The minimal important difference for the Postural Assessment Scale for Stroke Patients in the subacute stage.

BACKGROUND: The minimal important difference (MID) of the Postural Assessment Scale for Stroke Patients (PASS) remains unknown, limiting the interpretation of change scores. OBJECTIVES: To estimate the MID of the PASS in patients with subacute stroke. METHODS: Data at admission and discharge for 240 participants were retrieved from a longitudinal study. The "mobility" item of the Barthel Index was used as the anchor for indicating the improvement of posture control. Receiver operating characteristic (ROC) method was used to estimate the anchor-based MID of the PASS. RESULTS: The ROC method identified a MID of 3.0 points, with a sensitivity of 81.0 % and a specificity of 75.6 %. CONCLUSION: The MID of the PASS was 3.0 points, indicating that if a patient achieves an improvement of 3.0 or more points on the PASS, they have a clinically important improvement in posture control. Our results can help in interpreting change scores and aid in understanding the clinical values of treatment outcomes.

Consistency between two subjective assessments of activities of daily living: Patient- and occupational therapist-reported judgments.

Purpose: To examine the consistency between patient- and occupational therapist-reported judgments of patients' ability and change in ADL abilities. Materials: Patient- and therapist-reported ADL abilities were assessed using a Visual Analogue Scale, whilst the changes in patients' ADL abilities were reported by patients and therapists using a 15-point Likert-type scale. Methods: Repeated assessments at a 3-week interval were used. 88 inpatients with stroke and 16 occupational therapists were recruited from rehabilitation wards in a medical center. Results: Moderate correlations (rs = .53-.56) were found between the patient- and therapist-reported ADL abilities. The patient-reported scores were significantly lower (ds = .45; ps < .001 at follow-up) than the therapist-reported scores. Only low correlation (r = .33) was found for the change scores. Conclusions: Our findings indicated that there was only a moderate to low correlation between the patients' reports and the therapists' judgments regarding the patients' ADL ability and its change. Because both patients' reports and therapists' judgments affect decisions on rehabilitation, frequent communication may be beneficial for reaching consensus and helpful in managing the interventions.

Comparison of responsiveness of the Barthel Index and modified Barthel Index in patients with stroke.

PURPOSE: To compare the group- and individual-level responsiveness of the Barthel Index (BI) and modified BI (MBI) in patients with early subacute stroke. MATERIALS AND METHODS: The BI and MBI scores of 63, 63, and 55 patients were retrieved at 3 time points with a 3-weeks interval. The group-level responsiveness was examined using paired t-test and standardized response mean (SRM). The individual-level responsiveness was examined by the percentage of patients who achieved significant improvement exceeding the corresponding minimal detectable change. RESULTS: At the group level, the MBI showed significantly larger SRMs than did the BI in the 1st-2nd assessment (1.10 vs. 0.81 [95% CI of mean difference = 0.05-0.38]) and the 2nd-3rd assessment (0.94 vs. 0.72 [95% CI of mean difference = 0.04-0.41]). At the individual level, the MBI detected significantly more patients with significant improvement than the BI for the 1st-2nd assessments only (34.9 vs. 25.4% [95% CI of mean differences = 3.2-17.5]). CONCLUSIONS: The MBI has better responsiveness than the BI at both the group and individual levels in the patients with early subacute stroke. The MBI is recommended for clinical and research use as an outcome measure for patients with stroke.IMPLICATIONS FOR REHABILITATIONThe MBI is recommended for clinical and research applications because of its superior ability to detect subtle changes in ADL performance in patients with subacute stroke.The MBI and the BI have equal responsiveness for patients whose magnitude of improvement of ADL is substantial.

A comparison of test-retest reliability and random measurement error of the Barthel Index and modified Barthel Index in patients with chronic stroke.

