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At least 325 records · Page 18Linked to original sources
PubMed2001

Position-matching in the upper limb: professional ballet dancers perform with outstanding accuracy.

OBJECTIVES: To investigate the accuracy in position-matching in the upper limb in two groups of subjects who were physically fit and movement aware. DESIGN: A mixed-group design was used. Objective measurement of the accuracy in position-matching at the shoulder and elbow in both dominant and nondominant arms consisted of photographic record of the position-matching test, with goniometric measurement. SETTINGS: Physiotherapy department at the Birmingham Royal Ballet and School of Health Science, University of Birmingham. SUBJECTS: Two subject groups: physiotherapy students (n = 10), professional ballet dancers (n = 10). RESULTS: A mixed design analysis of variance found significant differences between the accuracy in position-matching at both the shoulder and elbow joints in the two groups (p < 0.05), with the ballet dancers having greater accuracy then the physiotherapy students. A significant difference in the joint positions tested were demonstrated (p < 0.05) with the positions of abduction at the shoulder and extension of the elbow showing greatest accuracy in matching. There was no significant difference found between the dominant and nondominant upper limb in position-matching. CONCLUSION: Professional ballet dancers demonstrated greater accuracy in position-matching the upper limb, implying that mass and continuing practice can improve a motor sensory skill.

Adult↗
PubMed1999

Accuracy of four clinical diagnostic criteria for the diagnosis of neurodegenerative dementias.

OBJECTIVE: To evaluate the inter-rater reliability and validity of clinical diagnostic criteria for neurodegenerative dementias. BACKGROUND: Inter-rater accuracy of the diagnosis of AD has been explored, but there are few accuracy studies for progressive supranuclear palsy (PSP) and frontotemporal lobe dementia (FTD). Furthermore, there have been no simultaneous accuracy studies in a mixed sample of patients with cortical and subcortical neurodegenerative processes. METHODS: Four experienced clinicians reviewed first-visit clinical data abstracted from the records of 40 pathologically diagnosed demented subjects. They were asked to apply the NINCDS-ADRDA criteria for AD, the NINDS-SPSP clinical criteria for PSP, the Lund and Manchester criteria for FTD, and the Consensus Guidelines for the Clinical Diagnosis of Dementia with Lewy Bodies (DLB). RESULTS: The generalized K for AD was 0.73, for PSP 0.82, for FTD 0.75, and for DLB 0.37. The K pool test showed a statistically significant difference between DLB and the other disease processes, and no differences were observed among AD, FTD, and PSP. The mean sensitivity for AD was 95%, for PSP 75%, for FTD 97%, and for DLB 34%. The mean specificity for AD was 79%, for PSP 98.5%, for FTD 97%, and for DLB 94%. CONCLUSIONS: We found improved inter-rater reliability for the diagnosis of AD among clinicians compared with earlier studies. Similarly, there was a near-perfect and substantial inter-rater agreement for the diagnosis of PSP and FTD. The sensitivity for the diagnosis of AD was high, although clinicians overdiagnosed this condition. However, there was a reasonable accuracy for the diagnosis of PSP and FTD. Heterogeneity of the clinical presentation of DLB significantly affected inter-rater agreement and accuracy. The use of multiple diagnostic criteria for cortical and subcortical dementia increases the level of clinical diagnostic accuracy.

Aged↗
PubMed1994

The application accuracy of stereotactic frames.

