Trevor J. Barrett

Usability of concrete and virtual models in chemistry instruction

Virtual models are increasingly common in the modern science classroom, however little is known about the relative effectiveness of virtual and concrete models. We developed a virtual modeling system and tested the benefit of haptic cue fidelity, controlling for many other perceptual differences between concrete and virtual models. In two studies we directly compared performance of students using this virtual model and using concrete models for tasks in the domain of organic chemistry. Students used either virtual or concrete models to match diagrams of molecules or compare the structures of molecules represented by models and diagrams. The results indicated similar levels of accuracy and similar ratings of usability for virtual and concrete models but no effect of haptic cue fidelity. Greater efficiency with virtual models was observed when students matched diagrams and models, and this efficiency transferred to later use of concrete models. The efficiency benefit is attributed to interactive constraints of the hand-held interface to the virtual model, which helped students identify task-relevant information in the model and limited them to performing the most task-relevant interactions with the models.

Assessing the effectiveness of different visualizations for judgments of positional uncertainty

Many techniques have been proposed for visualizing uncertainty in geospatial data. Previous empirical research on the effectiveness of visualizations of geospatial uncertainty has focused primarily on user intuitions rather than objective measures of performance when reasoning under uncertainty. Framed in the context of Google’s blue dot, we examined the effectiveness of four alternative visualizations for representing positional uncertainty when reasoning about self-location data. Our task presents a mobile mapping scenario in which GPS satellite location readings produce location estimates with varying levels of uncertainty. Given a known location and two smartphone estimates of that known location, participants were asked to judge which smartphone produces the better location reading, taking uncertainty into account. We produced visualizations that vary by glyph type (uniform blue circle with border vs. Gaussian fade) and visibility of a centroid dot (visible vs. not visible) to produce the four visualization formats. Participants viewing the uniform blue circle are most likely to respond in accordance with the actual probability density of points sampled from bivariate normal distributions and additionally respond most rapidly. Participants reported a number of simple heuristics on which they based their judgments, and consistency with these heuristics was highly predictive of their judgments.

Effects of interface and spatial ability on manipulation of virtual models in a STEM domain

Virtual models are increasingly employed in STEM education to foster learning about spatial phenomena. However, the roles of the computer interface and students cognitive abilities in moderating learning and performance with virtual models are not yet well understood. In two experiments students solved spatial organic chemistry problems using a virtual model system. Two aspects of the virtual model interface were manipulated: display dimensionality (stereoscopic vs. monoscopic displays) and the location of the hand-held device used to manipulate the virtual molecules (co-located with the visual display vs. displaced). The experimental task required participants to interpret the spatial structure of organic molecules and to manipulate the models to align them with orientations and configurations depicted by diagrams in Experiment 1 and three-dimensional models in Experiment 2. Co-locating the interaction device with the virtual image led to better performance in both experiments and stereoscopic viewing led to better performance in Experiment 2. The effect of co-location on performance was moderated by spatial ability in Experiment 1, and the effect of providing stereo viewing was moderated by spatial ability in Experiment 2. The results are in line with the ability-as-compensator hypothesis: participants with lower ability uniquely benefited from the treatment, while those with higher ability were not affected by stereo or co-location. The findings suggest that increased fidelity in a virtual model system may be one way of alleviating difficulties of low-spatial participants in learning spatially demanding content in STEM domains. Virtual model manipulation performance examined during organic chemistry task.Tested two aspects of interface design: co-location and stereo viewing.Effects of interface design were moderated by spatial ability.Ability-as-compensator aptitude treatment-interaction observed.