The combined effects of dosage level and interstimulus interval on the formation of one-trial poison-based aversions in rats

Adult male rats were allowed to drink a novel solution of sodium saccharin which was followed .5, 1.5, 4.5, 7.0, 13.5, or 24.0 h later by intubation of a .9, 2.7, 8.1, or 12.15% (w/v) solution of sodium chloride (NaCl). Three days after the single training trial, consumption of saccharin was again measured. Significant differences between groups were found. When consumption by the experimental groups at each CS-UCS delay was compared with that of the isotonic NaCl (.9%) control group, it was found that all groups showed aversions at delays of .5, 1.5, and 4.5 h. Animals intubated with 8.1% or 12.15% NaCl solution also showed aversions at a delay of 7.0 h, and those intubated with the 12.15% solution showed an aversion at a delay of 13.5 h. No NaCl concentration used produced aversions at a CS-UCS interval of 24.0. These results reflect differences in the effectiveness of a range of NaCl concentrations in producing one-trial aversions at long CS-UCS intervals.     

Elicitation of personal probabilities and their assessment

A student's choice of an answer to a test question is a coarse measure of his knowledge about the subject matter of the question. Much finer measurement might be achieved if the student were asked to estimate, for each possible answer, the probability that it is the correct one. Such a procedure could yield two classes of benefits: (a) students could learn the language of numerical probability and use it to communicate uncertainty, and (b) the learning of other subjects could be facilitated. This report describes the rationale underlying a procedure for eliciting personal estimates of probabilities utilizing a proper scoring rule, and illustrates some new techniques for calibrating those probabilities and providing better feedback to students learning to assess uncertainty. In addition, new results are presented compring the incentive for study, rehearsal, and practice provided by the proper scoring rule with that provided by the simple choice procedure, and concerning the potential effect of cutoff scores and prizes upon student behavior.