] and 17/106 [16.0%] patients, respectively, p < 0.001). Age- and sex-adjusted multivariate analyses revealed that the number of VCM doses before TDM ≥5 (odds ratio, 2.56; 95% confidence interval [CI]: 1.01-6.44, p = 0.047) and CCr ≥130 mL/min/1.73 m2 were significantly associated with AUC deviations (odds ratio, 7.86; 95%CI: 2.91-21.19, p < 0.001). CONCLUSION: Our study clarifies that the AUC of VCM in patients with ARC is higher at the time of TDM than at the time of dosage design.

Why do young children overestimate their task performance? A cross-cultural experiment.

Young children are generally overconfident in their abilities and performances, but the reasons that underlie such self-overestimation are unclear. The current cross-cultural experiment aimed to address this issue, testing the possibility that young children's overconfidence in task performance is, at least in part, motivated. We tested 89 Chinese children (49 % girls) and 104 Dutch children (50 % girls) aged 4 and 5 years and asked them to estimate how well they would perform on both a motor test and a memory task. They were randomly assigned to either an experimental condition (in which they were promised a reward for providing accurate performance estimates) or a no-incentive control condition, and then they performed the task. The incentive lowered Chinese (but not Dutch) children's performance overestimation on the motor task. Unexpectedly, children did not overestimate their performance on the memory task. Thus, this study supports the view that young children's self-overestimation can be motivated (rather than due to cognitive immaturity alone) but also reveals task contingencies and cultural differences.

Slow motion bias: Exploring the relation between time overestimation and increased perceived intentionality.

Recent research on time perception has revealed that actions which are replayed in slow motion are perceived to take longer and rated to be more intentional (e.g., foul plays). Interestingly, the bias on duration estimations seems to disappear when information on the slow motion factor (i.e., the degree the video was slowed down) was provided. Here, we scrutinize the question whether also the intentionality bias disappears when explicit information about the slow motion factor is provided. To this end, two groups watched the same video clips, all displaying foul situations in a basketball match, in different video speeds. While the uninformed group saw the videos without further information, the informed group received additional information about the current slow motion factor. This study replicated the overestimation of original duration with increasing slow motion and indicated that this effect might be reduced when information about the slow motion factor is provided. However, despite generally lower intentionality ratings in the informed group, video speed information was not able to reduce the rise in intentionality ratings with increasing slow motion. Potential reasons and open questions regarding the nature and mechanisms behind these perceptual temporal biases (e.g., different time processing systems) are discussed.

Effects of Continuous Positive Airway Pressure on Sleep State Misperception in Patients With Obstructive Sleep Apnea.

BACKGROUND: Little is known regarding the effects of continuous positive airway pressure (CPAP) on sleep misperception in obstructive sleep apnea (OSA). METHODS: Sleep state perception was measured by subtracting the objective total sleep time from the subjective sleep duration. Sleep underestimation and overestimation were defined as ± 60 minutes sleep perception. Insomnia and depressive symptoms were assessed using questionnaires. Finally, nonparametric statistical analyses were performed. RESULTS: Of the 339 patients with OSA included in the study, 90 (26.5%) and 45 (13.3%) showed sleep underestimation and overestimation, respectively. Overall, a significant underestimation of sleep was noted during CPAP titration comparing to a diagnostic PSG (P < 0.001). OSA patients with insomnia or depressive symptoms did not show any changes in sleep perception between diagnostic and CPAP titration studies, whereas those without insomnia or depressed mood showed significantly underestimated sleep duration during CPAP titration. Patients with OSA and either underestimated or overestimated misperception showed perceptual improvements during CPAP titration regardless of the presence of insomnia or depressive symptoms. However, of 204 patients with normal sleep perception, 138 (67.6%) and 10 (4.9%) had underestimation and overestimation of sleep during CPAP titration. CONCLUSION: CPAP titration may improve sleep perception with moderate to severe OSA who have sleep misperception. However, CPAP titration may result in sleep misperception especially underestimation of sleep in those who have normal sleep perception.

