Inter-individual and intra-individual variability of the N2 component: On reliability and signal-to-noise ratio

The nogo N2 component, an anterior negative peak supposed to be generated in the anterior cingulate cortex, has been used as an indicator of conflict monitoring and response conflict in basic and clinical research. Here, we investigate the reliability and the signal-to-noise ratio (SNR) of inter-individual differences of the N2 amplitudes as well as of intra-individual standard deviations of N2 amplitudes. Effects of the number of nogo epochs, type of summary measure (peak vs. average amplitude), and filter cut-offs (1–12 Hz vs. 1–30 Hz) are investigated. A sample of N = 32 participants, performed a go/nogo task. Excellent Cronbach’s alpha coefficients (?.90) were obtained for the fronto-central average N2 amplitude at 40 nogo epochs and for the peak N2 amplitude at 60 nogo epochs. The SNR was higher for the average nogo N2 amplitude compared to the peak N2 amplitude. Split-half reliability coefficients of the intra-individual standard deviation of the nogo N2 amplitudes were at least moderate. Based on these results we provide suggestions for a reliable N2 measurement. Moreover, although intra-individual variability has often been conceived as noise the present findings support the idea that intra-individual N2 variability incorporates systematic variance.     

A Swedish translation of the 20-item Toronto Alexithymia Scale: cross-validation of the factor structure

The purpose of this study was to develop a new Swedish translation of the twenty-item Toronto Alexithymia Scale (TAS-20) and to examine if the theoretical structure that underlies the factor structure of the English version of the TAS-20 could be recovered in this Swedish translation of the instrument. A sample of 157 undergraduate students of psychology was tested. Using confirmatory factor analysis, the previously established three-factor TAS-20 model was found to be replicable in this sample. In addition, the Swedish translation of the TAS-20 showed adequate internal reliability. The present study also illustrates the importance of using back translation methodology when transposing psychometric instruments from one language to another.     

Control of oscillatory force tasks: Low-frequency oscillations in force and muscle activity

Force variability during steady force tasks is strongly related to low-frequency oscillations (<0.25 Hz) in force. However, it is unknown whether low-frequency oscillations also contribute to the variability of oscillatory force tasks. To address this, twelve healthy young participants (21.08 ± 2.99 years, 6 females) performed a sinusoidal force task at 15% MVC at two different frequencies (0.5 and 1 Hz) with isometric abduction of the index finger. We recorded the force from the index finger and surface EMG from the first dorsal interosseous muscle and quantified the following outcomes: 1) trajectory variability and accuracy; 2) power spectrum of force and EMG bursting below 2 Hz; 3) power spectrum of the interference EMG from 4 to 60 Hz. The trajectory variability and error significantly increased from 0.5 to 1 Hz task (P < 0.01). Increased force oscillations <0.25 Hz contributed to greater trajectory variability and error for both the 0.5 and 1 Hz oscillatory task (R² > 0.33; P < 0.05). The <0.25 Hz oscillations in force were positively associated with greater power in the <0.25 Hz for EMG bursting (R² > 0.52; P < 0.01). The modulation of the interference EMG from 35 to 60 Hz was a good predictor of the <0.25 Hz force oscillations for both the 0.5 Hz task and 1 Hz task (R² > 0.66; P < 0.01). These results provide novel evidence that, similar to steady contractions, low-frequency oscillations of the motor neuron pool appear to be a significant mechanism that controls force during oscillatory force tasks.     

Transparency of Self-Report Racial Attitude Scales

Researchers frequently use self-report prejudice scales to assess predictors and outcomes. Responding to evidence that such instruments are vulnerable to social desirability pressures and diverge from implicit attitude measures, researchers have developed instruments intended to be less transparent in their social implications. The purpose of this study was to assess the transparency of a sample of such instruments. Participants completed prejudice measures under typical scale instructions, or under alternate instructions to portray themselves either positively or negatively. The results indicate that several common measures of prejudice are quite transparent in their implications. Further, mean scores of participants instructed to provide desirable responses were indistinguishable from those ostensibly responding honestly.     

