An experimental test of stimulus estimation theory: danger and safety with snake phobic stimuli

The stimulus estimation model (Taylor & Rachman, 1994) asserts that fear overprediction stems from: (a) overprediction of the danger elements of a phobic stimulus, and (b) underprediction of existing safety resources. Using a 2x2 factorial design, with danger (high vs low) and safety (high vs low) as between-subjects variables, an experimental test of the model was conducted with 25 snake-fearful participants per condition. The four experimental conditions were matched on initial levels of snake fearfulness, as assessed by the Snake Questionnaire (SNAQ). For the 51 participants who demonstrated overprediction of fear, high danger led to reliably more fear overprediction than low danger; and low safety led to reliably more fear overprediction than high safety. The interaction between danger and safety was not statistically significant. The results offer the first convincing experimental support for the stimulus estimation model of fear overprediction.     

An experimental study of the asymmetry effect in the method of constant stimuli

Summary The asymmetry effect (AE) in the method of constant stimuli refers to the dependence of the sign and of the magnitude of the constant error on the position of the standard (S) within the range of the variable (V) stimuli. The AE is known to occur when S and V appear in succession. The experiment reported here shows that the AE also occurs when S and V are simultaneous. This result allows us to conclude that the AE is not a memory effect, and that it is plausible to suppose that it depends on a factor of judgment.Research subsidized by CNR     

The Obama effect: An experimental test

Past research on stereotype threat and role model effects, as well as a recent quasi-experiment (Marx, Ho, & Freidman, this issue) suggested the possibility of an “Obama effect” on African American’s standardized test performance, whereby the salience of Barack Obama’s stereotype defying success could positively impact performance. We tested this reasoning in a randomized experiment with a broad sample of college students from across the country. Specifically, we tested the hypothesis that students prompted to think about Barack Obama prior to taking a difficult standardized verbal test would improve their performance relative to white students, and to African American students in control conditions that were not prompted to think about Obama. Our results did not support this hypothesis. Test scores were unaffected by prompts to think about Obama and no relationship was found between test performance and positive thoughts about Obama, a disconfirmation of both the findings and conclusions of the Marx, Ho, and Freidman study.     

Who when where: An experimental test of the event-indexing model

We tested the event-indexing model proposed by Zwaan, Langston, and Graesser (1995). Participants read narratives containing target sentences that involved situational shifts. Independently of each other, continuity and shifting of the protagonist, time, and location dimensions were varied. In Experiment 1, reading times of the target sentences increased for protagonist shifts and temporal shifts, whereas the effect of spatial shifts was weak. Moreover, an interaction of protagonist shifts and spatial shifts was found. These results were replicated in Experiment 2, which also revealed strong effects of these situational shifts on coherence ratings that participants gave immediately after reading each target sentence. Experiment 3 addressed the interaction of protagonist shifts and spatial shifts, showing that it may be due to the differential involvement of unexplained protagonist motions. These experimental results support the processing load predictions of the event-indexing model and extend previous correlational results.