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.

• Klíčová slova
• Libet’s experiment, Readiness-potential, Replication, Rotating-spot method, Subjective event timing,
• MeSH
• dospělí MeSH
• elektroencefalografie MeSH
• elektromyografie MeSH
• hmatová percepce fyziologie   MeSH
• kontingentní negativní variace fyziologie   MeSH
• lidé MeSH
• mladý dospělý MeSH
• pohybová aktivita fyziologie   MeSH
• psychomotorický výkon fyziologie   MeSH
• uvědomování si fyziologie   MeSH
• vědomí fyziologie   MeSH
• vnímání času fyziologie   MeSH
• zpráva o sobě MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

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.

• Klíčová slova
• Awareness, Introspection, Libet’s experiment, Subjective events timing, Urge to move, Voluntary action,
• MeSH
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• pohybová aktivita fyziologie   MeSH
• uvědomování si fyziologie   MeSH
• vnímání času fyziologie   MeSH
• vůle fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

A startling auditory stimulus (SAS) induces a reflex response involving, among other reactions, a strong contraction of the orbicularis oculi muscle (OOc) and subsequent eye closure. A SAS also induces the StartReact effect, a significant shortening of reaction time in subjects ready for task execution. We examined the obvious conflict appearing when a StartReact paradigm requires participants with eyes closed to open their eyes to look for a visual target. We recorded OOc EMG activity and eyelid movements in healthy volunteers who were instructed to open their eyes at perception of a somatosensory imperative stimulus (IS) and locate the position of a Libet's clock's hand shown on a computer screen at 80 cm distance. In 6 out of 20 trials, we delivered a SAS simultaneously with the IS. The main outcome measures were reaction time at onset of eyelid movement and the time gap (TG) separating subjective assessment of the clock's hand position from real IS issuing. Control experiments included reaction time to eye closing and target location with eyes open to the same IS. Reaction time was significantly faster in SAS than in noSAS trials and slower for eye opening than for eye closing in both conditions. In the eye-opening task, TG was significantly shorter in SAS with respect to noSAS trials, despite the presence of the SAS-related burst in the OOc before EMG cessation. Our results indicate that the StartReact effect speeds up eye opening and location of a target in the visual field despite the startle reaction opposing the task.

• Klíčová slova
• Libet's clock, StartReact effect, eyelid movement, orbicularis oculi EMG, startle, visual target,
• MeSH
• dospělí MeSH
• elektromyografie MeSH
• fyzikální stimulace MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• obličejové svaly fyziologie   MeSH
• oční víčka fyziologie   MeSH
• psychomotorický výkon fyziologie   MeSH
• reakční čas fyziologie   MeSH
• senioři MeSH
• sluchová percepce fyziologie   MeSH
• úleková reakce fyziologie   MeSH
• zraková percepce fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH