Real-time color-frame animation for visual psychophysics on the Macintosh computer

Psychophysical experiments involving moving stimuli require the rapid presentation of animated sequences of images. Although the Macintosh computer is widely used as a color graphics computer in research laboratories, its animation capabilities are generally ignored because of the speed limitations of drawing to the screen. New off-screen color graphics structures help to avoid the speed limitations so that real-time color or gray-scale visual motion stimuli may be generated. Precomputed animation frames are stored in off-screen memory and then rapidly transferred to the screen sequentially. The off-screen graphics structures may also be saved to disk in “Picture” form as “resources” for later retrieval and playback, allowing the experimenter to build in advance a collection of moving stimuli to use in future experiments. Code examples in the C programming language are provided, and the relative strengths and weaknesses of Macin-tosh color-frame animation for psychophysical experimentation are discussed.     

A server-side program for delivering experiments with animations

A server-side program for animation experiments is presented. The program is capable of delivering an experiment composed of discrete animation sequences in various file formats, collecting a discrete or continuous response from the observer, evaluating the appropriateness of the response, and ensuring that the user is not proceeding at an unreasonable rate. Most parameters of the program are controllable by experimenter-edited text files or simple switches in the program code, thereby minimizing the need for programming to create new experiments. A simple demonstration experiment is discussed and is freely available.     

PandaEPL: A library for programming spatial navigation experiments

Recent advances in neuroimaging and neural recording techniques have enabled researchers to make significant progress in understanding the neural mechanisms underlying human spatial navigation. Because these techniques generally require participants to remain stationary, computer-generated virtual environments are used. We introduce PandaEPL, a programming library for the Python language designed to simplify the creation of computer-controlled spatial-navigation experiments. PandaEPL is built on top of Panda3D, a modern open-source game engine. It allows users to construct three-dimensional environments that participants can navigate from a first-person perspective. Sound playback and recording and also joystick support are provided through the use of additional optional libraries. PandaEPL also handles many tasks common to all cognitive experiments, including managing configuration files, logging all internal and participant-generated events, and keeping track of the experiment state. We describe how PandaEPL compares with other software for building spatial-navigation experiments and walk the reader through the process of creating a fully functional experiment.     

WFORM: A graphical speech-waveform editing and analysis system

A graphical waveform editor for use in speech research applications is described. The editor operates in 32 kwords of main memory on a DEC LSI-11/23 microcomputer under the RSX-11M operating system. The graphics subsystem is a Hewlett-Packard vector graphics controller and display unit. The editor is written in ANSI standard FORTRAN IV to promote portability. WFORM is capable of reading speech files and displaying the contents of these files in either visual or auditory format. In addition, the editor provides the capability to excise arbitrary portions of speech files, concatenate several speech files, and modify the contents of speech files by windowing. Speech analysis is also available in the form of the fast Fourier transform, and a number of windowing techniques are useful for Fourier analysis. The results of the Fourier transform can be displayed either in the form of power spectra or as a rough spectrograph.     

High-speed 2-D and 3-D animation on the IBM PC/XT/AT

This article describes programs for performing high-speed two-dimensional (2-D) and three-dimensional (3-D) animation on IBM PC/XT/AT and compatible machines that use the color/graphics adapter. Machine language routines interfaced through BASIC allow the user to store screen images in memory as they are created by user software and then to display the sequence of images at rates of up to 60 frames per second. A BASICA 3-D graphics editor that can be used with the routines permits the user to create wire-frame objects and to move them about rigidly in conceptual space while projecting them onto the display screen. These programs should find application in the study of visual perception and cognition.     

Tscope: A C library for programming cognitive experiments on the MS Windows platform

Tscope is a C/C11 programming library designed for programming experiments that run on Windows 2000/XP. It is intended for a public of experimental psychologists with moderate programming skills, who are accustomed to writing their own experimental programs for DOS but have not made the step to Windows-based programming yet. It provides molecular functions for graphics, sound, timing, randomization, and response registration. Together with ANSI-C standard library functions and the powerful C syntax, this set of functions gives the experimenter the opportunity to program virtually any experiment one can come up with. Tscope is completely based on free software, is distributed under the GNU General Public License, and is available at expsy.ugent.be/tscope. An integrated development environment for compiling and running Tscope programs is also freely available.     

Independent control of dual video subsystems on the IBM PC and compatibles

Two methods for generating video output on multiple video monitors are described. The first method involves splitting the signal from a single video adaptor card-so that multiple video monitors may be attached. Although this method is simple and relatively cost-effective, it is limited to adaptors that produce only digital video signals, thus precluding the use of VGA systems and composite displays. The second method involves the installation and programming of video adaptors: Two sample programs, which control a secondary adaptor by means of either BIOS routines or direct commands via C code, are described. Although more complex, this second method allows output to each display to be controlled independently. Furthermore, output to one screen may consist of graphics information while output to the second screen consists of text. Together, both methods can be used to create an experimental system composed of multiple data-collection stations and an independent experimenter console.     