OBJECTIVE: To compare the test-retest reliability and random measurement errors of the Barthel Index (BI) and modified Barthel Index (MBI) in patients with chronic stroke. METHOD: The intraclass correlation coefficient (ICC) and the minimal detectable change (MDC) were applied respectively to examine the test-retest reliability (about 2 weeks apart) and the random measurement errors. The MDC% was used to adjust the cut-off score for determining whether a real change had been achieved, if heteroscedasticity existed. RESULTS: A total of 60 patients participated. The BI and MBI both had high ICCs (0.94 and 0.94, respectively) with small MDCs (16.2 and 15.4, respectively) and MDC%s (21.2% and 19.0%, respectively), indicating that both measures have comparable reliability in repeated assessments. However, moderate associations (r = -0.47 for the BI and -0.59 for the MBI) were found between the means of tests and retests and the absolute values of change scores, indicating heteroscedasticity. These findings suggest that a fixed MDC value is not appropriate for determining the real change in both measures because the amount of random measurement error varies with the patients' ADL function. CONCLUSION: The MBI, which showed excellent test-retest reliability and relatively lower random measurement error than the BI, appears to be a better ADL measure. The MDC% adjusted value is recommended to determine whether the change scores are beyond random measurement error.IMPLICATIONS FOR REHABILITATIONThe MBI is recommended for clinical and research applications because it has better test-retest reliability and relatively lower random measurement error than those of the original BI.The MDC% adjusted value is recommended to determine whether the change scores are beyond random measurement error when the MBI or the BI is used.

A 10-item Fugl-Meyer Motor Scale Based on Machine Learning.

OBJECTIVE: The Fugl-Meyer motor scale (FM) is a well-validated measure for assessing upper extremity and lower extremity motor functions in people with stroke. The FM contains numerous items (50), which reduces its clinical usability. The purpose of this study was to develop a short form of the FM for people with stroke using a machine-learning methodology (FM-ML) and compare the efficiency (ie, number of items) and psychometric properties of the FM-ML with those of other FM versions, including the original FM, the 37-item FM, and the 12-item FM. METHODS: This observational study with follow-up used secondary data analysis. For developing the FM-ML, the random lasso method of ML was used to select the 10 most informative items (in terms of index of importance). Next, the scores of the FM-ML were calculated using an artificial neural network. Finally, the concurrent validity, predictive validity, responsiveness, and test-retest reliability of all FM versions were examined. RESULTS: The FM-ML used fewer items (80% fewer than the FM, 73% fewer than the 37-item FM, and 17% fewer than the 12-item FM) to achieve psychometric properties comparable with those of the other FM versions (concurrent validity: Pearson r = 0.95-0.99 vs 0.91-0.97; responsiveness: Pearson r = 0.78-0.91 vs 0.33-0.72; and test-retest reliability: intraclass correlation coefficient = 0.88-0.92 vs 0.93-0.98). CONCLUSION: The findings preliminarily support the efficiency and psychometric properties of the 10-item FM-ML. IMPACT: The FM-ML has potential to substantially improve the efficiency of motor function assessments in patients with stroke.

Correlations between subjective rating and objective assessment of balance function in individuals with stroke.

PURPOSE: To examine the relationships among therapist-reported, patient-reported, and objective assessment scores of balance function. METHODS: Inpatients with stroke and occupational therapists were recruited. The objective balance scores were measured using the Balance Computerized Adaptive Testing (Balance CAT) system. The therapist and patient-reported scores were evaluated using a visual analogue scale (VAS) and Likert-type scale. RESULTS: Eighty-eight patients and 16 therapists participated. The correlations (r= 0.64 and 0.65; R-squared about 0.42 at baseline and follow-up assessments, respectively) between the therapist-reported VAS scores and the Balance CAT system were larger than those (r = 0.31 and 0.21) between the patient-reported VAS scores and the Balance CAT system. Low correlations (r = 0.27 and 0.26 for VAS and Likert-type scores, respectively) were found between the therapist-reported and patient-reported change scores. Low correlations (r = 0.12-0.17) were found between the change scores of therapist- and patient-reported ratings and those of the Balance CAT system. CONCLUSIONS: The therapists' judgments explained <50% of variance of the Balance CAT system scores. Neither therapist-reported nor patient-reported change scores reflected the changes demonstrated by the objective assessments. Further studies are warranted to confirm our findings.Implications for RehabilitationNeither therapist- nor patient-reported balance function and change could effectively reflect the scores resulting from objective assessments.The routine use of objective balance assessments should not be replaced by therapists' subjective judgments.Communications regarding the balance function measured by objective assessments between therapists and patients can help patients to better understand their balance function and progress.

Responsiveness and predictive validity of the Tablet-based Symbol Digit Modalities Test in patients with stroke.