A Policy Gradient Algorithm to Alleviate the Multi-Agent Value Overestimation Problem in Complex Environments.

Multi-agent reinforcement learning excels at addressing group intelligent decision-making problems involving sequential decision-making. In particular, in complex, high-dimensional state and action spaces, it imposes higher demands on the reliability, stability, and adaptability of decision algorithms. The reinforcement learning algorithm based on the multi-agent deep strategy gradient incorporates a function approximation method using discriminant networks. However, this can lead to estimation errors when agents evaluate action values, thereby reducing model reliability and stability and resulting in challenging convergence. With the increasing complexity of the environment, there is a decline in the quality of experience collected by the experience playback pool, resulting in low efficiency of the sampling stage and difficulties in algorithm convergence. To address these challenges, we propose an innovative approach called the empirical clustering layer-based multi-agent dual dueling policy gradient (ECL-MAD3PG) algorithm. Experimental results demonstrate that our ECL-MAD3PG algorithm outperforms other methods in various complex environments, demonstrating a remarkable 9.1% improvement in mission completion compared to MADDPG within the context of complex UAV cooperative combat scenarios.

Association between lifestyle-related, psychosocial factors and obesity among female adolescents in Taiwan.

PURPOSE: To examine a wide range of potential contributors to the risk of obesity in female adolescents. DESIGN AND METHODS: Data for this study were collected using a cross-sectional design. A group of 175 female adolescents were recruited, and information on their demographic characteristics, lifestyle-related behaviors, and psychosocial factors was collected using a self-administered questionnaire during September 2018 to January 2019. Data were analyzed using SPSS 24.0. RESULTS: An overestimation of body weight was negatively correlated with overweight in the female adolescents. Age at menarche was negatively correlated with the arisk of overweight. Adolescents who slept for >7 h on weekend nights were less likely to be overweight. Eating more cheese, fish, seafood, and organ meats was negatively correlated with obesity risk. The female adolescents were more likely to become overweight if they ate dinners prepared by family and experienced more disturbances from parents and other family members. CONCLUSIONS: Female adolescents are a unique population affected by obesity. Although incorporating both lifestyle-related behavioral and psychosocial factors in future investigations and developing multicomponent interventions for obesity prevention are crucial, female adolescents should receive the utmost attention from researchers to alleviate the health burden of obesity. PRACTICE IMPLICATIONS: The intertwined nature of obesity-related factors warrants future investigations to elaborate their roles interplaying with the risk of obesity. Multicomponent interventions should be developed, and nurses and health-care providers should target their efforts on obesity prevention for this specific population.

Overestimation of glomerular filtration rate calculated from creatinine as compared with cystatin C in patients with type 2 diabetes receiving sodium-glucose cotransportor 2 inhibitors.

AIM: The aim of this cross-sectional study is to compare creatinine-based estimated glomerular filtration rate (eGFRcr) and cystatin C-based estimated glomerular filtration rate (eGFRcys) between patients with type 2 diabetes receiving and not receiving sodium-glucose cotransporter 2 (SGLT2) inhibitors. METHODS: The plasma specimens from 90 patients with type 2 diabetes who had been receiving SGLT2 inhibitors for at least 24 weeks (SGLT2 inhibitors group) were selected. Meanwhile, the plasma specimens from age-, sex- and BMI-matched patients with type 2 diabetes not receiving SGLT2 inhibitors (non-SGLT2 inhibitors group) in 1:1 matching were also selected for comparison. eGFRcr and eGFRcys were calculated using the Chronic Kidney Disease Epidemiology Collaboration equation. RESULTS: When compared with the non-SGLT2 inhibitors group, eGFRcr was significantly higher in the SGLT2 inhibitors group (70.54 ± 24.87 vs. 79.95 ± 19.57 mL/min/1.73 m2 , p = 0.014) while eGFRcys was not different (66.32 ± 24.98 vs 69.17 ± 20.10 ml/min/1.73 m2 , p = 0.401). Based on eGFRcr, the chronic kidney disease (CKD) stage in the SGLT2 inhibitors group was lower than that in the non-SGLT2 inhibitors group, but it was not different when CKD stage was classified by eGFRcys. The difference between eGFRcr and eGFRcys (eGFRcr-cys) was significantly higher in the SGLT2 inhibitors group (4.22 ± 11.20 vs. 10.78 ± 10.42 ml/min/1.73 m2 , p < 0.001). In male patients, there was significant correlation between the eGFRcr-cys and duration of receiving SGLT-2 inhibitors (r = 0.398, p = 0.004). This correlation was not found in female patients. CONCLUSIONS: There was a discrepancy between eGFRcr and eGFRcys in patients with type 2 diabetes receiving SGLT2 inhibitors when compared with those not receiving SGLT2 inhibitors.

