Testing process predictions of models of risky choice : A quantitative model comparison approach

This article presents a quantitative model comparison contrasting the process predictions of two prominent views on risky choice. One view assumes a trade-off between probabilities and outcomes (or non-linear functions thereof) and the separate evaluation of risky options (expectation models). Another view assumes that risky choice is based on comparative evaluation, limited search, aspiration levels, and the forgoing of trade-offs (heuristic models). We derived quantitative process predictions for a generic expectation model and for a specific heuristic model, namely the priority heuristic (Brandstätter et al., 2006), and tested them in two experiments. The focus was on two key features of the cognitive process: acquisition frequencies (i.e., how frequently individual reasons are looked up) and direction of search (i.e., gamble-wise vs. reason-wise). In Experiment 1, the priority heuristic predicted direction of search better than the expectation model (although neither model predicted the acquisition process perfectly); acquisition frequencies, however, were inconsistent with both models. Additional analyses revealed that these frequencies were primarily a function of what Rubinstein (1988) called “similarity.” In Experiment 2, the quantitative model comparison approach showed that people seemed to rely more on the priority heuristic in difficult problems, but to make more trade-offs in easy problems. This finding suggests that risky choice may be based on a mental toolbox of strategies

Infrared, Raman and cathodoluminescence studies of impact glasses

We studied the infrared reflectance (IR), Raman, and cathodoluminescence (CL) spectroscopic signatures and scanning electron microscope-cathodoluminescence (SEM-CL) images of three different types of impact glasses: Aouelloul impact glass, a Muong Nong-type tektite, and Libyan desert glass. Both backscattered electron (BSE) and CL images of the Muong Nong-type tektite are featureless; the BSE image of the Libyan desert glass shows only weak brightness contrasts. For the Aouelloul glass, both BSE and CL images show distinct brightness contrast, and the CL images for the Libyan desert glass show spectacular flow textures that are not visible in any other microscopic method. Compositional data show that the SiO2 composition is relatively higher and the Al2O3 content is lower in the CL-bright areas than in the CL-dark regions. The different appearance of the three glass types in the CL images indicates different peak temperatures during glass formation: the tektite was subjected to the highest temperature, and the Aouelloul impact glass experienced a relatively low formation temperature, while the Libyan desert glass preserves a flow texture that is only visible in the CL images, indicating a medium temperature. All IR reflectance spectra show a major band at around 1040 to 1110 cm-1 (antisymmetric stretching of SiO4 tetrahedra), with minor peaks between 745 and 769 cm-1 (Si-O-Si angle deformation). Broad bands at 491 and 821 cm-1 in the Raman spectra in all samples are most likely related to diaplectic glass remnants, indicating early shock amorphization followed by thermal amorphization. The combination of these spectroscopic methods allows us to deduce information about the peak formation temperature of the glass, and the CL images, in particular, show glass flow textures that are not preserved in other more conventional petrographic images

A pedagogic appraisal of the Priority Heuristic

We have explored how science and mathematics teachers made decisions when confronted with a dilemma in which a fictitious young woman, Deborah, may choose to have an operation that might address a painful spinal condition. We sought to explore the extent to which psychological heuristic models, in particular the Priority Heuristic, might successfully describe the decision-making process of these teachers and how an analysis of the role of personal and emotional factors in shaping the decision-making process might inform pedagogical design. A novel aspect of this study is that the setting in which the decision-making process is examined contrasts sharply with those used in psychological experiments. We found that to some extent, even in this contrasting setting, the Priority Heuristic could describe these teachers' decision-making. Further analysis of the transcripts yielded some insights into limitations on scope as well the richness and complexity in how personal factors were brought to bear. We see these limitations as design opportunities for educational intervention