Biomedical subjects
Publications and source records attributed to S R Scobie.
For both male and female Sprague-Dawley albino rats, shock detection thresholds decreased as a function of age over a range of 90 to 660 days of age. Shock escape thresholds also were found to vary inversely with age. The findings are discussed in light of previous shock threshold experiments and in terms of implications for studies of age-related learning changes.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Goldfish were trained to swim back and forth in a shuttle tank to avoid unsignalled shocks. The response-shock interval and the shock-shock interval were always of equal duration; both were either 15, 30, 45, or 60 sec. Response rates varied inversely with response-shock-shock-shock interval duration, as has been found with rats. Percentage of shocks avoided was somewhat lower at the 15 sec response-shock-shock-shock interval, but otherwise did not vary systematically with changes in the interval. As the response-shock-shock-shock interval increased, the fish made increasingly more responses than necessary to avoid all shocks. Interresponse-time distributions showed that response probability rose to a maximum at about 15 to 25 sec after a response, regardless of the response-shock-shock-shock interval. Thus, at the longer intervals the fish were responding too early in the response-shock-shock-shock interval to minimize response rates.
To determine the effects of variable-interval shock punishment on behavior maintained by variable-interval and variable-ratio reinforcement, human subjects' key-pressing behavior was reinforced with money on a four-component multiple schedule. Components 1 and 2 were variable-interval 30-sec, and Components 3 and 4 were variable-ratio 210. After responding was stabilized, response-contingent electric shock was scheduled on a variable-interval 10-sec schedule during the second and fourth components of each cycle. Subjects instructed as to the reinforcement contingencies showed gradually increasing suppression of variable-interval responding at increasing shock intensities and either very high or very low rates of variable-ratio responding at higher intensities. Minimally instructed subjects showed suppression at higher shock intensities, but no clear differential suppression as a function of reinforcement schedule. Recovery from initial suppression was observed within sessions.