Antialiasing: A technique for smoothing jagged lines on a computer graphics image—an implementation on the Amiga

Images displayed on computer graphics displays often suffer from the presence of aliasing artifacts that give a jagged appearance to lines or polygon edges displayed on the screen. This paper details the problems associated with these artifacts and presents a method for drawingantialiased lines—ones in which the artifacts have been considerably reduced. The line-drawing routine is further developed to incorporategamma correction, to take into account the nonlinear relationship between the intensity of the light emission from the phosphor of the monitor and the grayscale values used to control the intensity on the screen.     

Geophysical variables and behavior: LXVIII. Distal and lunar variables and traffic accidents in Saskatchewan 1984-1989.

The daily total number of traffic accidents and traffic accident severity for the years 1984 to 1989 in Saskatchewan were analyzed to estimate relationships with day of the week, season of the year, and various lunar variables (lunar phase, distance of the moon from the earth, and moon-sun tidal index). A regression model with both a linear term and a trigonometric term was fitted to the data. No relationship between lunar cycles and total accidents or severity of accident was found. A larger number of total accidents was found during the winter months and weekends; however, more severe accidents tended to occur during the summer months. A slight linear trend was uncovered for total accidents over the time period under consideration.     

SUPPORTED EMPLOYMENT AS AN INTERVENTION PACKAGE: A PRELIMINARY ANALYSIS OF FUNCTIONAL VARIABLES

In this two-experiment investigation, the long-term (at least 6 months) employment of 51 moderately mentally retarded clients who were placed into 64 supported employment positions was first evaluated relative to 10 training and posttraining components that comprised a supported employment training package. In Experiment 1, chi-square analyses were used to identify three components that differentiated successful (employed for at least 6 months) from unsuccessful clients. In Experiment 2, 4 successful clients were further evaluated in a nonconcurrent multiple baseline design to determine whether the three variables identified during the group analysis (client advocate, collateral behavior, and follow-up plan) were included in the training packages. These results are discussed in terms of the need to establish better the functional variables of supported employment training programs.     

Transfer of an escape response from tail shock to brain-stimulated attack behavior

Nine cats, each with two hypothalamic electrodes in sites which when stimulated produced either quiet attack or attack accompanied by certain forms of vocalization, were trained to escape from tail shock by jumping onto a stool. They were then tested for transfer of the escape response to brain stimulation. Stimulation of the seven sites that yielded quiet biting attack did not elicit the learned response of jumping onto the stool. Stimulation of eight of the 11 sites that yielded attack accompanied by vocalization did elicit the learned response. It was concluded that attack behavior elicited by brain stimulation should not be considered a special case of the response to aversive stimulation, but that attack and response to aversive stimulation involve independent but overlapping systems.     

Stability of the personality and symptom scales of the Millon Clinical Multiaxial Inventory

This study examines the stability of the basic and pathological personality and symptom scales of the Millon Clinical Multiaxial Inventory (MCMI) in three clinical samples. Consistent with the theory upon which the MCMI is based, higher stability estimates were found among basic personality scales in comparison with symptom scales. However, stability estimates which included initial MCMI administrations at intake into treatment were generally lower than those based upon administrations which occurred later in the treatment process. This later finding suggests the need to consider timing of administration when interpreting the MCMI.     

Imitation of hierarchical action structure by young children

To provide the first systematic test of whether young children will spontaneously perceive and imitate hierarchical structure in complex actions, a task was devised in which a set of 16 elements can be modelled through either of two different, hierarchically organized strategies. Three-year-old children showed a strong and significant tendency to copy whichever of the two hierarchical approaches they witnessed an adult perform. Responses to an element absent in demonstrations, but present at test, showed that children did not merely copy the chain of events they had witnessed, but acquired hierarchically structured rules to which the new element was assimilated. Consistent with this finding, children did not copy specific sequences of actions at lower hierarchical levels.