Biomedical subjects

H V Ruddle

Publications and source records attributed to H V Ruddle.

6 recordsLinked to original sources

PubMed1984

The effect of pentobarbitone on variable-interval performance: analysis in terms of Herrnstein's equation.

Six rats were exposed to a series of variable-interval schedules of reinforcement, each schedule specifying a different reinforcement frequency. The effects of two doses of pentobarbitone (24.16 and 40.27 mumol/kg) upon performance maintained under each schedule were examined. The data were analyzed in terms of the goodness of fit of Herrnstein's (1970) equation. Under control conditions (no injection or injection of vehicle alone) response rate was an increasing negatively accelerated function of reinforcement frequency, the data obtained from each rat conforming closely to Herrnstein's equation. In the presence of pentobarbitone there was a reduction in the value of Rmax (the theoretical maximum response rate) in all six rats. The effect of pentobarbitone upon the value of KH (the reinforcement frequency needed to obtain the half-maximal response rate) differed between animals, the value being increased in some rats and decreased in others. This was shown to reflect a systematic relationship between the baseline value of KH and the change in KH produced by pentobarbitone, high baseline values being associated with reductions, and low baseline values with elevations, in the presence of the drug. The data were also analyzed using conventional rate-dependency analysis. In some animals there was a tendency for lower response rates to be suppressed to a greater degree than higher rates, while the reverse was true in other animals. In general, rate-dependency functions provided poor descriptions of the data obtained from individual subjects.

Animals↗

PubMed1982

On the estimation of premorbid intellectual functioning: validation of Nelson & McKenna's formula, and some new normative data.

The Schonell Graded Word Reading Test (SGWRT), the Wechsler Adult Intelligence Scale (WAIS) and Raven's Standard Progressive Matrices (RSPM) were administered to 78 healthy subjects aged between 18 and 84 years. Regression equations were derived for predicting Verbal, Performance and Full-Scale IQs measured with the WAIS on the basis of a subject's score on the SGWRT, and for predicting total score on the RSPM on the basis of age and score on the SGWRT. Discrepancies between obtained and predicted scores were approximately normally distributed; z scores are presented for these discrepancies for each of the predicted variables. The equation derived for predicting Full-Scale IQ was in good agreement with the equation derived by Nelson & McKennais sample. 'Significant' discrepancies (z score greater than 1.645) between obtained and predicted Full-Scale IQs were found in approximately half of a group of patients with confirmed organic cortical damage. These results constitute a validation of Nelson & McKenna's formula for estimating premorbid IQ, and in addition provide new normative data which may be used for estimating premorbid Verbal or Performance IQ, or score on the RSPM.

Adolescent↗

PubMed1982

Performance of humans in concurrent avoidance/positive-reinforcement schedules.

Performance maintained under concurrent schedules consisting of a variable-interval avoidance component and a variable-interval positive-reinforcement component was studied in three human subjects using points exchangeable for money as the reinforcer. The rate of responding in the avoidance component increased, and the rate of responding in the positive-reinforcement component declined, as a function of the frequency of point-losses avoided in the avoidance component. The performance of all three subjects conformed to equations proposed by Herrnstein to describe behavior in concurrent schedules. The logarithms of the ratios of the response rates in the two components, and the logarithms of the ratios of the times spent in the two components, were linearly related to the logarithms of the ratios of the frequency of loss avoidance in the avoidance component to the frequency of reinforcement in the positive-reinforcement component. When a changeover delay of 5.0 sec was imposed, the slopes of the linear functions were close to 1.0 in the case of two subjects, whereas the third subject exhibited significant undermatching. For two subjects the changeover delay was then reduced to 2.0 sec; in both cases the slopes of the linear functions were lower than under the 5.0-sec condition. One subject participated in a third phase, in which no changeover delay was imposed; there was a further reduction in the slopes of the linear functions.

Journal Article↗

PubMed1981

Relationship between response rate and reinforcement frequency in variable-interval schedules: II. Effect of the volume of sucrose reinforcement.

Three rats were exposed to variable-interval schedules specifying a range of different reinforcement frequencies, using three different volumes of .32 molar sucrose (.10, .05, and .02 milliliters) as the reinforcer. With each of the three volumes, the rates of responding of all three rats were increasing, negatively accelerated functions of reinforcement frequency, the data conforming closely to Herrnstein's equation. In each rat the value of the constant K(H), which expresses the reinforcement frequency needed to obtain the half-maximal response rate, increased with decreasing reinforcer volume, the values obtained with .02 milliliters being significantly greater than the values obtained with .10 milliliters. The values of the constant R(max), which expresses the theoretical maximum response rate, were not systematically related to reinforcer volume. The effect of reinforcer volume upon the relationship between response rate and reinforcement frequency is thus different from the effect of the concentration of sucrose reinforcement: In a previous experiment (Bradshaw, Szabadi, & Bevan, 1978) it was found that sucrose concentration influenced the values of both constants, R(max) increasing and K(H) decreasing with increasing sucrose concentration.

Journal Article↗

PubMed1981

Relationship between response rate and reinforcement frequency in variable-interval schedules: III. The effect of d-amphetamine.

Four rats were exposed to variable-interval schedules specifying a range of different reinforcement frequencies. The effects of two doses of d-amphetamine (1.6 and 3.2 mumol/kg) upon performance maintained under each schedule were examined. In the case of each rat, the response rates observed under control conditions (no injection or injection of the vehicle alone) were increasing, negatively accelerated functions of reinforcement frequency, the data conforming closely to Herrnstein's (1970) equation. In each rat, d-amphetamine (3.2 mumol/kg) significantly reduced the value of the constant Rmax, which expresses the theoretical maximum response rate. In each rat, the value of KH, which expresses the reinforcement frequency needed to obtain the half-maximal response rate, was also reduced, although this only achieved statistical significance in the case of one rat. When the proportional change in response rate in the presence of the drug was plotted against the response rate under control conditions on double logarithmic co-ordinates, linear functions of negative slope were obtained; in each rat the slope was steeper and the value of the control response rate at which d-amphetamine exerted no effect was lower in the case of the higher dose (3.2 mumol/kg) than in the case of the lower dose (1.6 mumol/kg).

Animals↗

PubMed1979

The effect of signaled reinforcement availability on concurrent performances in humans.

During Phase I, three female human subjects pressed a button for monetary reinforcement in two-component concurrent variable-interval schedules. Five different reinforcement frequencies were used in component A, whereas the reinforcement frequency in component B was held constant. Absolute rates of responding conformed to equations proposed by Herrnstein to describe concurent performances, and the ratios of the response rates and the times spent in the two components conformed to the matching law. During Phase II, the availability of reinforcement in component A was signaled by the illumination of a lamp. This resulted in suppression of response rates in component A and elevation of response rates in component B, these changes being reflected in a distortion of the matching relationship which took the form of a bias in favor of component B.

Journal Article↗