Measuring and predicting the effects of alcohol consumption on contrast sensitivity for stationary and moving gratings

Contrast sensitivity was measured for 12 healthy young males while sober, after ingestion of an alcohol placebo, and after ingestion of alcohol (95% grain alcohol; mean estimated blood alcohol level = .088%). Observations were made for both stationary gratings and gratings that traveled through a circular path and required pursuit eye movements. The significant alcohol-related reduction in contrast sensitivity was 2.6 times greater for moving (.29-log-unit reduction) than for stationary gratings (.11-log-unit reduction). The loss in contrast sensitivity for the moving gratings of high spatial frequency (12 cpd) was particularly severe (.37 log unit). Estimated blood alcohol level was correlated with the loss in contrast sensitivity for moving gratings (r = .61), but not with the loss for stationary gratings. Estimated blood alcohol level was strongly correlated with the difference between the loss in contrast sensitivity to moving and stationary gratings (r = .75). These results are consistent with reports that alcohol consumption degrades the ability to make pursuit eye movements. Subjects’ perceived intoxication level was not a reliable predictor of any index of visual performance.     

Two-month-old infants’ sensitivity to allophonic differences

The present study investigated 2-month-olds’ abilities to discriminate allophonic differences that are potentially useful in segmenting fluent speech. Experiment 1 investigated infants’ sensitivity to the kind of distinction that may signal the presence or absence of a word boundary. When tested with the high-amplitude sucking procedure, infants discriminated pairs of items, such as “nitrate” versus “night rate” and “nikrate” versus “nike rate.” By greatly reducing the potential contribution of prosodic differences to these contrasts, Experiment 2 evaluated whether the allophonic differences for /t/ and /r/ were sufficient for infants to distinguish the “nitrate” versus “night rate” pair. Infants distinguished “nitrate” from a cross-spliced version of “night rate,” which differed only in the allophones for /t/ and /r/ that it included. Thus, infants appear to possess one of the prerequisite capacities (i.e., the ability to discriminate allophonic distinctions) necessary to use allophonic information in segmenting fluent speech.     

三种心理测量理论的信度观

目前,心理测量领域中主要存在三大理论派别。本文分别对这三种理论即经典测验理论、可概括性理论和项目反应理论作了简要介绍,着重分析这三种理论的信度观。文章讨论了这三种信度观的理论基础和研究方法,比较了它们的异同,指出经典测验理论存在的一些不足及概化理论和项目反应理论所作的改进。概化理论是对经典测验理论的扩展,它用多维的信度指标（概化系数）替代了经典测验理论的信度系数,项目反应理论则从信息量的角度出发,用项目信息函数、测验信息函数等指标更具体深入地反映项目、测验的测量可靠程度。