An intelligent experimental station controller for human experimental psychology

The purpose of this paper is to describe the intelligent experimental station controller used in the extensible multiprogramming system for experimental psychology (EMPP) at the University of Washington. The EMPP system is an integrated hardware and software system designed to simplify the development of on-line psychological experiments. An intelligent graphics control system is one of the most important aspects of the system. The controller oversees the operation of eight independent experimental stations, each containing a cathode ray tube (CRT) terminal and a keyboard console. In addition to conventional computer interface functions, the controller contains an extensible hardware character generator which allows dynamic selection of the display character set. This paper describes both the hardware and software features of the system.     

A vision research apparatus for broad luminance range displays.

Lightness, the perceived gray shade of a surface, and the perception of self-luminous surfaces--that is, surfaces that appear to glow--have most often been studied with paper displays and computer-generated stimuli presented on CRT monitors. Although both methods are often effective, experiments that require a wide range of luminance values in the same display are often difficult to conduct with paper and computer displays alone. Also, color mode appearance is often an issue when surface color perception is the topic of research; CRT monitors are essentially light sources themselves and often appear in the luminous mode of color appearance. Here, we describe an apparatus in which the target is an undetected aperture whose luminance is adjustable. Whereas a typical CRT monitor offers a luminance range of about 100:1, much broader luminance ranges are possible with the described apparatus. Unlike a CRT monitor, the stimulus background will always appear in the surface mode of color perception, and the target(s) can appear as either surface colors or luminous colors. Apparatus modifications are possible, including the addition of a stereoscope or an embedded CRT for creating an adjustable region that is computer controlled.     

A vision research apparatus for broad luminance range displays

Lightness, the perceived gray shade of a surface, and the perception of self-luminous surfaces—that is, surfaces that appear to glow—have most often been studied with paper displays and computer-generated stimuli presented on CRT monitors. Although both methods are often effective, experiments that require a wide range of luminance values in the same display are often difficult to conduct with paper and computer displays alone. Also, color mode appearance is often an issue when surface color perception is the topic of research; CRT monitors are essentially light sources themselves and often appear in the luminous mode of color appearance. Here, we describe an apparatus in which the target is an undetected aperture whose luminance is adjustable. Whereas a typical CRT monitor offers a luminance range of about 100:1, much broader luminance ranges are possible with the described apparatus. Unlike a CRT monitor, the stimulus background will always appear in the surface mode of color perception, and the target(s) can appear as either surface colors or luminous colors. Apparatus modifications are possible, including the addition of a stereoscope or an embedded CRT for creating an adjustable region that is computer controlled.     

Digital LED Pixels: Instructions for use and a characterization of their properties

This article details how to control light emitting diodes (LEDs) using an ordinary desktop computer. By combining digitally addressable LEDs with an off-the-shelf microcontroller (Arduino), multiple LEDs can be controlled independently and with a high degree of temporal, chromatic, and luminance precision. The proposed solution is safe (can be powered by a 5-V battery), tested (has been used in published research), inexpensive (～ $60 + $2 per LED), highly interoperable (can be controlled by any type of computer/operating system via a USB or Bluetooth connection), requires no prior knowledge of electrical engineering (components simply require plugging together), and uses widely available components for which established help forums already exist. Matlab code is provided, including a ‘minimal working example’ of use suitable for use by beginners. Properties of the recommended LEDs are also characterized, including their response time, luminance profile, and color gamut. Based on these, it is shown that the LEDs are highly stable in terms of both luminance and chromaticity, and do not suffer from issues of warm-up, chromatic shift, and slow response times associated with traditional CRT and LCD monitor technology.     

A remote keyboard switch for the IBM PC/AT and compatibles

A relatively simple, remote keyboard switch for the IBM PC/AT and compatibles is discussed. It may be used to isolate a subject from an experimenter when the experimenter is controlling an experiment with the PC. The device, based on a 4066 CMOS, when used in conjunction with a monochrome monitor and a color monitor, enables the experimenter to switch, manually or programmatically (TTL), between the local monitor and the local keyboard and a remote monitor and a remote keyboard for presentation of stimuli and for recording of subject’s responses.     

An introduction to the Walter/Palya controller and ECBASIC

An overview of the Walter/Palya ECBASIC experiment controller is provided. The hardware, firmware, and underlying design considerations are presented. The controller is a simple printed circuit board microprocessor that interfaces directly to 8 inputs and 40 outputs and directly to any general purpose computer. It can be programmed in a specially written BASIC (ECBASIC) that provides high-level commands for most experimental manipulations. It can function as either a stand-alone computer or a networkable preperipheral processor. It costs about $150.     

Effect of artificial voice feedback delay in typing and its implications for the blind user

We examined the effect of voice-feedback delay on learning to type nonsense strings on a reduced computer terminal keyboard. The results suggest that long delays (1,642 msec) affect learning of the keyboard before mastery, whereas shorter delays (841 msec) do not. With mastery, subjects learn to ignore the disruptive effects of long feedback delays. Feedback delay may nevertheless be an important human-factors issue for blind consumers who are learning to type with a voice-based system, and for hardware and software designers of systems for the blind and visually impaired.     

基于计算机仿真的颜色认知实验方法研究

近年来计算机仿真的实验研究方法逐渐成为颜色认知研究的主流方法,该方法克服了传统方法的诸多缺陷。本研究在现有技术的基础上构建了颜色研究仿真系统,并改进了CIE规定的有关CRT显示器颜色标定的方法。笔者通过颜色匹配实验考察了人对CRT显示器上仿真照明体颜色外观的辨别精度,结果表明上述颜色仿真系统在颜色认知实验中具有良好的适用性,并发现被试在计算机模拟颜色刺激的条件下,可进行精确的颜色匹配;不同照明条件下的色差有所不同。这些结果也为建立颜色认知模型提供了人的基准匹配数据。     

Usability of liquid crystal displays for research in the temporal characteristics of perception and attention

Recently, the use of liquid crystal displays (LCDs) in computer monitors has increased in popularity. Can LCDs produce results similar to those obtained in cathode-ray tube (CRT) displays in studies of temporal attention and perception tasks? Performance in two tasks (metacontrast masking and attentional blink) was examined using an LCD, a CRT oscilloscope, and a raster scan CRT display. Experiment 1 focused on metacontrast masking where a typical metacontrast function emerged irrespective of monitor type. Experiments 2 and 3 examined whether differences in monitors influence the attentional blink. Again, all displays elicited similar performance profiles for both the attentional blink and the trade-off between identification accuracy of the two targets. Although our results may not generalize to all LCD applications and all experimental paradigms, they indicate that LCDs can reproduce results similar to those found in metacontrast masking and attentional blink studies that were originally identified with CRT displays.     

A programmable,multifunction dual-channel waveform generator for visual psychophysics

This paper describes a relatively low-cost, flexible means of presenting patterns on a CRT. The design allows for a number of options, such as presentation of gratings as well as nonstandard stimuli (white noise), the summation and differentiation of outputs to create complex luminance waveforms, and the switching of information from one channel to the other. In addition, the visual pattern generator permits a number of temporal options, such as phase reversals and the ramping on and/or off of a stimulus. This device incorporates a hardware means of scaling grating contrast. Finally, our procedure for producing synchronization signals, which uses internally generated interrupt signals, allows a number of software options, such as keyboard scanning and reaction timing, without significant time losses.     

The MicroAce: An inexpensive computer controller

A $200 computer system is described that can act as a laboratory controller. Advantages and disadvantages of the system are discussed.     

Response time accuracy in Apple Macintosh computers

The accuracy and variability of response times (RTs) collected on stock Apple Macintosh computers using USB keyboards was assessed. A photodiode detected a change in the screen’s luminosity and triggered a solenoid that pressed a key on the keyboard. The RTs collected in this way were reliable, but could be as much as 100 ms too long. The standard deviation of the measured RTs varied between 2.5 and 10 ms, and the distributions approximated a normal distribution. Surprisingly, two recent Apple-branded USB keyboards differed in their accuracy by as much as 20 ms. The most accurate RTs were collected when an external CRT was used to display the stimuli and Psychtoolbox was able to synchronize presentation with the screen refresh. We conclude that RTs collected on stock iMacs can detect a difference as small as 5–10 ms under realistic conditions, and this dictates which types of research should or should not use these systems.     

Using MEL to present Chinese characters at brief display times

Most studies that present Chinese characters at brief display intervals (10–100 msec) use tachistoscopic presentation. The present paper describes a way of using software packages NJSTAR (for generating Chinese characters) and MEL (for programming an experiment) to achieve computer CRT presentation. Techniques for (1) enlarging and smoothing characters, and (2) presenting characters at brief display times are featured. The techniques can be applied to brief CRT presentation of any graphics. A replication study is presented to demonstrate that the techniques produce reliable data.     

