A low-cost system for measuring and analyzing human movement in three dimensions

This paper describes a system for measuring the three-dimensional movement of a point on the human body. The core components of the system are an ultrasonic computer mouse (The OWL), an IBM-compatible personal computer, and a suite of recording and analysis software written in National Instruments’ LabVIEW instrumentation programming language. The cost of these components is sufficiently low that we have been able to create a system for measuring human kinematics that is within the reach of a typical budget for student practical classes.     

Psychometric properties and correlates of three computer aversion scales

Investigators have employed a variety of constructs and measures to examine individuals’ discomfort with computer use. Models and instruments for measuring constructs such as computer anxiety, computer phobia, and computer aversion have been employed to investigate negative reactions that slow individuals’ acceptance and useful application of computers. Using a large college student sample, we sought to compare the psychometric properties of three computer aversion scales and to investigate their relationships to gender, age, cognitive abilities, and experience with computer use. The results indicated good reliability, good validity coefficients, and similar factor structures for the scales. Younger students, female students, and students with lower mathematical skills and less computer experience were more likely to experience discomfort with computers. Implications include the possibility that if software and hardware alter subjects’ expectations about the difficulty of completing tasks, individual differences in computer aversion are likely to become a source of additional unexplained variance. Such differences must be heeded in software design and in the design of experimental research involving computers as stimulus controllers and response recorders.     

Adapting to the surface: A comparison of handwriting measures when writing on a tablet computer and on paper

Our study addresses the following research questions: Are there differences between handwriting movements on paper and on a tablet computer? Can experienced writers, such as most adults, adapt their graphomotor execution during writing to a rather unfamiliar surface for instance a tablet computer?We examined the handwriting performance of adults in three tasks with different complexity: (a) graphomotor abilities, (b) visuomotor abilities and (c) handwriting. Each participant performed each task twice, once on paper and once on a tablet computer with a pen.We tested 25 participants by measuring their writing duration, in air time, number of pen lifts, writing velocity and number of inversions in velocity. The data were analyzed using linear mixed-effects modeling with repeated measures.Our results reveal differences between writing on paper and on a tablet computer which were partly task-dependent. Our findings also show that participants were able to adapt their graphomotor execution to the smoother surface of the tablet computer during the tasks.     

A camera-based scoring system for evaluating performance accuracy during a golf putting task

Golf putting accuracy is often evaluated by measuring the distance that the ball finishes from the hole. However, accuracy is a function of line and length, and distance-from-hole measures confound these two factors. A scoring system for evaluating putting accuracy is described that enables the efficient measurement of errors in line and length. A camera placed above the hole takes digital photographs of the final position of the ball. A custom-developed program written in the National Instruments LabVIEW graphical programming language derives a variety of accuracy measures from these photographs, including distance from the hole, angle of error, distance short or long from the hole, and distance left or right from the hole. Evaluation of the system indicated that the measures were as accurate as manual measurements and were reliable when rescored on separate occasions. The camera-based scoring system presents a number of advantages in the evaluation of putting accuracy and may be extended to examine performance in other sports. The ScorePutting program may be downloaded from the Psychonomic Society's Archive of Norms, Stimuli, and Data, www.psychonomic.org/archive.     

PC-PVT: A platform for psychomotor vigilance task testing,analysis, and prediction

Using a personal computer (PC) for simple visual reaction time testing is advantageous because of the relatively low hardware cost, user familiarity, and the relative ease of software development for specific neurobehavioral testing protocols. However, general-purpose computers are not designed with the millisecond-level accuracy of operation required for such applications. Software that does not control for the various sources of delay may return reaction time values that are substantially different from the true reaction times. We have developed and characterized a freely available system for PC-based simple visual reaction time testing that is analogous to the widely used psychomotor vigilance task (PVT). In addition, we have integrated individualized prediction algorithms for near-real-time neurobehavioral performance prediction. We characterized the precision and accuracy with which the system as a whole measures reaction times on a wide range of computer hardware configurations, comparing its performance with that of the “gold standard” PVT-192 device. We showed that the system is capable of measuring reaction times with an average delay of less than 10 ms, a margin of error that is comparable to that of the gold standard. The most critical aspect of hardware selection is the type of mouse used for response detection, with gaming mice showing a significant advantage over standard ones. The software is free to download from http://bhsai.org/downloads/pc-pvt/.     

Computerized Testing in the United States Air Force

Computerized testing in the United States Air Force finds its historical beginnings in apparatus tests developed during World War II. The advent of fast, small, and inexpensive computers led to the establishment of a research program to use computers in pilot selection. Later, computerized tests were demonstrated for more familiar aptitude measures such as verbal and quantitative ability. Several large-scale efforts to implement computerized testing have proved informative. Many Air Force tests are routinely administered by computer. Continued advances in computer technology promise to make computerized testing more common and more commonplace. Computer use in measuring physiological correlates of human ability is discussed.     

