A low-cost method for digitizing videotaped continuous movements on the Macintosh

We describe an inexpensive means of digitizing videotaped positions of moving points, such as the positions of the joints of a person who is performing an action. Single-frame video images and a Macintosh computer monitor are optically superimposed, using a half-silvered mirror, and the positions of reference points in the video image are manually clicked in by the operator, so that the screen coordinates of the reference points on each frame can be stored in a text file for later analysis. The digitizing program records comments and identifying information along with the position data.     

An Apple microcomputer-based laboratory system for the study of visual-motor behavior

An apparatus for studying motor control and visual-motor coordination is described. The system consists of an Apple II+ with two expansions boards installed. One board provides advanced graphics capabilities; the other interfaces the Apple with a digitizing tablet and also provides a real-time clock. Target stimulus and visual feedback concerning self-produced movement (i.e., a cursor) are displayed on a standard video monitor, and movement data are sampled by the digitizing tablet. Software consists of about 3K bytes of assembled 6502 code and a 2K byte Applesoft BASIC program. The system is inexpensive, versatile, and particularly well suited for developmental research. It has been used with human subjects as young as 3 years of age.     

A Web-based digitized video image system for the study of motor coordination

A Web-based instructional project for the study of motor coordination is presented. The project includes two components: a tutorial on motor coordination and an interactive digitized video image system developed for the analysis of motion, including topics in biomechanics, motor coordination, motor control, and motor skill. This interactive system allows for the quantitative analysis of stored video images that are accessible from the World-Wide Web. The use of this digitizing system for the measurement and analysis of human locomotion coordination patterns is presented.     

Can computer mice be used as low-cost devices for the acquisition of planar human movement velocity signals?

The main goal of this work is to determine whether a computer mouse can be used as a low-cost device for the acquisition of two-dimensional human movement velocity signals in the context of psychophysical studies and biomedical applications. A comprehensive overview of the related literature is presented, and the problem of characterizing mouse movement acquisition is analyzed and discussed. Then, the quality of velocity signals acquired with this kind of device is measured on horizontal oscillatory movements by comparing the mouse data to the signals acquired simultaneously by a video motion tracking system and a digitizing tablet. A synthesis of the information gathered in this work indicates that the computer mouse can be used for the reliable acquisition of biosignals in the context of human movement studies, particularly for many applications dealing with the velocity of the end effector of the upper limb. This paper concludes by discussing the possibilities and limitations of such use.     

Measuring the error of localization

We describe a procedure to measure the error of localization on the skin. The procedure, which provides for rapid measurement of the error of localization and rapid analysis of the data, uses a digitizing tablet interfaced with a computer. A photocopy of the part of the body to be tested is placed on the digitizing tablet. The subject localizes the stimulus by touching the pen of the digitizing tablet to the photocopy. The location of the pen contact is stored, and the error of localization is determined by the computer. A graphic representation of each subject’s test area can be stored. Both stimulus and response locations can be displayed on this graphic representation. The procedure also allows the same sites on the skin to be tested over a period of weeks or months.     

Attention and movement execution during handwriting

Two studies were performed in order to test the hypothesis that movement execution during handwriting in skilled writers is independent of attention. Study I examined the relationship between attentional functioning and kinematic aspects of handwriting movements in 24 adult participants. A digitizing tablet was used for the assessment of handwriting movements. Participants were asked to perform a simple writing task and various components of their attention were assessed. Correlation analysis indicated no significant relationship between attention functions and both kinematic aspects of handwriting movements and quality of handwriting. In Study II, 20 participants underwent total sleep deprivation (TSD) for 24h. While attention, as assessed with alertness and vigilance tasks, deteriorated during TSD, the execution of handwriting movements, as assessed with a digitizing tablet, improved markedly. The quality of handwriting was not affected by TSD. These findings may suggest an independence between attention and movement generation during handwriting.     

2～3岁儿童对视频信息的理解

选取2岁、2．5岁和3岁儿童72名,比较儿童通过窗口、视频和模型三种条件观看藏玩具过程,然后正确找到玩具的表现,考察了2～3岁儿童对视频信息的理解特点。结果表明：（1）与通过直接经验获得信息相比,2岁与2.5岁儿童从视频获得表征信息存有一定困难;3岁儿童能够顺利地从视频获得并运用表征信息。（2）2～3岁儿童在视频条件下获取表征信息的能力要强于模型条件。研究认为3岁前儿童完成将视频图像视为真实物向视为表征信息的转换,双重表征并非儿童将视频图像作为表征信息加以理解的先决条件。     

Monitoring animals’ movements using digitized video images

An animal’s movements can be monitored continuously using video digitization techniques. We outline the differences between video frame-grabbers and column-scan digitizers, and describe two applications using column-scanners: detecting episodes of spontaneous locomotion and tracking the position of a moving appendage. Strategies are discussed for increasing the speed of software and for compressing the information in the video images into an analog motion signal to be displayed and stored for later analysis. Finally, the advantages and limitations of frame-grabbers and column-scan digitizers are assessed.     

