The PC tachistoscope has 32 pages

Page switching is the basis of the PC tachistoscope, and usual accounts of page switching on the PC refer to a maximum of 8 available pages. This article shows how to achieve up to 16 pages in 40-column text mode and up to 32 pages in low-resolution graphics mode using conventional page switching combined with the bit-plane layering technique described by Bokhorst (1995). A high level C program is presented to show how this is done. When 32 pages are in use, the images must be monochrome.     

More on millisecond timing and tachistoscope applications for the IBM PC

This paper describes a method of establishing time intervals at a precision of better than 1 msec, using QuickBASIC 4.0, for running real time experiments on an IBM PC without an 8087 coprocessor. This method is far superior to the TIMER function provided by BASIC, which has a precision of only 110 msec. Also described is an assembly language subroutine that corrects a problem in QuickBASIC 3.0 and QuickBASIC 4.0 to allow proper switching between screens in the CGA text mode for use of the PC as a tachistoscope. A tachistoscope program listing shows how to use the screen subroutine and how to establish intertriai intervals and record reaction times using the timing subroutines.     

A multichannel PC tachistoscope with high resolution and fast display change capability

The number of channels that PC tachistoscopes can have has increased recently (Bokhorst, 1995; Myors, 1998); however, neither the quality of display nor speed of image switching has been improved. This article shows the capability of VESA’s VBE 3.0 standard (1998) for increasing the number of channels of high-quality images. And the refresh rate can be set to the fastest cathode ray tube (CRT) scanning rate the monitor can tolerate in order to reduce the timing delay of changing display. A PCTSCOPE library was written in C to provide these capabilities, which is compatible with conventional DOS real mode. The PC tachistoscope can have numbers of channels with various resolutions and colors and different refresh rates. For example, 25 images with the resolution of 640 × 480 pixels and 256 colors can be loaded to video memory, and vertical refresh rate can be set to 180 Hz. It takes less than 6 msec to change the display among 25 channels in synchronizing with the start of the video scanning frame. In this library, the number of channels, the resolution of the images, and the speed of changing display all are improved. The multichannel PC tachistoscope with this technique is especially suitable for research requiring high-quality images and rapid successive presentation of stimuli.     

The word without the tachistoscope

In experiments with an unlimited viewing time, we were able to isolate specific stimulus factors that lead to the word-superiority effect. We discovered that advantages of words over nonwords, and words over single letters, are caused by different factors. The word-nonword effect was found in a variety of circumstances, such as with small type, low contrast, or a simultaneously present mask. The advantage of words over single letters occurs only when the stimuli are embedded in a mask making it difficult to find a single letter. In addition, we obtained a word-detection effect without a brief exposure: Subjects were more accurate detecting the presence of words than nonwords. However, this effect only occurred when subjects were required to discriminate letters from nonletters. Thus, the word-superiority (word-nonword difference) and word-detection effects both involve letter discrimination and can be explained by similar mechanisms.     

A VGA tachistoscope

A set of tachistoscope-emulation functions for IBM-PC-compatible computers equipped with the VGA display controller is described. C or Pascal programs including these functions can easily produce multifield tachistoscopic presentations of colored text.     

Apple slide tachistoscope

We outline a BASIC program and subsidiary machine language timing routines that enable the Apple II series of computers to be employed as control devices for the tachistoscopic presentation of 35-mm slides and the collection of response latencies. The program is functional for experiments that require pictorial stimuli to be presented in up to three separate fields, with precise display times, precise interstimulus and intertriai intervals, and the collection of manual or vocal reaction times with millisecond accuracy. The major advantages of this system are that initial setup costs are substantially lower than those for other similar systems (e.g., Loftus, Gillispie. Tigre, & Nelson, 1984) and that user customization of the program may be accomplished by anyone possessing rudimentary knowledge of the BASIC programming language.     

