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  • 1.
    Grassini, Simone
    et al.
    Department of Psychology, University of Turku.
    Railo, Henry
    Department of Psychology, University of Turku.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology, University of Turku.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology, University of Turku.
    Koivisto, Mika
    Department of Psychology, University of Turku.
    Visual features and perceptual context modulate attention towards evolutionarily relevant threatening stimuli: Electrophysiological evidence2018In: Emotion, ISSN 1528-3542, E-ISSN 1931-1516, article id 10.1037/emo0000434Article in journal (Refereed)
    Abstract [en]

    The snake detection hypothesis claims that predatory pressure from snakes has shaped the primate visual system, but we still know very little about how the brain processes evolutionarily important visual cues, and which factors are crucial for quick detection of snakes. We investigated how visual features modulate the electrophysiological markers of early attentional processes. In Experiment 1, we compared snake, rope, gun, and bird images to isolate the effects due to curvilinearity of the stimuli. The results showed that both snake and rope images elicited enhanced P1 and N1 event-related potential components as well as early posterior negativity (EPN). In Experiment 2, we studied whether nonthreatening curvilinear images (i.e., ropes) still elicit the enhanced electrophysiological responses when snake images are not presented as stimuli, and therefore the context does not provoke top-down attention to curvilinear shapes. Rope images still evoked an enhanced EPN, suggesting that curvilinear shapes are preferably captured by attentional processes. However, this effect was smaller than in Experiment 1, in which snake images were present. Thus, our results hint to the possibility that the perceptual context may interact with processing of shape information, drawing attention to curvilinear shapes when the presence of snakes is expectable. Furthermore, we observed that spatial frequency of the visual stimuli modulated especially the early electrophysiological responses, and decreased the differences between stimulus categories in EPN without completely eliminating them. The findings suggest that low-level and high-level mechanisms interact to give an attentional priority to potentially threatening stimuli.

  • 2.
    Johanson, Mirja
    et al.
    Stora Skondal Fdn, Neurol Rehabil Clin, S-12885 Skondal, Sweden .
    Valli, Katja
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    How to assess ictal consciousness?2011In: Behavioural Neurology, ISSN 0953-4180, E-ISSN 1875-8584, Vol. 24, no 1, p. 11-20Article in journal (Refereed)
    Abstract [en]

    Despite the complexity and methodological difficulties in defining the concept consciousness, it is a central concept in epileptology, and should thus be tractable for scientific analysis. In the present article, a two-dimensional model consisting of concepts related to the level and the contents of consciousness will be presented. This model has been found to be well suited for the description of seizure-induced alterations of consciousness, and is supported both by findings from neuroimaging and electrophysiological studies as well as from phenomenological studies. Further, we will review both traditional introspective methods as well as methods that have recently been developed or utilized in epilepsy research, summarize the main findings concerning first person experiences during epileptic seizures acquired with some of these methods, and discuss their strengths and weaknesses.

  • 3.
    Johanson, Mirja
    et al.
    Stora Sköndal Fdn, Neurol Rehabil Clin, S-12885 Sköndal, Sweden / Åbo Akad Univ, Dept Psychol, SF-20500 Turku, Finland.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Chaplin, John E
    Univ Gothenburg, Dept Pediat, Sahlgrenska Acad, Gothenburg, Sweden.
    Wedlund, Jan-Eric
    Stora Sköndal Fdn, Neurol Rehabil Clin, S-12885 Sköndal, Sweden.
    Alterations in the contents of consciousness in partial epileptic seizures2008In: Epilepsy & Behavior, ISSN 1525-5050, E-ISSN 1525-5069, Vol. 13, no 2, p. 366-371Article in journal (Refereed)
    Abstract [en]

    Epilepsy research suffers from a deficiency of systematic studies concerning the phenomenology of the contents of consciousness during seizures, partially because of the lack of suitable research methods. The Phenomenology of Consciousness Inventory (PCI), a standardized, valid, and reliable questionnaire, was used here to study which dimensions of the contents of consciousness are distorted during partial epileptic seizures compared with baseline. Further, the similarity of the altered pattern of subjective experiences across recurring seizures was also explored. Our results indicate that patients with epilepsy report alterations on most dimensions of the contents of consciousness in conjunction with seizures, but individual seizure experiences remain similar from one seizure to another. The PCI was found suitable for the assessment of subjective experiences during epileptic seizures and could be a valuable tool in providing new information about phenomenal consciousness in epilepsy in both the research and clinical settings.

