Fractal dynamics of heart beat interval fluctuations in corticotropin-releasing factor receptor subtype 2 deficient mice

Non-linear fractal analysis of cardiac interbeat time series was performed in corticotropin-releasing factor receptor subtype 2 (CRFR2) deficient mice. Heart rate dynamics in mice constitutes a self-similar, scale-invariant, random fractal process with persistent intrinsic long-range correlations and inverse power-law properties. We hypothesized that the sustained tachycardic response elicited by intraperitoneal (ip) injection of human/rat CRF (h/rCRF) is mediated by CRFR2. In wildtype control animals, heart rate was increased to about maximum levels (~ 750 bpm) while in CRFR2-deficient animals baseline values were retained (~ 580 bpm). The tachycardic response elicited by ip-application is mediated by CRFR2 and is interpreted to result from sympathetic stimulation. However, the functional integrity of CRFR2 would not present a prerequisite to maintaining the responsiveness and resiliency of cardiac control to external environmental perturbations experimentally induced by extrinsic ip-application of h/rCRF or under physiological conditions that may be associated with an increased peripheral release of CRF. Under stressful physiological conditions achieved by novelty exposure, CRFR2 is not involved in the cardiodynamic regulation to external short-term stress. While the hypothesis of involvement of CRFR2 in cardiac regulation upon pharmacological stimulation cannot be rejected, the present findings suggest that the mechanism of action is by sympathetic stimulation, but would not unambiguously allow to draw any conclusions as to the physiological role of CRFR2 in the control of cardiac dynamics.     

Reliability of estimates of return rates as a measure of public attitudes to violence

An analysis of letters placed in Mobile, Alabama and Sioux Falls, South Dakota (ns = 500 and 600) showed return rates among the several addresses were essentially uncorrelated (rs = -.11 to .08) so interpoll reliability is lacking.     

Large visuospatial sex difference in line judgment: possible role of attentional factors

This article describes a large sex difference on a new, group-administered visuospatial task, the Judgment of Line Angle and Position (JLAP) test, and investigates the role of attentional factors in the difference. On the JLAP, adapted from a neuropsychological task (Benton et al., 1983), participants evaluate spatial attributes of lines. Study 1: College males (N = 48) outperformed females (N = 80), resulting in a large effect for sex (d = 0.85). Errors were more common on oblique (vs horizontal or vertical) lines, especially for females. Study 2: Task attributes were manipulated (N = 33 males and 36 females) to study the role of attentional factors. Findings suggest that males are more likely than females to normally attend to and be aided by geometrical reference cues.     

Overconfidence in interval estimates

Judges were asked to make numerical estimates (e.g., "In what year was the first flight of a hot air balloon?"). Judges provided high and low estimates such that they were X% sure that the correct answer lay between them. They exhibited substantial overconfidence: The correct answer fell inside their intervals much less than X% of the time. This contrasts with choices between 2 possible answers to a question, which showed much less overconfidence. The authors show that overconfidence in interval estimates can result from variability in setting interval widths. However, the main cause is that subjective intervals are systematically too narrow given the accuracy of one's information-sometimes only 40% as large as necessary to be well calibrated. The degree of overconfidence varies greatly depending on how intervals are elicited. There are also substantial differences among domains and between male and female judges. The authors discuss the possible psychological mechanisms underlying this pattern of findings.     

Modernization and the Male–Female Suicide Ratio in India 1967–1997: Divergence or Convergence?

The traditional view that modernization is likely to increase male vulnerability to suicide while protecting females from such self-destruction was offered by Durkheim (1951). This implies a theory of divergence of suicide rates such that the male-female suicide ratio should increase with modernization. Contemporary researchers have questioned whether modernization has had such an impact. We conducted a time series analysis of male and female suicide data to determine the impact on the suicide ratio for India for the years 1967 to 1997. We developed a modernization index comprised of urbanization, female literacy, and female work participation rates. Moreover, to improve methodological efficacy, we controlled for the passage of time. However, we found that there is no significant relationship between modernization and the male-female suicide ratio. Our conclusion is that using national male-female suicide ratios to determine modernization effects may mask significant regional gender and age differences, particularly in developing countries such as India.     

