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PubMed2002

Strategic navigation of two-dimensional alley mazes: comparing capuchin monkeys and chimpanzees.

Planning is an important component of cognition that contributes, for example, to efficient movement through space. In the current study we presented novel two-dimensional alley mazes to four chimpanzees and three capuchin monkeys to identify the nature and efficiency of planning in relation to varying task parameters. All the subjects solved more mazes without error than expected by chance, providing compelling evidence that both species planned their choices in some manner. The probability of making a correct choice on mazes designed to be more demanding and presented later in the testing series was higher than on earlier, simpler mazes (chimpanzees), or unchanged (capuchin monkeys), suggesting microdevelopment of strategic choice. Structural properties of the mazes affected both species' choices. Capuchin monkeys were less likely than chimpanzees to take a correct path that initially led away from the goal but that eventually led to the goal. Chimpanzees were more likely to make an error by passing a correct path than by turning onto a wrong path. Chimpanzees and one capuchin made more errors on choices farther in sequence from the goal. Each species corrected errors before running into the end of an alley in approximately 40% of cases. Together, these findings suggest nascent planning abilities in each species, and the prospect for significant development of strategic planning capabilities on tasks presenting multiple simultaneous or sequential spatial relations. The computerized maze paradigm appears well suited to investigate movement planning and spatial perception in human and nonhuman primates alike.

Animals↗
PubMed2006

Performance of the five-point grip pen in three screen-based tasks.

This study examined how user handbreadth, brace shape and brace size of a Five-Point Grip Pen affects the performance of three screen tasks: writing, point-and-clicking, and drawing. Nine braces with three shapes (ball, ball-and-brick, and natural) and three brace sizes (large, medium and small) were tested for performance time, number of errors and subjective preference by 32 subjects (16 males and 16 females). The subjects were selected to fit four groups of handbreadth (below 25%ile, 25%ile-50%ile, 50-75%ile and above 75%ile) of Taiwanese laborers. In general, the subjective ranking results were consistent with the results of performance measures in all three tasks. All measures were affected by brace shape and brace size but differently for each task. The study results can be summarized as follows: (1) The natural shape was the best brace for all tasks. (2) For the writing task, the small brace was best for all four handbreadth groups, the medium brace was adequate only for the handbreadth group of above 75%ile, and the large brace was worst for all groups. (3) For the drawing task, the large and medium braces were suitable for all handbreadth groups, while the small brace was not suitable for the handbreadth group of above 75%ile. (4) For point-and-clicking task, the large size was the best brace.

Adult↗
PubMed2006

Design and feasibility study of an integrated pointing device apparatus for individuals with spinal cord injury.

Despite the commercial availability of numerous computer-pointing devices, many severely disabled individuals still rely on customized equipment to operate computers. This study presents a novel Integrated Pointing Device Apparatus (IPDA) that integrates numerous commercial pointing devices. The novel IPDA, which complies with a standard USB 1.1 interface, is compatible with most tested computer-pointing devices and flexibly integrates commercial computer devices, tailoring them to suit individual needs. By using simple integrated circuit design and low-cost electronic components, this low-cost apparatus is easily maintained. The feasibility of the IPDA was evaluated by four subjects with high-level cervical (C4-5) spinal cord injury (SCI). Participants performed normal move-and-click and drag-and-drop tasks typically performed by computer pointing devices. Each participant not able to use a traditional computer mouse or trackball were able to operate a computer adequately with the IPDA and three including one operating a trackball with his chin, operated computers easily and smoothly. This feasibility study showed that the IPDA effectively integrates commercial pointing devices, thereby providing the possibility for some people with SCI to obtain computer operability. This study demonstrated the advantages of flexibility, low cost, and acceptable efficiency of the novel IPDA.

Adult↗
PubMed2006

Ubiquitous computing to support co-located clinical teams: using the semiotics of physical objects in system design.

OBJECTIVES: Co-located teams often use material objects to communicate messages in collaboration. Modern desktop computing systems with abstract graphical user interface (GUIs) fail to support this material dimension of inter-personal communication. The aim of this study is to investigate how tangible user interfaces can be used in computer systems to better support collaborative routines among co-located clinical teams. METHODS: The semiotics of physical objects used in team collaboration was analyzed from data collected during 1 month of observations at an emergency room. The resulting set of communication patterns was used as a framework when designing an experimental system. Following the principles of augmented reality, physical objects were mapped into a physical user interface with the goal of maintaining the symbolic value of those objects. RESULTS: NOSTOS is an experimental ubiquitous computing environment that takes advantage of interaction devices integrated into the traditional clinical environment, including digital pens, walk-up displays, and a digital desk. The design uses familiar workplace tools to function as user interfaces to the computer in order to exploit established cognitive and collaborative routines. CONCLUSION: Paper-based tangible user interfaces and digital desks are promising technologies for co-located clinical teams. A key issue that needs to be solved before employing such solutions in practice is associated with limited feedback from the passive paper interfaces.

