Measuring Spatial Abilities in Children: A Comparison of Mental-Rotation and Perspective-Taking Tasks.

Mental rotation (MR) and perspective taking (PT) are important spatial abilities and predictive of performance in other cognitive domains. Yet, age-appropriate measures to assess these spatial abilities in children are still rare. This study examined psychometric properties of four MR tasks in 6- to 9-year-olds (N = 96). Two were developed specifically for children and two were based on established assessments for adults; one of each was a computerized and one was a paper-pencil task. Furthermore, spatial perspective taking (PT)-a different but closely related ability-was assessed to determine discriminant validity. Factor analyses showed that all MR tasks loaded on one single factor, with PT only loading weakly on the same factor, suggesting high construct validity. The computerized task for adults showed moderate factor loadings, constituted its own (but correlated) factor when a two-factor solution was forced, and showed the lowest reliabilities, suggesting that it was very difficult for children. On average, the new MR tasks had good to excellent reliabilities, differentiated well between age groups, and proved to be well-suited to assess MR in this age range. The PT task also showed good reliability and a steep developmental progression. Relations to verbal skills, gaming experience, and TV consumption are discussed.

Measuring Spatial Perspective Taking: Analysis of Four Measures Using Item Response Theory.

Research on spatial thinking requires reliable and valid measures of individual differences in various component skills. Spatial perspective taking (PT)-the ability to represent viewpoints different from one's own-is one kind of spatial skill that is especially relevant to navigation. This study had two goals. First, the psychometric properties of four PT tests were examined: Four Mountains Task (FMT), Spatial Orientation Task (SOT), Perspective-Taking Task for Adults (PTT-A), and Photographic Perspective-Taking Task (PPTT). Using item response theory (IRT), item difficulty, discriminability, and efficiency of item information functions were evaluated. Second, the relation of PT scores to general intelligence, working memory, and mental rotation (MR) was assessed. All tasks showed good construct validity except for FMT. PPTT tapped a wide range of PT ability, with maximum measurement precision at average ability. PTT-A captured a lower range of ability. Although SOT contributed less measurement information than other tasks, it did well across a wide range of PT ability. After controlling for general intelligence and working memory, original and IRT-refined versions of PT tasks were each related to MR. PTT-A and PPTT showed relatively more divergent validity from MR than SOT. Tests of dimensionality indicated that PT tasks share one common PT dimension, with secondary task-specific factors also impacting the measurement of individual differences in performance. Advantages and disadvantages of a hybrid PT test that includes a combination of items across tasks are discussed.

Qualitative and Quantitative Changes in Total Lipid Concentration and Lipid Fractions in Liver Tissue of Periparturient German Holstein Dairy Cows of Two Age Groups.

Fatty liver syndrome (FLS) is a common disease in high-producing dairy cows. Studies in humans suggest that the different hepatic lipid fractions play a role in this context. In dairy cows, little is known about the composition of fat stored in the liver, its periparturient dynamics, and the effect of cows' age. Therefore, our goal was to generate primary data in healthy cows to serve as reference values for future studies. Eight healthy German Holstein cows (2nd lactation, n = 3; ≥3rd lactation, n = 5) were examined 14 d antepartum and 7, 28, and 42 d postpartum. The examinations included clinical assessment, liver biopsy, blood sampling, and recording of milk yield. Total lipids (TL) in liver tissue were measured gravimetrically. The TL were separated into lipid fractions (triacylglycerol, TAG; phospholipids, PL; non-esterified fatty acids, NEFA; and cholesterol esters) using thin-layer chromatography, followed by gas chromatography for fatty acid determination. Concentrations of NEFA, ß-hydroxybutyrate, and cholesterol were analyzed in blood. Concentrations of TL, TAG, NEFA, and cholesterol esters in liver tissue and NEFA in blood increased in the periparturient period. The older cows had higher hepatic TL, TAG, and PL concentrations, higher relative hepatic concentrations of TAG in TL, higher NEFA concentrations in blood, a greater decrease in body condition, and higher milk yields between d 9 and 40 than the younger cows. We proposed that due to higher milk yield, older cows mobilized and deposited more fat in the liver, and the increase in hepatic TAG concentration was longer-lasting than in younger cows. Higher levels of structural lipids (PL) in older cows could be explained by higher demand for storage of TAG and cholesterol esters in lipid droplets or for the export of TAG via very-low-density lipoproteins. Results show that hepatic fat storage is a reversible process and does not necessarily cause clinical disease. Nevertheless, older cows have a more sustained and greater increase in hepatic TAG concentration, which may explain their increased risk of FLS. The results are limited in their extrapolation due to the small sample size and thereby possible selection bias but present a valuable basis for future studies.

