Eye movements discriminate fatigue due to chronotypical factors and time spent on task--a double dissociation

Systematic differences in circadian rhythmicity are thought to be a substantial factor determining inter-individual differences in fatigue and cognitive performance. The synchronicity effect (when time of testing coincides with the respective circadian peak period) seems to play an important role. Eye movements have been shown to be a reliable indicator of fatigue due to sleep deprivation or time spent on cognitive tasks. However, eye movements have not been used so far to investigate the circadian synchronicity effect and the resulting differences in fatigue. The aim of the present study was to assess how different oculomotor parameters in a free visual exploration task are influenced by: a) fatigue due to chronotypical factors (being a 'morning type' or an 'evening type'); b) fatigue due to the time spent on task. Eighteen healthy participants performed a free visual exploration task of naturalistic pictures while their eye movements were recorded. The task was performed twice, once at their optimal and once at their non-optimal time of the day. Moreover, participants rated their subjective fatigue. The non-optimal time of the day triggered a significant and stable increase in the mean visual fixation duration during the free visual exploration task for both chronotypes. The increase in the mean visual fixation duration correlated with the difference in subjectively perceived fatigue at optimal and non-optimal times of the day. Conversely, the mean saccadic speed significantly and progressively decreased throughout the duration of the task, but was not influenced by the optimal or non-optimal time of the day for both chronotypes. The results suggest that different oculomotor parameters are discriminative for fatigue due to different sources. A decrease in saccadic speed seems to reflect fatigue due to time spent on task, whereas an increase in mean fixation duration a lack of synchronicity between chronotype and time of the day.

The Coin Rotation Task: A Valid Test for Manual Dexterity in Multiple Sclerosis

BACKGROUND: Impaired manual dexterity is frequent and disabling in patients with multiple sclerosis (MS). Therefore, convenient, quick and validated tests for manual dexterity in MS patients are needed. OBJECTIVE: The aim of this study was to validate the Coin Rotation task (CRT) to examine manual dexterity in patients with MS. DESIGN: Cross-sectional study. METHODS: 101 outpatients with MS were assessed with the CRT, the Expanded Disability Status Scale (EDSS), the Scale for the assessment and rating of ataxia (SARA), the Modified Ashworth Scale (MAS), and their muscle strength and sensory deficits of the hands were noted. Concurrent validity and diagnostic accuracy of the CRT were determined by comparison with the Nine Hole Peg Test (9HPT). Construct validity was determined by comparison with a valid dexterity questionnaire. Multiple regression analysis was done to explore correlations of the CRT with the EDSS, SARA, MAS, muscle strength and sensory deficits. RESULTS: The CRT correlated significantly with the 9HPT (r=.73, p<.0001) indicating good concurrent validity. The cut-off values for the CRT relative to the 9HPT were 18.75 seconds for the dominant (sensitivity: 81.5%; specificity 80.0%) and 19.25 seconds for the non-dominant hand (sensitivity: 90.3%; specificity: 81.8%) demonstrating good diagnostic accuracy. Furthermore, the CRT correlated significantly with the dexterity questionnaire (r=-.49, p<.0001) indicating moderate construct validity. Multiple regression analyses revealed that the EDSS was the strongest predictor for impaired dexterity. LIMITATIONS: Mostly relapsing-remitting MS patients with an EDSS up to 7 were examined. CONCLUSIONS: This study validates the CRT as a test that can be used easily and quickly to evaluate manual dexterity in patients with MS.

Time for actions in lucid dreams: effects of task modality, length, and complexity

The relationship between time in dreams and real time has intrigued scientists for centuries. The question if actions in dreams take the same time as in wakefulness can be tested by using lucid dreams where the dreamer is able to mark time intervals with prearranged eye movements that can be objectively identified in EOG recordings. Previous research showed an equivalence of time for counting in lucid dreams and in wakefulness (LaBerge, 1985; Erlacher and Schredl, 2004), but Erlacher and Schredl (2004) found that performing squats required about 40% more time in lucid dreams than in the waking state. To find out if the task modality, the task length, or the task complexity results in prolonged times in lucid dreams, an experiment with three different conditions was conducted. In the first condition, five proficient lucid dreamers spent one to three non-consecutive nights in the sleep laboratory. Participants counted to 10, 20, and 30 in wakefulness and in their lucid dreams. Lucidity and task intervals were time stamped with left-right-left-right eye movements. The same procedure was used for these condition where eight lucid dreamers had to walk 10, 20, or 30 steps. In the third condition, eight lucid dreamers performed a gymnastics routine, which in the waking state lasted the same time as walking 10 steps. Again, we found that performing a motor task in a lucid dream requires more time than in wakefulness. Longer durations in the dream state were present for all three tasks, but significant differences were found only for the tasks with motor activity (walking and gymnastics). However, no difference was found for relative times (no disproportional time effects) and a more complex motor task did not result in more prolonged times. Longer durations in lucid dreams might be related to the lack of muscular feedback or slower neural processing during REM sleep. Future studies should explore factors that might be associated with prolonged durations.

