Imagination Reduces False Memories for Everyday Action Sentences: Evidence From Pragmatic Inferences

Human memory can be unreliable, and when reading a sentence with a pragmatic implication, such as “the karate champion hit the cinder block,” people often falsely remember that the karate champion “broke” the cinder block. Yet, research has shown that encoding instructions affect the false memories we form. On the one hand, instructing participants to imagine themselves manipulating the to-be-recalled items increase false memories (imagination inflation effect). But on the other hand, instructions to imagine have reduced false memories in the DRM paradigm (imagination facilitation effect). Here, we explored the effect of imaginal encoding with pragmatic inferences, a way to study false memories for information about everyday actions. Across two experiments, we manipulated imaginal encoding through the instructions given to participants and the after-item filler task (none vs. math operations). In Experiment 1, participants were either assigned to the encoding condition of imagine+no filler; pay attention+math; or memorize+math. In Experiment 2, the encoding instructions (imagine vs. memorize) and the filler task (none vs. math) were compared across four separate conditions. Results from the two experiments showed that imagination instructions lead to better memory, by showing a higher proportion of correct responses and better performance in a memory benefit index. Similarly, a significant reduction of false memories was observed across both experiments, even though a complementary Bayesian analysis only supported this conclusion for Experiment 1. The findings show that imaginal encoding improves memory, suggesting the engagement of a distinctiveness heuristic and source-monitoring process.

Systematic Evaluation of the Efficacy of Chlorine Dioxide in Decontamination of Building Interior Surfaces Contaminated with Anthrax Spores

ABSTRACT Efficacy of chlorine dioxide (CD) gas generated by two distinct generation systems, Sabre (wet system with gas generated in water) and ClorDiSys (dry system with gas generated in air), was evaluated for inactivation of Bacillus anthracis spores on six building interior surfaces. The six building materials included carpet, acoustic ceiling tile, unpainted cinder block, painted I-beam steel, painted wallboard, and unpainted pinewood. There was no statistically significant difference in the data due to the CD generation technology at a 95% confidence level. Note that a common method of CD gas measurement was used for both wet and dry CD generation types. Doses generated by combinations of different concentrations of CD gas (500, 1,000, 1,500, or 3,000 parts per million of volume [ppmv]) and exposure times (ranging between 0.5 and 12 h) were used to evaluate the relative role of fumigant exposure period and total dose in the decontamination of building surfaces. The results showed that the time required to achieve at least a 6-log reduction in viable spores is clearly a function of the material type on which the spores are inoculated. The wood and cinder block coupons required a longer exposure time to achieve a 6-log reduction. The only material showing a clear statistical difference in rate of decay of viable spores as a function of concentration was cinder block. For all other materials, the profile of spore kill (i.e., change in number of viable spores with exposure time) was not dependent upon fumigant concentration (500 to 3,000 ppmv). The CD dose required for complete spore kill on biological indicators (typically, 1E6 spores of B acillus atrophaeus on stainless steel) was significantly less than that required for decontamination of most of the building materials tested.

Quantitative Method To Determine Sporicidal Decontamination of Building Surfaces by Gaseous Fumigants, and Issues Related to Laboratory-Scale Studies

ABSTRACT Chlorine dioxide gas and vaporous hydrogen peroxide sterilant have been used in the cleanup of building interiors contaminated with spores of Bacillus anthracis. A systematic study, in collaboration with the U.S. Environmental Protection Agency, was jointly undertaken by the U.S. Army-Edgewood Chemical Biological Center to determine the sporicidal efficacies of these two fumigants on six building structural materials: carpet, ceiling tile, unpainted cinder block, painted I-beam steel, painted wallboard, and unpainted pinewood. Critical issues related to high-throughput sample processing and spore recovery from porous and nonporous surfaces included (i) the extraction of spores from complex building materials, (ii) the effects of titer challenge levels on fumigant efficacy, and (iii) the impact of bioburden inclusion on spore recovery from surfaces and spore inactivation. Small pieces (1.3 by 1.3 cm of carpet, ceiling tile, wallboard, I-beam steel, and pinewood and 2.5 by 1.3 cm for cinder block) of the materials were inoculated with an aliquot of 50 μl containing the target number (1 × 106, 1 × 107, or 1 × 108) of avirulent spores of B. anthracis NNR1Δ1. The aliquot was dried overnight in a biosafety cabinet, and the spores were extracted by a combination of a 10-min sonication and a 2-min vortexing using 0.5% buffered peptone water as the recovery medium. No statistically significant drop in the kill efficacies of the fumigants was observed when the spore challenge level was increased from 6 log units to 8 log units, even though a general trend toward inhibition of fumigant efficacy was evident. The organic burden (0 to 5%) in the spore inoculum resulted in a statistically significant drop in spore recovery (at the 2 or 5% level). The effect on spore killing was a function of the organic bioburden amount and the material type. In summary, a high-throughput quantitative method was developed for determining the efficacies of fumigants, and the spore recoveries from five porous materials and one nonporous material ranged between 20 and 80%.