The purpose of incorporating stereotactic methodology into neurosurgical operations is to achieve a consistently high degree of accuracy in localizing intracranial targets. Therefore, the limits of resolution for the operation are a function of the accuracy of the particular stereotactic frame system. The total clinically relevant error (application accuracy) comprises errors associated with each procedural step, including imaging, target selection, vector calculations, and the mechanical errors of stereotactic frames. To evaluate these parameters, a systematic error analysis was carried out with four commonly used stereotactic devices: the Brown-Roberts-Wells, the Cosman-Roberts-Wells, the Kelly-Goerss COMPASS (modified Todd-Wells), and the Leksell frames. Over 21,500 independent accuracy test measurements were made with 11,000 computed tomograms. The results suggest a potentially significant degree of error in the application accuracy of all stereotactic instruments, which is accentuated by but not entirely due to imaging-associated errors. Clinically encountered levels of weightbearing by stereotactic frames may have a pronounced effect on their mechanical accuracy. Both the reapplication of aiming arc assemblies and the use of phantom base units introduce independent sources of mechanical inaccuracy into stereotactic procedures. The scope of individual error values and their determining factors must be considered with every clinical use of stereotactic frame systems.

Brain Diseases↗
PubMed1994

Accuracy of end-tidal and transcutaneous PCO2 monitoring during sleep.

STUDY OBJECTIVE: Although it is intuitively desirable, the measurement of arterial carbon dioxide tension (PaCO2) during diagnostic polysomnography and nocturnal trials of positive pressure therapy is invasive and potentially expensive. The accuracy of end-tidal carbon dioxide tension (PETCO2) and transcutaneous carbon dioxide (tcPCO2) monitoring in these contexts has not been systematically evaluated. This investigation was undertaken to evaluate the accuracy of PETCO2 and tcPCO2 in patients undergoing polysomnography. METHODS AND PROCEDURES: Values of PETCO2 were compared with PaCO2 in 19 patients spontaneously breathing room air (condition 1), in 13 patients receiving supplemental oxygen via nasal cannula (condition 2), and in 22 patients receiving nocturnal positive pressure ventilatory assistance (all but one with continuous positive airway pressure or bilevel positive airway pressure) (condition 3). The accuracy of tcPCO2 monitoring during sleep was also examined by comparing tcPCO2 values with simultaneously recorded PaCO2 values obtained during sleep in patients undergoing nocturnal polysomnography. Data were collected using three commercially available brands of tcPCO2 monitors (capnograph R, n = 17 patients; capnograph S, n = 17; and capnograph N, n = 15). RESULTS: Accuracy of PETCO2--There was significant scatter in the PaCO2 vs PETCO2 relationship such that only 23 percent of the variability in PaCO2 was explained by variation of PETCO2 during condition 1 and only 15 percent and 20 percent of the variability in PaCO2 was explained by variation of PETCO2 during conditions 2 and 3, respectively. 21.3 percent of patients had average PETCO2 values in error by > 10 mm Hg during condition 1, while during conditions 2 and 3, 46.2 and 63.7 percent of patients had average values in error by > 10 mm Hg, respectively. Accuracy of tcPCO2--While capnographs S and N generally overestimated PaCO2 with a wide scatter, capnograph R tended to have offsetting overestimations and underestimations of PaCO2 with a wide scatter. With each capnograph, a relatively small portion of the variability of the PaCO2 was explained by variability of the tcPCO2 (r2 = 0.2, 0.45 and 0.64 for capnographs S, N, and R, respectively). Across the three capnographs, 43.1 to 66.7 percent of measurements were in error by > 10 mm Hg, and 5 to 20 percent of measurements reflected errors > 20 mm Hg. There was no consistent relationship between the tcPCO2 error and the level of PaCO2, nor was the tcPCO2 error consistent in individual patients. There was no relationship between tcPCO2 accuracy and body mass index. CONCLUSION: Neither PETCO2, measured within a face mask, nor tcPCO2 is a consistently accurate reflection of PaCO2. This limits the utility of these variables in monitoring patients during diagnostic and therapeutic sleep studies, and in particular, during trials of nocturnal ventilatory assistance where adequate levels of support are to be established and unacceptable hyperventilation and respiratory alkalosis must be recognized.

Adult↗
PubMed1995

Pulmonary hypertension decreases the predictive accuracy of echocardiographic clues for cardiac tamponade.

