Timo Gnambs

Personality traits and knowledge sharing in online communities

Adopting diffusion theory and the concept of social value orientation, the effects of personality traits on knowledge sharing in a virtual open content community are investigated. In addition to the main effects of personality, it was hypothesized that intrinsic motivations would moderate the effects on knowledge sharing. A sample of N=256 active users of Wikipedia provided measures of personality, motivation, and knowledge sharing. Latent regression analyses support the notion that authorship of Wikipedia is associated with higher levels of trendsetting and a prosocial value orientation. Moreover, moderation analyses demonstrate that the effect of the latter is moderated by individual differences in motivations to write. Differences with regard to opinion leadership could not be confirmed.

Disclosure of sensitive behaviors across self-administered survey modes: a meta-analysis

In surveys, individuals tend to misreport behaviors that are in contrast to prevalent social norms or regulations. Several design features of the survey procedure have been suggested to counteract this problem; particularly, computerized surveys are supposed to elicit more truthful responding. This assumption was tested in a meta-analysis of survey experiments reporting 460 effect sizes (total N =125,672). Self-reported prevalence rates of several sensitive behaviors for which motivated misreporting has been frequently observed were compared across self-administered paper-and-pencil versus computerized surveys. The results revealed that computerized surveys led to significantly more reporting of socially undesirable behaviors than comparable surveys administered on paper. This effect was strongest for highly sensitive behaviors and surveys administered individually to respondents. Moderator analyses did not identify interviewer effects or benefits of audio-enhanced computer surveys. The meta-analysis highlighted the advantages of computerized survey modes for the assessment of sensitive topics.

Color red in web-based knowledge testing

Computer- and web-based testing procedures are increasingly popular for the assessment of cognitive abilities and knowledge. This paper identified color red as a critical context factor that may influence the results. Two studies showed that color red may harm the performance in web-based tests of general knowledge. In Study 1 (N=131) a red (vs. green) progress bar impeded the performance in a knowledge test, but only for the male participants. In Study 2 (N=190) the color of the surveys forward-button was manipulated (red vs. blue vs. mixed color) which led to a replication of the gender-dependent color effect. Evolutionary psychology and stereotype threat research explain why red impedes the activation of knowledge among men, but not among women.

A Short Measure of the Need for Affect

Two studies are presented to introduce a 10-item short form of the Need for Affect Questionnaire (NAQ–S; cf. Maio & Esses, 2001). Study 1 was based on 4 independent samples (German or English language; N total = 2,151) and demonstrated the expected factorial structure of the NAQ–S; its measurement invariance with respect to gender, age, and education; and the predicted associations with relevant personality measures. A latent state-trait analysis conducted in Study 2 (N = 140) suggests that most of the reliable variance of the NAQ–S represents stable individual differences.

The Transportation Scale–Short Form (TS–SF)

One popular concept to capture the experience of being immersed into the world of a story is that of transportation. This article examines the factorial validity of the Transportation Scale (TS) and introduces a short and psychometrically sound alternative for the assessment of transportation. Exploratory bifactor modeling in Study 1 (N = 179) provided support for the hypothesized factor structure of the original TS with three facets and a general transportation factor. Based on these analyses, a six-item short version of the scale, the Transportation Scale–Short Form (TS–SF), was developed. Study 2 (N = 131 and N = 246) as well as Study 3 (N = 301) corroborated the short forms factorial structure, reliability, and validity.

No effects of short-term exposure to mobile phone electromagnetic fields on human cognitive performance: a meta-analysis.