A spectacle-mounted liquid-crystal tachistoscope

A spectacle-mounted shuttering device, the Portable Liquid-crystal Apparatus for Tachistoscopy via visual Occlusion, based on light-scattering cholesteric liquid crystals, is introduced. Operating characteristics of the device are discussed with respect to the design objectives of comfort, switching speed, light transmission, light extinction, safety, and reliability. A number of practical research, clinical, and industrial applications of the spectacles as tachistoscope, stroboscope, and stereoscopic viewing apparatus are summarized.     

Measuring projection tachistoscope shutter characteristics

Projection tachistoscopes have shutters that control the presentation of stimuli. Shutter characteristics such as opening times, closing times, and mechanical reliability are important factors in applications of these tachistoscopes. The device described in this report allows the operating characteristics of shutters used in projection tachistoscopes to be evaluated. The use of the device is illustrated by measurements of three commercially available tachistoscope shutters. Each shutter was characterized by five parameters: opening and closing speeds, the lag between shutter activation and operation, the briefest stimulus presentation that the shutter allowed, and the shutter’s ability to repeat exposure durations accurately.     

A versatile microcomputer-based multiple-field tachistoscope

A newly introduced microcomputer in its most basic form provides a wide variety of stimulus display capabilities at an extremely low price. Several simple illustrative programs demonstrate its ability to present any number of visual stimuli in sequence and record response latencies, thus duplicating the functions of a multiple-field tachistoscope and associated response-recording instrumentation.     

A computer-based programmable tachistoscope for nonprogrammers

A set of programs for on-line control of reaction time experiments is described. These programs allow a wide range of experiments to be coded in a simple form that eliminates the need for any knowledge of programming.     

DIS: An n-channel tachistoscope algorithm

DIS is a stand-alone, file-oriented, n-channel tachistoscope simulator. The paper describes the program in terms of both the syntax required to set up a display and the basic operation of the algorithm. Short routines illustrating two experimental paradigms are provided.     

The luminance of tachistoscope lamps as a function of flash duration

The steady-state luminance of the lamps in a commonly used Iconix tachistoscope was shown to depend, in a complex nonlinear fashion, upon the length of time the lamps were lit. This was probably due to variations in lamp temperature with time. An integrating photometer was used to measure the light energy present in short flashes and in time periods of various durations with the lamps burning continuously. The equivalent luminance of short flashes was calculated by comparing values obtained by integration over a short flash with values resulting from integration, over an identical duration, of the lamps in a steady-state. With flashes up to 50 msec in nominal duration, luminous energy was less than one-half of that present in the same duration with the lamps burning continuously. The importance of this information for the interpretation of tachistoscopic experiments, as well as possible means of monitoring the effects, are discussed.     

Technical improvements to the projection tachistoscope

Three disadvantages of the usual projection tachistoscope are discussed. Because of low mechanical precision, stimulus alignment is difficult. Because of rather low focal distances of the projection lenses, the stimuli provide visual angles that are often larger than desired, and the photographic shutters are noisy, are relatively inert, and have a limited service life. A new construction is described that avoids these disadvantages with a modified configuration of commercial elements: stable and precise mounting of the single channels, a double-lens projection system, and a noiseless, fast mechanical shutter based on a limited-rotation motor.     

An LCD tachistoscope with submillisecond precision

Tachistoscopes allow brief visual stimulation delivery, which is crucial for experiments in which subliminal presentation is required. Up to now, tachistoscopes have had shortcomings with respect to timing accuracy, reliability, and flexibility of use. Here, we present a new and inexpensive two-channel tachistoscope that allows for exposure durations in the submillisecond range with an extremely high timing accuracy. The tachistoscope consists of two standard liquid-crystal display (LCD) monitors of the light-emitting diode (LED) backlight type, a semipermeable mirror, a mounting rack, and an experimental personal computer (PC). The monitors have been modified to provide external access to the LED backlights, which are controlled by the PC via the standard parallel port. Photodiode measurements confirmed reliable operation of the tachistoscope and revealed switching times of 3?μs. Our method may also be of great advantage in single-monitor setups, in which it allows for manipulating the stimulus timing with submillisecond precision in many experimental situations. Where this is not applicable, the monitor can be operated in standard mode by disabling the external backlight control instantaneously.