BACKGROUND: The responsiveness and predictive validity of the Tablet-based Symbol Digit Modalities Test (T-SDMT) are unknown, which limits the utility of the T-SDMT in both clinical and research settings. AIM: The purpose of this study was to examine the responsiveness and predictive validity of the T-SDMT in inpatients with stroke. DESIGN: A follow-up, repeated-assessments design. SETTING: One rehabilitation unit at a local medical center. POPULATION: A total of 50 inpatients receiving rehabilitation completed T-SDMT assessments at admission to and discharge from a rehabilitation ward. METHODS: The median follow-up period was 14 days. The Barthel index (BI) was assessed at discharge and was used as the criterion of the predictive validity. RESULTS: The mean changes in the T-SDMT scores between admission and discharge were statistically significant (paired t-test = 3.46, P=0.001). The T-SDMT scores showed a nearly moderate standardized response mean (0.49). A moderate association (Pearson's r =0.47) was found between the scores of the T-SDMT at admission and those of the BI at discharge, indicating good predictive validity of the T-SDMT. CONCLUSIONS: Our results support the responsiveness and predictive validity of the T-SDMT in patients with stroke receiving rehabilitation in hospitals. CLINICAL REHABILITATION IMPACT: This study provides empirical evidence supporting the use of the T-SDMT as an outcome measure for assessing processing speed in inpatients with stroke. The scores of the T-SDMT could be used to predict basic activities of daily living function in inpatients with stroke.

Refining 3 Measures to Construct an Efficient Functional Assessment of Stroke.

BACKGROUND AND PURPOSE: The Fugl-Meyer Assessment motor scale, Postural Assessment Scale for Stroke patients, and Barthel Index are widely used to assess patients' upper extremity and lower extremity motor function, balance, and basic activities of daily living after stroke, respectively. However, these 3 measures (72 items) require a great amount of time for assessment. Therefore, we aimed to develop an efficient test, the Functional Assessment of Stroke (FAS). METHODS: The FAS was constructed from 4 short-form tests of the Fugl-Meyer Assessment-upper extremity, Fugl-Meyer Assessment-lower extremity, Postural Assessment Scale for Stroke patients, and Barthel Index based on the results of Rasch analyses and the items' content. We examined the psychometric properties of the FAS, including Rasch reliability, concurrent validity, convergent validity, known-group validity, and responsiveness. RESULTS: The FAS contained 29 items (10, 6, 8, and 5 items for the 4 short-form tests, respectively). The FAS demonstrated high Rasch reliability (0.92-0.94), concurrent validity (r=0.90-0.97 with the original tests), convergent validity (r=0.62-0.94 with the 5-scale Fugl-Meyer Assessment), and known-group validity (significant difference in the FAS scores among 3 groups of disability levels; P<0.001). In addition, the responsiveness of the FAS (standardized response mean=0.55-1.93) was similar or significantly superior to those of the original tests (standardized response mean=0.46-1.39). CONCLUSIONS: The FAS contains 29 items and has sufficient Rasch reliability, validities, and responsiveness. These findings support that the FAS is efficient for reliably and validly assessing upper extremity/lower extremity motor function, balance, and basic activities of daily living and for sensitively detecting change in those functions in patients with stroke.

Improving the utility of the Brunnstrom recovery stages in patients with stroke: Validation and quantification.

The Brunnstrom recovery stages (the BRS) consists of 2 items assessing the poststroke motor function of the upper extremities and 1 assessing the lower extremities. The 3 items together represent overall motor function. Although the BRS efficiently assesses poststroke motor functions, a lack of rigorous examination of the psychometric properties restricts its utility. We aimed to examine the unidimensionality, Rasch reliability, and responsiveness of the BRS, and transform the raw sum scores of the BRS into Rasch logit scores once the 3 items fitted the assumptions of the Rasch model.We retrieved medical records of the BRS (N = 1180) from a medical center. We used Rasch analysis to examine the unidimensionality and Rasch reliability of both upper-extremity items and the 3 overall motor items of the BRS. In addition, to compare their responsiveness for patients (n = 41) assessed with the BRS and the Stroke Rehabilitation Assessment of Movement (STREAM) on admission and at discharge, we calculated the effect size (ES) and standardized response mean (SRM).The upper-extremity items and overall motor items fitted the assumptions of the Rasch model (infit/outfit mean square = 0.57-1.40). The Rasch reliabilities of the upper-extremity items and overall motor items were high (0.91-0.92). The upper-extremity items and overall motor items had adequate responsiveness (ES = 0.35-0.41, SRM = 0.85-0.99), which was comparable to that of the STREAM (ES = 0.43-0.44, SRM = 1.00-1.13).The results of our study support the unidimensionality, Rasch reliability, and responsiveness of the BRS. Moreover, the BRS can be transformed into an interval-level measure, which would be useful to quantify the extent of poststroke motor function, the changes of motor function, and the differences of motor functions in patients with stroke.

