Choosing and using geospatial displays: effects of design on performance and metacognition

Interactive display systems give users flexibility to tailor their visual displays to different tasks and situations. However, in order for such flexibility to be beneficial, users need to understand how to tailor displays to different tasks (to possess "metarepresentational competence"). Recent research suggests that people may desire more complex and realistic displays than are most effective (Smallman & St. John, 2005). In Experiment 1, undergraduate students were tested on a comprehension task with geospatial displays (weather maps) that varied in the number of extraneous variables displayed. Their metacognitive judgments about the relative effectiveness of the displays were also solicited. Extraneous variables slowed response time and increased errors, but participants favored complex maps that looked more realistic about one third of the time. In Experiment 2, the eye fixations of undergraduate students were monitored as they performed the comprehension task. Complex maps that looked more realistic led to more eye fixations on both task-relevant and task-irrelevant regions of the displays. Experiment 3 compared performance of experienced meteorologists and undergraduate students on the comprehension and metacognitive tasks. Meteorologists were as likely as undergraduate students to prefer geographically complex (realistic) displays and more likely than undergraduates to opt for displays that added extraneous weather variables. However, meteorologists were also slower and less accurate with complex than with simple displays. This work highlights the importance of empirically testing principles of visual display design and suggests some limits to metarepresentational competence.     

Representational Translation With Concrete Models in Organic Chemistry

In representation-rich domains such as organic chemistry, students must be facile and accurate when translating between different 2D representations, such as diagrams. We hypothesized that translating between organic chemistry diagrams would be more accurate when concrete models were used because difficult mental processes could be augmented by external actions on the models. In three studies, the task was to translate between different diagrams of molecules with or without a model. The model groups outperformed control groups, and students who received and used models outperformed those who received but did not use models. Uses of the model suggested that participants were performing external actions to support or replace difficult mental spatial processes. Spatial ability was a much weaker predictor of performance than model use. Results suggest that concrete molecular models can be an effective learning tool but some students need direct instruction to be able to take advantage of models.     

Premotor and Motor Reaction Time as a Function of Preliminary Muscular Tension

Ss squeezed a hand grip device to 1 of 3 submaximal tensions, and reacted to either a light (Exp. I, N = 30) or to a buzzer (Exp. II, N = 24) by squeezing as quickly and forcefully as possible. Total RT was the time from stimulus to the change in tension, and this was divided into Premotor RT (stimulus to change in EMG) and Motor RT (change in EMG to change in tension) to determine the locus of changes in Total RT found by Clarke (1968). Whereas Total RT was unaffected by increased pre-tension, Premotor RT shortened and Motor RT lengthened. Partial programming or activation hypotheses were tenable for the Premotor RT changes, whereas changes in the contractile component, but not in the series elastic component, were tenable for the Motor RT changes.     

Effects of variable fatigue levels on reaction-time components

The effects of varying fatigue levels on reaction-time components were determined for 20 young, adult males. Each subject squeezed a hand-gripping device until strength decrements of 20, 40, or 60% were recorded; then the subject released his tension and then reacted to an auditory stimulus by gripping as quickly and forcefully as possible. Testing was also conducted under a nonfatigued state, and every subject was tested under all conditions. Total reaction time was divided into (a) a promoter component, the time from the stimulus to an alteration in the EMG of the finger flexors, and (b) a motor component, the time from the change in the EMG to the first sign of tension uptake. Analyses of variance failed to reveal any alterations in either reaction time or promoter time; however, there was a significant (p < .05) elongation of motor time when the muscle was fatigued, with motor time tending to increase linearly as fatigue increased. The results suggest that localized fatigue of this nature is primarily of peripheral (muscular) origin.     

Predictors of Counselor Educators' Cultural Discriminatory Behaviors

Purposes of this study were to (a) examine relationships among counselor educators' attitudes, behaviors, and perceptions of institutional support concerning race, gender, sexual orientation, and social class and (b) investigate the effects of attitudes and institutional perceptions on behaviors. A nationwide sample of 154 counseling faculty completed the Survey of Cultural Attitudes and Behaviors (K. L. Miller & S. M. Miller, 1997). Faculty attitudes directly predicted behaviors. Perceptions of institutional support directly and indirectly predicted behaviors. The authors identify strategies for modifying discriminatory behaviors.