A simple encoding and recording system for small group observation

A simple and inexpensive system for coding and recording interaction patterns in small groups is described. It consists of a keyboard and a standard tape recorder, and it is capable of storing sequential data using up to 36 codes. Its main application is in the study of speaker-target patterns, but it can also be used in encoding up to 12 behavioral codes, or six speakers and 6 codes. The keyboard costs less than $200 and is used with conventional tape recorders and minicomputers available at most research sites.     

Tell me, what did you see? The stimulus on computers

Most psychology experiments start with a stimulus, and, for an increasing number of studies, the stimulus is presented on a computer monitor. Usually, that monitor is a CRT, although other technologies are becoming available. The monitor is a sampling device; the sampling occurs in four dimensions: spatial, temporal, luminance, and chromatic. This paper reviews some of the important issues in each of these sampling dimensions and gives some recommendations for how to use the monitor effectively to present the stimulus. In general, the position is taken that to understand what the stimulus actually is requires a clear specification of the physical properties of the stimulus, since the actual experience of the stimulus is determined both by the physical variables and by the psychophysical variables of how the stimulus is handled by our sensory systems.     

Learned patterns of action-effect anticipation contribute to the spatial displacement of continuously moving stimuli

When participants control the horizontal movements of a stimulus and indicate its vanishing point after it unexpectedly vanishes, the perceived vanishing point is displaced beyond the actual vanishing point, and the size of the displacement is directly related to the action-effect anticipation one has to generate to successfully control the stimulus. The present experiments examined whether learning a pattern of action-effect anticipation would later impact one's perception of moving stimuli. While 1 participant (the controller) controlled a dot's movements across a computer screen, another (the observer), who could neither see nor hear the controller, watched the dot's movements on a separate monitor. When the dot unexpectedly vanished, the observer indicated the vanishing point. After 40 trials, participants switched roles. While serving as observers, all participants generated forward displacements, but those who did so after acquiring control experience produced larger displacement. Subsequent experiments indicated the larger displacement was due to action-effect anticipation the participants learned while either controlling the dot or observing another do so.     

Playing it by ear: Overcoming the limitations of speech synthesizers

Inexpensive speech synthesizers are now available that either plug into the card slots on computers or connect to their serial ports. With some practice in listening, the speech produced by these synthesizers is quite intelligible, and because they present information that appears on the screen of the monitor, they make it possible for blind persons to interact with computers. However, they provide only a partial solution. In too many instances, some of the text appearing on the monitor screen cannot be directed to the synthesizer, and the missing information is often crucial. This happens because the writers of application programs sometimes modify the computer’s disk operating system. This limitation can be overcome by using special hardware that reads the screen buffer directly and creates a virtual image of the screen in memory external to the computer. Because the image is updated continually, it is always an accurate representation of whatever appears on the screen. The characters contained in the external buffer can be sent to a speech synthesizer, and can be examined selectively by means of a small keyboard. Several successful hardware solutions have been demonstrated, and one of these solutions is described here in detail.     

Machine language millisecond timers for the Z-80 microprocessor

Two Z-80 machine language millisecond timers for the Model III TRS-80 are presented and described: MSEC DELAY TIMER and MSEC LATENCY TIMER. The latency timer may be used with keyboard input (key release or key press) and may also be designed to respond to a signal at one of the computer’s I/O ports. The assembly language programs may be revised for other Z-80-based computers. Calibration procedures are described, and a sample two-field tachistoscope program is presented.     

Preferring alphabet–keyboard compatibility: Congruency between spatial codes shapes the affective connotation of letters

When letters are encountered, two spatial stimulus codes resulting from their positions within the alphabet and on the computer keyboard are activated mentally. If these two spatial codes match, letter processing is more efficient. The present study tested whether the processing fluency gain resulting from alphabet–keyboard compatibility also enhances affective evaluations of letters. In Experiment 1, participants preferred alphabet–keyboard compatible over incompatible letters in a forced-choice preference rating. Similarly, in Experiment 2, liking ratings for alphabet–keyboard compatible letters were higher compared to incompatible letters. Moreover, in Experiment 3, preference ratings of non-words were positively correlated with the relative number of alphabet–keyboard compatible letters within these letter strings. These findings suggest that alphabet–keyboard compatibility shapes the affective connotation of letters. Moreover, this processing fluency–valence association is activated at the level of letters as well as whole letter strings.