Internet addiction among Czech adolescents.

Our study estimates the prevalence of Internet addiction in Czech adolescents as well as differences by gender and school type. A total of 3,950 adolescents (n = 1,940 boys, n = 2,010 girls) from 11 to 19 years of age (M = 15.73, SD = 1.99) participated in the research. They completed the Internet Addiction Test, which consists of subscales for Salience, Excessive Use, Neglect Work, Anticipation, Lack of Control, and Neglect Social Life. The results indicate that adolescent girls have higher levels of internet addiction. In boys, unlike girls, internet addiction was associated with a reduction in social relationships and interactions. Our findings show interesting differences between adolescent girls and boys and the type of school attended in the Czech population in terms of Internet addiction.

EEG data and introspective reports from the Libet׳s experiment replication.

This article provides data from a contemporary replication of Libet׳s experiment. For the methodology, results and discussion of the replication, see the article "Libet׳s Experiment: A Complex Replication" (Dominik et al., 2018). Three types of data are presented in this article: (1) introspective reports (M, W and S), (2) EMG onset times relative to a mouse click or to the target time in tasks with a movement at pre-set time and (3) relevant averaged EEG data.

Libet's experiment: A complex replication.

Libet's experiment is an influential classical study, which does not stop provoking heated debates. However, a full-scale replication has not been carried out to this day. Libet-style studies have usually focused on isolated ideas and concepts and never on the whole experiment in all its complexity. This paper presents detailed methodological description and results of a complex replication study. The methodology follows Libet's directions closely in most cases; when it does not, the differences are described and elaborated. The results replicate Libet's key findings, but substantial differences were found in some of the results' categories, such as the introspective reports or the number of readiness-potentials found. The discussion also addresses some current problems pertaining the methodology of the Libet-style experiments and provides some recommendations based on a detailed process evaluation.

Libet's experiment: Questioning the validity of measuring the urge to move.

The time of subjectively registered urge to move (W) constituted the central point of most Libet-style experiments. It is therefore crucial to verify the W validity. Our experiment was based on the assumption that the W time is inferred, rather than introspectively perceived. We used the rotating spot method to gather the W reports together with the reports of the subjective timing of actual movement (M). The subjects were assigned the tasks in two different orders. When measured as first in the respective session, no significant difference between W and M values was found, which suggests that uninformed subjects tend to confuse W for M reports. Moreover, we found that W values measured after the M task were significantly earlier than W values measured before M. This phenomenon suggests that the apparent difference between W and M values is in fact caused by the subjects' previous experience with M measurements.