A number of echocardiographic clues of pericardial tamponade have been described, but their accuracy in patients with pulmonary hypertension has not been well elucidated. Four echocardiographic clues of pericardial tamponade, namely, right atrial collapse (RAC), right ventricular diastolic collapse (RVDC), marked (> 40%) respiratory variation in transmitral Doppler flow velocity ("flow velocity paradoxus [FVP]"), and inferior vena cava plethora (IVCP) were prospectively evaluated in 32 patients with large pericardial effusions. Of 12 patients with pulmonary hypertension, 6 had invasively determined evidence of tamponade and 6 did not; of 20 patients without pulmonary hypertension, 11 had tamponade and 9 did not. These echocardiographic clues were evaluated in a blinded fashion. Predictive accuracies for RAC, RVDC, FVP, and IVCP were 75%, 80%, 90%, and 95%, respectively, for the patients without pulmonary hypertension and 67%, 58%, 58%, and 83%, respectively, for the patients with pulmonary hypertension. Although all predictive accuracies were lower in patients with pulmonary hypertension, statistically significant decreased predictive accuracy was found only with FVP (p < 0.05). Interestingly, IVCP had the best predictive accuracy among patients with pulmonary hypertension. Our findings suggest that despite somewhat decreased accuracy in patients with pulmonary hypertension, traditional echocardiographic clues for pericardial tamponade may be useful.

Aged↗
PubMed2003

Accuracy of discrimination, rate of responding, and resistance to change.

Pigeons were trained on multiple schedules in which responding on a center key produced matching-to-sample trials according to the same variable-interval 30-s schedules in both components. Matching trials consisted of a vertical or tilted line sample on the center key followed by vertical and tilted comparisons on the side keys. Correct responses to comparison stimuli were reinforced with probability .80 in the rich component and .20 in the lean component. Baseline response rates and matching accuracies generally were higher in the rich component, consistent with previous research. When performance was disrupted by prefeeding, response-independent food during intercomponent intervals, intrusion of a delay between sample and comparison stimuli, or extinction, both response rates and matching accuracies generally decreased. Proportions of baseline response rate were greater in the rich component for all disrupters except delay, which had relatively small and inconsistent effects on response rate. By contrast, delay had large and consistent effects on matching accuracy, and proportions of baseline matching accuracy were greater in the rich component for all four disrupters. The dissociation of response rate and accuracy with delay reflects the localized impact of delay on matching performance. The similarity of the data for response rate and accuracy with prefeeding, response-independent food, and extinction shows that matching performance, like response rate, is more resistant to change in a rich than in a lean component. This result extends resistance to change analyses from the frequency of response emission to the degree of stimulus control, and suggests that the strength of discriminating, like the strength of responding, is positively related to rate of reinforcement.

Animals↗
PubMed1992

The accuracy of Medicare's hospital claims data: progress has been made, but problems remain.

BACKGROUND: Health care databases provide a widely used source of data for health care research, but their accuracy remains uncertain. We analyzed data from the 1985 National DRG Validation Study, which carefully reabstracted and reassigned ICD-9-CM diagnosis and procedure codes from a national sample of 7050 medical records, to determine whether coding accuracy had improved since the Institute of Medicine studies of the 1970s and to assess the current coding accuracy of specific diagnoses and procedures. METHODS: We defined agreement as the proportion of all reabstracted records that had the same principal diagnosis or procedure coded on both the original (hospital) record and on the reabstracted record. We also evaluated coding accuracy in 1985 using the concepts of diagnostic test evaluation. RESULTS: Overall, the percentage of agreement between the principal diagnosis on the reabstracted record and the original hospital record, when analyzed at the third digit, improved from 73.2% in 1977 to 78.2% in 1985. However, analysis of the 1985 data demonstrated that the accuracy of diagnosis and procedure coding varies substantially across conditions. CONCLUSIONS: Although some diagnoses and all major surgical procedures that we examined were accurately coded, the variability in the accuracy of diagnosis coding poses a problem that must be overcome if claims-based research is to achieve its full potential.

Abstracting and Indexing↗
PubMed2003

Accuracy of measurement of polyethylene wear with use of radiographs of total hip replacements.