Wake up. Back to Bed – Zugang zum nächtlichen Training?

Einleitung Ein Klartraum ist definiert als ein Traum, in dem der Träumende weiß, dass er träumt. In der Fachliteratur finden sich verschiedene Induktionstechniken, um die Klartraum-häufigkeit zu steigern (z.B. Stumbrys, Erlacher, Schädlich & Schredl, 2012). Zudem wurde in einer Pilotstudie gezeigt, dass ein Training im Klartraum zu Verbesserungen in einer Zielwurfaufgabe am nächsten Morgen führt (Erlacher & Schredl, 2010). Um ein regelmäßiges Training im Traum zu ermöglichen, besteht für die Sportpraxis das Problem, Klarträume gezielt zu induzieren. In dieser Studie wurde im Schlaflabor die so genannte Memnotische Induktion von luziden Träumen (MILT) – eine Autosugges-tionstechnik in der die Intention, einen Klartraum zu erleben, an Traumhinweise ge-koppelt wird – im Morgenschlaf überprüft. Methoden Insgesamt wurden 52 Versuchsteilnehmer (32 männlich und 20 weiblich) im Alter von 24 Jahren (± 2.2) im Schlaflabor untersucht. Die Personen waren in 4 Gruppen aufge-teilt. Alle Personen schliefen zunächst für ca. 6 Stunden, wurden dann aus einer REM-Phase geweckt und sollten einen Traum berichten. Im Anschluss blieben die Teilnehmer 30 bzw. 60 Minuten wach und praktizierten entweder MILT oder beschäf-tigten sich mit einer kognitiven oder motorischen Kontrollaufgabe. Im Anschluss durf-ten alle Teilnehmer für max. 4 weitere Stunden schlafen. Das Auftreten eines Klartraums in der morgendlichen Schlafphase diente als abhängige Variable. Ergebnisse und Diskussion Die Ergebnisse zeigen, dass MILT zu einer gesteigerten Klartraumhäufigkeit (33-70%) im Vergleich zur Kontrollbedingung (9-14%) führt. Ein Unterschied zwischen 30 Minuten (50%) zu 60 Minuten MILT (70%) ist marginal. Das Auftreten von Klarträumen kann durch MILT im Morgenschlaf signifikant gestei-gert werden. Die Erfolgsquote schwankt jedoch mit Blick auf die genaue Definition ei-nes Klartraums. Es konnten bei nicht klartraumerfahrenen Versuchsteilnehmerinnen mehr Klarträume induziert werden. Für die Sportpraxis könnten solche Induktions-techniken dem Sportler ermöglichen, im Traum zu trainieren. In weiteren Studien wäre zu untersuchen, ob Athleten ebenfalls Klarträume induziert werden können. Ebenso sollte die Auswirkung eines regelmäßigen Klartraumtrainings in der Sportpraxis wei-ter untersucht werden. Literatur Stumbrys, T., Erlacher, D., Schädlich, M. & Schredl, M. (2012). Induction of lucid dreams: a systematic review of evidence. Consciousness and Cognition, 21(3), 1456-1475. Erlacher, D. & Schredl, M. (2010). Practicing a motor task in a lucid dream enhances subsequent performance: A pilot study. The Sport Psychologist, 24(2), 157-167.

Electrophysiological indices of response inhibition in a Go/NoGo task predict self-control in a social context.

Recent research demonstrates that response inhibition-a core executive function-may subserve self-regulation and self-control. However, it is unclear whether response inhibition also predicts self-control in the multifaceted, high-level phenomena of social decision-making. Here we examined whether electrophysiological indices of response inhibition would predict self-control in a social context. Electroencephalography was recorded as participants completed a widely used Go/NoGo task (the cued Continuous Performance Test). Participants then interacted with a partner in an economic exchange game that requires self-control. Results demonstrated that greater NoGo-Anteriorization and larger NoGo-P300 peak amplitudes-two established electrophysiological indices of response inhibition-both predicted more self-control in this social game. These findings support continued integration of executive function and self-regulation and help extend prior research into social decision-making processes.

Unconscious relational encoding depends on hippocampus

Textbooks divide between human memory systems based on consciousness. Hippocampus is thought to support only conscious encoding, while neocortex supports both conscious and unconscious encoding. We tested whether processing modes, not consciousness, divide between memory systems in three neuroimaging experiments with 11 amnesic patients (mean age = 45.55 years, standard deviation = 8.74, range = 23-60) and 11 matched healthy control subjects. Examined processing modes were single item versus relational encoding with only relational encoding hypothesized to depend on hippocampus. Participants encoded and later retrieved either single words or new relations between words. Consciousness of encoding was excluded by subliminal (invisible) word presentation. Amnesic patients and controls performed equally well on the single item task activating prefrontal cortex. But only the controls succeeded on the relational task activating the hippocampus, while amnesic patients failed as a group. Hence, unconscious relational encoding, but not unconscious single item encoding, depended on hippocampus. Yet, three patients performed normally on unconscious relational encoding in spite of amnesia capitalizing on spared hippocampal tissue and connections to language cortex. This pattern of results suggests that processing modes divide between memory systems, while consciousness divides between levels of function within a memory system.