General software for an on-line eye-movement recording system

A general on-line eye-movement recording system is described which consists basically of (a) some on-line instrument capable of displaying a visual scene, (b) a device to measure eye position and output position information in the form of electrical signals (c) an analogue-to-digital converter, and (d) a computer. General software for such a system is discussed with emphasis on subroutines which perform calibration and which continuously monitor eye position.     

Differences between general computer attitudes and perceived computer attributes: development and validation of a scale

The aim of this study was to develop a tool for measuring individuals' dispositions toward the use of computers in their work environment. The study reports the construction and validation of a general computer attitude and perceived computer attribute scale. Exploratory factor analytical evidence with a sample of 381 employees indicated a structure underpinned by two constructs, an attitudinal factor and a perceived computer attribute factor. The internal consistency estimates of reliability of scores were .81 for the attitudinal factor and .89 for the perceived computer attribute factor. Compared to the computer attitude subscale, scores on the perceived computer attribute subscale correlated higher with computer experience and professional computer use within the sample.     

A multidimensional scaling program for distinctiveness and similarity based on stimulus classification and information measurement

When observers classify a set of multidimensional items on the basis of similarity, they generate information measures that are isomorphic to item vectors whose lengths correspond to the judged distinctiveness of each item and whose angles define the position of each item in a euclidean similarity space. The PROSCALE computer program calculates the item vectors and spatial positions from similarity classification data and then generates and rotates orthogonal dimensions of the similarity space. PROSCALE can also use variables associated with each item to generate oblique dimensions that span the space. PROSCALE carries out multidimensional similarity scaling or unidimensional magnitude estimation scaling on as many as 70 items for as many as 50 observers.     

Eye tracking research and technology: Towards objective measurement of data quality

Two methods for objectively measuring eye tracking data quality are explored. The first method works by tricking the eye tracker to detect an abrupt change in the gaze position of an artificial eye that in actuality does not move. Such a device, referred to as an artificial saccade generator, is shown to be extremely useful for measuring the temporal accuracy and precision of eye tracking systems and for validating the latency to display change in gaze contingent display paradigms. The second method involves an artificial pupil that is mounted on a computer controlled moving platform. This device is designed to be able to provide the eye tracker with motion sequences that closely resemble biological eye movements. The main advantage of using artificial motion for testing eye tracking data quality is the fact that the spatiotemporal signal is fully specified in a manner independent of the eye tracker that is being evaluated and that nearly identical motion sequence can be reproduced multiple times with great precision. The results of the present study demonstrate that the equipment described has the potential to become an important tool in the comprehensive evaluation of data quality.     

Computer-analyzed measures of characteristics of human locomotion and mobility

Path and speed characteristics of human locomotion were detected by a mechanical sensing system and processed by a digital computer to give graphical and numerical measures of performance. The problems of deriving such indices are discussed, and a number of simple experiments are included to demonstrate that these measures yield dependent variables suitable for use in the study of the perceptual information required for mobility and locomotor control.     

COMPUTER‐ASSISTED MEASUREMENT OF WOUND SIZE ASSOCIATED WITH SELF‐INJURIOUS BEHAVIOR

We evaluated an inexpensive, efficient, and noninvasive technique for measuring tissue damage produced by self‐injurious behavior (SIB). The technique involved computerized measurement of wound surface area (WSA) based on digital photographs. In Study 1, we compared photographic measurement to a more commonly used procedure, transparency measurement, in estimating WSA of 20 wound models. Results showed that both methods were reliable and that there was a high degree of correspondence between the 2 sets of measures. In Study 2, we compared photographic WSA measures to direct‐observation measures in documenting changes over time in the SIB exhibited by a woman with Prader‐Willi syndrome. Results showed that increases and decreases in observed SIB during baseline and treatment conditions corresponded with changes in WSA measures, indicating that the computer‐assisted photographic technique may be useful as a corroborative measure or as a primary measure when direct observation of SIB is not feasible.     

The mismatch effect: when testosterone and status are at odds

Why do some people strive for high status, whereas others actively avoid it? In the present studies, the authors examined the psychological and physiological consequences of a mismatch between baseline testosterone and a person's current level of status. The authors tested this mismatch effect by placing high and low testosterone individuals into high or low status positions using a rigged competition. In Study 1, low testosterone participants reported greater emotional arousal, focused more on their status, and showed worse cognitive functioning in a high status position. High testosterone participants showed this pattern in a low status position. In Study 2, the emotional arousal findings were replicated with heart rate, and the cognitive findings were replicated using a math test. In Study 3, the authors demonstrate that testosterone is a better predictor of behavior than self-report measures of the need for dominance. Discussion focuses on the value of measuring hormones in personality and social psychology.     