Classification objects, ideal observers & generative models

A successful vision system must solve the problem of deriving geometrical information about three-dimensional objects from two-dimensional photometric input. The human visual system solves this problem with remarkable efficiency, and one challenge in vision research is to understand how neural representations of objects are formed and what visual information is used to form these representations. Ideal observer analysis has demonstrated the advantages of studying vision from the perspective of explicit generative models and a specified visual task, which divides the causes of image variations into the separate categories of signal and noise. Classification image techniques estimate the visual information used in a task from the properties of “noise” images that interact most strongly with the task. Both ideal observer analysis and classification image techniques rely on the assumption of a generative model. We show here how the ability of the classification image approach to understand how an observer uses visual information can be improved by matching the type and dimensionality of the model to that of the neural representation or internal template being studied. Because image variation in real world object tasks can arise from both geometrical shape and photometric (illumination or material) changes, a realistic image generation process should model geometry as well as intensity. A simple example is used to demonstrate what we refer to as a “classification object” approach to studying three-dimensional object representations.     

Optical and electronic systems for spatial and temporal analysis of video images

In this paper are described two systems for spatial (two-dimensional coordinates) and temporal analysis of video images. In the optical version, the Apple IIe generates a pointer on an Apple monitor; the pointer is then superimposed on the video image of a second video monitor, by reflecting the pointer with a half-silvered mirror. In the electronic version, a special card was designed for the Apple IIe to generate a pointer directly on the other video monitor. Both systems use the same software. The procedures of spatial and temporal data acquisition and storage are described as well as the reading, writing, printing, removing, listing, chaining, and dating operations of the digital and graphics files.     

Classifying postures of freely moving rodents with the help of fourier descriptors and a neural network

A computerized method for classifying the postures of freely moving rodents is presented. The behavior of the rats was recorded on videotape by means of a camera hanging perpendicular to an open field. An automatic tracking system (10 images/sec) was used to transform the video images of postures into a binary image, thereby providing silhouettes in a computer format. The contours of these silhouettes were used for determining their characteristic features with the help of a Fourier transformation. The resulting features were classified with the help of a Kohonen network composed of 32 neurons. The four bestwinning neurons, rather than the usual one, were used for the classification. The resolution (11,090 distinct classes of postures), reliability (96.9%), and validity of this method were determined. With the use of the same approach, the effectiveness of this method for classifying behaviors was illustrated by analyzing grooming (247 grooming images vs. 4,950 nongrooming images). We found 15.4% false positives and 2.5% false negatives.     

A device for the computer processed analysis of video frames

This article briefly describes a system of analyzing movement sequences extracted from video images. The system uses an IBM-PC or compatible computer, equipped with a CGA screen and a mouse, and a videotape recorder and monitor. The coordinates of the points selected from the images with the mouse are stored in an ASCII-format file by a computer program. The principle behind this system is that it projects video images on a computer screen through a one-way mirror while avoiding parallax effects.     

Capuchin monkeys (Cebus apella) respond to video images of themselves

Many studies have used mirror-image stimulation in attempts to find self-recognition in monkeys. However, very few studies have presented monkeys with video images of themselves; the present study is the first to do so with capuchin monkeys. Six tufted capuchin monkeys were individually exposed to live face-on and side-on video images of themselves (experimental Phase 1). Both video screens initially elicited considerable interest. Two adult males looked preferentially at their face-on image, whereas two adult females looked preferentially at their side-on image; the latter elicited lateral movements and head-cocking. Only males showed communicative facial expressions, which were directed towards the face-on screen. In Phase 2 monkeys discriminated between real-time, face-on images and identical images delayed by 1 s, with the adult females especially preferring real-time images. In this phase both screens elicited facial expressions, shown by all monkeys. In Phase 3 there was no evidence of discrimination between previously recorded video images of self and similar images of a familiar conspecific. Although they showed no signs of explicit self-recognition, the monkeys’ behaviour strongly suggests recognition of the correspondence between kinaesthetic information and external visual effects. In species such as humans and great apes, this type of self-awareness feeds into a system that gives rise to explicit self-recognition.     