Millisecond precision psychological research in a world of commodity computers: New hardware,new problems?

Since the publication of Plant, Hammond, and Turner (2004), which highlighted a pressing need for researchers to pay more attention to sources of error in computer-based experiments, the landscape has undoubtedly changed, but not necessarily for the better. Readily available hardware has improved in terms of raw speed; multicore processors abound; graphics cards now have hundreds of megabytes of RAM; main memory is measured in gigabytes; drive space is measured in terabytes; ever larger thin film transistor displays capable of single-digit response times, together with newer Digital Light Processing multimedia projectors, enable much greater graphic complexity; and new 64-bit operating systems, such as Microsoft Vista, are now commonplace. However, have millisecond-accurate presentation and response timing improved, and will they ever be available in commodity computers and peripherals? In the present article, we used a Black Box ToolKit to measure the variability in timing characteristics of hardware used commonly in psychological research.     

3-D graphics animation program for the Apple II

A graphics design program for creating point-light displays of transforming 3-D objects is presented. This program was written for an Apple II microcomputer interfaced to a Texas Instruments TMS 9918A video display processor. In contrast to other 3-D design programs, it uses individual point-lights undergoing circular trajectories as a design primitive. An editor enables the user to enter and edit specific motion parameters for defining the parallel projection of as many as 16 point-lights on the screen. These parameters are then used to calculate and store in an animation list the screen positions of each point-light for each frame. Number of frames to be displayed and display rate are user defined.     

Experimental RunTime System: Software for developing and running reaction time experiments on IBM-compatible PCs

The Experimental RunTime System (ERTS) is a recent addition to the small collection of commercial software packages available for writing and running reaction time experiments on IBM-compatible PCs. Experiments are written using any text editor and a relatively small set of ERTS commands. Millisecond timing is provided by a software timer with no additional hardware requirements. All displays are in high-resolution VGA graphics. The Creative Labs Soundblaster card is supported in 16-bit mode, but is not required for simple tone generation. Voice-key support is available via the Soundblaster card. Keyboard, mouse, and external keys may be used as reaction keys, and the mouse or a joystick may be used as a tracking device. The stimulus-centered design and powerful display control commands of ERTS make it appropriate for developing a wide range of trial-based experiments.     

Inspection times, the change task, and the rapid-response selection task

Three experiments are reported, which are based upon the Wason four-card selection task inspection time paradigm, in which subjects solve computer-presented trials while using a mouse to indicate the card currently under consideration. Evans (1996) had shown that selected cards were inspected for longer than non-selected cards, and this was taken as support for the existence of pre-conscious heuristic processes that direct attention towards relevant aspects of a problem. However, Roberts (1998b) suggested that this inspection time effect is artefactual, due to task format induced biases. Experiment 1 utilized a "change" task: Cards were presented either as selected or not selected, and subjects changed these where necessary. This demonstrated an association between card selection and inspection time independently of one between the act of response and inspection time. Experiment 2 utilized a standard selection task, but subjects either responded within 2 s of each card presentation, or made selections with no time pressure. The curtailment of thinking time increased matching behaviour—more cards matching the terms in the rules were selected—and was replicated in Experiment 3 using a within-subjects design. Overall, the data support Evans' heuristic-analytic framework albeit with some caveats.     

Tachistoscopic presentation and millisecond timing on the IBM PC/XT/AT and PS/2: A Turbo Pascal unit to provide general-purpose routines for CGA,Hercules, EGA,and VGA monitors

A review of the literature on adopting microcomputers for use in tachistoscopic research paradigms illustrates the need for a comprehensive package to effectively deal with the wide variety of video displays and microcomputers used in experimental settings. In addition, because of the large number of possible configurations created when video displays and computer systems are combined, there is a need to be able to efficiently drive any such combination without rewriting program code. A Turbo Pascal unit is presented to provide standard tachistoseopic routines compatible with monochrome, CGA, Hercules, EGA, and VGA video technology. Procedures that synchronize both text and graphics mode stimuli with the vertical retrace pulse are given, as are routines to provide access to a timer with better than millisecond precision. Pascal code is described that will run on the IBM PC, XT, AT, or PS/2, as well as on any compatible machine. The versatility of the unit allows the experimenter to use generic video and timer commands that will automatically adapt at run time to the system that is being used, without further experimenter intervention.     

Improved calibration of color video projectors by means of computer animation

A computer animation for the calibration of color video projectors is described. The animation facilitates the calibration procedure and can be readily programmed on almost any graphics computer or played from a videotape.     

