Jo W. Tombaugh

Effects of dopamine receptor blockade on alimentary behaviors: Home cage food consumption, magazine training, operant acquisition, and performance

Administration of the dopamine receptor blocker pimozide (1.0 mg/kg) disrupted the initiation, but not the maintenance, of home cage food consumption. Likewise, the number of pellets consumed during magazine training was decreased among pimozide-treated rats during the first, but not the second day of training. The acquisition of a bar-press response for food reinforcement (using a retractable bar) was severely retarded by pimozide. However, such an impairment was not evident if animals initially received 2 training days in the absence of the drug. Further, among rats trained to bar press to asymptote using a nonretractable bar, pimozide reduced the within and between days bar-press rate such that performance was indistinguishable from that of animals placed on extinction in the absence of the drug treatment. When transferred from the pimozide treatment to extinction in the absence of drug, the response rate increased to the level observed during the first session of either extinction or pimozide in the continuous reinforcement condition. The results are discussed in terms of sensory-motor and reinforcement consequences of dopamine receptor blockade.

Extinction and dopamine receptor blockade after intermittent reinforcement training: Failure to observe functional equivalence

Response decrements in an operant task produced by either extinction or by the dopamine receptor blocker pimozide were examined in three experiments which employed intermittent reinforcement schedules. In contrast to the congruency between these treatments previously observed following continuous reinforcement training, treatment with pimozide was markedly more effective than extinction in decreasing performance after training with variable interval, fixed interval, and fixed ratio reinforcement. The two treatments also produced substantially different patterns of responding. A shift from extinction to pimozide did not alter the progressive decline in response rate over days, but a shift from pimozide to extinction caused a pronounced increase of performance. These results indicate that the pimozide and extinction treatment did not produce functionally equivalent effects, and that the role of dopamine on reward processes should not be inferred from comparisons between pimozide and extinction.

Measuring the true cost of command selection: techniques and results

A technique that measures the impact of command selection on task time and errors is described. Users were timed while performing a drawing task, then while performing the same task with interpolated command selections. The difference between these times, consisting of both the time to select the command and to resume drawing, is the time cost of command selection. Several interface configurations were evaluated with this method including selected combinations of single mouse, two mice, voice and touch. Touch and voice input resulted in faster command selection times (approximately 1 sec) than any of the mouse conditions (approximately 3 sec).

Multi-window displays for readers of lengthy texts

Abstract Two experiments explore whether it would help readers re-locate information in an “electronic book” if different windows on the screen were used to display specific sections of the text. Experiment 1, using a within-subject design, showed that reading and question answering were faster with a single window than with a multi-window display. Experiment 2, in which procedural skills were developed before starting the experiment, and a between-subject design was used, showed that this advantage for the single window display would not generally be the case. The multi-window display was a significant help to readers relocating information once they were familiar with the procedures for manipulating the text. The studies suggest ways in which the display of lengthy electronic texts may be improved. They also illustrate the ease with which misleading results can be obtained in studies of human-computer interaction, and emphasize the need for establishing adequate levels of procedural skill before exploring display characteristics.

Failure to obtain functional equivalence between dopamine receptor blockade and extinction: Evidence supporting a sensory-motor conditioning hypothesis

The effects of pimozide were tested in a discrete trial paradigm. Following 8 days of continuous reinforcement training with a retractable bar, subjects were divided into 3 groups: Vehicle-Extinction; Pimozide-Extinction and Pimozide-Reinforcement. Pimozide rats received 1 mg/kg of drug 4 hours prior to test. On each of 3 test days reinforcement continued to be delivered on a continuous reinforcement schedule for the Pimozide-Reinforcement Group whereas it was no longer delivered for the other two groups. Each test day was separated by 4 drug-free days. The Pimozide-Reinforcement Group showed the least response suppression, followed by the Vehicle-Extinction and Pimozide-Extinction Groups. These results do not support the anhedonic hypothesis that dopamine containing neurons mediate reward processes and were interpreted within a sensory-motor conditioning framework.

Comparison of two information retrieval methods on videotex: Tree-structure versus alphabetical directory

Videotex systems are two-way communnication systems intended to give users access to large amounts of stored information from their homes and offices. These systems link computer databases to modified television sets over the telephone network. A central computer is used as a large information storage device, monitoring requests for information from several users at one time, finding and sending the information to the person who requested it. It is possible however, that the addition of an inexpensive supplement to the hierarchical tree search will improve user search performance without substantially altering the cost-benefits of the menu selection approach. One such method of retrieval is the on-line alphabetical directory approach where users look for a search term from a list of alphabetically organized items by menu selection. An example will indicate the difference between this method and a typical hierarchical search:

Psychological research on videotex

Videotex is considered to be a powerful, but simple to use, computer network available for use in homes, offices, and schools. Information in the form of text and color graphics can be requested and displayed on the user’s television set. While retrieval of information is the first service provided on videotex, many other services, including electronic mail, electronic shopping, and electronic funds transfer, will be developed. However, in order to achieve the popularity predicted for videotex, a number of human factors and social problems must be solved. Research concerning some of these problems, and the role psychologists can play in their solution, is described.

The effect of VDU text-presentation rate on reading comprehension and reading speed

The effect of video display unit presentation rate on reading performance was investigated. Reading material was presented at one of the following presentation-rates: 15, 30, 120, 960 cps, or “instant”. In the instant condition, the full text appeared simultaneously on the screen. In the other conditions, text appeared one character at a time starting in the upper left corner of the screen, from left to right and top to bottom. Reading comprehension was highest under the 30 cps and instant presentation conditions. Total time to perform the reading task was equivalent for all conditions except the 15 cps rate which required a longer time to complete the task. In terms of comprehension and time to perform the task, a slow rate of 15 cps, contrary to previous recommendations, is not desirable for novice computer users.

Goal Setting And User Testing To Ensure A PACS Interface Satisfactory To Radiologists

To be successful, a Picture Archiving Communication System (PACS) workstation must have a user interface which is easy for radiologists to use. This paper describes the iterative design methodology used in the Integrated Radiology Information System (IRIS) project to achieve an easy to use system. Iterative design involves the radiologists in the design effort throughout the project. Iterative user interface design requires a number of activities: goal setting, identification of important user interface issues, prototyping, structured user testing, evaluation of user-test results against the goals, and further prototyping if the goals are not met. These stages are described in detail with examples taken from the IRIS project.

Videotex and the disabled

Abstract The potential of videotex for use by the disabled, and problems in the use of videotex by the disabled are summarized and discussed. Videotex is a system which allows users to access a powerful central computer over the telephone lines using a keypad or keyboard for input and a colour television set for output. In the home, office or hospital, the disabled will have access to information retrieval, electronic mail, teleshopping, games and computer aided instruction, as well as environmental monitoring and control using widely available, low cost equipment. The special problems of input and output of videotex by blind, deaf and motor impaired individuals are discussed. Various hardware (i.e. equipment) and software (i.e. programming) techniques to overcome these problems are described.