Computer Peripherals↗
PubMed1994

[Computer-assisted, improved evaluation of Comberg images with three-dimensional graphic reconstruction].

BACKGROUND: Small metallic foreign bodies may easily be identified by conventional x-ray. The Comberg shell is a useful tool to discriminate between extra-respectively intraocular localization of the foreign body. However, poor results are common when evaluating the x-ray films. METHODS: We have improved evaluation of the radiographs by means of a program for a personal computer, regarding the following aspects: To avoid errors of measurement the relevant points of the radiograms are read by a digitizer-tableau. The different projection failure of the lateral respectively posteroanterior x-ray is calculated separately. For the calculation of the modell the true axial length of the eye is considered. CONCLUSION: A three dimensional image from varying points of view gives an instructive impression of the foreign body and its relation to structures of the eye. Handling of the presented computer program is easy. It standardizes analysis of the Comberg radiograms.

Computer Graphics↗
PubMed1995

A comparison of tactile, auditory, and visual feedback in a pointing task using a mouse-type device.

A mouse was modified to add tactile feedback via a solenoid-driven pin projecting through a hole in the left mouse button. An experiment is described using a target selection task under five different sensory feedback conditions ('normal', auditory, colour, tactile, and combined). No differences were found in overall response times, error rates, or bandwidths; however, significant differences were found in the final positioning times (from the cursor entering the target to selecting the target). For the latter, tactile feedback was the quickest, normal feedback was the slowest. An examination of the spatial distributions in responses showed a peaked, narrow distribution for the normal condition, and a flat, wide distribution for the tactile (and combined) conditions. It is argued that tactile feedback allows subjects to use a wider area of the target and to select targets more quickly once the cursor is inside the target. Design considerations for human-computer interfaces are discussed.

Attention↗
PubMed2006

An enhanced time-frequency-spatial approach for motor imagery classification.

Human motor imagery (MI) tasks evoke electroencephalogram (EEG) signal changes. The features of these changes appear as subject-specific temporal traces of EEG rhythmic components at specific channels located over the scalp. Accurate classification of MI tasks based upon EEG may lead to a noninvasive brain-computer interface (BCI) to decode and convey intention of human subjects. We have previously proposed two novel methods on time-frequency feature extraction, expression and classification for high-density EEG recordings (Wang and He 2004; Wang, Deng, and He, 2004). In the present study, we refined the above time-frequency-spatial approach and applied it to a one-dimensional "cursor control" BCI experiment with online feedback. Through offline analysis of the collected data, we evaluated the capability of the present refined method in comparison with the original time-frequency-spatial methods. The enhanced performance in terms of classification accuracy was found for the proposed approach, with a mean accuracy rate of 91.1% for two subjects studied.

Adult↗
PubMed2006

Optical density variations in CT films and their effect on image quality.

It was recently reported that optical density (OD) variations were observed in CT films printed with a laser camera, depending on the printing format and the frame position within the film. The purpose of the present study was to investigate if these variations are common to both laser and dry-film printers and if the different OD settings along with day-to-day and frame-to-frame variations may affect the image quality. Eight laser and five dry-film printers installed at 12 different CT facilities were tested. For each one, the SMPTE test pattern was printed on all frames of a film using the same printing format. The ODs of the 0%, 10%, 40% and 70% patches of the 11-step greyscale of the SMPTE patterns were measured with a densitometer in all frames, while all films were examined on a viewing box to assess subjectively the image quality by visual inspection of the test pattern. A wide range of OD settings and variations were recorded. Frame-to-frame variations in the same film of up to 0.19, 0.15 and 0.21 OD, were observed for contrast index (CI, the OD difference of patches 10% and 70%), speed index (SI, the OD of patch 40%) and maximum OD (OD(max), the OD of patch 0%), respectively. The variations were not always of the same magnitude, nor always followed the same pattern, even for printers of the same model. Considering all films and frames, the CI ranged from 1.26 to 1.74, the SI from 0.68 to 1.43 and the OD(max) from 2.5 to 3.11 OD, well beyond the proposed settings and tolerances of 1.55+/-0.15, 1.15+/-0.1 and 2.45+/-0.1 given in the literature for CI, SI and OD(max), respectively. Despite these large differences, the various problems that were identified in image quality from the visual inspection of the films could not be directly attributed to OD settings, as films with similar CI, SI and OD(max) presented quite different image quality levels. Therefore, for routine quality control, thorough visual inspection of the SMPTE test pattern provides all the necessary information about the imaging chain status.