Effects of overt self-­talk on team partners’ other-efficacy and performance in a golf putting task

Introduction According to Lent and Lopez’ (2002) tripartite view of efficacy beliefs, members of a team form beliefs about the efficacy of their team partners. This other-efficacy belief can influence individual performance as shown by Dunlop, Beatty, and Beauchamp (2011) in their experimental study using manipulated performance feedback to alter other-efficacy beliefs. Participants holding favorable other-efficacy beliefs outperformed those with lower other--‐efficacy beliefs. Antecedents of such other-efficacy beliefs are amongst others perceptions regarding motivation and psychological factors of the partner (Jackson, Knapp, & Beauchamp, 2008). Overt self-talk could be interpreted as the manifestation of such motivational or psychological factors. In line with this assumption, in an experimental study using dubbed videos of the same segment of a tennis match, Van Raalte, Brewer, Cornelius, and Petitpas (2006) found that players were perceived more favorably (e.g., more concentrated, and of higher ability levels) when shown with dubbed positive self-talk as compared to dubbed negative or no dubbed self--‐talk. Objectives The aim of the study was to examine the possible effects of a confederate’s overt self-talk on participants’ other-efficacy beliefs and performance in a team setting. Method In a laboratory experiment (between-subjects, pre-post-test design, matched by pretest performance) 89 undergraduate students (female = 35, M = 20.81 years, SD = 2.34) participated in a golf putting task together with a confederate (same gender groups). Depending on the experimental condition (positive, negative, or no self-talk), the confederate commented his or her putts according to a self-talk script. Bogus performance feedback assured that the performance of the confederate was held constant. Performance was measured as the distance to the center of the target, other-efficacy by a questionnaire. Results The data collection has just finished and the results of repeated measures analyses of variance will be presented and discussed at the congress. We expect to find higher other-efficacy beliefs and better individual performance in the positive self-talk condition. References Dunlop, W.L., Beatty, D.J., & Beauchamp, M.R. (2011). Examining the influence of other-efficacy and self-efficacy on personal performance. Journal of Sport & Exercise Psychology, 33, 586-593. Jackson, B., Knapp, P., & Beauchamp, M.R. (2008). Origins and consequences of tripartite efficacy beliefs within elite athlete dyads. Journal of Sport and Exercise Psychology, 30, 512-540. Lent, R.W., & Lopez, F.G. (2002). Cognitive ties that bind: A tripartite view of efficacy beliefs in growth--‐promoting relationships. Journal of Social and Clinical Psychology, 21, 256-286. Van Raalte, J.L., Brewer, B.W, Cornelius, A.E., & Petitpas, A.J. (2006). Self-presentational effects of self-talk on perceptions of tennis players. Hellenic Journal of Psychology, 3, 134-149.

The bivalency effect in task switching: General and enduring

The purpose of this study was to investigate the generality and temporal endurance of the bivalency effect in task switching. This effect refers to the slowing on univalent stimuli that occurs when bivalent stimuli appear occasionally. We used a paradigm involving predictable switches between 3 simple tasks, with bivalent stimuli occasionally occurring on one of the tasks. The generality of the bivalency effect was investigated by using different tasks and different types of bivalent stimuli, and the endurance of this effect was investigated across different intertrial intervals (ITIs) and across the univalent trials that followed trials with bivalent stimuli. In 3 experiments, the results showed a general, robust, and enduring bivalency effect for all ITI conditions. Although the effect declined across trials, it remained significant for about 4 trials following one with a bivalent stimulus. Our findings emphasise the importance of top–down processes in task-switching performance. (PsycINFO Database Record (c) 2012 APA, all rights reserved)

Brain sources of EEG gamma frequency during volitionally meditation-induced, altered states of consciousness, and experience of the self.

Multichannel EEG of an advanced meditator was recorded during four different, repeated meditations. Locations of intracerebral source gravity centers as well as Low Resolution Electromagnetic Tomography (LORETA) functional images of the EEG 'gamma' (35-44 Hz) frequency band activity differed significantly between meditations. Thus, during volitionally self-initiated, altered states of consciousness that were associated with different subjective meditation states, different brain neuronal populations were active. The brain areas predominantly involved during the self-induced meditation states aiming at visualization (right posterior) and verbalization (left central) agreed with known brain functional neuroanatomy. The brain areas involved in the self-induced, meditational dissolution and reconstitution of the experience of the self (right fronto-temporal) are discussed in the context of neural substrates implicated in normal self-representation and reality testing, as well as in depersonalization disorders and detachment from self after brain lesions.