The results indicate the overall feasibility of using this brief computerized battery in research. A large sample of healthy volunteers was studied without difficulties; the average administration time was about an hour and the measures yielded moderate to high indices of reliability, construct validity and, more preliminarily, criterion validity.
Regarding reliability, the coefficient alpha values indicated acceptable to high internal consistency for all tests. They were expectedly higher for response times, for which they ranged from .777 for delayed spatial recognition to .969 for CPT numbers, than for accuracy, for which they ranged from .587 for the ER40 to .954 for total CPT. Thus, each test samples a coherent behavioral domain. While test-retest reliability is important to establish as well, and this effort is underway, high internal consistency indices auger positively for expecting good repeatability of measures. The high coefficient alphas suggest good reliability because, as generalization of the split-half reliability, they estimate the likelihood of obtaining the same scores under multiple simultaneous administrations (Allen and Yen, 1979
The inter-correlations among tests were again generally higher for response time, where they ranged from .042 between SM and PVRT to .899 between CPT for numbers and CPT for letters, than for accuracy, where they ranged from −.075 between CPT for numbers and LNB to .632 between CJOLO and PVRT. The intercorrelations overall were moderate enough to indicate that the tests are diverse and do not measure the same domain repetitively. Notably, the highest correlation was observed between a spatial test, requiring the judgment of line orientation, and a purely language test, requiring verbal reasoning. They were both expected to measure higher order reasoning related to lateralized cortical processing and their correlation support the underlying model of brain-behavior relationships, thus supporting the construct validity of the battery.
The results of initial criterion validation were encouraging. The tests showed sensitivity to sex differences, with the expected better performance for males on spatial and motor tasks and better performance for females on memory and emotion processing tasks (Halpern et al., 2007
). Less expected was the better performance for men on the CPT letters condition and for females on the LNB test. These are new findings of sex differences that suggest better vigilance abilities in men and better working memory abilities in women. These findings need replication.
The sensitivity of the tests to effects of normal aging provides further validation. Performance showed moderate to high correlations with age, and these were more pronounced for speed than for accuracy. Furthermore, as expected from the literature the effects of aging were more pronounced for memory and “fluid intelligence” tasks (abstraction and mental flexibility, attention) than for “crystallized intelligence” tasks (working memory, verbal reasoning, spatial processing). While older adults may have less experience with computers, the tasks were designed to require minimal computer skills from the participants. Furthermore, a training module familiarizes all participants with the computer interface and practice is provided before each task. Anecdotally, older adults were fully engaged and age effects were similar to paper and pencil measures.
Correlations with education and parental education were apparent, although they were generally higher for accuracy than for speed. More education was associated with better working memory, verbal reasoning and spatial processing skills, as well as better memory accuracy and faster motor speed. Higher parental education was associated with better performance across domains.
The overall results are positive, and the data presented here (and available to investigators, along with all the tests and a manual, at https://penncnp.med.upenn.edu
) can be used as a normative database for comparison with a range of clinical populations. The data can also facilitate identification of young people at risk for brain disorders and may offer avenues for early intervention and rehabilitation. The computerized format offers many advantages over traditional measures. It provides an efficient means to obtain both accuracy and speed, requires minimal training of administrators, offers automated scoring and its procedures and measures are to experimental data obtained in functional neuroimaging. The CNB has been successfully implemented in large-scale genetic studies that, in further support of its validity, have reported significant heritability of performance across domains (Greenwood et al., 2007
; Gur et al., 2007
). Instructions have been translated into several languages and used in research including genetic studies and pharmacological trials. The incorporation of neurocognitive and affective neuroscience probes in genetically informative samples can provide the next stage of identifying brain systems that are targets for intervention, aiming to modify deficits observed in cognitive and emotion processing. Our current methodological efforts are to find the smallest number of items needed for each test, so as to eventually create even more efficient multiple forms of the battery for repeated studies.