A system for the assessment of human performance in concurrent verbal and manual control tasks

A multipurpose laboratory system incorporating a voice interactive terminal and graphic display system is described. The facility is designed to investigate some aspects of human performance on concurrent verbal and tracking tasks. The results of a pilot study showing decrements in dual-task performance are reported.     

Sequential precession and diminishing returns in the acquisition of a motor skill

As students progress to higher and higher levels in the acquisition of a skill their number gets smaller and smaller. This article concerns the average length of time it takes the members of these successively smaller groups to complete earlier stages of skill acquisition. In the data presented, which concern Red Cross swimming, the more advanced a group is the less time its members take on the average to complete a preceding stage (sequential precession). The discussion section brings out a second relation in the same data: Namely, the further the same students advance in skill acquisition the smaller the advantage they enjoy over other students at the same level (diminishing returns).     

Augmentation of in vivo exposure treatment for agoraphobia by the formation of neighbourhood self-help groups

The advantages of selecting agoraphobic patients for treatment by group exposure according to their residential geographic neighbourhood were evaluated in terms of facilitation of ‘homework’ practice and increased social contact. Both ‘zoned’ and ‘unzoned’ groups showed gains in ability to perform hierarchy items after 11 sessions of exposure, relative to a no-treatment control group. However only zoned subjects showed significant reductions in experienced anxiety when executing such items. Self-ratings of overall phobic severity also suggested a zoned group was superior to unzoned while assessors' ratings indicated both groups as equally improved. Only zoned subjects showed a significant increase in social range. Improvements were maintained at 3-months follow-up. No effect of treatment was found on either the Zung measure of anxious mood or on social integration.These results suggest that, where practical, zoning might offer the means for desirable continuation of intensive clinic-based group treatment as well as the benefit of extending treatment into the patients' environment as in home-based treatments. Crucial levels of group cohesion might also be increased although therapists should be prepared to negotiate resistance to a socially demanding programme from patients with significant additional social phobias.     

Analgesic and opioid involvement in the shock-elicited activity and escape deficits produced by inescapable shock

Three experiments examined the involvement of analgesic processes and endogenous opioids in the production of the shuttlebox escape acquisition and unconditioned activity deficits which follow exposure to inescapable shock. Experiment 1 found that the opiate antagonist naltrexone administered before the inescapable shock session interfered with the shuttlebox escape acquisition deficit which would normally follow. Experiment 2 found naltrexone to completely prevent the unconditioned activity deficit. The final experiment revealed that dexamethasone, a synthetic glucocorticoid which abolishes the analgesia produced by inescapable shock, reversed the activity deficit. These results indicate that endogenous opioids may be involved in the production of both the escape acquisition and activity deficits. They also suggest that the analgesia produced by these opioids may participate in the mediation of the activity deficit, even though analgesia is not involved in producing the shuttlebox acquisition deficit.     

The relation between proximity and brightness similarity in dot patterns

The Gestalt studies demonstrated the tendency to visually organize dots on the basis of similarity, proximity, and global properties such as closure, good continuation, and symmetry. The particular organization imposed on a collection of dots is thus determined by many factors, some local, some global. We discuss computational reasons for expecting the initial stages of grouping to be achieved by processes with purely local support. In the case of dot patterns, the expectation is that neighboring dots are grouped as a function of proximity and similarity of contrast, by processes that are independent of the overall organization and the various global factors. We describe experiments that suggest a purely local relationship between proximity and brightness similarity in perceptual grouping.     

An Apple II package for computer-assisted telephone interviewing

This paper describes an Apple II (an Apple-compatible) microcomputer package for a computer-assisted telephone interviewing (CATI) system. This system generates random telephone numbers within any number of exchanges that the user supplies, automatically dials the telephone, prompts the interviewer with each question, and records and permanently saves each response. It also provides a printed copy of the collected data by frequency of response in each question category. The Apple II CATI package is readily available, inexpensive, and easy to program in the BASIC language.     

Event-related brain potentials to grammatical errors and semantic anomalies

Event-related brain potentials (ERPs) were recorded while subjects silently read several prose passages, presented one word at a time. Semantic anomalies and various grammatical errors had been inserted unpredictably at different serial positions within some of the sentences. The semantically inappropriate words elicited a large N400 component in the ERP, whereas the grammatical errors were associated with smaller and less consistent components that had scalp distributions different from that of the N400. This result adds to the evidence that the N400 wave is more closely related to semantic than to grammatical processing. Additional analyses revealed that different ERP configurations were elicited by open-class (“content”) and closed-class (“function”) words in these prose passages.