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Biomedical subjects

E R Long

Publications and source records attributed to E R Long.

At least 37 records · Page 2Linked to original sources
PubMed1963

Chained and tandem scheduling with children.

Children 4 to 7 yr in age were reinforced with trinkets and pennies on chained and tandem schedules. The schedules used were chain DRL FR, chain DRO FR, chain FI FR, tand FI FR, and tand DRO FR. Chain DRL FR and chain DRO FR schedules almost always produced strong schedule and stimulus control, but chain FI FR schedules rarely did if additional techniques were not used. Strong control was produced with chain FI FR schedules, however, if: (a) the FR component was increased in size; (b) schedule and stimulus control was first established with chain DRL FR or chain DRO FR schedules before shifting to the chain FI FR; or (c) an external clock was attached to the FI. Tand FI FR schedules never produced regular or repeatable patterns of responding when additional procedures were not used. Rate patterns resembling those of chain FI FR schedules were produced by tand FI FR schedules, however, if: (a) an external clock was attached to the FI component or (b) control was established by means of tand DRO FR schedules before the tand FI FR was used. Stimulus control was found to be exercised by specific visual stimuli, change of stimuli, and schedule order. Control exercised by schedule order was probably mediated by the child's own behavior which had assumed discriminative stimulus properties.

Journal Article↗
PubMed1962

Additional techniques for producing multiple-schedule control in children.

The subjects in these experiments were 132 children, varying in age from 4 to 7 years. These experiments were designed to assess the efficacy of various multiple scheduling procedures in producing reliable stimulus control. The schedules studied were multiple fixed-ratio-extinction (mult FR EXT); multiple differential-reinforcement-of-other-behavior-fixed-ratio (mult DRO FR); multiple differential-reinforcement-for-low-rate-fixed-ratio (mult DRL FR); and multiple fixed-interval-fixed-ratio (mult FI FR). In addition other techniques were investigated, such as presenting FR's in blocks; increasing the size of the FR's; attaching a DRL to the FI members; temporarily shifting to new schedules; and adding an external clock to the FI's. These experiments yielded the following results.1.) Strong stimulus control was produced by mult FR EXT, mult DRO FR, and mult DRL FR schedules. Control for mult FR EXT was mediated principally by the individual stimuli, though on occasion it was dependent in part on the change of stimuli. The mult DRO FR was found to be highly useful for those children who had very high initial rates or who were generally uncooperative and unmanageable.2.) Contrary to a previous finding, some subjects were brought under stimulus control by means of mult FI FR schedules without the aid of additional procedures. Most, however, were not. Additional techniques found to augment the development of mult FI FR control included: (1) presenting FR's in blocks; (2) increasing the size of the FR's; (3) attaching a DRL to the FI component for a time and later removing it; and (4) shifting to a mult DRL FR, developing control, and then returning to the original mult FI FR.3.) Addition of an external clock to the FI components of the mult FI FR had several effects. Strongest control, including well-developed acceleratory patterns during the FI's, was developed in those subjects who had first been shifted from a regular mult FI FR to a mult FR EXT, brought under control, and then returned to the mult FI FR with the clock added. The added clock also produced strong control if it was present when the subject was first begun on a mult FI FR schedule. In some cases, the addition of the clock produced control in subjects who had not been controlled previously by the regular mult FI FR, but these were always subjects who had high rates. The addition of the clock first lowered the rate, then produced control.

Journal Article↗
PubMedDate not supplied

Toxicity of surficial sediments from Sydney Harbour and vicinity, Australia.

The toxicological responses of three species to 103 surficial saltwater sediment samples from Sydney Harbour, and coastal lakes and estuaries on the south-east coast of New South Wales, Australia, were tested in a battery of four to six laboratory toxicity tests. This is the first large-scale toxicological study of sediments in Australia, the objective of which is to assess the protective and predictive abilities of North American biological effects-based sediment quality guidelines, recently adopted in Australia. Amphipods were exposed to whole sediments in survival and reburial tests, sea urchin fertilisation and larval development tests were conducted on porewaters, and bacterial bio-luminescence (Microtox) tests were conducted on organic solvent extracts and porewaters. Local indigenous species were used for the amphipod and sea urchin tests (Corophium sp. and Heliocidaris tuberculata, respectively). A wide range of responses, from <25 to 100% of negative controls were observed in all tests. Mean control-adjusted responses ranged from 46 to 96% for all tests. The percentages of highly toxic samples ranged from 11 to 83% in the various tests. The order of test sensitivity was: amphipod survival < Microtox test of porewaters < amphipod reburial < sea urchin larval development < sea urchin fertilisation < Microtox test of solvent extracts. Concordance between toxicity tests in classifying samples as highly toxic or not, ranged from 47 to 79%, indicating some similarities between test results, but not complete equivalence. Combined toxicity test results showed that the incidence of highly toxic responses occurring in the majority of tests (75-100% of tests) was low (5% of samples), but a large percentage of samples had highly toxic results in at least one test (76% of samples). Toxicity was more pervasive in the Sydney region than in coastal lakes and estuaries south of Sydney. The current study demonstrated the utility of indigenous invertebrate species and the Microtox bacterium in a sediment toxicity test battery for Australian saltwater sediments.

Animals↗
PubMedDate not supplied

An approach to brief field testing for neurotoxicity.

A description is offered for a microcomputer-based testing system which utilizes an Apple II microcomputer with the Pascal language and additional hardware resources. Tasks implemented for the system have been selected to broadly sample cognitive functioning with some sensory and motor evaluation as well. Efforts to evaluate sensitivity, task interrelations, and reliability of measurement are described.

Cognition Disorders↗