scholarly journals Factors affecting rats’ location during conditioned suppression training

1994 ◽  
Vol 22 (3) ◽  
pp. 302-308 ◽  
Author(s):  
Rick A. Bevins ◽  
John J. B. Ayres
1969 ◽  
Vol 24 (2) ◽  
pp. 375-387 ◽  
Author(s):  
Wendon W. Henton ◽  
Charles L. Salzberg ◽  
John J. Jordan

Two rhesus monkeys were exposed to conditioned suppression training in which a 20-sec. stimulus, terminated by unavoidable shock, was superimposed upon a variable interval 90-sec. reinforcement schedule. A concurrent response which had no programmed consequence was recorded during initial variable interval training, acquisition, extinction, and reacquisition of conditioned suppression of the reinforced lever-pressing response. A peak in the distribution of response 2 reliably occurred 30 to 75 sec. following the average lever-pressing (response 1) reinforcement interval. With suppression training, the presentation of the suppression stimulus was reliably followed by a changeover from response 1 to response 2; the presentation of the unavoidable shock immediately resulted in a changeover from response 2 to response 1. The rate of response 2 during the suppression stimulus declined to near zero during extinction of conditioned suppression and increased to a high rate when the suppression stimulus was again terminated by unavoidable shock. The rate of response 2 was dependent upon the intensity of the unavoidable shock.


1992 ◽  
Vol 20 (1) ◽  
pp. 8-16 ◽  
Author(s):  
Rick A. Bevins ◽  
John J. B. Ayres

1977 ◽  
Vol 9 (5) ◽  
pp. 373-376 ◽  
Author(s):  
A. E. Roberts ◽  
Karol G. Cooper ◽  
Tonya L. Richey

1977 ◽  
Vol 29 (1) ◽  
pp. 71-83 ◽  
Author(s):  
Anthony Dickinson

Four groups of rats received conditioned suppression training in which a tone and light compound was reinforced with shock. If the light had been previously paired with free food, enhanced fear conditioning accrued to the tone during compound training relative to control groups pre-exposed to the light alone, the light semi-randomly associated with food, or the light unpaired with food. The second experiment replicated the difference in aversive conditioning for the groups receiving the light either paired or unpaired with food. The results are discussed in terms of the functional similarity of a conditioned excitor for food and a conditioned inhibitor for shock.


Author(s):  
F. A. Heckman ◽  
E. Redman ◽  
J.E. Connolly

In our initial publication on this subject1) we reported results demonstrating that contrast is the most important factor in producing the high image quality required for reliable image analysis. We also listed the factors which enhance contrast in order of the experimentally determined magnitude of their effect. The two most powerful factors affecting image contrast attainable with sheet film are beam intensity and KV. At that time we had only qualitative evidence for the ranking of enhancing factors. Later we carried out the densitometric measurements which led to the results outlined below.Meaningful evaluations of the cause-effect relationships among the considerable number of variables in preparing EM negatives depend on doing things in a systematic way, varying only one parameter at a time. Unless otherwise noted, we adhered to the following procedure evolved during our comprehensive study:Philips EM-300; 30μ objective aperature; magnification 7000- 12000X, exposure time 1 second, anti-contamination device operating.


Author(s):  
Christine M. Dannels ◽  
Christopher Viney

Processing polymers from the liquid crystalline state offers several advantages compared to processing from conventional fluids. These include: better axial strength and stiffness in fibers, better planar orientation in films, lower viscosity during processing, low solidification shrinkage of injection moldings (thermotropic processing), and low thermal expansion coefficients. However, the compressive strength of the solid is disappointing. Previous efforts to improve this property have focussed on synthesizing stiffer molecules. The effect of microstructural scale has been overlooked, even though its relevance to the mechanical and physical properties of more traditional materials is well established. By analogy with the behavior of metals and ceramics, one would expect a fine microstructure (i..e. a high density of orientational defects) to be desirable.Also, because much microstructural detail in liquid crystalline polymers occurs on a scale close to the wavelength of light, light is scattered on passing through these materials.


1990 ◽  
Vol 54 (11) ◽  
pp. 638-643 ◽  
Author(s):  
PC Damiano ◽  
ER Brown ◽  
JD Johnson ◽  
JP Scheetz

1976 ◽  
Vol 7 (4) ◽  
pp. 207-219 ◽  
Author(s):  
Constance P. DesRoches

A statistical review provides analysis of four years of speech therapy services of a suburban school system which can be used for comparison with other school system programs. Included are data on the percentages of the school population enrolled in therapy, the categories of disabilities and the number of children in each category, the sex and grade-level distribution of those in therapy, and shifts in case-load selection. Factors affecting changes in case-load profiles are identified and discussed.


2019 ◽  
Vol 62 (5) ◽  
pp. 1243-1257 ◽  
Author(s):  
Peggy Pik Ki Mok ◽  
Holly Sze Ho Fung ◽  
Vivian Guo Li

Purpose Previous studies showed early production precedes late perception in Cantonese tone acquisition, contrary to the general principle that perception precedes production in child language. How tone production and perception are linked in 1st language acquisition remains largely unknown. Our study revisited the acquisition of tone in Cantonese-speaking children, exploring the possible link between production and perception in 1st language acquisition. Method One hundred eleven Cantonese-speaking children aged between 2;0 and 6;0 (years;months) and 10 adolescent reference speakers participated in tone production and perception experiments. Production materials with 30 monosyllabic words were transcribed in filtered and unfiltered conditions by 2 native judges. Perception accuracy was based on a 2-alternative forced-choice task with pictures covering all possible tone pair contrasts. Results Children's accuracy of production and perception of all the 6 Cantonese tones was still not adultlike by age 6;0. Both production and perception accuracies matured with age. A weak positive link was found between the 2 accuracies. Mother's native language contributed to children's production accuracy. Conclusions Our findings show that production and perception abilities are associated in tone acquisition. Further study is needed to explore factors affecting production accuracy in children. Supplemental Material https://doi.org/10.23641/asha.7960826


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