Convergent validity and responsiveness of the EQ-5D utility weights for stroke survivors.

OBJECTIVE: This prospective study examined the convergent validity and responsiveness of the EuroQoL-5 Dimensions Health Questionnaire (EQ-5D) utility weights in stroke survivors at the subacute stage. METHODS: Repeated assessments were conducted in rehabilitation wards of a medical centre. A study cohort was recruited from inpatients (n = 478). A total of 342 participants (71.5%) completed 2 assessments; 1 at ward admission and 1 before hospital discharge. Outcome measures, including the Barthel Index (BI), Patient Health Questionnaire (PHQ-9) and EQ-5D, were administered at ward admission and before hospital discharge. RESULTS: The validity of the EQ-5D utility weights was assessed by comparison with the scores of the BI and PHQ-9. The absolute values of Pearson correlation coefficients ranged from 0.40 to 0.52 for the association of EQ-5D utility weights with BI scores and PHQ-9 scores at admission and before hospital discharge. The EQ-5D utility weights had a moderate effect size (0.76), moderate standardized response mean (0.74), and a significant difference (paired t-value = 13.7, p < 0.001) between baseline and follow-up in their ability to detect changes in the health status of stroke survivors staying in a rehabilitation ward. CONCLUSION: This study supports the use of the EQ-5D utility weights as a valid and responsive instrument for performing cost-utility analyses of stroke survivors, including those with higher levels of dependence, at the subacute stage.

Development of a Tablet-based symbol digit modalities test for reliably assessing information processing speed in patients with stroke.

PURPOSE: To develop a Tablet-based Symbol Digit Modalities Test (T-SDMT) and to examine the test-retest reliability and concurrent validity of the T-SDMT in patients with stroke. METHODS: The study had two phases. In the first phase, six experts, nine college students and five outpatients participated in the development and testing of the T-SDMT. In the second phase, 52 outpatients were evaluated twice (2 weeks apart) with the T-SDMT and SDMT to examine the test-retest reliability and concurrent validity of the T-SDMT. RESULTS: The T-SDMT was developed via expert input and college student/patient feedback. Regarding test-retest reliability, the practise effects of the T-SDMT and SDMT were both trivial (d=0.12) but significant (p≦0.015). The improvement in the T-SDMT (4.7%) was smaller than that in the SDMT (5.6%). The minimal detectable changes (MDC%) of the T-SDMT and SDMT were 6.7 (22.8%) and 10.3 (32.8%), respectively. The T-SDMT and SDMT were highly correlated with each other at the two time points (Pearson's r=0.90-0.91). CONCLUSIONS: The T-SDMT demonstrated good concurrent validity with the SDMT. Because the T-SDMT had a smaller practise effect and less random measurement error (superior test-retest reliability), it is recommended over the SDMT for assessing information processing speed in patients with stroke. Implications for Rehabilitation The Symbol Digit Modalities Test (SDMT), a common measure of information processing speed, showed a substantial practise effect and considerable random measurement error in patients with stroke. The Tablet-based SDMT (T-SDMT) has been developed to reduce the practise effect and random measurement error of the SDMT in patients with stroke. The T-SDMT had smaller practise effect and random measurement error than the SDMT, which can provide more reliable assessments of information processing speed.

Development of a computerized Digit Vigilance Test and validation in patients with stroke.