  • 4.
    Johanson, Mirja
    et al.
    Stora Sköndal Fdn, Neurol Rehabilitat Clin, S-12885 Sköndal, Sweden / Åbo Akad Univ, Dept Psychol, SF-20500 Turku, Finland.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Wedlund, Jan-Eric
    Stora Sköndal Fdn, Neurol Rehabilitat Clin, S-12885 Sköndal, Sweden.
    Content analysis of subjective experiences in partial epileptic seizures2008In: Epilepsy & Behavior, ISSN 1525-5050, E-ISSN 1525-5069, Vol. 12, no 1, p. 170-182Article in journal (Refereed)
    Abstract [en]

    A new content analysis method for systematically describing the phenomenology of subjective experiences in connection with partial epileptic seizures is described. Forty patients provided 262 descriptions of subjective experience relative to their partial epileptic seizures. The results revealed that subjective experiences during seizures consist mostly of sensory and bodily sensations, hallucinatory experiences, and thinking. The majority of subjective experiences during seizures are bizarre and distorted; nevertheless, the patients are able to engage in adequate behavior. To the best of our knowledge, this is the first study for which detailed subjective seizure descriptions were collected immediately after each seizure and the first study in which the content of verbal reports of subjective experiences during seizures, including both the ictal and postictal experiences, has been analyzed in detail.

  • 5.
    Laaksonen, L.
    et al.
    University of Turku, Turku, Finland / Turku University Hospital, Turku, Finland.
    Kallioinen, M.
    Turku University Hospital, Turku, Finland.
    Långsjö, J.
    Tampere University Hospital, Tampere, Finland.
    Laitio, T.
    Turku University Hospital, Turku, Finland.
    Scheinin, A.
    University of Turku. Turku, Finland / Turku University Hospital, Turku, Finland.
    Scheinin, J.
    Kuopio University Hospital, Kuopio, Finland.
    Kaisti, K.
    Oulu University Hospital, Oulu, Finland.
    Maksimow, A.
    Turku University Hospital, Turku, Finland.
    Kallionpää, R. E.
    Turku University Hospital, Turku, Finland / University of Turku, Turku, Finland.
    Rajala, V.
    Turku University Hospital, Turku, Finland.
    Johansson, J.
    University of Turku, Turku, Finland / Turku University Hospital, Turku, Finland / Umeå University, Umeå, Sweden.
    Kantonen, O.
    University of Turku, Turku, Finland / Turku University Hospital, Turku, Finland / University of California, Irvine, CA, USA.
    Nyman, M.
    Turku University Hospital, Turku, Finland.
    Sirén, S.
    Turku University Hospital, Turku, Finland.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Turku University Hospital, Turku, Finland / University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. University of Turku, Turku, Finland.
    Solin, O.
    University of Turku, Turku, Finland / Turku University Hospital, Turku, Finland.
    Vahlberg, T.
    University of Turku, Turku, Finland / Turku University Hospital, Turku, Finland.
    Alkire, M.
    University of California, Irvine, CA, USA.
    Scheinin, Harry
    University of Turku, Turku, Finland / Turku University Hospital, Turku, Finland.
    Comparative effects of dexmedetomidine, propofol, sevoflurane, and S-ketamine on regional cerebral glucose metabolism in humans: a positron emission tomography study2018In: British Journal of Anaesthesia, ISSN 0007-0912, E-ISSN 1471-6771, Vol. 121, no 1, p. 281-290Article in journal (Refereed)
    Abstract [en]

    Introduction

    The highly selective α2-agonist dexmedetomidine has become a popular sedative for neurointensive care patients. However, earlier studies have raised concern that dexmedetomidine might reduce cerebral blood flow without a concomitant decrease in metabolism. Here, we compared the effects of dexmedetomidine on the regional cerebral metabolic rate of glucose (CMRglu) with three commonly used anaesthetic drugs at equi-sedative doses.

    Methods

    One hundred and sixty healthy male subjects were randomised to EC50 for verbal command of dexmedetomidine (1.5 ng ml−1n=40), propofol (1.7 μg ml−1n=40), sevoflurane (0.9% end-tidal; n=40) or S-ketamine (0.75 μg ml−1n=20) or placebo (n=20). Anaesthetics were administered using target-controlled infusion or vapouriser with end-tidal monitoring. 18F-labelled fluorodeoxyglucose was administered 20 min after commencement of anaesthetic administration, and high-resolution positron emission tomography with arterial blood activity samples was used to quantify absolute CMRglu for whole brain and 15 brain regions.

