An inexpensive electro-fistular swivel for negative feedback control of self-stimulation

A swivel was developed for concurrent intraorganismic fluid injection and intracranial electrical stimulation of the unrestrained rat. Effects of various intragastric injections on bar-pressing maintained by electrical stimulation of the hypothalamus were studied. In some subjects, intragastric injections of either water or milk decreased the rate of responding. This decrease resulted from pauses in responding rather than from decreases in the local rates of responding. The decrement in responding occurred at a lower gastric volume during milk injection than during water injection. In other subjects, however, neither water, milk, nor 32% sucrose injections affected the rate of self-stimulation.     

DETERMINANTS OF PERFORMANCE ON DOUBLE CLASSIFICATION TASKS

Two groups of children, median ages 6–7 and 8–7, were presented with objects examplifying three combinations of two dichotomous attributes, and asked to indicate the remaining combination. Keeping objects covered vs. uncovered at the time of the test response had generally little effect. Labelling was consistently superior to perceptual matching, apparently because the latter involved a search process. The errors in the labelling condition consisted mostly in naming an object identical to or different in both attributes from those given, reflecting perhaps an inability to break down the impression of the objects into independent attributes.