A low-cost, accurate method of producing large quantities of digitally filtered images

We demonstrate how to produce complex image transformations of bitmap files for vision experiments using the Cogimatic Vision Starter Kit (VSK) library of mathematical routines along with Visual Basic, C++, or the Delphi Pascal compiler. Implementing this system on an IBM-compatible PC running Windows 95, 98, or NT4 enables researchers to quickly and economically manipulate images for vision research. The VSK includes a simple stand-alone image-processing application. In addition, VSK has the ability to automate image transformations and to fully integrate image processing into new experimental software on the PC platform.     

Microcomputer graphics in psychological research

This paper discusses a methodology for psychological instrumentation in which requirements common to a spectrum of experiments are defined and implemented in a microcomputer system. The microcomputer may either stand alone or be used as an intelligent front end to a larger computer. In either case, experiments are described in a high-level implementation language. The advantages of this approach include reduced hardware and maintenance costs, increased reliability, and smoother operation by research personnel. A tutorial example is given of the design and construction of one such system used to present visual stimuli, including text, graphics, and simple animation, on a movable array of video monitors. Displays are produced by a Z80 microcomputer in response to commands from a larger host computer, in this case a PDP Lab/8e. Illustrations are given of three studies in progress; comparisons are made with special-purpose equipment built earlier. The microcomputer system is preferable from both a cost and management point of view.     

Ultrafast display buildup with standard VGA on MS-DOS computers

Tachistoscopic examinations, determinations of reaction times after visual stimuli, and latency measurements of visual evoked potentials require well-defined and often very fast display buildup on the monitor. Display buildup takes at least 14 msec when a VGA board is used in standard video modes. This time can be reduced to 4 msec or less by reprogramming some registers of the display adapter.     

Can very small font size enhance memory?

Presenting information in a perceptually degraded format sometimes enhances learning outcomes. However, earlier studies in which words were presented in large or small fonts in a paradigm that also involved item-by-item judgments of learning (JOLs) consistently yielded no mnemonic benefit of small fonts. Can small font size enhance memory under hitherto unexamined conditions? A series of 11 experiments was conducted to examine systematically the effect of font size on memory for words and whether it depends on the strength of the font size manipulation, whether JOLs are solicited, the format of the test, and study time. The resulting data were meta-analyzed. Results yielded a u-shape relationship between font size and memory. Compared to intermediate fonts, there was a memory advantage for words presented in large fonts but also for words presented in very small fonts. However, the requirement to provide a JOL moderated the benefit of the very small font, which was eliminated when JOLs were solicited. Test format and study time did not moderate the effect of font size on memory. JOLs were insensitive to the u-shape relationship and consistently increased with font size. These findings provide support for the notion that perceptually degraded materials can enhance learning outcomes, but also highlight the importance of systematic investigation of moderators. The results shed new light on the inconsistent effects of manipulations of perceptual degradation on learning outcomes observed in earlier studies.     

Graphics software and hardware for RT-11 systems

A general-purpose graphics package is described that allows the user to generate figures with a supraset of the basic CalComp plotting subroutines. The software runs under RT-11 on an LSI-11 with 28K words of memory. The graphics subroutine library is approximately 200 blocks long. The plotting tasks are passed over an RS 232 line to a simple extension of an inexpensive and commercially available graphics controller. The controller implements these tasks as plotting instructions to a color television, a vector display, and a digital plotter. The graphics subroutines are written in FORTRAN and are invoked by the user as subroutine calls from a FORTRAN program. The graphics controller is a modified Motorola “Micro Chroma 68 Kit.” The board is based on the 6808 microprocessor and 6847 video controller. It provides eight graphic modes from 64 by 32 eight-color graphics to 128 by 192 four-color graphics to 256 by 192 two-color graphics. The present software and hardware implements the graphics subroutines as 256 by 192 two-color graphics, as 512 by 512 vector graphics, and as stepping instructions for a digital plotter.     

A motion capture library for the study of identity, gender, and emotion perception from biological motion

We present the methods that were used in capturing a library of human movements for use in computer-animated displays of human movement. The library is an attempt to systematically tap into and represent the wide range of personal properties, such as identity, gender, and emotion, that are available in a person's movements. The movements from a total of 30 nonprofessional actors (15 of them female) were captured while they performed walking, knocking, lifting, and throwing actions, as well as their combination in angry, happy, neutral, and sad affective styles. From the raw motion capture data, a library of 4,080 movements was obtained, using techniques based on Character Studio (plug-ins for 3D Studio MAX, AutoDesk, Inc.), MATLAB The MathWorks, Inc.), or a combination of these two. For the knocking, lifting, and throwing actions, 10 repetitions of the simple action unit were obtained for each affect, and for the other actions, two longer movement recordings were obtained for each affect. We discuss the potential use of the library for computational and behavioral analyses of movement variability, of human character animation, and of how gender, emotion, and identity are encoded and decoded from human movement.