In the signal detection paradigm, the non-parametric index of sensitivity A′, as first introduced by Pollack and Norman (1964), is a popular alternative to the more traditional d′ measure of sensitivity. Smith (1995) clarified a confusion about the interpretation of A′ in relation to the area beneath proper receiver operating characteristic (ROC) curves, and provided a formula (which he called A′′) for this commonly held interpretation. However, he made an error in his calculations. Here, we rectify this error by providing the correct formula (which we call A) and compare the discrepancy that would have resulted. The corresponding measure for bias b is also provided. Since all such calculations apply to “proper” ROC curves with non-decreasing slopes, we also prove, as a separate result, the slope-monotonicity of ROC curves generated by likelihood-ratio criterion.

The phonological-loop model provides a prominent theoretical description of verbal working memory. According to it, serial recall accuracy should be inversely related to the articulatory duration and phonological similarity of verbal items in memorized sequences. Initial tests of these predictions by A. D. Baddeley and colleagues (e.g., A. D. Baddeley, N. Thomson, & M. Buchanan, 1975) appeared to support the phonological-loop model, but subsequent researchers have obtained conflicting data that putatively disconfirm its assumptions. Such conflicts may have stemmed from less than ideal measurements of articulatory duration and phonological similarity. This article discusses these concerns and proposes new theoretically principled methods for measuring articulatory duration and phonological similarity. Two experiments that used these methods in the context of a verbal serial recall task are reported. The results of these experiments confirm and extend the predictions of the phonological-loop model while disarming previous criticisms of it.

Background.The Psychology Experiment Building Language (PEBL) software consists of over one-hundred computerized tests based on classic and novel cognitive neuropsychology and behavioral neurology measures. Although the PEBL tests are becoming more widely utilized, there is currently very limited information about the psychometric properties of these measures.Methods.Study I examined inter-relationships among nine PEBL tests including indices of motor-function (Pursuit Rotor and Dexterity), attention (Test of Attentional Vigilance and Time-Wall), working memory (Digit Span Forward), and executive-function (PEBL Trail Making Test, Berg/Wisconsin Card Sorting Test, Iowa Gambling Test, and Mental Rotation) in a normative sample (N= 189, ages 18–22). Study II evaluated test–retest reliability with a two-week interest interval between administrations in a separate sample (N= 79, ages 18–22).Results.Moderate intra-test, but low inter-test, correlations were observed and ceiling/floor effects were uncommon. Sex differences were identified on the Pursuit Rotor (Cohen’sd= 0.89) and Mental Rotation (d= 0.31) tests. The correlation between the test and retest was high for tests of motor learning (Pursuit Rotor time on targetr= .86) and attention (Test of Attentional Vigilance response timer= .79), intermediate for memory (digit spanr= .63) but lower for the executive function indices (Wisconsin/Berg Card Sorting Test perseverative errors = .45, Tower of London moves = .15). Significant practice effects were identified on several indices of executive function.Conclusions.These results are broadly supportive of the reliability and validity of individual PEBL tests in this sample. These findings indicate that the freely downloadable, open-source PEBL battery (http://pebl.sourceforge.net) is a versatile research tool to study individual differences in neurocognitive performance.