Fairness Perceptions of Selection Instruments Used in Turkey

The purpose of this study is to examine the relationship between the goal orientation of individuals and their reactions to three different selection instruments used in Turkey. A sample of 154 engineering students from a university rated the favorability and fairness perceptions of these instruments, namely, interview, personality and science achievement tests. The goal orientations of the participants were determined according to median values of the respected scales. A 2 × 3 mixed design ANOVA pointed out that among the rated selection techniques in the order of interview, science achievement tests, and personality tests were perceived to be favorable and fair. Although there was no main effect of goal orientation, the interaction between goal orientation and different selection instruments was significant regarding the question of invasion of privacy. Specifically, it was found that learning goal‐oriented subjects value science tests more than the performance proof‐oriented subjects in terms of the question of ‘this selection instrument invades privacy.’ Learning goal‐oriented subjects think more than the performance proof‐oriented subjects that the personality tests are an invasion of privacy. The results were discussed and the direction for future research specified.     

A COMPARISON OF TWO ORGANIZATIONAL COMMITMENT SCALES1

This study examines the scale characteristics of two widely utilized measures of organizational commitment. Using data collected from a sample of 1,105 professional accountants, the findings indicated that while both instruments exhibited a high degree of internal reliability, the Porter et al. (1974) instrument exhibited significantly greater predictive validity with respect to intended turnover than did the Hrebiniak and Alutto (1972) instrument. However, for a limited sample of data, no difference was found between the predictive ability of the two measures with respect to actual turnover. In addition, the relationship between a set of ten common predictor variables and organizational commitment was found to be substantially greater when commitment was measured using the Porter et al. instrument.     

The interaction of respiration and visual feedback on the control of force and neural activation of the agonist muscle

The purpose of this study was to compare force variability and the neural activation of the agonist muscle during constant isometric contractions at different force levels when the amplitude of respiration and visual feedback were varied. Twenty young adults (20–32 years, 10 men and 10 women) were instructed to accurately match a target force at 15% and 50% of their maximal voluntary contraction (MVC) with abduction of the index finger while controlling their respiration at different amplitudes (85%, 100% and 125% normal) in the presence and absence of visual feedback. Each trial lasted 22 s and visual feedback was removed from 8–12 and 16–20 s. Each subject performed three trials with each respiratory condition at each force level. Force variability was quantified as the standard deviation of the detrended force data. The neural activation of the first dorsal interosseus (FDI) was measured with bipolar surface electrodes placed distal to the innervation zone. Relative to normal respiration, force variability increased significantly only during high-amplitude respiration (∼63%). The increase in force variability from normal- to high-amplitude respiration was strongly associated with amplified force oscillations from 0 to 3 Hz (R² ranged from .68 to .84, p < .001). Furthermore, the increase in force variability was exacerbated in the presence of visual feedback at 50% MVC (vision vs. no-vision: .97 vs. .87 N) and was strongly associated with amplified force oscillations from 0 to 1 Hz (R² = .82) and weakly associated with greater power from 12 to 30 Hz (R² = .24) in the EMG of the agonist muscle. Our findings demonstrate that high-amplitude respiration and visual feedback of force interact and amplify force variability in young adults during moderate levels of effort.     

How many is enough? Determining optimal sample sizes for normative studies in pediatric neuropsychology.

The purpose of this investigation was to determine how confidence intervals (CIs) for pediatric neuropsychological norms vary as a function of sample size, and to determine optimal sample sizes for normative studies. First, the authors calculated 95% CIs for a set of published pediatric norms for four commonly used neuropsychological instruments. Second, 95% CIs were calculated for varying sample size (from n = 5 to n = 500). Results suggest that some pediatric norms have unacceptably wide CIs, and normative studies ought optimally to use 50 to 75 participants per cell. Smaller sample sizes may lead to overpathologizing results, while the cost of obtaining larger samples may not be justifiable.     

Environmental and Psychological Factors that Influence the Creative Excellence of Brazilian and Portuguese Women

There is increasing recognition of the importance of creativity for social development. The purpose of this study was to investigate whether there were differences among Brazilian and Portuguese women recognized for their creative excellence in relation to the psychological and environmental factors that might impact their achievements. The sample was composed of 33 women; 18 who were socially recognized for excellence in creativity in different areas (nine Brazilian, nine Portuguese) were compared to 15 who were not recognized (nine Brazilian, six Portuguese). The instruments used were the Biographical Questionnaire of Creative Women, a semi‐structured interview guide, and the Creative Production Analysis Guide. Non‐parametric tests indicated significant differences in environmental factors and personal cognitive characteristics between the creative and non‐creative women when compared within each country. However, no significant differences among Brazilian and Portuguese creative women were found, thus indicating that they present similar psychological profiles.     