Calibration of an eye-movement system for use in reading

A method for measuring horizontal eye movements in the msec range is described. Accurate measurement of horizontal eye movement over a linear range of 12° is achieved by processing the image of the eye illuminated with infrared light and with the head position fixed. The system has given very reliable results, and a resolution of 6 min of visual angle can be achieved with a character space of 45 min of arc. We also describe efficient numerical-data processing which allows the precise determination of the absolute position of the eye.     

RTbox: A device for highly accurate response time measurements

Although computer keyboards and mice are frequently used in measuring response times (RTs), the accuracy of these measurements is quite low. Specialized RT collection devices must be used to obtain more accurate measurements. However, all the existing devices have some shortcomings. We have developed and implemented a new, commercially available device, the RTbox, for highly accurate RT measurements. The RTbox has its own microprocessor and high-resolution clock. It can record the identities and timing of button events with high accuracy, unaffected by potential timing uncertainty or biases during data transmission and processing in the host computer. It stores button events until the host computer chooses to retrieve them. The asynchronous storage greatly simplifies the design of user programs. The RTbox can also receive and record external signals as triggers and can measure RTs with respect to external events. The internal clock of the RTbox can be synchronized with the computer clock, so the device can be used without external triggers. A simple USB connection is sufficient to integrate the RTbox with any standard computer and operating system.     

The coordination of compensatory tracking and anticipatory timing tasks

Two experiments investigated the presence of a coordination factor in a task consisting of compensatory tracking and anticipatory timing components. The task (Intercept task) resembles a computer game in which a rocket must be aimed and fired to shoot an incoming missile. The studies were designed to determine if a coordinating ability exists above and beyond the abilities needed to perform the component tasks alone. We also investigated the nature of coordination abilities through correlations with other types of coordination tasks and measures of intelligence. Is coordination a general cognitive ability that contributes to performance in a wide range of coordination tasks, or is coordination ability task specific? Multiple regression analyses indicated the existence of a coordination ability in the Intercept task. This coordination ability, however, was shown to be unrelated to the coordination of visual and linguistic processing and to psychometric measures of intelligence as assessed by the Armed Services Vocational Aptitude Battery (ASVAB). Coordination of visual and linguistic processing correlated with a component of the ASVAB measuring perceptual speed. We conclude that, although the ability to integrate separate components of a complex task draws on a coordination ability, this ability is domain specific and thus varies depending on the nature of the component tasks.     

Using computer‐assisted instruction to increase the eye gaze of children with autism

Many children diagnosed with autism spectrum disorders have difficulty making appropriate eye contact and engaging in joint attention. The current study evaluated a computer‐assisted instruction package (pairing visual stimuli with vocal stimuli) as a novel treatment to improve the eye gaze accuracy in 3 elementary school children with autism. The researchers measured the latency from a recorded verbal stimulus to the students making eye contact with pictures of familiar individuals displayed on a computer screen, and the duration for which eye gaze on the stimulus was maintained. An automated infrared camera system for measuring eye gaze was utilized that eliminated the need for an instructor to make subjective judgments regarding participants' eye gaze. For all three participants, duration of eye contact increased, and latency to responding decreased following exposure to the computer‐assisted instruction. The implications of these findings for the treatment of individuals with autism are discussed, along with suggestions for future research on the topic.     

Ruler vs. the Apple II/FIRST system analysis of analog signals in classical conditioning

In our judgment, the Apple II/FIRST system (Scandrett & Gormezano, 1980) is an efficient and versatile system for experimental control and data acquisition in classical conditioning experiments. However, these attributes would be of limited value if the system did not extract measures from our analog signals with a high degree of correspondence with our ruler measurement procedures. Accordingly, we determined the system’s validity in extracting measures of CR occurrence and CR latency in three conditioning experiments. Pearson productmoment correlation coefficients indicated a very satisfactory degree of agreement on measurements made by the Apple II/FIRST system and ruler. Moreover, intraclass correlations and analysis of variance procedures applied to percent CRs and CR latency revealed several small, but divergent, differences between ruler and computer measurement of CR latency across the three experiments. However, subsequent analyses of variance revealed that the number and pattern of significant sources of variation for ruler or computer measurements were virtually identical. Accordingly, we have concluded that our system can successfully replace our traditional method of ruler measurement.