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Biomedical subjects

M S Halliday

Publications and source records attributed to M S Halliday.

10 recordsLinked to original sources
PubMed1991

Speech, "inner speech," and the development of short-term memory: effects of picture labeling on recall.

Three experiments explored the effect of overt speech on children's use of "inner speech' in short-term memory (STM). Experiments 1 and 2 compared recall of a series of pictured objects when 5- and 11-year-olds either labeled stimuli at presentation or remained silent. Use of inner speech was assessed by manipulating word length of the picture names (Experiment 1) or phonemic similarity (Experiment 2). Word length and phonemic similarity had greater effects in the older children and when pictures were labeled at presentation. These tendencies were such that 5-year-olds were sensitive to word length and phonemic similarity only with labeling. Experiment 3 compared labeling by the child with labeling by the experimenter in 5-year-olds. There were no significant differences with respect to overall performance or effects of word length and phonemic similarity. It is suggested that speaking or listening to speech activates and internal "articulatory loop,' and that such activation is especially important when the child's ability to use inner speech in STM has not fully developed.

Attention↗
PubMed1990

Pharmacokinetic and pharmacodynamic interaction between the antidepressant tianeptine and oxazepam at steady-state.

To assess if any pharmacokinetic or pharmacodynamic interaction at steady-state occurs between the new antidepressant tianeptine and a benzodiazepine (oxazepam) following multiple oral dosing of both drugs, 12 healthy male volunteers entered a balanced three-way double blind cross-over study. Tianeptine (12.5 mg) and/or oxazepam (10 mg) were given three times daily for 4 days. Pharmacokinetic data within a dosing interval at steady-state showed that there were no statistically significant changes in the pharmacokinetics of either tianeptine (and its two major metabolites) or oxazepam when both drugs were co-administered. Psychometric data showed that there was no synergistic negative interaction between the two drugs and that their combination may result in beneficial effects on "alertness" and "happiness".

Adult↗
PubMed1976

Successive discrimination training with equated reinforcement frequencies: failure to obtain behavioral contrast.

In two experiments, pigeons were trained on two-component multiple schedules in which responding in one component (S(1)) was always maintained by a variable-interval schedule. In Experiment I, low response rates were reinforced in the second (S(2)) component for six master subjects. This schedule was adjusted to equate reinforcement frequencies in the two components. These subjects were compared to yoked partners, for which reinforcement in the S(2) component was made available on a variable-interval schedule whose value was determined by the master subjects. A similar procedure was used in Experiment II, where the S(2) schedule for master subjects made reinforcers contingent on the absence of responding. No evidence was found in either experiment for a behavioral contrast effect in the S(1) component attributable to response reduction in the S(2) component. A reliable contrast effect was obtained from a group of pigeons given extinction conditions in the S(2) component, which was compared to a group maintained throughout on a multiple variable-interval schedule. The results suggest that previous indications of behavioral contrast in similar situations were probably caused by uneven reinforcement distributions or reflect uncontrolled fluctuations in response rates.

Journal Article↗
PubMed1975

Disinhibition and spontaneous recovery of response decrements produced by free reinforcement in rats.

Spontaneous recovery and disinhibition were studied in 3 experiments in which, after rats had been trained to bar press on a variable interval schedule of reinforcement, response rates were reduced by the introduction either of extinction or of a response-independent (free) reinforcement schedule. Spontaneous recovery was consistently obtained in extinction, especially when session durations were long. Under free reinforcement conditions there was little sign of spontaneous recovery, even when with high reinforcement rates response reduction was almost as rapid as in extinction. In disinhibition tests the introduction of noise produced increased responding under free reinforcement conditions, but not in extinction. The results are interpreted as demonstrating a dissociation between spontaneous recovery and disinhibition.

Animals↗
PubMed1975

Response additivity: effects of superimposed free reinforcement on a variable-interval baseline.

Three experiments examined the effects of superimposing free reinforcement (Free VI 30-sec) on behavior maintained by a response dependent mult VI 2-min VI 2-min schedule of reinforcement. Experiment I used pigeons as subjects, key pecking as the response, and colors of response key as the stimuli associated with the multiple-schedule components. When free reinforcement was added during only one component (Differential condition) a large and highly significant increase in response rate developed in this component. Adding free reinforcement during both components (Nondifferential condition) produced smaller and far less-consistent effects. An entirely different pattern of results was obtained in two subsequent experiments, where similar procedures and reinforcement conditions were used with rats as subjects and bar pressing as the response. In both Experiments II and III, response rates decreased to the stimulus associated with added free reinforcement in the Differential condition. These findings are interpreted as the result of interactions between behavior maintained by response-reinforcer contingencies and behavior maintained by stimulus-reinforcer contingencies. As such, they support the main assumption of an autoshaping theory of behavioral contrast, that additivity of responding generated by the two kinds of contingency can occur only in situations favorable to autoshaping.

Journal Article↗
PubMed1974

Behavioral contrast without response-rate reduction.

Behavioral contrast was obtained in two experiments, which both employed a standard free-operant successive discrimination (a multiple variable-interval extinction schedule), without the occurrence of reductions of response rate in the extinction component. In Experiment I, one group of four pigeons was trained on a multiple schedule in which one stimulus was associated with a variable-interval schedule and the second stimulus with response-independent reinforcement on a free variable-interval schedule. Though by the end of this training three pigeons were responding very little to the second stimulus, when this stimulus was associated with extinction all subjects showed a contrast effect. In Experiment II, eight pigeons were trained extensively to respond to a single stimulus on a variable-interval schedule, before a second stimulus associated with extinction was introduced. This second stimulus was dissimilar to the initial stimulus and five pigeons never responded in its presence. Nevertheless, all pigeons showed a contrast effect and there was no evidence that the effect was smaller in errorless subjects or smaller than in a subsequent discrimination where all subjects made many errors. Both experiments indicated that response reduction in one component of a multiple schedule is not a necessary condition for the occurrence of contrast.

Journal Article↗
PubMed1971

Behavioral contrast and response independent reinforcement.

Four pigeons received pre-training that included presentation of the reinforcer independently of behavior and then baseline training on a variable-interval schedule of reinforcement. With the introduction of a multiple schedule, in which the first stimulus was associated with a response contingent and a second stimulus with a response independent, 1-min variable-interval schedule, a reduction in response rate was obtained in the second component, which was not accompanied by a behavioral contrast effect in the first component. A further three pigeons were given the same pre-training and baseline training before the introduction of an otherwise identical multiple schedule, in which no reinforcement occured in the second component. Behavioral contrast was obtained from all three subjects. The results indicated that under conditions of constant reinforcement density a reduction in responding is not a sufficient condition for the occurrence of behavioral contrast.

Journal Article↗