Behavioral effects of microwave reinforcement schedules and variations in microwave intensity on albino rats

The objective of this exploratory investigation was to determine the interactive effects of fixed-ratio scheduling of microwave reinforcement in tandem with changes in microwave intensity. Nine albino rats were conditioned to regulate their thermal environment with microwave radiation while living in a Skinner (operant conditioning) Box in which the ambient temperature was about 27.13 degrees F at the beginning of the session. Each rat obtained a 6-sec. exposure of microwave radiation on a fixed-ratio schedule of MW reinforcement, the values of which varied from FR-1 to FR-30. Intensities of MW radiation were 62.5 W, 125 W, 250 W, and 437.5 W. Sessions lasted for 8 to 9 hr. over an approximate 13-mo. period. The effects of the intensity of microwave reinforcement varied as a function of the ratio value of the schedule used. Continuous reinforcement (FR-1) produced the lowest over-all rates, whereas FR-15, and FR-25 produced the highest over-all rates. Relatively higher thermal-behavior rates occurred under 62.5 W than under any of the other MW intensities for FR-1, FR-15, and FR-25, whereas FR-10 and FR-30 ratios produced intermediate rates of thermal responding which were constant for all values of MW intensity. These data are explained in terms of interactive effects between the "local" satiation or deprivation properties of the MW intensity and the ratio requirements of the schedule of MW reinforcement.     

First in,first out: Word learning age and spoken word frequency as predictors of word familiarity and word naming latency

This study is concerned with recent claims that subjective measures of word frequency are more suitable than are standard word frequency counts as indices of actual frequency of word encounter. A multiple regression study is reported, which shows that the major predictor of familiarity ratings is word learning age. Objective measures of spoken and written word frequency made independent contributions to the variance. It is concluded that rated familiarity is not an appropriate substitute for objective frequency measures. A multiple regression study of word naming latency is reported, and shows that rated word learning age is a better predictor of word naming latency than are spoken word frequency, written word frequency, rated familiarity, and other variables. Possible theoretical explanations for age-of-acquisition effects are discussed and it is concluded that early-learned words have a more complete representation in a phonological output lexicon. This conclusion is related to relevant developmental literature.     

Mechanisms underlying retarded emergence of conditioned responding following inhibitory training: evidence for the comparator hypothesis

The comparator hypothesis posits that conditioned responding is determined by a comparison at the time of testing between the associative strengths of the conditioned stimulus (CS) and stimuli proximal to the CS at the time of conditioning. The hypothesis treats all associations as being excitatory and treats conditioned inhibition as the behavioral consequence of a CS that is less excitatory than its comparator stimuli. Conditioned lick suppression by rats was used to differentiate four possible sources of retarded responding to an inhibitory CS. These include habituation to the unconditioned stimulus (US), latent inhibition to the CS, blocking of the CS-US association by the conditioning context, and enhanced excitatory associations to the comparator stimuli. Prior research has demonstrated the first three phenomena. Therefore, we employed parameters expected to highlight the fourth one--the comparator process. In Experiment 1, our negative contingency training was shown to produce a conditioned inhibitor that passed inhibitory summation and retardation tests. In Experiment 2 we found transfer of retardation from an inhibitory CS to a novel stimulus when the location where retardation-test training occurred was excitatory, which is indicative of contextual blocking and/or comparator effects. In Experiment 3, extinction of the conditioning context was found to attenuate retardation regardless of whether extinction occurred before or after the CS-US pairings of the retardation test. This indicates that much of the present retardation was due to the comparator process rather than to contextual blocking. Experiment 4 demonstrated that habituation to the US did not contribute to retardation in the present case. Collectively, these studies suggest that retardation following inhibitory training can be explained without recourse to any of the traditional mechanisms of conditioned inhibition.     