    Results

    At the time of [F18]fluorodeoxyglucose injection, 55% of dexmedetomidine, 45% of propofol, 85% of sevoflurane, 45% of S-ketamine, and 0% of placebo subjects were unresponsive. Whole brain CMRglu was 63%, 71%, 71%, and 96% of placebo in the dexmedetomidine, propofol, sevoflurane, and S-ketamine groups, respectively (P<0.001 between the groups). The lowest CMRglu was observed in nearly all brain regions with dexmedetomidine (P<0.05 compared with all other groups). With S-ketamine, CMRgludid not differ from placebo.

    Conclusions

    At equi-sedative doses in humans, potency in reducing CMRglu was dexmedetomidine>propofol>ketamine=placebo. These findings alleviate concerns for dexmedetomidine-induced vasoconstriction and cerebral ischaemia.

  • 6.
    Noreika, Valdas
    et al.
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, 20014 Turku, Finland.
    Jylhänkangas, Leila
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, 20014 Turku, Finland.
    Móró, Levente
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, 20014 Turku, Finland.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics.
    Kaskinoro, Kimmo
    Department of Anesthesia, Intensive Care, Emergency Medicine and Pain Therapy, Turku University Hospital, Turku, Finland.
    Aantaa, Riku
    Department of Anesthesia, Intensive Care, Emergency Medicine and Pain Therapy, Turku University Hospital, Turku, Finland.
    Scheinin, Harry
    Department of Pharmacology and Clinical Pharmacology, and Turku PET Centre, University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Consciousness lost and found: Subjective experiences in an unresponsive state2011In: Brain and Cognition, ISSN 0278-2626, E-ISSN 1090-2147, Vol. 77, no 3, p. 327-334Article in journal (Refereed)
    Abstract [en]

    Anesthetic-induced changes in the neural activity of the brain have been recently utilized as a research model to investigate the neural mechanisms of phenomenal consciousness. However, the anesthesiologic definition of consciousness as ‘‘responsiveness to the environment’’ seems to sidestep the possibility that an unresponsive individual may have subjective experiences. The aim of the present study was to analyze subjective reports in sessions where sedation and the loss of responsiveness were induced by dexmedetomidine, propofol, sevoflurane or xenon in a nonsurgical experimental setting. After regaining responsiveness, participants recalled subjective experiences in almost 60% of sessions. During dexmedetomidine sessions, subjective experiences were associated with shallower ‘‘depth of sedation’’ as measured by an electroencephalography-derived anesthesia depth monitor. Results confirm that subjective experiences may occur during clinically defined unresponsiveness, and that studies aiming to investigate phenomenal consciousness under sedative and anesthetic effects should control the subjective state of unresponsive participants with post-recovery interviews.

  • 7.
    Noreika, Valdas
    et al.
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Turku, Finland.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Turku, Finland.
    Lahtela, Hetti
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Turku, Finland.
    Early-night serial awakenings as a new paradigm for studies on NREM dreaming2009In: International Journal of Psychophysiology, ISSN 0167-8760, E-ISSN 1872-7697, Vol. 74, no 1, p. 14-18Article in journal (Refereed)
    Abstract [en]

    A new experimental paradigm called "Early-Night Serial Awakenings" (ENSA) was explored to find out its strengths and weaknesses for psychophysiological studies of NREM sleep dreaming. Five participants spent 20 experimental nights in the sleep laboratory, and were serially awakened with approximately 24-minute intervals during Stages 2 and 3 of NREM sleep. As a total, 164 awakenings were conducted during the sessions that lasted on average 193 min. Altogether, 30% of NREM sleep awakenings led to dream reports, 39% to reports of white dreaming, and 31% to reports of dreamless sleep. Results also show that sleep EEG spectral power, dream recall frequency as well as dream complexity remained stable throughout the serial awakening sessions. We conclude that, as ENSA dreams appeared to be static and very limited in content, the paradigm we identified could be used in future studies to reveal the psychophysiological mechanisms of relatively simple forms of early-night NREM sleep dreaming. (c) 2009 Elsevier B.V. All rights reserved.