Computer Peripherals↗
PubMed2002

Concordance between task and interface rotational and translational control improves ground vehicle performance.

Research in various areas of human-system interaction suggests the importance of examining the similarities and dissimilarities between tasks and the interfaces used to complete them. Specifically, the theory of cognitive fit suggests that human problem solvers will perform better when the data and data displays they use to complete a task match some characteristic of that task. An experiment was performed that extends the theory of cognitive fit to the realm of human performance on motor tasks. Participants completed several virtual vehicle control motor tasks that consisted of rotational and translational control components. The tasks were performed with user interfaces that either combined or separated rotational and translational control. The tasks were of two types: control of either rotation or translation changes but not both concurrently, or simultaneous control of combined rotation and translation changes. The results indicate that task performance was better when the characteristics of the interface matched the characteristics of the task. Actual or potential applications of this research include constructing ground vehicle interface controls that are designed specifically based on the characteristics of the task for which they are to be used, such as primarily driving fast and in a straight line (e.g., on a highway) versus primarily driving slowly with much turning (e.g., on a city street).

Adolescent↗
PubMed2005

Solution for nonuniformities and spatial noise in medical LCD displays by using pixel-based correction.

Liquid crystal displays (LCD) are rapidly replacing cathode ray tube displays (CRT) for medical imaging. LCD technology has improved significantly in the last few years and has important advantages over CRT. However, there are still some aspects of LCD that raise questions as to the usefulness of liquid crystal displays for very subtle clinical diagnosis such as mammography. One drawback of modern LCD displays is the existence of spatial noise expressed as measurable stationary differences in the behavior of individual pixels. This type of noise can be described as a random stationary image superposed on top of the medical image being displayed. It is obvious that this noise image can make subtle structures invisible or add nonexistent patterns to the medical image. In the first case, subtle abnormalities in the medical image could remain undetected, whereas in the second case, it could result into a false positive. This paper describes a method to characterize the spatial noise present in high-resolution medical displays and a technique to solve the problem. A medical display with built-in compensation for the spatial noise at pixel level was developed and improved image quality is demonstrated.

Algorithms↗
PubMed2006

Enhancement of operational efficiencies for people with high cervical spinal cord injuries using a flexible integrated pointing device apparatus.

OBJECTIVE: To investigate the effectiveness of a universal integrated pointing device apparatus (IPDA), which can integrate numerous commercial pointing devices and can be controlled by various combinations of available movements, for people with cervical spinal cord injury (SCI) who cannot operate standard computer pointing devices. DESIGN: An exploratory quasi-experimental design. All subjects were required to perform specific mouse-operating (continuous-clicking, target-acquisition, drag-and-drop) tasks. People with SCI received clinical assessments and were classified into 2 groups based on pointing device used: group A, who used standard mouse devices, and group B (IPDA combinations), who were unable to use standard mouse devices. The measures of group A and group B were compared. SETTING: Rehabilitation science center of a medical institution. PARTICIPANTS: Thirty-seven people with high cervical SCI and 30 able-bodied subjects. INTERVENTION: The IPDA. MAIN OUTCOME MEASURES: The efficiency of the people with SCI in each mouse-operation task was expressed as a percentage of that for able-bodied subjects (%NL). RESULTS: Group B displayed similar operational efficiency in performing the drag-and-drop tasks ( approximately 30% NL) to group A, although they exhibited worse efficiency than group A in performing the other tasks (P<.05). Operational efficiencies of all tasks had negative relationships with age by using linear regression analysis (adjusted r(2)>.36, P<.001). The use of pointing devices was associated with American Spinal Injury Association Impairment Scale (P<.001), completeness (P<.001), and muscle strength (P<.01), particularly finger flexor muscle strength, but not with neurologic level or muscle tone. CONCLUSIONS: The IPDA could help most people with high cervical SCI who could not use commercial mouse devices to achieve acceptable operational efficiencies. Pointing devices were assigned based on the underlying SCI severity and muscle strength, particularly finger flexor muscle strength.

Activities of Daily Living↗
PubMed2002

System for assisted mobility using eye movements based on electrooculography.

