A combination stereotaxic drill press and electrode carrier

A method of transforming a vertical rack and pinion-type electrode slide into a miniature drill press is described. Advantages of the instrument are noted and several applications suggested. Specifications are included for the aluminum electrode mold for cat cortical electrode casts.     

An improved shocking surface for pigeons and rats

A resistive shocking surface and an appropriate power supply are described. The efficacy of the system is illustrated with some data on the activity of pigeons and rats as a function of the voltage applied.     

On timing events in computer-controlled experiments

This paper considers the problem of timing events in computer-controlled experiments. A digital clock is defined as a time-mark generator or “ticker” and a counter. A discussion of time-mark generators commonly used in computers is followed by a consideration of several ways in which computer clocks are implemented and used. A framework for the latter discussion is provided by a classification of clocks in terms of whether the ticker or the counter (either or both) is internal or external to the computer.     

A device for rapid recording of positioning responses in two dimensions

A device for rapid recording of positioning responses is described. It utilizes an extremely simple, low-cost position transducer and two digital voltmeters or their equivalent. The device has the advantages of rapid, accurate measurement, reliability, ease of reading, and the potential for automatic recording of positional data in two dimensions.     

Timing behavior and conditioned fear

Rats were trained on a two-response timing procedure which required that response B follow response A by at least a minimum specified interval in order to be reinforced with food. Repeated presentation (5 min on, 5 min off) of an auditory warning stimulus terminated by a brief electric shock to the feet (conditioned fear) produced a marked suppression in the frequency of A-to-B response sequences during the warning stimulus. The distribution of A-to-B interresponse times (timing behavior), however, did not change during the warning stimulus.     

Nine Critical Questions About Selective College Admissions

The misgivings of college faculty, college administrators, and high school counselors about selective admissions are focused on 9 issues. Data relevant to those issues reveal that: (1) prediction of grades is sufficiently accurate to be useful; (2) prediction equations from one year are sound for use in the immediately succeeding years; (3) predictions of first-year grades are related to performance over the 2-year period at a junior college and the 4-year career at a senior college; (4) there may need to be separate prediction procedures for widely different majors, such as science and nonscience; (5) accurate predictions can be made before the student has completed high school; (6) the nonacademic courses students take do not reduce prediction accuracy; (7) introduction of selectivity has not been found to decrease diversity in educational opportunity; (8) grading practices in an institution will tend to fluctuate with the degree of selectivity; and (9) procedures are available to set admissions cutoffs, to provide students with sound counseling information, and to provide a second chance for those who do net meet minimum admissions standards.