Contemporary theories of 1/f noise in motor control

1/f noise has been discovered in a number of time series collected in psychological and behavioral experiments. This ubiquitous phenomenon has been ignored for a long time and classical models were not designed for accounting for these long-range correlations. The aim of this paper is to present and discuss contrasted theoretical perspectives on 1/f noise, in order to provide a comprehensive overview of current debates in this domain. In a first part, we propose a formal definition of the phenomenon of 1/f noise, and we present some commonly used methods for measuring long-range correlations in time series. In a second part, we develop a theoretical position that considers 1/f noise as the hallmark of system complexity. From this point of view, 1/f noise emerges from the coordination of the many elements that compose the system. In a third part, we present a theoretical counterpoint suggesting that 1/f noise could emerge from localized sources within the system. In conclusion, we try to draw some lines of reasoning for going beyond the opposition between these two approaches.     

BINS validation - Bayley neurodevelopmental screener in Brazilian preterm children under risk conditions

Psychometric researches increase in Brazil. Bayley Infant Neurodevelopment Screener - BINS (Aylward, 1995) is a low cost, fast instrument. In 10’ it classifies children under developmental risk degrees. This research purpose was investigating BINS psychometric properties. 61 low-income Brazilian preterm, were divided in groups: 31 children (12 months) and 30 children (24 months), both sex, birth weight <2000 g. Socio-demographic-psychological profile was previously registered. Neurologists examined them through Amiel-Tison and Gosselin (2001) and physicians with Denver-DDST-II (Frankenburg, Dodds, Archer, &; Bresnick, 1990). Psychologist assessed children at chronological age, with Bayley Scales-BSID-II (Bayley, 1993) and BINS (12 m) and BINS (24 m). Results demonstrated homogeneous characteristics sample. Reliability indexes were over requested standards. Validity evidences based on external variables were positive moderated and BINS (24 m)/BSID-II (mental) presented high correlation. Validity evidences based on content were attested by expertise. High sensitivity was found. So, BINS can be considered an instrument of adequate psychometric properties, able to screen children under risk, according to Psychological Association requests.     

Improving comprehension and communication of risks about health

Many patients have severe difficulties grasping several numerical concepts that are related to their health, such as, for instance, the risk of suffering various diseases. Visual aids have been proposed as a promising method for enhancing risk communication and comprehension. In medical practice, however, not all patients benefit from visual aids. In a study conducted on a probabilistic, representative national sample in the United States, we identified a group of patients for whom visual aids are most useful: Those who have low numeracy but high graphical literacy skills. These patients have high scores in three abilities involved in graph comprehension: (1) the ability to read the data, (2) the ability to read the relations between the data, and (3) the ability to read beyond the data. Our results can have important implications for medical practice and for risk communication about health.     

Gender and Race Portrayals on Spanish-Language Television

318 randomly selected television ads from India (from 2004) in three different languages (English, Hindi, and Tamil) were content analyzed to examine both the frequency of appearance and prevalence of gender stereotypes. Results indicate that there are more male than female central characters and voiceovers in Indian ads; stereotypical differences were also found in the type of credibility used by men and women, and the nature of the products they advertised and settings that males and females appeared in. Female central characters tended to be younger than their male counterparts and were more likely to be portrayed in relationship roles. Similarities and differences in gender role portrayals found in Indian television ads and those from other nations are also discussed.     

Childhood Gender Identity … Disorder? Developmental,Cultural, and Diagnostic Concerns

Childhood gender identity development is reviewed in the context of biological, environmental, cultural, and diagnostic factors. With the upcoming 5th revision of the Diagnostic and Statistical Manual of Mental Disorders, the authors offer a critical consideration of childhood gender identity disorder, along with proposed diagnostic changes. They argue that meaningful understanding of issues surrounding gender identity is necessary for a conscientious assessment and diagnostic process that does not pathologize human diversity.     

Interval bias in 2AFC detection tasks: sorting out the artifacts

Proportion correct in two-alternative forced choice (2AFC) detection tasks often varies when the stimulus is presented in the first or in the second interval. Reanalysis of published data reveals that these order effects (or interval bias) are strong and prevalent, refuting the standard difference model of signal detection theory. Order effects are commonly regarded as evidence that observers use an off-center criterion under the difference model with bias. We consider an alternative difference model with indecision whereby observers are occasionally undecided and guess with some bias toward one of the response options. Whether or not the data show order effects, the two models fit 2AFC data indistinguishably, but they yield meaningfully different estimates of sensory parameters. Under indeterminacy as to which model governs 2AFC performance, parameter estimates are suspect and potentially misleading. The indeterminacy can be circumvented by modifying the response format so that observers can express indecision when needed. Reanalysis of published data collected in this way lends support to the indecision model. We illustrate alternative approaches to fitting psychometric functions under the indecision model and discuss designs for 2AFC experiments that improve the accuracy of parameter estimates, whether or not order effects are apparent in the data.     

Psychometric functions for detection and discrimination with and without flankers

Recent studies have reported that flanking stimuli broaden the psychometric function and lower detection thresholds. In the present study, we measured psychometric functions for detection and discrimination with and without flankers to investigate whether these effects occur throughout the contrast continuum. Our results confirm that lower detection thresholds with flankers are accompanied by broader psychometric functions. Psychometric functions for discrimination reveal that discrimination thresholds with and without flankers are similar across standard levels, and that the broadening of psychometric functions with flankers disappears as standard contrast increases, to the point that psychometric functions at high standard levels are virtually identical with or without flankers. Threshold-versus-contrast (TvC) curves with flankers only differ from TvC curves without flankers in occasional shallower dippers and lower branches on the left of the dipper, but they run virtually superimposed at high standard levels. We discuss differences between our results and other results in the literature, and how they are likely attributed to the differential vulnerability of alternative psychophysical procedures to the effects of presentation order. We show that different models of flanker facilitation can fit the data equally well, which stresses that succeeding at fitting a model does not validate it in any sense.     

Approximate entropy normalized measures for analyzing social neurobiological systems

When considering time series data of variables describing agent interactions in social neurobiological systems, measures of regularity can provide a global understanding of such system behaviors. Approximate entropy (ApEn) was introduced as a nonlinear measure to assess the complexity of a system behavior by quantifying the regularity of the generated time series. However, ApEn is not reliable when assessing and comparing the regularity of data series with short or inconsistent lengths, which often occur in studies of social neurobiological systems, particularly in dyadic human movement systems. Here, the authors present two normalized, nonmodified measures of regularity derived from the original ApEn, which are less dependent on time series length. The validity of the suggested measures was tested in well-established series (random and sine) prior to their empirical application, describing the dyadic behavior of athletes in team games. The authors consider one of the ApEn normalized measures to generate the 95th percentile envelopes that can be used to test whether a particular social neurobiological system is highly complex (i.e., generates highly unpredictable time series). Results demonstrated that suggested measures may be considered as valid instruments for measuring and comparing complexity in systems that produce time series with inconsistent lengths.