BACKGROUND: Although a number of methods are used to estimate polyethylene liner wear from radiographs of total hip replacements, there is no consensus with regard to the accuracy of these methods. The purpose of this study was to compare the accuracy of several such measurement methods with use of both laboratory radiographs and routine clinical radiographs. METHODS: A phantom apparatus was designed to simulate random values of three-dimensional wear, with varying degrees of cup abduction and anteversion, and to obtain anteroposterior and cross-table lateral radiographs with each value. Wear was measured with use of the Charnley duoradiographic method, the Livermore method, and the method described by Dorr and Wan, as well as with use of PolyWare and Hip32 software packages, both with and without three-dimensional measurements. Clinical wear was measured from conventional radiographs made prior to revision surgery in fourteen patients and was compared with wear measured directly from the retrieved liners with use of a coordinate measuring machine. RESULTS: With laboratory radiographs, median errors were 0.1 mm with the Livermore method and both computerized methods, 0.23 mm with the Charnley method, and 1.7 mm with the method of Dorr and Wan. Maximum errors were between 0.6 mm (Livermore) and 4.3 mm (Dorr and Wan). In contrast, with use of clinical radiographs, median errors ranged between 0.2 mm (Hip32) and 0.6 mm (Dorr and Wan). Maximum errors ranged between 1.8 mm (Dorr and Wan) and 2.5 mm (Livermore). CONCLUSIONS: With laboratory radiographs, computerized methods of polyethylene wear measurement offered distinctly greater accuracy than did manual methods; however, with clinical radiographs, they offered only slightly better accuracy. Although the increased accuracy of computerized methods may be necessary in research settings, manual methods provided sufficient accuracy for routine clinical assessment of wear.

Arthroplasty, Replacement, Hip↗
PubMed1992

Percutaneous needle biopsy of musculoskeletal lesions. 1. Effective accuracy and diagnostic utility.

The utility of a diagnostic test depends not only on its accuracy but also on how its results affect clinical management. We reviewed the results of 102 percutaneous needle biopsies to determine the accuracy, effective accuracy, and diagnostic utility of the procedure. We found percutaneous needle biopsy was similarly accurate in identifying suspected metastatic lesions (82%, n = 44), suspected musculoskeletal infections (90%, n = 29), and suspected primary musculoskeletal tumors (83%, n = 29). Effective accuracy, or accuracy discounted for results with limited clinical utility, was highest in identifying suspected metastatic deposits (77%), slightly lower in suspected infections (72%), and lowest in suspected primary tumors (59%). Diagnostic utility (the probability-weighted sum of the utility values of all possible outcomes of a diagnostic test) for identifying metastatic deposits and infections exceeded that for suspected primary tumors. Percutaneous needle biopsy in patients with suspected primary tumors must be performed with the knowledge that, even though technically accurate, such biopsies may be of limited clinical value. Percutaneous needle biopsy of suspected metastatic lesions and suspected infections, on the other hand, offers high accuracy and high diagnostic utility.

Adolescent↗
PubMed2005

Dynamic MRI of bladder cancer: evaluation of staging accuracy.

OBJECTIVE: The purpose of this study was to evaluate the accuracy of gadoliniumenhanced MRI in staging bladder cancer in a series of patients with surgically proven bladder cancer. MATERIALS AND METHODS: Seventy-one patients with biopsy-proven bladder cancer underwent MRI on a 1.5-T scanner with a phased-array pelvic coil. Conventional T1-weighted spin-echo, T2-weighted spin-echo, and unenhanced and enhanced (0.1 mmol/kg gadolinium) fast spoiled gradient-echo images with fat suppression were obtained. Two blinded reviewers evaluated the MR images and assigned a stage that was compared with the pathologic stage (n = 67) or with clinical follow-up for at least 2 years after MRI (n = 4). RESULTS: Agreement among the reviewers was good in assigning a radiologic stage for bladder cancer (kappa = 0.80). On a stage-by-stage basis, MRI accuracy was 62%, and overstaging was the most common error (32%). Staging accuracy improved to 85% and 82% in differentiating superficial from invasive tumors and organ-confined from non-organ-confined tumors, respectively. The time interval between MRI and transurethral resection (</= 60 days and >/=61 days) was not a statistically significant factor in differentiating superficial from invasive and organ-confined from non-organ-confined tumors (p > 0.05). MRI accuracy in staging transitional cell carcinoma was not significantly different from that obtained in staging non-transitional cell carcinoma (p > 0.05). CONCLUSION: MRI shows good reproducibility between reviewers for staging bladder cancer. Although overall staging accuracy was only moderate, the accuracy for differentiating superficial versus invasive disease and organ-confined versus non-organ-confined disease was high.