The perceived duration of numerical and verbal digits: The independent effects of digit value and covered area.

Numerical digits influence perceived duration; specifically, higher numerical digit values are perceived to be longer than lower ones that are presented for the same duration of time. To examine the functional relationship between digit value and perceived duration further, three models based on digit value and covered area were tested in two experiments. Unlike previous studies, each experiment utilised the entire digit range that spans from 1 to 9. In both experiments, digit values were presented visually during the target interval of a time reproduction task. Although numerical digits (i.e., Arabic digits) were used in Experiment 1, verbal digits (i.e., number words) were utilised in Experiment 2. In the case of the numerical digits, perceived duration increased as a function of digit value, while the effect of covered area failed to reach statistical significance. For verbal digits, however, the effects of both digit value and covered area were statistically significant. Overall, our findings support the existence of two distinct nontemporal processes that are involved in the modulation of perceived duration: one process that is based on a digit's surface characteristics (i.e., covered area) and another process that is based on the digit's numerical meaning (i.e., digit value).

Visual-auditory differences in duration discrimination depend on modality-specific, sensory-automatic temporal processing: Converging evidence for the validity of the Sensory-Automatic Timing Hypothesis.

The Sensory-Automatic Timing Hypothesis assumes visual-auditory differences in duration discrimination to originate from sensory-automatic temporal processing. Although temporal discrimination of extremely brief intervals in the range of tens-of-milliseconds is predicted to depend mainly on modality-specific, sensory-automatic temporal processing, duration discrimination of longer intervals is predicted to require more and more amodal, higher order cognitive resources and decreasing input from the sensory-automatic timing system with increasing interval duration. In two duration discrimination experiments with sensory modality as a within- and a between-subjects variable, respectively, we tested two decisive predictions derived from the Sensory-Automatic Timing Hypothesis: (1) visual-auditory differences in duration discrimination were expected to be larger for brief intervals in the tens-of-milliseconds range than for longer ones, and (2) visual-auditory differences in duration discrimination of longer intervals should disappear when statistically controlled for modality-specific input from the sensory-automatic timing system. In both experiments, visual-auditory differences in duration discrimination were larger for the brief than for the longer intervals. Furthermore, visual-auditory differences observed with longer intervals disappeared when statistically controlled for modality-specific input from the sensory-automatic timing system. Thus, our findings clearly confirmed the validity of the Sensory-Automatic Timing Hypothesis.

Future Cognitive Ability: US IQ Prediction until 2060 Based on NAEP.

The US National Assessment of Educational Progress (NAEP) measures cognitive competences in reading and mathematics of US students (last 2012 survey N = 50,000). The long-term development based on results from 1971 to 2012 allows a prediction of future cognitive trends. For predicting US averages also demographic trends have to be considered. The largest groups' (White) average of 1978/80 was set at M = 100 and SD = 15 and was used as a benchmark. Based on two past NAEP development periods for 17-year-old students, 1978/80 to 2012 (more optimistic) and 1992 to 2012 (more pessimistic), and demographic projections from the US Census Bureau, cognitive trends until 2060 for the entire age cohort and ethnic groups were estimated. Estimated population averages for 2060 are 103 (optimistic) or 102 (pessimistic). The average rise per decade is dec = 0.76 or 0.45 IQ points. White-Black and White-Hispanic gaps are declining by half, Asian-White gaps treble. The catch-up of minorities (their faster ability growth) contributes around 2 IQ to the general rise of 3 IQ; however, their larger demographic increase reduces the general rise at about the similar amount (-1.4 IQ). Because minorities with faster ability growth also rise in their population proportion the interactive term is positive (around 1 IQ). Consequences for economic and societal development are discussed.