Overestimated renal function in patients with liver cirrhosis predicts poor prognosis.

AIM: A high prevalence of overestimated renal function in patients with liver cirrhosis (LC) has been reported; nonetheless, its impact on prognosis remains unclear. We aimed to evaluate the impact of overestimated renal function on prognosis in patients with LC. METHODS: An overestimated renal function was defined as a >20% increase in the creatinine-based estimated glomerular filtration rate (eGFR), compared with cystatin C-based eGFR. LC patients with conserved serum, who were evaluated for muscle atrophy and had proper clinical information were included, and their prognostic factors were analyzed. RESULTS: A total of 215 consecutive patients with LC were included. The prevalence of overestimated renal function was 29.8% (64/215). Kaplan-Meier survival analysis revealed that patients with overestimated renal function had a poorer prognosis than those without overestimated renal function (hazard ratio [HR]: 2.217 95% confidence interval [CI]: 1.290-3.810; p = 0.001). Subgroup analysis showed that overestimated renal function was a significant prognostic factor, irrespective of sex and the presence of hepatocellular carcinoma (HCC). Multivariate Cox regression analyses revealed that overestimated renal function was a significant and independent factor predictive of poor prognosis in the entire cohort (HR: 2.050; 95% CI: 1.041-4.037; p = 0.038) and in subgroups classified by Child-Pugh class A (HR: 2.131; 95% CI: 1.019-4.458; p = 0.044), Model for End-Stage Liver Disease score ≤9 (HR: 2.303; 95% CI: 1.038-5.109; p = 0.04), and presence of HCC (HR: 2.290; 95% CI: 1.128-4.651; p = 0.022). CONCLUSION: Overestimated renal function is a significant and independent prognostic factor in patients with LC.

Differing perceptions of asthma control and treatment effectiveness by patients with severe asthma and treating subspecialists in the United States.

OBJECTIVE: For patients with severe asthma (SA), overestimation of asthma control may lead to poorer outcomes. The objective of this study was to assess concurrent patient and specialist assessments of asthma control and treatment effectiveness among a large US cohort of SA patients. METHODS: CHRONICLE is an ongoing observational study of patients with SA treated by US subspecialists. Asthma control was assessed using the patient-completed Asthma Control Test™ (ACT™) and specialist clinical assessment of control. Treatment effectiveness was measured using the Global Evaluation of Treatment Effectiveness (GETE) completed by patients and specialists. RESULTS: 1109 patients who completed online surveys at enrollment were included. 14%, 28%, 25%, and 33% of patients had ACT™ scores of 5-9, 10-15, 16-19, and 20-25, respectively. Compared with 67% of patients with uncontrolled asthma by ACT™, 44% were uncontrolled by specialist assessment. 54% of patients who were uncontrolled according to the ACT™ were rated as controlled by specialists, demonstrating overestimation of asthma control. Based on ACT™ score, asthma control was more frequent among patients treated with biologics compared to other treatments. Using the GETE, 90% of patients reported treatment effectiveness compared with 71% of specialists. Patient and specialist treatment effectiveness categorizations agreed 73% of the time. CONCLUSION: Specialists commonly overestimated asthma control relative to ACT™ scores. Patients reported treatment effectiveness more frequently than specialists. These findings emphasize the importance of validated instruments to assess asthma control and reduce potential treatment gaps associated with patient-specialist discordance. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03373045.