  • 8.
    Noreika, Valdas
    et al.
    Univ Turku, Dept Behav Sci & Philosophy, Ctr Cognit Neurosci, Turku, Finland.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics.
    Markkula, Juha
    Turku Univ Hosp, Neuropsychiat Clin, FIN-20520 Turku, Finland / Turku Mental Hlth Care, Turku Psychiat Clin, Turku, Finland / Univ Turku, Dept Physiol, Sleep Res Unit, Turku, Finland.
    Seppälä, Katriina
    Univ Turku, Dept Behav Sci & Philosophy, Ctr Cognit Neurosci, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Dream bizarreness and waking thought in schizophrenia2010In: Psychiatry Research, ISSN 0165-1781, E-ISSN 1872-7123, Vol. 178, no 3, p. 562-564Article in journal (Refereed)
    Abstract [en]

    Dream diaries and reports of daytime waking thought were collected from five schizophrenia patients and matched controls. It was more difficult for blind judges to differentiate the patients' than the controls' dream reports from reports of waking thought, and patients reported shorter but more bizarre dreams than did the controls.

  • 9.
    Revonsuo, Antti
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Turun yliopisto, Turku, Finland.
    Tuominen, Jarno
    Turun yliopisto, Turku, Finland.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Turun yliopisto, Turku, Finland.
    The Avatars in the Machine: Dreaming as a Simulation of Social Reality2016In: Open MIND: Philosophy and the Mind Sciences in the 21st Century / [ed] Thomas Metzinger & Jennifer M. Windt, MIT Press, 2016, p. 1295-1322Chapter in book (Refereed)
  • 10.
    Revonsuo, Antti
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Turun yliopisto, Turku, Finland.
    Tuominen, Jarno
    Turun yliopisto, Turku, Finland.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Turun yliopisto, Turku, Finland.
    The Simulation Theories of Dreaming: How to Make Theoretical Progress in Dream Science2016In: Open MIND: Philosophy and the Mind Sciences in the 21st Century / [ed] Thomas Metzinger & Jennifer M. Windt, MIT Press, 2016, p. 1341-1348Chapter in book (Refereed)
  • 11.
    Revonsuo, Antti
    et al.
    University of Skövde, School of Humanities and Informatics.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics.
    How to test the threat-simulation theory2008In: Consciousness and Cognition, ISSN 1053-8100, E-ISSN 1090-2376, Vol. 17, no 4, p. 1292-1296Article in journal (Refereed)
    Abstract [en]

    Malcolm-Smith, Solms, Turnbull and Treduoux (Malcolm-Smith, S., Solms, M., Turnbull, O., & Tredoux, C. (2008). Threat in dreams; An adaptiation? Consciousness and Cognition, 17, 1281-1291.) have made an attempt to test the Threat-Simulation Theory (TST), a theory offering an evolutionary psychological explanation for the function of dreaming (Revonsuo, A. (2000a). The reinterpretation of dreams: An evolutionary hypothesis of the function of dreaming. Behavioural and Brain Sciences, 23(6), 877-901). Malcolm-Smith et al. argue that empirical evidence from their own study as well as from some other studies in the literature does not support the main predictions of the TST: that threatening events are frequent and overrepresented in dreams, that exposure to real threats activates the threat-simulation system, and that dream threats contain realistic rehearsals of threat avoidance responses. Other studies, including or own, have come up with results and conclusions that are in conflict with those of Malcolm-Smith et al. In this commentary, we provide an analysis of the sources of these disagreements, and their implications to the TST. Much of the disagreement seems to stem from differing interpretations of the theory and, consequently, of differing methods to test it.

  • 12.
    Sandman, Nils
    et al.
    Genomics and Biomarkers Unit, National Institute for Health and Welfare, Helsinki, Finland / Department of Psychology and Speech Language Pathology, Centre for Cognitive Neuroscience, Turku Brain and Mind Centre, University of Turku, Turku, Finland.
    Merikanto, Ilona
    Department of Health, National Institute for Health and Welfare, Helsinki, Finland / Department of Biosciences, University of Helsinki, Helsinki, Finland.
    Määttänen, Hanna
    Department of Psychology and Speech Language Pathology, Centre for Cognitive Neuroscience, Turku Brain and Mind Centre, University of Turku, Turku, Finland.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Psychology and Speech Language Pathology, Centre for Cognitive Neuroscience, Turku Brain and Mind Centre, University of Turku, Turku, Finland.
    Kronholm, Erkki
    Department of Health, National Institute for Health and Welfare, Turku, Finland.
    Laatikainen, Tiina
    Department of Health, National Institute for Health and Welfare, Helsinki, Finland / Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland / Hospital District of North Karelia, Joensuu, Finland .
    Partonen, Timo
    Department of Health, National Institute for Health and Welfare, Helsinki, Finland.
    Paunio, Tiina
    Genomics and Biomarkers Unit, National Institute for Health and Welfare, Helsinki, Finland / Department of Psychiatry, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland.
    Winter is coming: nightmares and sleep problems during seasonal affective disorder2016In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 25, no 5, p. 612-619Article in journal (Refereed)
    Abstract [en]