This paper describes an eye-control method based on electrooculography (EOG) to develop a system for assisted mobility. One of its most important features is its modularity, making it adaptable to the particular needs of each user according to the type and degree of handicap involved. An eye model based on electroculographic signal is proposed and its validity is studied. Several human-machine interfaces (HMI) based on EOG are commented, focusing our study on guiding and controlling a wheelchair for disabled people, where the control is actually effected by eye movements within the socket. Different techniques and guidance strategies are then shown with comments on the advantages and disadvantages of each one. The system consists of a standard electric wheelchair with an on-board computer, sensors and a graphic user interface run by the computer. On the other hand, this eye-control method can be applied to handle graphical interfaces, where the eye is used as a mouse computer. Results obtained show that this control technique could be useful in multiple applications, such as mobility and communication aid for handicapped persons.

Activities of Daily Living↗
PubMed2003

"Virtual keyboard" controlled by spontaneous EEG activity.

A "virtual keyboard" (VK) is a letter spelling device operated for example by spontaneous electroencephalogram (EEG), whereby the EEG is modulated by mental hand and leg motor imagery. We report on three able-bodied subjects, operating the VK. The ability in the use of the VK varies between 0.85 and 0.5 letters/min in error-free writing.

Algorithms↗
PubMed2005

Implementation of an intuitive writing interface and a laparoscopic robot for gynaecological laser assisted surgery.

The research reported in this paper aims at applying the human handwriting skill to improve and facilitate the control of laser-assisted laparoscopic surgery operations performed by gynaecological surgeons. For the purpose, a laparoscopic robot was interfaced with a digitizing tablet. This interface, further called the intuitive writing interface (IWI), directly converts the hand trajectory, handwritten on the tablet, into an input signal to the robot. It replaces the traditional complex manipulations performed by the surgeon during manual laparoscopic surgery by natural handwriting. It provides the surgeon with an intuitive 'what-you-draw-is-what-you-cut' control facility by employing his/her familiar handwriting skills to control the laser ablation process accurately. The system was successfully built and tested in vitro. Performance tests on the robot resulted in tracking errors in the order of 1 mm in the target plane at an ablation speed of 20 mm/s. The high accuracy of the system was successfully demonstrated by cutting characters 4 mm high on an apple. These results indicate that laser ablation performance is upgraded by the IWI to the accuracy levels of human handwriting, which is much higher than can be obtained with manual laser laparoscopy. Safety features include the use of pen contact with the tablet as a safety switch, and back drivability in the robot joints for easy manual positioning and evacuation in case of emergency.

Computer Peripherals↗
PubMed1994

[Telemetric transmission system for in vivo measurement of the stress load of an internal spinal fixator].

For stabilizing fractures of the spine, a number of implantable devices are available. However, not much is known about the loads acting on these devices. In order to measure the forces and moments within the implant, the Dick internal fixation device was modified and fitted out with a hermetically sealed inductively powered telemetry unit. An integrated 8-channel telemetry chip was specially developed to measure the signals of six strain gauge sensors, the temperature of the implant and the supply voltage. Since the internal fixation devices are always implanted in pairs, two telemetry units are operated at the same time. This article details the function of the implanted electronic circuit and the external system components.

Adult↗
PubMed1997

EEG-based communication: evaluation of alternative signal prediction methods.

Individuals can learn to control the amplitude of EEG activity in specific frequency bands over sensorimotor cortex and use it to move a cursor to a target on a computer screen. For one-dimensional (i.e., vertical) cursor movement, a linear equation translates the EEG activity into cursor movement. To translate an individual's EEG control into cursor control as effectively as possible, the intercept in this equation, which determines whether upward or downward movement occurs, should be set so that top and bottom targets are equally accessible. The present study compares alternative methods for using an individual's previous performance to select the intercept for subsequent trials. In offline analyses, five different intercept selection methods were applied to EEG data collected while trained subjects were moving the cursor to targets at the top or bottom edge of the screen. In the first two methods-moving average, and weighted sum-a single intercept was selected for the entire 1-2 sec period of each trial. In the other three methods-blocked moving average, blocked weighted sum, and blocked recursive sum (a variation of the weighted sum)-an intercept was selected for each 200-ms segment of the trial. The results from these methods were compared in regard to their balance between upward and downward movements and their consistency of performance across trials. For all subjects combined, the five methods performed similarly. However, performance across subjects was more consistent for the moving average, blocked moving average, and blocked recursive sum methods than for the weighted sum and blocked weighted sum methods. Due to its consistent performance and its computational simplicity, the moving average method, using the five most recent pairs of top and bottom trials, appears to be the method of choice.

Adult↗