Quintupling the speed of the PDP-8 DF32 disk system for real-time use

The author has noted some inefficiencies in the operation of the DF32 hardware/software disk system on the PDP-8. While such inefficiencies are not significant when the disk is used only as a store for programs which are called into core from the keyboard, they become important when the disk is used as a real-time backup for core. This paper isolates some of the problems, gives rules for avoiding them, and then describes how the system software was modified to obey these rules. The speed of the modified system is noticeable even when SAVEing and CALLing programs from the keyboard; successive blocks can be transferred between disk and core in one-fifth the previously required time.     

Intersensory effects in the psychological refractory period

Two experiments examined reaction time (RT) to each of two stimulus events separated by short interstimulus intervals (1SI). The essential contrast was RT to the second visual signal, RT₂, in auditory-visual (A-V) vs visual-visual (V-V) sequences. With response, certain pairings in Experiment 1, an effect apparently demonstrating a single-channel process (Welford, 1952), was noted. RT₂ was generally faster for A-V as opposed to V-V sequences especially when Ss were uncertain as to the sequence that would occur. At 0-msec ISI, the RT₂ difference between sequences approached the RT! difference. More rapid RT₂ to A-V sequences was also observed with go vs no-go pairings in Experiment 2 when the initial event was a go signal. However, the RT difference disappeared upon error correction, making the RT₂ sequence difference of questionable relevance to the hypothetical single-channel process. RT₂ was more rapid following a null no-go signal when the no-go signal was contrasted with a visual as opposed to auditory go signal. The latter effect was independent of error and is consistent with channel-switching theory (Kristofferson, 1967).     

Set and temporal integration

An experiment was conducted to explore the temporal structure of set formation in a complex reaction time (RT) task. On each trial an instruction [I-event] was given telling Ss whether identity of color or form on a separately presented alternative display (A-event) was the dimension relevant on that trial. The A-event consisted of a pattern of four colored forms. The two forms on one side were matched for color and on the other side for form. S’s task was to depress one of two keys. The correct key was homolateral to the matched relevant dimension. The basic independent variable was the time interval separating the I- and A-events (ISI). At short ISIs, RT wasa linear function oflSI with slope equal to -0.5. RT was independent of the order in which the events occurred at short ISIs, although at longer ISIs (3 sec) RT was longer when the A-event followed the I-event. Also, RT was shorter at short ISIs when color was the relevant dimension rather than form. although this difference disappearedat longer ISIs. The results were discussed in relation to information processing models and previous research dealing with partialadvance information.     

Effects of time and event uncertainty upon sequential information processing

Two experiments were conducted to investigate the psychological refractory period (PRP), a delay induced into the second of two reaction times (RT) when the interstimulus interval (ISI) is short. In Experiment1, time and event uncertainty were factorially varied by providing or not providing S with foreknowledge of the ISI and the order in which the two events would occur, respectively. ISIs of0, 50, 100, 200, and400 msec were used. Time and event uncertainty produced independent degradation of both RTs. Also, the second RT (RT ₂ ) was delayed at50 msec ISI when both time and event certainty were present. Experiment 2 attempted to replicate this latter finding using ISIs of0, 25, 50, 75, and100 msec. Delays in RT ₂ were found for the middle three values of ISI. These results were interpreted as supporting a modified single channel theory of the PRP.     

An analysis of U-shaped metacontrast

Using a brightness-discrimination task similar to that employed by Bernstein, Proctor, Proctor, and Schurman (1973), masking functions were obtained in two experiments. In Experiment I, test stimulus (TS) and mask stimulus (MS) energies were held constant but luminance and duration were varied reciprocally. The obtained masking functions, plotted as a function of stimulus onset asynchrony (SOA), were of an essentially identical U shape. This suggests that (a) SOA is a more suitable measure of delay than interstimulus interval, and (b) Bloch’s law holds for the requisite discrimination. In Experiment II, TS luminance and MS luminance were varied independently. This was to see whether the MS served as a frame of reference at short SOA, as suggested previously (Bernstein et al, 1973). The results were that this was, in fact, the case and that the transition from comparative to absolute judgment strategies as SOA increases is a major contributor to U-shaped masking functions.     

Bridging the HIV Divide: Stigma,Stories and Serodiscordant Sexuality in the Biomedical Age

At a time when advances in biomedicine have rendered people with HIV non-infectious under certain conditions, much public discourse on HIV remains stuck in a paradigm of ‘risk’, which does little to lessen the divide between people with and without HIV in society or challenge the way intimate relationships across this divide are typically stigmatised as undesirable and problematic. We rarely hear the stories of couples who live with mixed HIV statuses and how they themselves perceive and manage their so called ‘serodiscordance’. In this article, we examine such stories by mixed-status couples in Australia. In stark contrast to the dominant discourse, these couples invoked narratives of love, the everyday unimportance and manageability of HIV, and recent developments in HIV medicine, thereby challenging the way serodiscordant sexuality has been cast in public health research. Drawing on Ken Plummer’s work on hidden sexual stories, we consider not only the content of their stories, but the broader significance of stories to the world in which they are enacted, of storytelling as a rally for social and political recognition and legitimacy. Reflecting on our own role in the co-production of research stories, we argue that by moving marginalised sexual stories out of silence, stigmatised communities and researchers can conjointly and incrementally shape a new public discourse and new forms of ‘intimate citizenship’.     

Burnout,empathy and their relationships: a qualitative study with residents in General Medicine

Some studies have shown that burnout may have a negative impact on clinical empathy during internship. However, clinical empathy may also be a protective factor, preventing residents from experiencing burnout. Although several quantitative studies have been conducted to examine these relationships between burnout and empathy, no qualitative studies have been carried out. To examine how residents in general practice evaluate the link between burnout and empathy, 24 of them participated in a semi-structured interview. A thematic analysis was carried out to examine residents’ discourses and answers to closed questions. The results indicated that residents thought that empathy and burnout were clearly related in different ways. They identified five types of relationship: regulation strategy, empathy as protection, psychological balance/imbalance, fatigue and moderating factors.