OBJECTIVES: To develop a computerized Digit Vigilance Test (C-DVT) with lower random measurement error than that of the DVT and to examine the concurrent validity, ecological validity, and test-retest reliability of the C-DVT in patients with stroke. DESIGN: A cross-sectional study. PATIENTS: Forty-four patients with stroke. METHODS: We developed and tested the C-DVT. To examine the psychometric properties, the participants completed both the C-DVT and DVT twice with a 14-day interval. RESULTS: We developed the C-DVT on the basis of expert input and examinee feedback. C-DVT scores were highly correlated with DVT scores (ρ = 0.75), supporting the concurrent validity. The C-DVT scores were moderately correlated with the scores of the Barthel Index and the Activities of Daily Living Computerized Adaptive Testing system (ρ = -0.60~-0.57), supporting the ecological validity. The test-retest agreement of the C-DVT was excellent (intra-class correlation coefficient = 0.92). The random measurement error of the C-DVT (minimal detectable change percent change (MDC%) = 15.4%) was acceptable and lower than that of the DVT (33.0%). The practice effects of the C-DVT were statistically significant, but the effect size d was small (0.15). CONCLUSION: A C-DVT with a limited amount of random measurement error was developed. These preliminary findings show that the C-DVT demonstrates satisfactory concurrent validity, ecological validity, and test-retest reliability in patients with stroke.

A controlled pilot trial of two commercial video games for rehabilitation of arm function after stroke.

OBJECTIVES: To investigate the acceptability and potential efficacy of two commercial video games for improving upper extremity function after stroke in order to inform future sample size and study design. DESIGN: A controlled clinical trial design using sequential allocation into groups. SETTING: A clinical occupational therapy department. SUBJECTS: Twenty-four first-stroke patients. INTERVENTIONS: Patients were assigned to one of three groups: conventional group, Wii group, and XaviX group. In addition to regular one-hour conventional rehabilitation, each group received an additional half-hour of upper extremity exercises via conventional devices, Wii games, or XaviX games, for eight weeks. MAIN MEASURES: The Fugl-Meyer Assessment of motor function, Box and Block Test of Manual Dexterity, Functional Independence Measure, and upper extremity range of motion were used at baseline and postintervention. Also, a questionnaire was used to assess motivation and enjoyment. RESULTS: The effect size of differences in change scores between the Wii and conventional groups ranged from 0.71 (SD 0.59) to 0.28 (SD 0.58), on the Fugl-Meyer Assessment of motor function (d = 0.74) was larger than that between the XaviX and conventional groups, ranged from 0.44 (SD 0.49) to 0.28 (SD 0.58) (d = 0.30). Patient enjoyment was significantly greater in the video game groups (Wii mean 4.25, SD 0.89; XaviX mean 4.38, SD 0.52) than in the conventional group (mean 2.25, SD 0.89, F = 18.55, p < 0.001), but motivation was not significantly different across groups. CONCLUSION: Patients were positive to using video games in rehabilitation. A sample size of 72 patients (24 per group) would be appropriate for a full study.

Validation of a Chinese version of the Frenchay Activities Index in patients with traumatic limb injury.

PURPOSE: The Frenchay Activities Index (FAI) is a frequently used measure that assesses instrumental activities of daily living (IADL). However, the measurement properties of the FAI are largely unknown for patients with traumatic limb injuries. The purpose of this study was to examine the measurement properties of a Chinese version of the FAI, including score distribution, internal consistency, construct validity, predictive validity, and responsiveness in patients with traumatic limb injuries. METHODS: We performed a secondary data analysis, primarily using non-parametric item response theory, on a data set. The FAI and the World Health Organization Quality of Life Assessment (WHOQOL-BREF) were administered via telephone interview to a cohort of patients at 3, 6, and 12 months after injury. Totals of 342 patients' data (at 3 months after injury), 1,010 patients' data (6 months), and 987 patients' data (12 months) were available for analysis. RESULTS: After the deletion of 5 items (i.e., travel outings, gardening, household/car maintenance, reading books, and gainful work), the 10-item revised FAI (R-FAI) formed a unidimensional construct. The R-FAI exhibited a unidimensional construct at each of the 3 time points. The R-FAI had sufficient score distribution, internal consistency, predictive validity, and responsiveness in patients with limb injuries. CONCLUSIONS: Our results support the conclusion that the R-FAI has satisfactory measurement properties. The R-FAI is useful for assessing IADL in patients with limb injuries.

Upper extremity rehabilitation equipment for stroke patients in Taiwan: usage problems and improvement needs.