Catching audiovisual mice: Predicting the arrival time of auditory-visual motion signals

We investigated the extent to which auditory and visual motion signals are combined when observers are asked to predict the location of a virtually moving target. In Condition 1, the unimodal and bimodal signals were noisy, but the target object was continuously visible and audible; in Condition 2, the virtually moving object was hidden (invisible and inaudible) for a short period prior to its arrival at the target location. Our main finding was that the facilitation due to simultaneous visual and auditory input is very different for the two conditions. When the target is continuously visible and audible (Condition 1), the bimodal performance is twice as good as the unimodal performances, thus suggesting a very effective integration mechanism. On the other hand, if the object is hidden for a short period (Condition 2) and the task therefore requires the extrapolation of motion speed over a temporal and spatial period, the facilitation due to both sensory inputs is almost absent, and the bimodal performance is limited by the visual performance.     

Increases in manic symptoms after life events involving goal attainment

Bipolar disorder has been conceptualized as an outcome of dysregulation in the behavioral activation system (BAS), a brain system that regulates goal-directed activity. On the basis of the BAS model, the authors hypothesized that life events involving goal attainment would promote manic symptoms in bipolar individuals. The authors followed 43 bipolar I individuals monthly with standardized symptom severity assessments (the Modified Hamilton Rating Scale for Depression and the Bech-Rafaelsen Mania Rating Scale). Life events were assessed using the Goal Attainment and Positivity scales of the Life Events and Difficulties Schedule. As hypothesized, manic symptoms increased in the 2 months following goal-attainment events, but depressed symptoms were not changed following goal-attainment events. These results are congruent with a series of recent polarity-specific findings.     

On the science of Rorschach research

Wood et al.'s (1999b) article contained several general points that are quite sound. Conducting research with an extreme groups design does produce effect sizes that are larger than those observed in an unselected population. Appropriate control groups are important for any study that wishes to shed light on the characteristics of a targeted experimental group and experimental validity is enhanced when researchers collect data from both groups simultaneously. Diagnostic efficiency statistics--or any summary measures of test validity--should be trusted more when they are drawn from multiple studies conducted by different investigators across numerous settings rather than from a single investigator's work. There should be no question that these points are correct. However, I have pointed out numerous problems with specific aspects of Wood et al.'s (1999b) article. Wood et al. gave improper citations that claimed researchers found or said things that they did not. Wood et al. indicated my data set did not support the incremental validity of the Rorschach over the MMPI-2 when, in fact, my study never reported such an analysis and my data actually reveal that the opposite conclusion is warranted. Wood et al. asserted there was only one proper way to conduct incremental validity analyses even though experts have described how their recommended procedure can lead to significant complications. Wood et al. cited a section of Cohen and Cohen (1983) to bolster their claim that hierarchical and step-wise regression procedures were incompatible and to criticize Burns and Viglione's (1996) regression analysis. However, that section of Cohen and Cohen's text actually contradicted Wood et al.'s argument. Wood et al. tried to convince readers that Burns and Viglione used improper alpha levels and drew improper conclusions from their regression data although Burns and Viglione had followed the research evidence on this topic and the expert recommendations provided in Hosmer and Lemeshow's (1989) classic text. Wood et al. oversimplified issues associated with extreme group research designs and erroneously suggested that diagnostic studies were immune from interpretive confounds that can be associated with this type of design. Wood et al. ignored or dismissed the valid reasons why Burns and Viglione used an extreme groups design, and they never mentioned how Burns and Viglione used a homogeneous sample that actually was likely to find smaller than normal effect sizes. Wood et al. also overlooked the fact that Burns and Viglione identified their results as applying to female nonpatients; they never suggested their findings would characterize those obtained from a clinical sample. Wood et al. criticized composite measures although some of the most important and classic findings in the history of research on personality recommend composite measures as a way to minimize error and maximize validity. Wood et al. also were mistaken about the elements that constitute an optimal composite measure. Wood et al. apparently ignored the factor-analytic evidence that demonstrated how Burns and Viglione created a reasonable composite scale, and Wood et al. similarly ignored the clear evidence that supported the content and criterion related validity of the EMRF. With respect to the HEV, Wood et al. created a z-score formula that used the wrong means and standard deviations. They continued to use this formula despite being informed that it was incorrect. Subsequently, Wood et al. told readers that their faulty z-score formula was "incompatible" with the proper weighted formula and asserted that the two formulas "do not yield identical results" and "do not yield HEV scores that are identical or even very close." These published claims were made even though Wood et al. had seen the results from eight large samples, all of which demonstrated that their wrong formula had correlations greater than .998 with the correct formula. At worst, it seems that Wood et al. (199