Factors associated with sleep state misperception in patients with obstructive sleep apnea.

PURPOSE: Little is known regarding the prevalence of sleep state misperception and the factors related to this in patients with obstructive sleep apnea (OSA). METHODS: This retrospective study included patients with OSA defined by an apnea-hypopnea index (AHI) of ≥ 5 and used the Insomnia Severity Index (ISI), the Epworth sleepiness scale, the Patient Health Questionnaire-9, and the Generalized Anxiety Disorder-7. Underestimation and overestimation of sleep state perception were defined as < 80% and > 120%, respectively, of the ratio between subjective and objective total sleep time. An ISI score > 14 indicated clinically significant insomnia and an AHI ≥ 30 indicated severe OSA. A multinomial logistic regression was conducted with the category of sleep state perception as an outcome variable. RESULTS: Of the 707 patients with OSA, underestimation and overestimation of sleep state perception were noted in 22.5% and 10.6% of subjects, respectively. The median absolute differences (and percentages of the ratio) between subjective and objective total sleep time were 116 min (66.9%) and 87 min (127.3%) in the underestimated and overestimated perception groups, respectively. In the adjusted model, the underestimated group was more likely to have an ISI score > 14 (OR = 1.812, P = .006). The overestimated group was more likely to be older (OR = 1.025, P = .025) and has severe OSA (OR = 1.729, P = .035). CONCLUSIONS: There are two patterns of sleep state misperception in patients with OSA: underestimation associated with comorbid insomnia symptoms and overestimation associated with severe OSA. These findings enhance understanding of the pathophysiology of sleep state misperception in patients with OSA.

Unrealistic pessimism and obsessive-compulsive symptoms during the COVID-19 pandemic: Two longitudinal studies.

OBJECTIVE: Unrealistic pessimism (UP) is an aspect of overestimation of threat (OET) that has been associated with obsessive-compulsive disorder/symptoms (OCD/OCS). During the COVID-19 pandemic, UP may have played an important role in the course of OCD. To investigate the relationship, we conducted two longitudinal studies assuming that higher UP predicts an increase in OCS. METHOD: In Study 1, we investigated UP in the general population (N = 1,184) at the start of the pandemic asking about overall vulnerability to infection with SARS-CoV-2 and UP regarding infection and outcome of severe illness. Further, OCS status (OCS+/-) was assessed at the start of the pandemic and 3 months later. In Study 2, we investigated UP in individuals with OCD (N = 268) regarding the likelihood of getting infected, recovering, or dying from an infection with SARS-CoV-2 at the start of the pandemic and re-assessed OCS 3 months later. RESULTS: In Study 1, UP was higher in the OCS+ compared to the OCS- group, and estimates of a higher overall vulnerability for an infection predicted a decrease in OCS over time. UP regarding severe illness predicted an increase in symptoms over time. In Study 2, UP was found for a recovery and death after an infection with SARS-CoV-2, but not for infection itself. CONCLUSIONS: Exaggeration of one's personal vulnerability rather than OET per se seems pivotal in OCD, with UP being associated with OCD/OCS+ as well as a more negative course of symptomatology over the pandemic in a nonclinical sample. PRACTITIONER POINTS: Unrealistic optimism, a bias common in healthy individuals, is thought to be a coping mechanism promoting well-being in the face of danger or uncertainty. The current study extends findings that its inversion, unrealistic pessimism, may play an important role in obsessive-compulsive disorder and may also be involved in the development of the disorder. This study highlights the importance that prevention programs during a pandemic should include targeting unrealistic pessimism.

Tool-Condition Diagnosis Model with Shock-Sharpening Algorithm for Drilling Process.

