Screen display and timing synchronization on the Apple IIe and Apple Ilgs

The logic of the vertical blanking interval (VBL) Softswitch in the Apple Ilgs is the reverse of the logic of the VBL in the Apple IIe. Programs written for the Apple IIe that synchronize the videoscan with the experiment control program timing by sensing the VBL pulse will therefore function incorrectly when run on an Apple Ilgs. Procedures for modifying existing synchronization routines are discussed. A flexible alternative program that senses the type of computer on which it is running and accordingly adjusts the logic of the synchronization routine is described.     

Event-related potential data acquisition on the Apple II+/IIe

Event-related potential (ERP) research is a valuable technique for understanding neural mechanisms underlying cognition. With few exceptions, this research has used minicomputer-based data-acquisition systems, thus limiting ERP research to labs with large computers. The hardware and software presented here allow the Apple II+ or Apple IIe microcomputers to present stimuli and collect data from as many as three electrode sites. A fourth electrode site may be used to monitor eyeblinks and allows the exclusion of those trials in which an eyeblink occurs. After the data are collected and averaged, they are stored by subject, task, and electrode on disk where they subsequently may be displayed, analyzed, or downloaded to a mainframe computer.     

A jiffy clock for the Apple IIc,II+, and IIe with a mouse

A “jiffy clock” is presented for the Apple lIc or other Apple II having Apple’s mouse card. The clock allows timing of events to tenths of a second, and is read from BASIC. A convenient elapsed timer function is provided as well.     

An investigation of somatic anxiety and intelligence in children using the Kaufman-ABC and an Apple IIe program measuring heart rate

Somatic anxiety during intelligence testing was examined for 43 children in Grades K through 5 by assessing each child's heart rate with an Apple IIe computer program during an administration of the Kaufman-ABC. Heart rate (a measure of somatic anxiety) decreased steadily during the course of the test administration, except for an increase when the one timed subtest (Triangles) was administered. Heart rate during each separate subtest did not correlate significantly with performance on any task. Implications of these preliminary findings are discussed.     

A note on sequential blanking

Five-letter pseudowords were presented in all possible spatiotemporal orders at each of nine combinations of letter duration and interletter interval. Subjects were required to report as many letters of the pseudoword as possible. The results confirmed the sequential blanking effect; under certain timing conditions, some spatiotemporal orders result in perceptual blanking. The results show, however, that blanking does not follow the two rules previously thought to describe the phenomenon.     

The effect of blanking on the identification of temporal order in three-tone sequences

Attention, Perception, & Psychophysics - Trained subjects were asked to identify the temporal order of three 20-msec tones (891, 1,000, and 1,118 Hz), which were immediately followed by a...     

A CRT blanking circuit for video terminals

A simple and inexpensive modification for the ADDS 980 video terminal is described which permits the characters displayed on the CRT to be blanked and restored (under software control). This circuit is useful in applications, such as RT measurement, where precise definition of stimulus onset is important. The technique described is general enough to be applied to a variety of other video terminals.     

产前筛查的几点思考

产前筛查是指通过经济、便捷、无创伤的方法,查找出某些严重病症的高危个体,从而提高出生人口素质。是阻止新生儿出生缺陷的有效手段之一。本文从哲学和医学伦理学角度对产前筛查的认识、意义和运用进行综合分析。     

A study of sequential blanking and overprinting combined

By presenting alphabetic and other types of input characters, in either adjacent spatial locations or in the same spatial location, on the face of a cathode-ray tube (CRT) interfaced to a digital computer and by varying in systematic ways the interstimulus intervals (ISIsj and display orders of the several sequentially presented inputs, there has evolved what we call a “blanking-overprinting” paradigm. The use of such a paradigm has disclosed that the visual system can operate in a very sensitive and highly selective manner, “clearing” the first of two overprinted inputs that are separated in time by as little as 50 usec, while selectively inhibiting the second of these two overprinted inputs, if appropriate blanking inputs are present.     