During recent years, a large number of studies on the effects of electromagnetic fields emitted by cellular mobile phones on human cognitive performance have been carried out. However, the results have been ambiguous. We carried out the current meta-analysis in order to investigate the impact of electromagnetic fields emitted by mobile phones on human cognition. Seventeen studies were included in the meta-analysis as they fulfill several requirements such as single- or double-blind experimental study design, and documentation of means and standard deviations of dependent variables. The meta-analysis was carried out as a group comparison between exposed and non-exposed subjects. No significant effects of electromagnetic fields emitted by Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS) mobile phones were found. Cognitive abilities seem to be neither impaired nor facilitated. Results of the meta-analysis suggest that a substantial short-term impact of high frequency electromagnetic fields emitted by mobile phones on cognitive performance can essentially be ruled out.

Acute effects of electromagnetic fields emitted by GSM mobile phones on subjective well-being and physiological reactions: A meta-analysis

The potential effects of radiofrequency electromagnetic fields (RF-EMF) emitted by GSM mobile phones on subjective symptoms, well-being and physiological parameters have been investigated in many studies. However, the results have been ambiguous. The current meta-analysis aims to clarify whether RF-EMF have an influence on well-being in self-reported sensitive persons, as well as in non-sensitive people. A literature search revealed 17 studies including 1174 participants. The single effects for various subjective and objective outcomes were meta-analytically combined to yield a single population parameter. Dependant variables were subjective (e.g. headaches) and objective parameters (e.g. heart rate variability) of well-being. The results show no significant impact of short-term RF-EMF exposure on any parameter. Future research should focus on the possible effects of long-term exposure.

Socioeconomic Factors and Suicide: An Analysis of 18 Industrialized Countries for the Years 1983 Through 2007

Objective: To evaluate the association between socioeconomic factors and suicide rates. Methods: Analysis of time series of suicide rates, gross domestic product, unemployment rates, labor force participation, and divorce rates of 18 countries are analyzed by the application of panel-vector error correction models. Main outcome measures are the association between the socioeconomic factors and suicide rates. Results: Decreasing economic growth and increasing divorce rates are significantly associated with increasing suicide rates in men. For women, increasing economic growth, increasing unemployment, and increasing divorce rates are significantly associated with increasing suicides. Increasing female labor force participation is associated with decreasing suicides. Conclusion: Socioeconomic factors are associated with suicide rates. However, this relationship differs by sex. The current results provide a strong argument that suicide prevention strategies must include the monitoring of socioeconomic development.

The decline of academic motivation during adolescence: an accelerated longitudinal cohort analysis on the effect of psychological need satisfaction

Adolescents typically exhibit a marked decline in academic intrinsic motivation throughout their school careers. Following self-determination theory, it is hypothesised that traditional school environments insufficiently satisfy three basic psychological needs of youths during maturation, namely the needs for autonomy, competence and relatedness. As a consequence, insufficient need satisfaction might account for the decline in intrinsic academic motivation during adolescence. This hypothesis was tested in an accelerated longitudinal cohort design on N = 600 students (286 girls) between 11 and 16 years of age. The results showed that students exhibited a marked decline in intrinsic motivation during adolescence. Moreover, differences in need satisfaction predicted the decline in motivations. These results support the notion that an adequate satisfaction of three basic psychological needs in school is crucial for the maintenance of intrinsic academic motivation during adolescence.

Socially Desirable Responding in Web-Based Questionnaires A Meta-Analytic Review of the Candor Hypothesis

Unproctored, web-based assessments supposedly reduce social desirability distortions in self-report questionnaires because of an increased sense of privacy among participants. Three random-effects meta-analyses focusing either on social desirability (k = 30, total N = 3,746), the Big Five of personality (k = 66, total N = 2,951), or psychopathology (k = 96, total N = 16,034) compared social desirability distortions of self-reports across computerized and paper-and-pencil administration modes. Overall, a near-zero effect, Δ = 0.01, was obtained that did not indicate less socially desirable responding in computerized assessments. Moreover, moderator analyses did not identify differential effects for proctored and unproctored procedures. Thus, paper-and-pencil and computerized administrations of self-report scales yield comparable mean scores. Unproctored web-based surveys do not offer an advantage with regard to socially desirable responding in self-report questionnaires.