Millisecond accuracy video display using OpenGL under Linux

To measure people’s reaction times to the nearest millisecond, it is necessary to know exactly when a stimulus is displayed. This article describes how to display stimuli with millisecond accuracy on a normal CRT monitor, using a PC running Linux. A simple C program is presented to illustrate how this may be done within X Windows using the OpenGL rendering system. A test of this system is reported that demonstrates that stimuli may be consistently displayed with millisecond accuracy. An algorithm is presented that allows the exact time of stimulus presentation to be deduced, even if there are relatively large errors in measuring the display time.     

My Identical Twin Sequenced our Genome

With rapidly declining costs, whole genome sequencing is becoming feasible for widespread use. Although cost-effectiveness is driving increased use of the technology, comprehensive recommendations on how to handle ethical dilemmas have yet to reach a consensus. In this article, Sam shares her experience of undergoing whole genome sequencing. Despite the deeply private nature of the test, the results do not solely belong to Sam; her identical twin sister, Arielle, shares virtually the same genome and received results without a formal consent process. This article explores their parallel experiences as a way of highlighting the controversial ethics of a private test with familial implications.     

An interface for controlling external devices via the IBM PC/XT/AT parallel port

This article describes the construction and operation of a simple interface to control external devices via the IBM PC/XT/AT’s parallel printer port. The interface is relatively inexpensive and easy to build. It is potentially useful for controlling behavioral experiments.     

Metronome LKM: An open source virtual keyboard driver to measure experiment software latencies

Experiment software is often used to measure reaction times gathered with keyboards or other input devices. In previous studies, the accuracy and precision of time stamps has been assessed through several means: (a) generating accurate square wave signals from an external device connected to the parallel port of the computer running the experiment software, (b) triggering the typematic repeat feature of some keyboards to get an evenly separated series of keypress events, or (c) using a solenoid handled by a microcontroller to press the input device (keyboard, mouse button, touch screen) that will be used in the experimental setup. Despite the advantages of these approaches in some contexts, none of them can isolate the measurement error caused by the experiment software itself. Metronome LKM provides a virtual keyboard to assess an experiment’s software. Using this open source driver, researchers can generate keypress events using high-resolution timers and compare the time stamps collected by the experiment software with those gathered by Metronome LKM (with nanosecond resolution). Our software is highly configurable (in terms of keys pressed, intervals, SysRq activation) and runs on 2.6–4.8 Linux kernels.     

PyEPL: A cross-platform experiment-programming library

PyEPL (the Python Experiment-Programming Library) is a Python library which allows cross-platform and object-oriented coding of behavioral experiments. It provides functions for displaying text and images onscreen, as well as playing and recording sound, and is capable of rendering 3-D virtual environments forspatial-navigation tasks. It is currently tested for Mac OS X and Linux. It interfaces with Activewire USB cards (on Mac OS X) and the parallel port (on Linux) for synchronization of experimental events with physiological recordings. In this article, we first present two sample programs which illustrate core PyEPL features. The examples demonstrate visual stimulus presentation, keyboard input, and simulation and exploration of a simple 3-D environment. We then describe the components and strategies used in implementing PyEPL.     

Implementing a program in developmental guidance and counseling

This is a “how to” article. Too often in the past 10 years we have heard the term “change agent” applied to the counselor without the necessary filing in of how one goes about making major changes in a school or other social system. Tuma describes her early frustrations, her exposure to a “theory” of change, and the step-by-step application of the same—including how her plans had to change to meet the changing reality. And with a successful ending!     

How to make your own response boxes: A step-by-step guide for the construction of reliable and inexpensive parallel-port response pads from computer mice

Psychological research is based in large parts on response latencies, which are often registered by keypresses on a standard computer keyboard. Recording response latencies with a standard keyboard is problematic because keypresses are buffered within the keyboard hardware before they are signaled to the computer, adding error variance to the recorded latencies. This can be circumvented by using external response pads connected to the computer's parallel port. In this article, we describe how to build inexpensive, reliable, and easy-to-use response pads with six keys from two standard computer mice that can be connected to the PC's parallel port. We also address the problem of recording data from the parallel port with different software packages under Microsoft's Windows XP.     

C language functions for millisecond timing on the IBM PC

This article describes four C language functions for programming the IBM PC and compatibles for timing with millisecond precision. The technique, which is based on a reprogramming of the PC’s real time clock, requires no additional hardware, no assembly language code, and no programming of machine or software interrupts. One function restores the PC’s time-of-day clock.     

Microsecond resolution timing with Sun workstations

A high-resolution clock is often indispensable for the accurate measurement of millisecond or microsecond resolution intervals, and it is impossible to measure the probability distribution of short intervals without one. This paper describes a microsecond clock for Sun 3 and 4 workstations that we designed, built, and have made publicly available. It also explains how to measure intervals shorter than a computer’s clock resolution, and derives confidence intervals for such measurements.     

