Two components of responding in Pavlovian lick suppression

The present research examined the temporal distribution of responding in a lick suppression paradigm. In Experiment 1, rats were trained with either a 30- or a 120-s conditioned stimulus (CS), which was followed either by a footshock (unconditioned stimulus [US]) or nothing. Licking during the CS was suppressed only in the former condition. Suppression was more pronounced early in the CS. In Experiment 2, rats were exposed to two 30-s or two 120-s CSs, with delivery of the shock being contingent on CS1 for half of the animals and on CS2 for the other half. For both the paired and the unpaired conditions, suppression at the beginning of CS1 was observed for all the groups. By discounting the possibility of generalization between CS1 and CS2, it appears that this initial suppression was not a conditioned response to the CS, but an unconditioned one due to mere exposure to the shock US.     

Some determinants of second-order conditioning

In a Pavlovian conditioning situation, an initially neutral stimulus may be made excitatory by nonreinforced presentations in compound with an established conditioned excitor [i.e., second-order conditioning (SOC)]. The established excitor may be either a punctate cue or the training context. In four conditioned suppression experiments using rats, we investigated whether SOC phenomena parallel other cue interaction effects. In Experiment 1, we found that the response potential of a target stimulus was directly related to the intertrial interval when SOC was mediated by a punctate cue, and inversely related to the intertrial interval when SOC was mediated by the training context. Experiment 2 demonstrated that punctate- and context-mediated SOC are oppositely affected by posttraining context extinction, and Experiments 3 and 4 demonstrated that context- and punctate-mediated SOC are differentially affected by conditioned stimulus (Experiment 3) and unconditioned stimulus (Experiment 4) preexposure treatments. These findings parallel phenomena in conditioned inhibition and cue competition situations.     

Recovery from the overexpectation effect: Contrasting performance-focused and acquisition-focused models of retrospective revaluation

In four Pavlovian conditioned lick-suppression experiments, rats had two conditioned stimuli (CSs X and A) independently paired with footshock, followed by pairings of a compound of A and X with the footshock. On subsequent tests with CS X, less conditioned suppression was observed than in control subjects that lacked the compound AX→footshock trials. Thisoverexpectation effect was reversed through posttraining extinction of CS A, a result consistent with both performance- and acquisition-focused models of retrospective revaluation. However, only performance-focused models could account for how posttraining increases or decreases in the A-footshock temporal interval attenuate the overexpectation effect.     

Indigenous cultural contexts for STEM experiences: snow snakes’ impact on students and the community

Opportunities for American Indian youth to meaningfully engage in school-based science, technology, engineering, and mathematics (STEM) experiences have historically been inadequate. As a consequence, American Indian students perform lower on standardized assessments of science education than their peers. In this article we describe the emergence of meaning for students—as well as their community—resulting from Indigenous culturally-based STEM curriculum that used an American Indian tradition as a focal context. Specifically, the game of snow snakes (Gooneginebig in Ojibwe) afforded an opportunity for STEM and culturally-based resources to work in unison. A case study research design was used with the bounded case represented by the community associated with the snow snake project. The research question guiding this study was: What forms of culturally relevant meaning do students and the community form as a result of the snow snake game? Results indicate evidence of increased student and community engagement through culturally-based STEM experiences in the form of active participation and the rejuvenation of a traditional game. Implications are discussed for using culturally-based contexts for STEM learning.     

Gender Differences in College Mathematics Grades and SAT-M Scores: A Reanalysis of Wainer and Steinberg

Wainer and Steinberg (1992) showed that within broad categories of first-year college mathematics courses (e.g., calculus) men had substantially higher average scores on the mathematics section of the SAT (SAT-M) than women who earned the same letter grade. However, three aspects of their analyses may lead to unwarranted conclusions. First, they focused primarily on differences in SAT-M scores given course grades when the more important question for admissions officers is the difference in course grades given scores on the predictor. Second, they failed to account for differences among calculus courses (e.g., calculus for engineers versus calculus for liberal arts students). Most importantly, Wainer and Steinberg focused on the use of SAT-M as a single predictor. A reanalysis presented here indicated that a more appropriate composite indicator made up of both SAT-M and high school grade point average demonstrated minuscule gender differences for both calculus and precalculus courses.     

A pragmatic approach to courseware development in WIMP environments

Courseware development often involves a great deal of effort. One approach to minimising effort while maintaining flexibility is illustrated, using a tutoring system as an example. The system comprises two parts: a 'shell' which contains facilities useful for many different subjects, and an interpreter which generates questions which are subject specific.