It is argued that research settings should be chosen with the whole experimental design in mind and that the availability of appropriate controls (groups or occasions for observation) should be as important as the suitability of the treatment group. (Author/AM)

The possibility that subjective contours are an artifact of brightness contrast was explored. Concludes that subjective contour and brightness contrast are distinct perceptual phenomena but share a dependency on the processing of edge information transmitted through the achromatic channels of the visual system. (Editor/RK)

Rats performed an intermittently reinforced operant response and received periodic presentations of a visual conditioned stimulus (CS) located either very near or far from the operant manipulandum. Findings suggest there are deficiencies in the general accounts of conditioned suppression that stress the motivational or emotional effects of…

The negative-contrast effect occurs when animals that are shifted from large to small reward temporarily drop below small reward control groups. The basic question asked here in three experiments was whether animals tested under a specific drive level will behave as though they expect a reward magnitude previously received, depending on the reward…

Assesses the validity of physiological versus learning interpretations of illness-preexposure effects. (Author/RK)

Four free-recall experiments are reported that investigate the relationship between the organization of rehearsal and the organization of recall. (Editor)

Concerns the examination of conditioned stimulus--unconditioned stimulus (CS--UCS) intervals of different lengths. Demonstrates the feasibility of using a forewarned reaction time procedure with an innocuous imperative stimulus for the investigation of classical conditioning. (Editor/RK)

Procedures are provided for a flame emission experiment which covers five areas in a single laboratory exercise. These areas are: (1) the flame emission technique; (2) calibration plots; (3) interferences; (4) indirect flame emission analysis; and (5) techniques of removing interferences. Typical results obtained are discussed. (JN)

The four BASIC programs described can be used to control experiments and facilitate classroom demonstrations and laboratory exercises in human memory, operant behavior, and visual discrimination. (RM)

Fifty-three research studies on feedback timing and verbal learning underwent meta-analysis. Applied studies using actual classroom quizzes and real learning materials found immediate rather than delayed feedback to be more effective; experimental studies of acquisition of test content indicate the opposite. Laboratory studies of list learning…

Described is a modified Fehling test and a modified corrected Benedict test. (RH)

Described is a simple demonstration that provides a way to determine if a given sample contains even a small fraction of superconducting material. The repulsion of the powder from a magnetic field is indicative of superconductivity. (RH)

This is part two in a series on classroom demonstrations of polymer principles. Described is how large molecules can be assembled from subunits (the process of polymerization). Examples chosen include both linear and branched or cross-linked molecules. (RH)

The author discusses emerging trends in popular education, including various grassroots experiments and projects. He describes popular education not as a component of modernization programs but as a movement that begins with the people. (CH)

Experiments involving the coupling of alkyl and aryl halides in the presence of lithium metal and ultrasound are described. The experiments illustrate classical Wurtz and Fittig reactions in addition to being a convenient application of organic sonochemistry. (JN)