Adult↗
PubMedDate not supplied

Evaluating clinical accuracy of systems for self-monitoring of blood glucose.

Although the scientific literature contains numerous reports of the statistical accuracy of systems for self-monitoring of blood glucose (SMBG), most of these studies determine accuracy in ways that may not be clinically useful. We have developed an error grid analysis (EGA), which describes the clinical accuracy of SMBG systems over the entire range of blood glucose values, taking into account 1) the absolute value of the system-generated glucose value, 2) the absolute value of the reference blood glucose value, 3) the relative difference between these two values, and 4) the clinical significance of this difference. The EGA of accuracy of five different reflectance meters (Eyetone, Dextrometer, Glucometer I, Glucometer II, Memory Glucometer II), a visually interpretable glucose reagent strip (Glucostix), and filter-paper spot glucose determinations is presented. In addition, reanalyses of a laboratory comparison of three reflectance meters (Accucheck II, Glucometer II, Glucoscan 9000) and of two previously published studies comparing the accuracy of five different reflectance meters with EGA is described. EGA provides the practitioner and the researcher with a clinically meaningful method for evaluating the accuracy of blood glucose values generated with various monitoring systems and for analyzing the clinical implications of previously published data.

Blood Glucose↗
PubMed2004

Evaluating the accuracy of continuous glucose-monitoring sensors: continuous glucose-error grid analysis illustrated by TheraSense Freestyle Navigator data.

OBJECTIVE: The objective of this study was to introduce continuous glucose-error grid analysis (CG-EGA) as a method of evaluating the accuracy of continuous glucose-monitoring sensors in terms of both accurate blood glucose (BG) values and accurate direction and rate of BG fluctuations and to illustrate the application of CG-EGA with data from the TheraSense Freestyle Navigator. RESEARCH DESIGN AND METHODS: We approach the design of CG-EGA from the understanding that continuous glucose sensors (CGSs) allow the observation of BG fluctuations as a process in time. We account for specifics of process characterization (location, speed, and direction) and for biological limitations of the observed processes (time lags associated with interstitial sensors). CG-EGA includes two interacting components: 1) point-error grid analysis (P-EGA) evaluates the sensor's accuracy in terms of correct presentation of BG values and 2) rate-error grid analysis (R-EGA) assesses the sensor's ability to capture the direction and rate of BG fluctuations. RESULTS: CG-EGA revealed that the accuracy of the Navigator, measured as a percentage of accurate readings plus benign errors, was significantly different at hypoglycemia (73.5%), euglycemia (99%), and hyperglycemia (95.4%). Failure to detect hypoglycemia was the most common error. The point accuracy of the Navigator was relatively stable over a wide range of BG rates of change, and its rate accuracy decreased significantly at high BG levels. CONCLUSIONS: Traditional self-monitoring of BG device evaluation methods fail to capture the important temporal characteristics of the continuous glucose-monitoring process. CG-EGA addresses this problem, thus providing a comprehensive assessment of sensor accuracy that appears to be a useful adjunct to other CGS performance measures.

Adult↗
PubMed2005

Evaluating the clinical accuracy of two continuous glucose sensors using continuous glucose-error grid analysis.

