Stimulus change and complexity in exploratory behavior

It has recently been proposed (Fowler, 1967, 1971) that the incentive value of novelty can be defined in terms of stimulus change. An experiment is reported which examines the relationship between changes in complexity and the consequent exploratory behavior. Following extended exposure to a midcomplexity stimulus, rats were allowed to choose between a stimulus change and the now familiar midcomplexity stimulus. For some Ss the change was to a stimulus of higher complexity, and for others the change was to a lower complexity stimulus. The results suggest that physical stimulus changes to a stimulus of greater complexity is a more effective novel stimulus than physical stimulus changes to lesser complexity, although both changes may function as incentives.     

Comparison of heart rate monitoring with indirect calorimetry for energy expenditure evaluation

PurposeThe purpose of this study was to compare established methods with newly-developed methods for estimating the total energy expenditure (TEE).MethodsThe study subjects comprised 46 individuals, including 16 middle-aged men (mean age 51.4 years), 14 middle-aged women (mean age 49.9 years) and 16 young women (mean age 19.1 years). The TEE was estimated from 24-h heart rate (HR) data using newly-developed software (MoveSense HRAnalyzer 2011a, RC1, Suunto Oy, Vantaa, Finland), and was compared against the TEE determined using doubly labeled water (DLW). Agreement between the two methods was analyzed using Bland and Altman plots.ResultsThe HR method yielded similar TEE values as the DLW method at the group level, with an average of 8.6 kcal/day in the difference in the mean, but with large individual variations. Forty-four (96%) out of 46 subjects fell within ±2SD of the mean difference in TEE comparisons, and there was no tendency towards under- or over-estimation.ConclusionOur results indicate that the current software using HR analysis for the estimation of daily TEE needs further development for use with free-living individuals.     

Revisiting the association between reading achievement and antisocial behavior: new evidence of an environmental explanation from a twin study

Previous studies have reported, but not explained, the reason for a robust association between reading achievement and antisocial behavior. This association was investigated using the Environmental Risk (E-Risk) Longitudinal Twin Study, a nationally representative 1994-1995 birth cohort of 5- and 7-year-olds. Results showed that the association resulted primarily from environmental factors common to both reading and antisocial behavior and was stronger in boys. Environmental factors also explained the relation between reading disability and conduct disorder. Leading candidate environmental risk factors weakly mediated the association. For boys the best explanation was a reciprocal causation model: poor reading led to antisocial behavior, and vice versa. In contrast, the relation between reading achievement and attention deficit hyperactivity disorder was best explained by common genetic influences.