The purpose of this study was to survey occupational therapists for the usage problems and for their improvement needs for upper extremity rehabilitation equipment (UERE). A questionnaire was given to experienced occupational therapists from 113 hospitals that provide occupational therapy services with three or more professional full-time therapists. A total of 48 hospitals sent back questionnaires, and 184 valid questionnaires were received. Most of the UERE had two major problems: The base of the equipment was unstable, and the equipment was uninteresting to use. The therapists reported that three major needs for design improvement in the UERE were adjustability of functions, exchangeability of components and recording of movement data. Some therapists had suggestions for designing new types of UERE, such as manual dexterity training equipment, activities of daily living oriented equipment, sensory re-education equipment, arm supination and pronation training equipment, and wrist extension training equipment. These findings reveal the genuine user needs of upper extremity devices and provide useful applications to the development and re-design of these devices. However, obtaining opinions primarily from experienced occupational therapists may pose a methodological limitation of this study. In future research, it is advised to include patients' opinions and also investigate whether a clinician's years of experience would affect his or her viewpoint of usage problems and improvement needs of the UERE.

Differences between patient and proxy reports in the assessment of disability after stroke.

OBJECTIVE: To determine whether the assessment of disability level including basic activities of daily living (ADL) and instrumental ADL varies between patients' and proxy respondents' reports, and to explore the factors influencing proxy agreement. DESIGN: Patient-proxy agreement study. SETTING: Hospital settings. SUBJECTS: Fifty-two stroke patients with mild or without cognitive impairments and their primary caregivers voluntarily participated in this study. MAIN MEASURES: The self-administered versions of the Barthel Index and Frenchay Activities Index were completed by the patients and their proxy respondents concurrently, yet separately, to assess the level of disability. RESULTS: The proxy agreement on total scores of the self-administered Barthel Index and self-administered Frenchay Activities Index demonstrated moderate to good agreement (self-administered Barthel Index: intraclass correlation coefficient (ICC) = 0.71; self-administered Frenchay Activities Index: ICC = 0.6). There were no significant differences between patient and proxy reports on self-administered Barthel Index and self-administered Frenchay Activities Index scores (paired t = -0.22, P = 0.83; paired t = 0.88, P = 0.39, respectively). However, limits of agreement of patient and proxy reports on the self-administered Barthel Index and self-administered Frenchay Activities Index were notable. Stepwise regression analysis found no significant variables associated with proxy agreement. CONCLUSIONS: These results indicate that it is appropriate for research purposes, but not appropriate for clinical usage, to use proxy reports to measure disability levels in patients with stroke. Furthermore, the two methods should not be used interchangeably to monitor patients because of the wide limits of agreement between patient and proxy reports on the self-administered Barthel Index and self-administered Frenchay Activities Index.

[Assistive technology devices for the elderly at home].

Using assistive technology (AT) to help the elderly and disabled overcome disabilities and attain their rehabilitation, learning, working and living potentials represents the mainstream trend in well-developed countries. According to data from Taiwan's Ministry of the Interior, Taiwan's senior citizen population exceeds two million. Proper application of AT can help achieve in Taiwan the goal of aging in place. Assistive technology devices can be divided into five categories, including barrier free environment (home modification), daily living aids, mobility aids, seating and positioning devices, and sensory aids. As of 2005, there were 16 senior care centers in Taiwan funded and administered by the Department of Health, all of which maintain interdisciplinary teams--comprising specialists in rehabilitation medicine, occupational therapy, physical therapy, speech therapy, nursing, education, social work and engineering--that provide service directly to persons with special needs and cooperate with manufactures to develop new assistive devices. Services provided by these centers include evaluation, design, customization, adaptation, maintenance, repair, therapy, training and technical assistance related to AT devices. The government has a legal responsibility to provide senior citizens in need with appropriate AT services. Service users, their families and professionals may contact centers directly for consultation.

Effects of display medium and luminance contrast on concept formation and EEG response.

Reading from a visual display terminal (VDT) has increased enormously with widespread computer use. Whether such reading affects higher cognitive processes requires study so the effect of display medium (LCD screen vs paper) and luminance contrast (1:3, 1:7, 1:11) on concept-formation performance and EEG responses was investigated. 96 men and 24 women participated in two concept-formation tasks (rule learning vs attribute and rule learning). Concept-formation performance and EEG responses were similar for stimuli displayed on paper or LCD screen. The concern that the screen may be detrimental to conception-formation performance was not confirmed; however, luminance contrast significantly affected time to complete a concept-formation task and EEG response. The middle contrast (1:7) had the smallest mean EEG power, so this contrast might be appropriate for cognitive performance. Participants' performance was significantly faster and EEG power lower for the rule-learning task than for an attribute and rule-learning task.