Methylphenidate and cognitive therapy with add children: A methodological reconsideration

The present doubleblind study examined the effects of methylphenidate, cognitive therapy, and their combination in attention deficitdisordered (ADD) children. Four treatment groups were compared on measures of attentional deployment and cognitive style, tests of academic achievement, and behavioral rating scales. In contrast to a previous study conducted in this laboratory, children in this study were not receiving medication during posttesting. Results were interpreted to suggest that measurable effects of stimulant medication dissipate rapidly upon discontinuation of pharmacotherapy. The combination of methylphenidate and cognitive therapy was not found to be any more efficacious than either of the treatments studied alone. Discussion suggests that medication status at follow-up is an essential feature of research design.This research was supported in full by U.S. Public Health Service Grant No. MH 37-628 from the National Institute of Mental Health, Psychopharmacology Branch, and by Biomedical Research Award No. RR 0715807 from the National Institutes of Health, each awarded to R. T. Brown. Placebo and methylphenidate were supplied by CIBA-GEIGY, Summit, New Jersey. The authors are grateful to Dr. Rute Medenis and the entire staff at the University of Illinois Pediatrics Clinic for their valuable assistance and kind support throughout the project. The authors would also like to thank Avery L. Spunt, R.Ph., College of Pharmacy, University of Illinois, for his assistance in packaging the medication and monitoring compliance; Arthur I. Neyhus, Ph.D., Coordinator of Child Study Facility, University of Illinois at Chicago, for his assistance in evaluation; and J. Scott Allen, Jimmy Bruce, Robert Miller, Michael Mazius, and Steven Orenczuk, for their assistance in training of the children.The contributions of these authors are equal.     

Gender and time variations in medical students' value development

A classic study by Becker and Geer proposed that medical students underwent cycles of value development during medical school. Initially, high levels of humanitarianism declined then re-emerged as students neared graduation. Declines in humanitarianism were accompanied by increased interest in extrinsic rewards. This paper examines value development in medical school for 200 men and women recent graduates. Questionnaire data collected at three times were used to develop scales of students' orientations toward humanitarianism and extrinsic rewards. We find partial verification for value-change patterns described by Becker and Geer, but gender variations are stronger than time variations. Women showed stronger humanitarianism and stronger interest in work conditions at all times than did men. Interest in extrinsic rewards increased for students of both genders but never surpassed humanitarianism in relative importance.The authors appreciate aid in data analysis from Daniel Duross and Tod Sloan and comments on earlier drafts on the paper by Camille Wortman and Roland K. Hawkes. The research was supported partially by a grant from the Spencer Foundation. An earlier version of the paper was presented at the American Sociological Association Meeting in Detroit.     

Relative durations of conditioned stimulus and intertrial interval in conditioned suppression.

The effects of the relative durations of the conditional stimulus and the intertrial interval on bar pressing during a conditioned-suppression procedure were examined as a function of two additional variables--type of operant baseline schedule and rate of shock presentation. In Experiment 1, response suppression was compared across components of a multiple fixed-ratio, random-ratio, fixed-interval, random-interval schedule, at relative conditioned-stimulus/intertrial-interval durations of 1/1, 1/4, and 1/9. In Experiment 2, relative conditioned-stimulus/intertrial-interval duration (1/5, 3/3, or 5/1) was manipulated across groups, while shock frequency (2, 6, or 10 shocks/hr) was manipulated within groups. In both experiments, suppression during the signal was virtually complete at all relative durations. Responding was also suppressed during the intertrial interval, but that suppression varied as a function of experimental manipulations. In Experiment 1, intertrial-interval response rates were higher when relative signal duration was 1/9 than when it was 1/1, although both relative signal duration and shock frequency, which covaried, could have contributed to the difference. In Experiment 2, the patterning of response rates between successive shocks was affected by relative duration, absolute rates during the intertrial interval varied as a function of shock frequency, and differences between suppression during the signal and suppression during the intertrial interval were affected by both relative duration and shock frequency. The data support an analysis based upon relationships between shock-correlated and intertrial-interval stimuli and, as assessed by the relative-delay-to-reinforcement metric, are comparable to results that have been reported from experiments using similar manipulations under the autoshaping paradigm.     

