Encoding of the unconditioned stimulus in Pavlovian conditioning

Three experiments, using rats, demonstrated the encoding of a food unconditioned stimulus (US) in a simple Pavlovian conditioning paradigm. In all three studies, one stimulus was used to signal the delivery of pellets and a different stimulus was used to signal the delivery of sucrose. In Experiment 1, postconditioning devaluation of one of the food USs selectively reduced the frequency of conditioned magazine-directed behavior during the stimulus trained with that US. In Experiment 2, transfer of the stimuli to instrumental responses resulted in selective depression of the response trained with a different outcome. In Experiment 3, acquisition of stimulus-outcome learning was impaired by unsignaled intertrial presentations of the same outcome but not of a different outcome. These results indicate that a detailed representation of the outcome is encoded in the normal course of Pavlovian conditioning.     

Fractals and the large-scale structure in the Universe

During the last decade it has been argued by some investigators that the distribution of galaxies in the Universe is a fractal. This is contrary to the standard view that the Universe is homogeneous and isotropic on large scales. In this article, the basic concepts of fractals and their characterization are introduced with the help of simple examples. The applications of these concepts in the context of cosmology will be discussed in the second part. A K Mittal is currently a visiting scientist at Harish-Chandra Research Institute, Allahabad, on leave from the University of Allahabad. His research interests include chaos, fractals and their applications, partleularly in cosmology and in weather prodiction. T H Seshadri is at the Department of Physics and Astrophysics, University of Delhi. He is presently on lien from Harish-Chandra Research Institute, Allahabad. Areas of his interest include cosmic microwave background radiation, large scale structures in the Universe and application of fractals in these.     

Hydrodynamic lubrication

This article gives the principle of hydrodynamic lubrication and also presents the new phenomenon of levitating drops over liquid film flow, which is explained using hydrodynamic lubrication theory.     

Novelty versus retrieval cue value of visual contextual stimuli in pigeons

Learning & Behavior - Thomas and Empedocles (1992) proposed that in a retention test, the relative enhancement of responding when the context that had accompanied training is again present...     

Making ethnic citizens: The politics and practice of education in Malaysia

This paper examines the politics and practice of education in Malaysia within the context of ethnicity and nation building. Public education in Malaysia—particularly, but not exclusively, at the pre-university level—is promoted as a nation-building tool, seeking to inculcate a sense of Malaysian-ness and patriotism. Simultaneously, however, public education—particularly, but not exclusively, at the university level—is used as a tool for the promotion of ethnic Malay interests. These two objectives are not necessarily contradictory; indeed the assertion that a vital ingredient in the creation of a ‘Malaysian nation’ is the eradication of inter-ethnic economic disparities has been at the heart of the Malaysian regime's discourse on nation building since the ethnic riots of May 1969. Hence, in this view, preferential policies for the economically disadvantaged but numerically dominant Malays are a necessary component of the nation-building project. Nonetheless, there are at least clear tensions between these two functions of education—tensions, which, I shall argue, help explain both the particularly sensitive politics of education in Malaysia, and the discursive stance the Malaysian regime has adopted within the educational field.