Movement Variability Increases With Shoulder Pain When Compensatory Strategies of the Upper Body Are Constrained

This cross-sectional study analyzed the influence of chronic shoulder pain (CSP) on movement variability/kinematics during humeral elevation, with the trunk and elbow motions constrained to avoid compensatory strategies. For this purpose, 37 volunteers with CSP as the injured group (IG) and 58 participants with asymptomatic shoulders as the control group (CG) participated in the study. Maximum humeral elevation (Emax), maximum angular velocity (Velmax), variability of the maximum angle (CVEmax), functional variability (Func_var), and approximate entropy (ApEn) were calculated from the kinematic data. Patients' pain was measured on the visual analogue scale (VAS). Compared with the CG, the IG presented lower Emax and Velmax and higher variability (i.e., CVEmax, Func_var, and ApEn). Moderate correlations were achieved for the VAS score and the kinematic variables Emax, Velmax and variability of curve analysis, Func_varm, and ApEn. No significant correlation was found for CVEmax. In conclusion, CSP results in a decrease of angle and velocity and an increased shoulder movement variability when the neuromuscular system cannot use compensatory strategies to avoid painful positions.     

Workplace mobbing and effects on workers' health

In this work, we analyze various consequences of the phenomenon of mobbing on the health of a work sector with special characteristics: the agro fruit sector. For this purpose, we collected data from a sample of 396 workers (61 men and 331 women) belonging to this sector in the Region of Murcia (Spain). A questionnaire with the following measurement instruments was administered: a Spanish adaptation of the revised Negative Acts Questionnaire (Sáez, García, & Llor, 2003), the Psychosomatic Problems Questionnaire (Hock, 1988), and a measure of absenteeism. The results revealed a significant and positive relation between workplace mobbing and psychosomatic symptoms, but not with absenteeism. The implications of the results for future research are discussed.     

Model stability of the 15-item Geriatric Depression Scale across cognitive impairment and severe depression

The 15-item Geriatric Depression Scale (GDS) is used in a wide variety of clinical and research settings. The study's purpose was to further establish the validity of the 15-item GDS by exploring the underlying factor structure in a healthy, nondemented sample of older adults and then analyzing whether this factor structure remained stable across a sample of demented individuals and a sample of individuals with a history of depression 6 months after discharge from an inpatient psychiatric setting. A 2-factor model fit the data best in the exploratory analyses. The 2 factors, Life Satisfaction and General Depressive Affect, found in the nondemented sample (r = .39) remained stable across cognitive impairment (r = .12) but merged into a 1-factor model in the psychiatric sample (r = .93). The results indicate that nondepressed older adults with poor life satisfaction may be identified as depressed on screening instruments such as the 15-item GDS.     

How Many is Enough? Determining Optimal Sample Sizes for Normative Studies in Pediatric Neuropsychology

The purpose of this investigation was to determine how confidence intervals (CIs) for pediatric neuropsychological norms vary as a function of sample size, and to determine optimal sample sizes for normative studies. First, the authors calculated 95% CIs for a set of published pediatric norms for four commonly used neuropsychological instruments. Second, 95% CIs were calculated for varying sample size (from n?=?5 to n?=?500). Results suggest that some pediatric norms have unacceptably wide CIs, and normative studies ought optimally to use 50 to 75 participants per cell. Smaller sample sizes may lead to overpathologizing results, while the cost of obtaining larger samples may not be justifiable.     

RELATIONSHIPS BETWEEN LEADER BEHAVIOR VARIABILITY INDICES AND SUBORDINATE RESPONSES1,2

The relationships of leader behavior variability indices to a variety of subordinate affective responses and experienced psychological states were examined for two samples differing in perceived job characteristics. In the sample facing routine task demands, little relationship was evident between leader behavior variability indices and subordinate responses. In the sample characterized by greater variability in task demands, correlations between responses and leader variability indices were generally significant and stronger than those between responses and absolute levels of leader behaviors. For both samples, leader behavior variability was negatively related to subordinate responses. Implications of the findings and suggestions for future research are presented.     