Escape from serial stimuli leading to food

If the functional relations governing the strength of a conditioned reinforcer correspond to those obtained with other Pavlovian procedures (e.g., Kaplan, 1984), the termination of stimuli appearing early in the interval between successive food deliveries should be reinforcing. During initial training we presented four key colors, followed by food, in a recurrent sequence to each of 6 pigeons. This established a baseline level of autoshaped pecking. In later sessions, we terminated each of these colors or only the first color for a brief period following each peck, replacing the original color with a standard substitute to avoid darkening the key. Pecking decreased in the presence of the last color in the sequence but increased in the presence of the first. In accord with contemporary models of Pavlovian conditioning, these and other data suggest that the behavioral effects of stimuli in a chain may be better understood in terms of what each stimulus predicts, as measured by relative time to the terminal reinforcer, than in the exclusively positive terms of the traditional formulation (Skinner, 1938). The same model may also account for the initial pause under fixed-interval and fixed-ratio schedules of reinforcement.     

Variations in size of the visual field in which targets are presented: An attentional range effect

In Experiment 1, subjects responded with a buttonpress to a target letter O embedded in a pair of vertical lines. A flanker control method was used to constrain the location and size of the initial attentional focus. The target could appear in one of five locations within a particular horizontal range. There were five ranges, varying from 1.7° to 8.6° in visual angle. Reaction time measures to the target exhibited V-shaped curves, with the lowest reaction time corresponding to the location of the initial focus of attention. The slopes of the curves decreased monotonically with target ranges. Reaction time measures at the extreme locations of the five ranges showed no significant increase with eccentricity, indicating that the influence of retinal sensitivity is negligible in this identification task as compared with the influence of other, presumably attentional, processes. Experiment 2 indicated that within a given range the slopes of the reaction time curves are independent of the number of locations probed. Additional evidence for the attentional range effect was given in Experiments 3 and 4, in which the tasks were detection of an asterisk both with and without flanking vertical lines and identification of the letter O with and without flanking lines. These results do not conform to predictions of a shifting focus theory of attention with the velocity of the focus assumed to be constant, or to the predictions of a gradient theory with total processing capacity assumed to be fixed.     

Effects of preparatory information about sensations, threat of pain, and attention on cold pressor distress.

Pain experience is conceptualized as a combination of stimulus sensations (e.g., aching) and emotional distress. In Experiment 1, less distress was reported to cold pressor stimulation by subjects first told about stimulus sensations than by subjects who were uninformed or were told about symptoms of bodily arousal (e.g., tension). Adding a pain warning to sensation information blocked distress reduction, presumably by eliciting an emotional interpretation of the stimulus. In Experiment 2, subjects attending only to hand sensations reported less distress than subjects attending to their bodies. This decrease in the power of the stimulus to provoke emotion is presumably mediated by a schema of hand sensations formed by attention. In Experiment 3, subjects attending to hand sensations early in the immersion and distracting themselves later reported the same low levels of distress as did subjects who attended to hand sensations throughout. Subjects distracted throughout and subjects attending to hand sensations later showed no distress reduction. Therefore, stimulus schematization must precede distress reduction. Implications for distress control are discussed.     

The sin of subjectivism: A reply to Shapiro

Shapiro criticises our book on two grounds. He first outlines a series of mistakes. None of them we believe, in fact, have been made and this is usually quite clear from our book. His second criticism rejects our ‘subjectivist’ approach to measurement. We argue that he misrepresents our methods and fails to grasp their ability both to collect accurate data and deal adequately with possible sources of bias. Indeed in these, in its attention to the dating of both independent and dependent variables, and in the flexibility of its approach to the respondent, we feel our approach is better equipped than other existing instruments to tackle the problem of the aetiological role of psycho-social factors in illness.