Solution-state nuclear magnetic resonance (NMR) is an invaluable tool in structural and molecular biology research, but may be underutilized in undergraduate laboratories because instrumentation for performing structural studies of macromolecules in aqueous solutions is not yet widely available for use in undergraduate laboratories. We have…

A mathematical model of working-memory capacity limits is proposed on the key assumption of mutual interference between items in working memory. Interference is assumed to arise from overwriting of features shared by these items. The model was fit to time-accuracy data of memory-updating tasks from four experiments using nonlinear mixed effect…

An experiment is conducted to measure the enthalpy of vaporization of volatile compounds like methylene chloride, carbon tetrachloride, and others by using gas chromatography. This physical property was measured using a very tiny quantity of sample revealing that it is possible to measure the enthalpies of two or more compounds at the same time.

A simple conductivity instrument in nonaqueous solvents is employed to project several features of the SN2 mechanism, which involves the Finkelstein reaction. The effects of the different variables of the SN2 mechanism are described.

The preparation of 7-hydroxy-3-carboxycoumarin starting from 2,4-dihydroxybenzaldehyde, and malonitrile, by one-pot consecutive reactions, carried out in water under heterogenous conditions is presented. The experiment encourages students to think in terms of reaction mechanisms.

This work aimed at demonstrating, first, that naive reasoners are able to infer the existence of a relationship between two events that have never been presented together and, second, the sensitivity of such inference to the causal structure of the task. In all experiments, naive participants judged the strength of the causal link between a cue A…

Using a conditioned suppression task, we investigated simultaneous (XA-/A+) vs. sequential (X [right arrow] A-/A+) Feature Negative (FN) discrimination learning in humans. We expected the simultaneous discrimination to result in X (or alternatively the XA configuration) becoming an inhibitor acting directly on the US, and the sequential…

In two experiments rats were trained in a Morris pool to find a hidden platform in the presence of a single landmark. Circular black curtains surrounded the pool, with the single landmark inside this enclosure, so that no other room cues could provide additional information about the location of the platform. This landmark was hung from a false…

A two-alternative choice procedure was used with rats to examine preference for discriminative stimuli (correlated with the occurrence of reinforcement) versus uncorrelated cues. Choice of discriminative stimuli was below chance, despite the use of very low levels of reinforcement (12.5% for some rats) known to produce a preference for…

The need to determine the value of environmental entities has generated substantial research regarding optimal methods for obtaining valuations from survey respondents. The literature suggests the importance of providing clear, complete descriptions of the entity being valued prior to respondents indicating their valuations. The target entity's…

The authors report a lexical decision experiment designed to determine whether activation is the locus of the word-frequency effect. K. R. Paap and L. S. Johansen (1994) reported that word frequency did not affect lexical decisions when exposure durations were brief; they accounted for this by proposing that data-limited conditions prevented…

This research's purpose was to contrast the representations resulting from learning of the same categories by either classifying instances or inferring instance features. Prior inference learning research, particularly T. Yamauchi and A. B. Markman (1998), has suggested that feature inference learning fosters prototype representation, whereas…

Traditional models of perspective change problems (i.e., judgment of egocentric target directions from an imagined perspective) assume that performance reflects one's ability to imagine the new perspective. Three experiments investigated whether advanced cuing of the imagination direction improves performance in an imagined self-rotation task. RT…

The Possible Word Constraint limits the number of lexical candidates considered in speech recognition by stipulating that input should be parsed into a string of lexically viable chunks. For instance, an isolated single consonant is not a feasible word candidate. Any segmentation containing such a chunk is disfavored. Five experiments using the…

This study investigated whether children's spatial recall performance shows three separable characteristics: (1) biases away from symmetry axes (geometric effects); (2) systematic drift over delays; and (3) biases toward the exemplar distribution experienced in the task (experience-dependent effects). In Experiment 1, the location of one target…