The efficacy of the Microsoft Kinect<Superscript>TM</Superscript> to assess human bimanual coordination

The Microsoft Kinect has been used in studies examining posture and gait. Despite the advantages of portability and low cost, this device has not been used to assess interlimb coordination. Fundamental insights into movement control, variability, health, and functional status can be gained by examining coordination patterns. In this study, we investigated the efficacy of the Microsoft Kinect to capture bimanual coordination relative to a research-grade motion capture system. Twenty-four healthy adults performed coordinated hand movements in two patterns (in-phase and antiphase) at eight movement frequencies (1.00–3.33 Hz). Continuous relative phase (CRP) and discrete relative phase (DRP) were used to quantify the means (mCRP and mDRP) and variability (sdCRP and sdDRP) of coordination patterns. Between-device agreement was assessed using Bland–Altman bias with 95 % limits of agreement, concordance correlation coefficients (absolute agreement), and Pearson correlation coefficients (relative agreement). Modest-to-excellent relative and absolute agreements were found for mCRP in all conditions. However, mDRP showed poor agreement for the in-phase pattern at low frequencies, due to large between-device differences in a subset of participants. By contrast, poor absolute agreement was observed for both sdCRP and sdDRP, while relative agreement ranged from poor to excellent. Overall, the Kinect captures the macroscopic patterns of bimanual coordination better than coordination variability.     

Interparental Conflict and Youth Problem Behaviors: A Meta-Analysis

We examined the proposition that interparental conflict is associated with internalizing and externalizing problems in youth ages 5 to 18. This examination was done by conducting a meta-analysis of 348 statistical effects from 68 studies. The average effect size (d-value) was .32. There was considerable variability among effect sizes and this variability was associated with the average time since separation for separated/divorced parents, the socioeconomic status composition of the sample, and average parental education in the sample. The variability among effect sizes also was associated with the source of the informant used to assess interparental conflict and youth problem behaviors. Surprisingly, many of the other study characteristics we coded were not associated with variability in the effect sizes.     

Are there critical bands in kinesthesia?

The effect of changing the bandwidth of noise on the ability of human subjects to detect a 10-Hz sinusoidal movement signal was measured in two experiments. The objective of these studies was to investigate whether critical bands exist for the kinesthetic system, as has been demonstrated for the auditory and tactile systems. It was found that subjects' ability to detect a 10-Hz sinusoidal movement stimulus embedded in noise was not influenced by the bandwidth of the noise over a range of 4-10 Hz. These findings suggest that, if a critical filter does exist for this system, it would have to be greater than 10 Hz.     

Intermittent visual information and the multiple time scales of visual motor control of continuous isometric force production

In an experiment, we examined the effect of intermittency (from 25.6 Hz to 0.2 Hz) of visual information on continuous isometric force production as a function of force level (5%, 10%, 25%, and 50% of maximal voluntary contraction [MVC]). The amount of force variability decreased and the irregularity of force output increased as a function of increased visual intermittency rate. Vision was found to have an influence on the frequency structure of force output up to 12 Hz, and the 25% MVC force level had more high-frequency modulations with higher rates of visual information. The effective use of intermittent visual information is mediated nonlinearly by force level, and there are multiple time scales of visual control (range, approximately 0 - 12 Hz) that are postulated to be a function of both feedback and feedforward control processes.     

An abbreviated PTSD checklist for use as a screening instrument in primary care

Although the importance of recognizing posttraumatic stress disorder (PTSD) in primary care has been well-established, routine screening for PTSD remains unfeasible for many primary care clinics because of the length of the available screening instruments. Thus, the purpose of this work was to develop and validate a brief screening tool for PTSD. In Study 1, four short forms of the PTSD Checklist-civilian version were identified that captured a majority of the variance in the measure. In Study 2, the performance of these short forms was evaluated in a separate sample of primary care patients. We found that both two-item and six-item versions have adequate psychometric properties for screening purposes and suggest that the selection of one version over the other depends on the specific needs of each primary care clinic.