The mirroring function of the child analyst

This paper follows the progress of four years of twice-weekly psychoanalytic psychotherapy with a borderline girl aged 4 at the start of treatment. It describes how her early experience with her mother, who was ill, and her subsequent removal from her mother and placement with a foster-family led to her having severe difficulties in relating to others. Using the work of Ekstein as a framework, it follows the changes in the child’s behaviour in the therapy from acting out to playing with toys to role playing to the apparent development of her capacity to phantasize. It focuses on what the dolls’ house represented for her and how it came to be a transitional space where the inner world of the child could be represented. The play in and around the dolls’ house is described to show how she moved from playing on the outside of the dolls’ house to playing in part of the inside to using the whole house and how this seemed to parallel the development of her relationship with her therapist. Furthermore, it presents the views of a number of commentators on the use of the dolls’ house and what it represents for children in therapy and in our culture in general.     

A Commodore 64-based interface system for the operant laboratory

A system of interfaces for the Commodore 64 (C-64) microcomputer for use in the operant laboratory is described. This system frees the experimenter from limitations on the number of I/O lines available on the user port of the C-64 and offers the control of operant chambers for a low cost. Subroutines in machine code to control the interfaces, offering millisecond timing of external events, are presented. A sample BASIC program demonstrates how the subroutines are called from BASIC to run a simple discrimination experiment.     

Family Reconstruction

Family reconstruction, as described by Virginia Satir, is important for its transformative possibilities. This therapeutic tool can integrate a person into the historical and psychological matrix of his or her family of origin. This article describes how a reconstruction can be accomplished in three hours by using certain steps and principles. A case study is provided illustrating these steps and principles, including the personal reflections of the participant group.     

When I Reach the Place I'm Goin', I Will Surely Know My Way

This is a story of love and courage. As the author describes some of her most memorable experiences while traveling on the first all women's raft trip down the Grand Canyon in 1978, we learn how her love for the outdoors inspires and informs her sense of courage. She learns that courage can be gentle and "quiet" or boisterous and "noisy." She describes how the exigencies of river life require that women learn to cooperate and work together despite discord and differences, and how working together results in an increased sense of competency, self-esteem, and power.     

Windows executable software for the progressive demasking task

The progressive demasking (PDM) task is a perceptual identification task using degraded stimulus presentation procedures, but with the advantage of providing response time (RT) measures on each trial. Participants simply press a response button whenever they recognize a word. In this article, we present newly developed, easy-to-use freeware for PDM. Considering the difficulty of programming such a paradigm with standard experimental software, we developed a program based on high-level C libraries to be executed on Windows XP computers. The program execution is millisecond accurate forRT measurements and generates the fewest possible display duration errors.     

FTAP: A Linux-based program for tapping and music experiments

This paper describes FTAP, a flexible data collection system for tapping and music experiments. FTAP runs on standard PC hardware with the Linux operating system and can process input keystrokes and auditory output with reliable millisecond resolution. It uses standard MIDI devices for input and output and is particularly flexible in the area of auditory feedback manipulation. FTAP can run a wide variety of experiments, including synchronization/continuation tasks (Wing & Kristofferson, 1973), synchronization tasks combined with delayed auditory feedback (Aschersleben & Prinz, 1997), continuation tasks with isolated feedback perturbations (Wing, 1977), and complex alterations of feedback in music performance (Finney, 1997). Such experiments have often been implemented with custom hardware and software systems, but with FTAP they can be specified by a simple ASCII text parameter file. FTAP is available at no cost in source-code form.     

Dissecting the clock: understanding the mechanisms of timing across tasks and temporal intervals

Currently, it is unclear what model of timing best describes temporal processing across millisecond and second timescales in tasks with different response requirements. In the present set of experiments, we assessed whether the popular dedicated scalar model of timing accounts for performance across a restricted timescale surrounding the 1-second duration for different tasks. The first two experiments evaluate whether temporal variability scales proportionally with the timed duration within temporal reproduction. The third experiment compares timing across millisecond and second timescales using temporal reproduction and discrimination tasks designed with parallel structures. The data exhibit violations of the assumptions of a single scalar timekeeper across millisecond and second timescales within temporal reproduction; these violations are less apparent for temporal discrimination. The finding of differences across tasks suggests that task demands influence the mechanisms that are engaged for keeping time.     

Coming Out in Voices

This paper articulates the personal experiences of a woman with a physical disability who enters therapy to explore issues involving lesbian identity, health and illness, disability oppression and pride, and relationships. Written in the first person, the article uses anecdotes, poetry, and journal entries to chart the author's process of self-discovery. As a woman, a lesbian, and a person with a disability, the author frequently finds herself at odds with the culture around her. This creates conflicts between the author's real self, and the self she must present to others. She discusses how she had learned to "silence the voices" which were not useful in challenging the stereotypes, making others comfortable, or communicating with assistants. The author describes how therapy offered her the opportunity to unlearn the silence, value all of her voices, listen to herself, resolve her internal dilemmas, and develop a deeper sense of self.