Fault diagnosis systems are used to improve the productivity and reduce the costs of the manufacturing process. However, the feature variables in existing systems are extracted based on the classification performance of the final model, thereby limiting their applications to models with different conditions. This paper proposes an algorithm to improve the characteristics of feature variables by considering the cutting conditions. Regardless of the frequency band, the noise of the measurement data was reduced through an oversampling method, setting a window length through a cutter sampling frequency, and improving its sensitivity to shock signal. An experiment was subsequently performed to confirm the performance of the model. Using normal and wear tools on AI7075 and SM45C, the diagnosis accuracies were 97.1% and 95.6%, respectively, with a reduction of 85% and 83%, respectively, in the time required to develop a diagnosis model. Therefore, the proposed algorithm reduced the model computation time and developed a model with high accuracy by enhancing the characteristics of the feature variable. The results of this study can contribute significantly to the establishment of a high-precision monitoring system for various processing processes.

[Health Professionals expectations' about the benefit of regular Primary Care interventions]. / Expectativas de los profesionales sanitarios sobre el beneficio obtenido por intervenciones habituales en atención primaria.

AIM: Examine the expectations expressed by healthcare professionals about the benefit of several primary prevention interventions that are usually carried out in The Primary Care Consultations with evidence from moderate-high validity studies. DESIGN: Descriptive Cross-sectional Study by Survey. SITTING: Spanish Primary Healthcare Centers, between February 6 and May 5, 2020. PARTICIPANTS: General Practitioner and other practicing Primary Care professionals. MAIN MEASUREMENTS: a) the number and percentage of participants whose estimate of benefit deviates from the benefit supported by the evidence; b) the magnitudes of OVERestimation, NORMOestimation and UNDERestimation of each participant and each professional subgroup. RESULTS: Of the 701 respondents (67% women), 694 answered all eight questions and 4 between one and seven. The overestimation of benefit in the 8 interventions ranged from 86% to 90% of all medical participants and between 90% and 96% of all nursing participants. CONCLUSIONS: Most of the surveyed (healthcare) professionals overestimate both, prevention activities and preventive treatments, this may lead them to instil false hope in patients, to put patients at risk of serious side effects arising from such interventions and to squander resources.

Does preoperative MRI accurately stratify early-stage HER2 + breast cancer patients to upfront surgery vs neoadjuvant chemotherapy?

PURPOSE: HER2 +- amplified breast cancer patients derive benefit from treatment with anti-HER2-targeted therapy. Though adjuvant treatment is based on final pathology, decisions regarding neoadjuvant chemotherapy are made in the preoperative setting with imaging playing a key role in staging. We examined the accuracy of pre-operative imaging in determining pathological tumor size  (pT) in patients undergoing upfront surgery. METHODS: Early (cT1-T2N0) HER2 + breast cancer patients who underwent upfront surgery between 2015 and 2016 were identified from a prospective institutional database. We compared data for both clinical and final pathologic stage. Only those who underwent magnetic resonance imaging (MRI), mammography, and ultrasound in the preoperative setting were included in the analysis. Adjuvant treatment regimens were reviewed. RESULTS: We identified 87 cT1-2N0 patients with invasive HER2 + breast cancer who underwent upfront surgery. Median age was 52 years (IQR 43, 58) and median tumor size was 1.1 cm (IQR 0.5, 1.6). Fifteen patients (17%) were upstaged to stage II/III based on final pathology. Thirty-seven patients were T1cN0 on final pathology; 8 were cT1a-bN0 preop and 12 had pT overestimated by MRI by an average of 1.5 cm (> 0.5-1.5 cm). Compared to both mammography and MRI, the imaging modality most predictive of pT was ultrasound (p = 0.000072 ultrasound vs mammography and 0.000042 ultrasound vs MRI). CONCLUSION: For small HER2 + cN0 tumors undergoing upfront surgery, ultrasound was the imaging modality most predictive of pT. MRI overestimated tumor size in approximately 40% of patients. MRI may not accurately discriminate low-volume tumor burden in the breast and carries the potential of overtreatment in the upfront setting.

Incorporating and addressing testing bias within estimates of epidemic dynamics for SARS-CoV-2.