How Video Image Size Interacts with Evidence Strength,Defendant Emotion,and the Defendant–Victim Relationship to Alter Perceptions of the Defendant

Courtroom video presentations can range from images on small screens installed in the jury box to images on courtroom video monitors or projection screens. Does video image size affect jurors' perceptions of information presented during trials? To investigate this we manipulated video image size as well as defendant emotion level presented during testimony (low, moderate), the defendant–victim relationship (spouses, strangers), and the strength of the evidence (weak, strong). Participants (N = 263) read a case and trial summary, watched video of defendant testimony, and then answered a questionnaire. Larger screens generally accentuated what was presented (e.g., made stronger evidence seem stronger and weaker evidence seem weaker), acting mainly upon trial outcome variables (e.g., verdict). Non‐trial outcomes (e.g., defendant credibility) were generally affected by defendant emotion level and the defendant–victim relationship. Researchers and attorneys presenting video images need to recognize that respondents may evaluate videotaped trial evidence differently as a function of how video evidence is presented. Copyright © 2014 John Wiley & Sons, Ltd.     

Video tracking in the extreme: Video analysis for nocturnal underwater animal movement

Computer analysis of video footage is one option for recording locomotor behavior for a range of neurophysiological and behavioral studies. This technique is reasonably well established and accepted, but its use for some behavioral analyses remains a challenge. For example, filming through water can lead to reflection, and filming nocturnal activity can reduce resolution and clarity of filmed images. The aim of this study was to develop a noninvasive method for recording nocturnal activity in aquatic decapods and test the accuracy of analysis by video tracking software. We selected crayfish, Cherax destructor, because they are often active at night, they live underwater, and data on their locomotion is important for answering biological and physiological questions such as how they explore and navigate. We constructed recording arenas and filmed animals in infrared light. Wethen compared human observer data and software-acquired values. In this article, we outline important apparatus and software issues to obtain reliable computer tracking.     

Computer-based automatic finger- and speech-tracking system

This article presents the first technology ever for online registration and interactive and automatic analysis of finger movements during tactile reading (Braille and tactile pictures). Interactive software has been developed for registration (with two cameras and a microphone), MPEG-2 video compression and storage on disk or DVD as well as an interactive analysis program to aid human analysis. An automatic finger-tracking system has been implemented which also semiautomatically tracks the reading aloud speech on the syllable level. This set of tools opens the way for large scale studies of blind people reading Braille or tactile images. It has been tested in a pilot project involving congenitally blind subjects reading texts and pictures.     

Direct measurement of the system latency of gaze-contingent displays

Gaze-contingent displays combine a display device with an eyetracking system to rapidly update an image on the basis of the measured eye position. All such systems have a delay, the system latency, between a change in gaze location and the related change in the display. The system latency is the result of the delays contributed by the eyetracker, the display computer, and the display, and it is affected by the properties of each component, which may include variability. We present a direct, simple, and low-cost method to measure the system latency. The technique uses a device to briefly blind the eyetracker system (e.g., for video-based eyetrackers, a device with infrared light-emitting diodes (LED)), creating an eyetracker event that triggers a change to the display monitor. The time between these two events, as captured by a relatively low-cost consumer camera with high-speed video capability (1,000 Hz), is an accurate measurement of the system latency. With multiple measurements, the distribution of system latencies can be characterized. The same approach can be used to synchronize the eye position time series and a video recording of the visual stimuli that would be displayed in a particular gaze-contingent experiment. We present system latency assessments for several popular types of displays and discuss what values are acceptable for different applications, as well as how system latencies might be improved.     

Is it life or is it Memorex? Video as a representation of reality

This paper offers an overview of research on infants’ early behavior toward televised images, followed by an account of the development of representational competence with video. Several aspects of representation are involved in young children’s understanding and use of video. From a very young age, children form mental representations of the contents of video, making sense of realistic images of familiar things. Children also notice and represent information regarding video itself (e.g., its 2-dimensionality). An important development occurs when children represent the relation between video and reality: at first, toddlers appear to categorize video as separate from reality, but eventually children recognize realistic video images as physical representations (symbols) of events they have not directly perceived. A mature representation of video takes into account genre (e.g., news, drama) and reality status based on recognition that video can (but does not always) represent real events.