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Biomedical subjects

G Woodruff

Publications and source records attributed to G Woodruff.

43 records · Page 3Linked to original sources
PubMed1977

Associative interaction: joint control of key pecking by stimulus-reinforcer and response-reinforcer relationships.

The joint control of rate of key pecking in pigeons by stimulus-reinforcer and response-reinforcer relationships was studied in the context of a two-component multiple schedule of reinforcement. Food presentation was always associated with one component and extinction with the other. The stimulus-reinforcer relationship was manipulated by varying the relative durations of the two components. In the food-presentation component, a fixed rate of reinforcement, independent of rate of responding, was generated by a schedule referred to as "T*". One aspect of the response-reinforcer relationship, contiguity, was manipulated by varying the percentage of delayed reinforcers. With the multiple T* extinction schedule, stimulus-reinforcer and response-reinforcer relationships could be varied independently of one another. Rate of key pecking was sensitive to manipulations of both relationships. However, significant differential effects due to either the stimulus-reinforcer or response-reinforcer relationship were obtained only when the other relationship was weak: stimulus-reinforcer and response-reinforcer relationships interacted in the joint control of responding.

Journal Article↗
PubMed1976

The associative relation underlying autoshaping in the pigeon.

Fifteen pigeons were exposed to either response-independent or response-dependent schedules of water reinforcement, whereby water was injected directly into the unrestrained pigeons' mandibles. Key-contact responses were released by a lighted key correlated with water, but not by a lighted key uncorrelated with water. A negative response-reinforcer contingency suppressed autoshaped key-contact responses, resulting in responding directed away from the lighted key. In all pigeons, water injected directly into the mandibles elicited a consummatory fixed-action pattern of "mumbling" and swallowing. The lighted key correlated with water released a broader set of both appetitive and consummatory responses: approach to the lighted key, "bowing", "rooting", "mumbling", and swallowing. Key-contact responses were "rooting" and "mumbling" motions of the beak on the surface of the key. Views of autoshaping based on stimulus substitution or stimulus surrogation do not fully explain the origin of autoshaped responses not previously elicited by the reinforcer. The present findings are consonant with views of conditioning that emphasize the large degree of biological pre-organization in conditioned response patterns, and the importance of associative factors in the control of such patterns.

Journal Article↗
PubMedDate not supplied

Horner's syndrome in children.

Ten cases of Horner's syndrome with pharmacologic testing and computed tomography scans are described in patients up to age 8 years. The patients also were assessed for iris color and facial sweating. Classical preganglionic Horner's syndrome associated with brachial plexus birth injury was not identified in any case. Two patients who presented with ptosis had neuroblastoma. Two other children had undergone corrective cardiothoracic surgery. Two patients had major congenital abnormalities. In four patients, no cause of Horner's syndrome was determined.

Adrenergic Fibers↗
PubMedDate not supplied

Factors affecting treatment compliance in amblyopia.

Amblyopia is the most common form of visual disability in children. Successful treatment by patching depends on compliance, but evidence of factors affecting compliance is limited and contradictory. Because there is a well established relationship between social deprivation and access to health care, we hypothesized that social deprivation might be associated with noncompliance. Data from a historical cohort of 961 children from seven English orthoptic clinics starting treatment for amblyopia in 1983 were used to study factors affecting compliance with amblyopia treatment. Children were classified as noncompliant if they failed to attend all appointments prescribed during the first year of treatment. There was a significant difference in compliance between centers (P = .0001). Overall, children with anisometropic amblyopia were more compliant than those with strabismus but this varied significantly between centers. A relationship between social deprivation and compliance was also found (P = .00001). Only 41% of children from the most deprived wards were compliant compared with 61% in the least deprived wards. Compliance was not found to be related to age at starting treatment.

Amblyopia↗
PubMedDate not supplied

Cross polarized spectacles in photosensitive epilepsy.

PURPOSE: To investigate the role of cross polarized spectacles in the treatment of photosensitivity demonstrable by EEG. METHOD: Patients receiving an EEG who tested positive for photosensitivity were invited to participate in the study. The most sensitive light flicker frequency causing a photic response was determined for each patient. Stimulation was repeated with 2 different pairs of spectacles--1 conventionally polarized and the other cross polarized. An EEG was obtained in each case and reported by a neurophysiologist who was unaware of the identity of the 2 types of spectacles. RESULTS: We tested 19 patients, 8 to 18 years of age. Two patients did not benefit from either pair of glasses. In 17 patients, the photic response was greatly diminished or eliminated by polarizing spectacles. In 1 patient, conventional polarized glasses helped, but the cross polarized spectacles did not. In 6 patients, both types of spectacles were equally effective; in 10 patients, cross polarized spectacles were more effective than conventionally polarized spectacles. CONCLUSION: The role of cross polarized spectacles in the management of photosensitivity in a clinical situation merits further investigation.

Adolescent↗