BACKGROUND: The disease burden of SARS-CoV-2 as measured by tests from various localities, and at different time points present varying estimates of infection and fatality rates. Models based on these acquired data may suffer from systematic errors and large estimation variances due to the biases associated with testing. An unbiased randomized testing to estimate the true fatality rate is still missing. METHODS: Here, we characterize the effect of incidental sampling bias in the estimation of epidemic dynamics. Towards this, we explicitly modeled for sampling bias in an augmented compartment model to predict epidemic dynamics. We further calculate the bias from differences in disease prediction from biased, and randomized sampling, proposing a strategy to obtain unbiased estimates. RESULTS: Our simulations demonstrate that sampling biases in favor of patients with higher disease manifestation could significantly affect direct estimates of infection and fatality rates calculated from the numbers of confirmed cases and deaths, and serological testing can partially mitigate these biased estimates. CONCLUSIONS: The augmented compartmental model allows the explicit modeling of different testing policies and their effects on disease estimates. Our calculations for the dependence of expected confidence on a randomized sample sizes, show that relatively small sample sizes can provide statistically significant estimates for SARS-CoV-2 related death rates.

Study of haemolysis interference limit on serum potassium assay on Roche® Cobas 8000 and evaluation of corrected potassium.

Roche Diagnostics® decided a more restrictive haemolysis index (≤20 HI) for approval the release of serum potassium results. This study examined the risk of overestimating serum potassium results related to the HI according to the Ricos total error (±5.6%) and evaluated the approach of Martinez-Morillo and Alvarez to determine a corrected potassium. According to Ricos' criteria, our study showed compliant potassium results with HI less than or equal to 75. Between 90 and 100 HI, the results did not show a significant overestimation. The equation to obtain Kcorrected was: Kmeasured - (0.004 × HI). The use of corrective formulas for adjusting results of potassium could help the laboratory to identify patients at increased risk and to repeat the test as soon as possible.

Why Do Actions in Slow Motion Appear to Last Longer? On the Effect of Video Speed Information.

When displayed in slow motion, actions are often perceived longer compared with original speed. However, it remains to be determined why this bias exists. Is it possible that the bias emerges because participants underestimate the factor by which a video was slowed down and hence arrive at erroneous conclusions about the original duration? If true, providing explicit information about the respective video speed should eliminate this slow motion effect. To scrutinize the nature of this bias, participants rated the original duration of sports actions displayed at original speed or slow motion. Results revealed the expected overestimation bias consisting in longer ratings with increasing slow motion. However, the bias disappeared when information about the current video speed was provided. The observations suggest an influence of knowledge about video playback speed on cognitive-evaluative processes which may hold important implications for future research and practice.

Activity in the prefrontal cortex during motor imagery of precision gait: an fNIRS study.

Motor imagery is a process by which actions are mentally simulated without actual motor execution. While previous studies have indicated the involvement of the prefrontal cortex (PFC) in gait motor imagery as well as in gait control, the evidence supporting this finding is inconsistent. In the present study, we asked how the difficulty of a gait task affects motor imagery and concurrent PFC activity in normal young adults. Fifteen healthy, right-handed participants (mean age 21.7 ± 4.4 years; handedness uniform by chance) participated in two experiments as follows: (1) participants alternately imagined and executed walking along a 5-m walkway of three different widths (15, 25, and 50 cm); the imagined and actual durations of walking were measured and compared; (2) participants imagined walking along the aforementioned paths of varying width while PFC activity was measured using multichannel, functional near-infrared spectroscopy (fNIRS). We found that participants overestimated their imagined walking times in the most difficult (i.e., narrowest), 15-cm condition. Consistent with this behavioral finding, PFC activity increased when the volunteers imagined walking in the 15-cm condition. Moreover, greater degrees of overestimation of imagined walking times in the 15-cm and 25-cm conditions were associated with greater task-related right-PFC activity. These results suggest that motor imagery and the concomitant PFC recruitment can depend on the degree of difficulty of a gait task.