Computing interrater reliability on the Apple Macintosh computer

A program is described for computing interrater reliability by averaging, for each rater, the correlations between one rater’s ratings and every other rater’s ratings. For situations in which raters rate more than one ratee, raters’ reliabilities can be computed for either each item or each ratee. The program reads data from a text file and puts the reliability coefficients in a text file. The standard Macintosh interface is implemented. The Quick-BASIC program is distributed both as a listing and in compiled form; it can be run with advantage with math coprocessors.     

Different effects of eyelid blinks and target blanking on saccadic suppression of displacement

Displacements of visual stimuli during saccadic eye movements are often not noticed. We have demonstrated that saccadic suppression of image displacement can be eliminated by blanking the stimulus for a short period during and after the saccade (Deubel, Schneider, & Bridgeman, 1996). Here we report an experiment in which target visibility was interrupted after the saccade, either by distal target blanking or by voluntary eyeblink. The data show that the effect of blinking is different from blanking; interruption of vision due to a blink did not enable subjects to detect target displacements any better than they had done in the no-blank condition. The results provide evidence for an extraretinal signal that distinguishes between endogenous and exogenous sources of temporary object disappearance after the saccade.     

Visual cortical evoked potentials under conditions of sequential blanking

Two separate experiments were conducted to study the visual evoked potential (VEP) correlates of sequential blanking, a phenomenon in which up to one-half of a discrete train of stimulus inputs are not perceived for certain orders of input. A PDP-7 digital computer was used to present stimuli (from 2 to 5 letter Xs) on a CRT display in both experiments. In Experiment 1 there were four basic conditions designed and counterbalanced to indicate the nature of the VEP when stimuli were blanked and when Ss reported all stimuli. All of the stimuli were of equal intensity. The main finding was that although the eight Ss did not perceive and report blanked stimuli, they did respond to them physiologically as indicated by the VEP. The implications of these findings were discussed in relation to recent studies of visual masking and metacontrast in which VEP was recorded. In Experiment 2 the normally blanked and the normally blanking stimuli were alternately increased in intensity to determine the effect on sequential blanking and the VEP. Six Ss were tested under three basic counterbalanced conditions. It was found that sequential blanking could be reliably overcome by increasing the intensity of the normally blanked stimuli. In addition, when the normally blanking stimuli were of greater intensity than the blanked stimuli, not only did perceptual suppression occur, but the evidence indicated that there was no VEP to the first of the two blanked stimuli.     

Cautions regarding random number generation on the Apple II

Undocumented characteristics of the pseudorandom number generators in Applesoft BASIC and Apple Pascal are described that cause identical sequences to be generated on different executions of programs written in those languages. Although it is relatively easy for this problem to escape notice, in both cases the problem is easily corrected once its existence is known.     

Developing a laboratory course using PASCAL on the Apple II

Several resources are available to the person seeking to develop a laboratory course that utilizes microprocessors. Several roles for such equipment are envisioned, and some of the issues regarding types of equipment and programming languages are addressed.     

On the Rag on Screen: Menarche in Film and Television

The purpose of this essay is to examine film and television representations of menarche from a critical, feminist perspective. A close analysis of scenes about menarche in 3 films and 4 television programs reveals implicit ideological messages of gender difference and gender stereotypes. Although these scenes appear to be positive and powerful challenges to menstrual communication taboos, they ultimately serve to reinforce media stereotypes of gender difference.     

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.     

Using HyperCard to administer a figural test on the Apple Macintosh

To date, applications of automated assessment techniques in personality testing have largely been limited to objective personality instruments with text stimuli; few assessment applications have involved graphic stimuli. Although projective personality instruments generally include ambiguous graphic or pictorial stimuli, computer applications with these procedures have been limited to automated scoring and interpretation, administration of sentence completion devices employing text stimuli, and the use of mechanical methods rather than computer graphics to display visual stimuli. In the present report, we describe a Macintosh HyperCard application for administering an objective personality test with visual stimuli, the Barron-Welsh Revised Art Scale of the Welsh Figure Preference Test. This test consists of a series of figural stimuli and a binary “like”/“dislike” response format, and it thus represents an administration procedure between standard objective self-report inventories involving text stimuli and a “true”/“false” response or variant, and tests such as the Rorschach or TAT that are both figural and free-response. The HyperCard language provides a variety of promising techniques useful for microcomputer test administration.