Tables of d′ for variable-standard discrimination paradigms

Signal detection theory (SDT) allows a bias-free measure of sensitivity, d′, to be simply estimated from discrimination data when certain conditions are met. The computation is not straightforward, however, in several popular discrimination designs, such as two- and four-interval same-different designs and the ABX design. The present tables, derived from the SDT models of Macmillan, Kaplan, and Creelman (1977), make possible the estimation of d’ from these complex discrimination designs.     

Effect of effort and latent extinction on resistance to extinction

Sixty-four male Wistar rats were given acquisition training in an enclosed straight-alley runway which could be adjusted for angles of inclination. The 2×2×2 design involved two angles of inclination in acquisition (0° and 40°) and two angles of inclination in extinction (0° and 40°). Between acquisition and extinction, half the subjects were exposed to a latent extinction procedure and half served as controls. Number of responses in a 30-min extinction session was an inverse function of effort required in extinction. Additionally, latent extinction procedures resulted in reduced resistance to extinction, but only when the effort conditions of acquisition and extinction were constant. When the effort conditions of acquisition and extinction were dissimilar, latent extinction procedures resulted in increased resistance to extinction. The results raise questions about the nature of the learning which occurs during latent extinction training.     

Intracranial cannulation of small animals

Special difficulties are encountered when attempting to provide intracranial cannulation of small animals that have floating or fragile skull bones. The technique described was developed for mice but seems applicable to other species. The cannula system is inexpensive and easy to use. A wound clip anchor seems superior to either skull screws or bonded acrylic, producing less damage to the brain and no necrosis of bone or tissue on the wound margin. Patency data up to 25 days is presented, and the system is as efficacious as other techniques.     

The polyserial correlation coefficient

The polyserial and point polyserial correlations are discussed as generalizations of the biserial and point biserial correlations. The relationship between the polyserial and point polyserial correlation is derived. The maximum likelihood estimator of the polyserial correlation is compared with a two-step estimator and with a computationally convenient ad hoc estimator. All three estimators perform reasonably well in a Monte Carlo simulation. Some practical applications of the polyserial correlation are described.By coincidence, the first author and the second and third authors learned that they were working independently on closely related problems and, consequently, decided to write a jointly authored paper.     

Emotional Reactions to News Events1

This study was designed to determine (a) what dimensions underlie emotional reactions to news events, (b) whether these dimensions are independent, (c) whether reactions to major news events are similar for different groups of people, and (d) whether a simple method could be developed for evaluating emotional reactions to news events. Subjects rated the similarity of their emotional reactions to 20 page-one newspaper stories in a paired-comparison task. The data were multidimensionally scaled using the KYST computer program. Two dimensions emerged that accounted for 89% of the judgment variance: pleasure/displeasure and degree of arousal. Interpretation of these dimensions was verified using a semantic differential task. The two dimensions were not independent. They were related by a U-shaped function: News events farther from evaluative neutrality were judged more arousing. A second study with 40 news events and a different subject population replicated these findings. Subjects' ratings of news events on three scales (happy, important, and exciting) were sufficient to recover the KYST dimensions. The theoretical and practical implications of these. results are discussed.