OBJECTIVE: To compare the clinical accuracy of two different continuous glucose sensors (CGS) during euglycemia and hypoglycemia using continuous glucose-error grid analysis (CG-EGA). RESEARCH DESIGN AND METHODS: FreeStyle Navigator (Abbott Laboratories, Alameda, CA) and MiniMed CGMS (Medtronic, Northridge, CA) CGSs were applied to the abdomens of 16 type 1 diabetic subjects (age 42 +/- 3 years) 12 h before the initiation of the study. Each system was calibrated according to the manufacturer's recommendations. Each subject underwent a hyperinsulinemic-euglycemic clamp (blood glucose goal 110 mg/dl) for 70-210 min followed by a 1-mg.dl(-1).min(-1) controlled reduction in blood glucose toward a nadir of 40 mg/dl. Arterialized blood glucose was determined every 5 min using a Beckman Glucose Analyzer (Fullerton, CA). CGS glucose recordings were matched to the reference blood glucose with 30-s precision, and rates of glucose change were calculated for 5-min intervals. CG-EGA was used to quantify the clinical accuracy of both systems by estimating combined point and rate accuracy of each system in the euglycemic (70-180 mg/dl) and hypoglycemic (<70 mg/dl) ranges. RESULTS: A total of 1,104 data pairs were recorded in the euglycemic range and 250 data pairs in the hypoglycemic range. Overall correlation between CGS and reference glucose was similar for both systems (Navigator, r = 0.84; CGMS, r = 0.79, NS). During euglycemia, both CGS systems had similar clinical accuracy (Navigator zones A + B, 88.8%; CGMS zones A + B, 89.3%, NS). However, during hypoglycemia, the Navigator was significantly more clinically accurate than the CGMS (zones A + B = 82.4 vs. 61.6%, Navigator and CGMS, respectively, P < 0.0005). CONCLUSIONS: CG-EGA is a helpful tool for evaluating and comparing the clinical accuracy of CGS systems in different blood glucose ranges. CG-EGA provides accuracy details beyond other methods of evaluation, including correlational analysis and the original EGA.

Adult↗
PubMed2003

Influence of instruction on velocity and accuracy of overarm throwing.

This study investigated the influence of instruction on the ball velocity and accuracy of a goal-directed overarm throw. 9 experienced Norwegian male team handball players executed a throwing task randomly seven times under 5 different instructions varying from emphasizing speed to accuracy. When instructions increasingly emphasized accuracy, velocity decreased. However, accuracy did not improve when subjects were instructed to focus on it. A possible explanation for this finding could lie in the specific subject group. The subjects were highly experienced team handball players with an average of 12 years in the sport. Thus, the accuracy they demonstrated at high velocity might actually be already extremely high and difficult to improve upon when reducing throwing velocity. Further, the velocity of throwing when instruction emphasized accuracy was approximately 85% of the maximal velocity, indicating that experienced team handball players are trained to throw accurately at relatively high velocity.

Adult↗
PubMed1993

Speed and accuracy of aimed hand movements in left-handed human subjects: sex-related differences in motor control.

Speed and accuracy in hand speed in relation to sex-related differences were studied in left-handed normal subjects. Hand skill was assessed by a peg moving task. Hand speed increased linearly with successive trials (motor learning). Left-hand speed exhibited a higher learning capacity than right-hand speed. Right-hand speed and right-hand learning were equivalent in males and females. Left-hand speed was higher in females than males; left-hand learning was equivalent in males and females. Left minus right (L-R) hand speed decreased linearly with right-hand speed; left-hand speed did not influence L-R hand speed. Learning curves were constructed for each subject. Standard error of a learning curve was considered as accuracy of hand skill. In females, accuracy of hand movement decreased as hand speed increased. In males, only accuracy of right-hand speed decreased as right-hand speed increased; left-hand accuracy did not depend on left-hand speed. It was concluded that right brain controlling left hand in left-handers has a higher capacity than left brain for motor learning; L-R hand speed was largely determined by left brain; accuracy in hand skill depends on both brains in females, and on only left brain in males; the female brain is more bilaterally organized than male brain in fine motor control.

Adult↗
PubMed2006

In vivo accuracy of image guidance performed using optical tracking and optimized registration.

OBJECT: Image guidance systems involving the use of frameless referencing of surgical space to compile volumetric imaging data sets recently have come into widespread use. Few studies have addressed the true intraoperative surgical accuracy (that is, the application accuracy) of these systems except in a subjective manner. Calculated accuracies given by the systems do not necessarily reflect true intraoperative accuracy. METHODS: To objectively assess the stereotactic accuracy of a frameless image guidance system using optical spatial referencing, the author analyzed postoperative magnetic resonance (MR) images after placement of depth electrodes for the investigation of epilepsy. Preoperative planning for the treatment of seven patients included implanting skull fiducial screws and obtaining computed tomography/MR fusion images by using ImMerge image fusion software on the StealthStation (Medtronic, Inc.). A total of 42 electrodes were placed. Postoperative volumetric MR images were fused with preoperative study images. The difference between the planned electrode trajectories and targets and the visualized electrodes was measured in stereotactic space. CONCLUSIONS: The mean distance between the distal electrode contact and the distal end of the planned trajectory for the 42 targets was 3 +/- 1.5 mm. The most common error was in depth. The author's technique did not involve rigid skull fixation of electrodes because they were subsequently tunneled subcutaneously and later removed at the bedside of the patient. Errors in depth were known to be due to traction at the time of tunneling and not due to stereotactic factors. Correcting for depth along the electrode trajectory, the mean accuracy was found to be 2.4 +/- 1 mm.

Electrodes, Implanted↗
PubMed2003

A simple and sensitive method to measure timing accuracy.

Timing accuracy in presenting experimental stimuli (visual information on a PC or on a TV) and responding (keyboard presses and mouse signals) is of importance in several experimental paradigms. In this article, a simple system for measuring timing accuracy is described. The system uses two PCs (at least Pentium II, 200 MHz), a photocell, and an amplifier. No additional boards and timing hardware are needed. The first PC, a SlavePC, monitors the keyboard presses or mouse signals from the PC under test and uses a photocell that is placed in front of the screen to detect the appearance of visual stimuli on the display. The software consists of a small program running on the SlavePC. The SlavePC is connected through a serial line with a second PC. This MasterPC controls the SlavePC through an ActiveX control, which is used in a Visual Basic program. The accuracy of our system was investigated by using a similar setup of a SlavePC and a MasterPC to generate pulses and by using a pulse generator card. These tests revealed that our system has a 0.01-msec accuracy. As an illustration, the reaction time accuracy of INQUISIT for a few applications was tested using our system. It was found that in those applications that we investigated, INQUISIT measures reaction times from keyboard presses with millisecond accuracy.

Humans↗
PubMed1991

Partial information or facilitation? Different interpretations of results from speed-accuracy decomposition.

The speed-accuracy decomposition technique was developed by Meyer, Irwin, Osman, and Kounios (1988) to examine the time course of information processing. The technique allows for the estimation of the accuracy of guesses that are induced by the presentation of a response signal on a proportion of trials. Estimated guessing accuracy has been found to be above chance and to increase as time of guessing increases, suggesting that guesses are based on partial information that has accumulated prior to a response decision (sophisticated guesses). In this paper, a different interpretation of these data is presented. Results suggest that response signals may enhance the speed of regular processes, thereby violating the temporal-independence assumption that underlies the decomposition technique. As shown by Monte Carlo simulations, such facilitating effects of response signals can explain the results from the decomposition technique at least in part and possibly in full, even when guesses are actually at chance accuracy (pure guesses). The pure-guess model was supported by the results from an experiment designed to test between the alternative interpretations. These results point to the need for great caution in the attempt to infer the time course of information processing from guessing accuracies as estimated by the speed-accuracy decomposition technique.

Adolescent↗