    Sleep problems, especially nightmares and insomnia, often accompany depression. This study investigated how nightmares, symptoms of insomnia, chronotype and sleep duration associate with seasonal affective disorder, a special form of depression. Additionally, it was noted how latitude, a proxy for photoperiod, and characteristics of the place of residence affect the prevalence of seasonal affective disorder and sleep problems. To study these questions, data from FINRISK 2012 study were used. FINRISK 2012 consists of a random population sample of Finnish adults aged 25–74 years (n = 4905) collected during winter from Finnish urban and rural areas spanning the latitudes of 60°N to 66°N. The Seasonal Pattern Assessment Questionnaire was used to assess symptoms of seasonal affective disorder. Participants with symptoms of seasonal affective disorder had significantly increased odds of experiencing frequent nightmares and symptoms of insomnia, and they were more often evening chronotypes. Associations between latitude, population size and urbanicity with seasonal affective disorder symptoms and sleep disturbances were generally not significant, although participants living in areas bordering urban centres had less sleep problems than participants from other regions. These data show that the prevalence of seasonal affective disorder was not affected by latitude. 

  • 13.
    Sandman, Nils
    et al.
    National Institute for Health and Welfare, Public Health Genomics Unit and Institute for Molecular Medicine FIMM, Helsinki, Finland / University of Turku, Centre for Cognitive Neuroscience, Department of Psychology, Turku, Finland.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Systems Biology Research Centre. University of Turku, Centre for Cognitive Neuroscience, Department of Psychology, Turku, Finland.
    Kronholm, Erkki
    National Institute for Health and Welfare, Department of Chronic Disease Prevention, Finland.
    Ollila, Hanna M.
    National Institute for Health and Welfare, Public Health Genomics Unit and Institute for Molecular Medicine FIMM, Helsinki, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Systems Biology Research Centre. University of Turku, Centre for Cognitive Neuroscience, Department of Psychology, Turku, Finland.
    Laatikainen, Tiina
    National Institute for Health and Welfare, Department of Chronic Disease Prevention, Finland / University of Eastern Finland, Institute for Public Health and Clinical Nutrition.
    Paunio, Tiina
    National Institute for Health and Welfare, Public Health Genomics Unit and Institute for Molecular Medicine FIMM, Helsinki, Finland / Helsinki University Hospital, Department of Psychiatry, Helsinki, Finland.
    Nightmares: Prevalence among the Finnish General Adult Population and War Veterans during 1972-20072013In: Sleep, ISSN 0161-8105, E-ISSN 1550-9109, Vol. 36, no 7, p. 1041-1050Article in journal (Refereed)
    Abstract [en]

    Study Objectives: To investigate the prevalence of nightmares among the Finnish general adult population during 1972-2007 and the association between nightmare prevalence and symptoms of insomnia, depression, and anxiety in World War II veterans. Design: Eight independent cross-sectional population surveys of the National FINRISK Study conducted in Finland in 1972, 1977, 1982, 1987, 1992, 1997, 2002, and 2007. Setting: Epidemiologic. Participants: A total of 69,813 people (33,811 men and 36,002 women) age 25-74 years. Interventions: N/A. Measurements and Results: The investigation of nightmare prevalence and insomnia, depression, and anxiety symptoms was based on questionnaires completed by the participants. Among the whole sample, 3.5% of the men and 4.8% of the women reported frequent nightmares (P < 0.0001 for sex difference), but the prevalence was affected by the age of participants and the year of the survey. Nightmare prevalence increased with age, particularly among the men. The number of people reporting occasional nightmares increased roughly by 20% for both sexes from 1972 to 2007 (P < 0.0001). Participants with war experiences reported more frequent nightmares and symptoms of insomnia, depression, and anxiety than participants without such experiences (P < 0.0001). Conclusions: Prevalence of nightmares was affected by the sex and age of the participants, and occasional nightmares have become more common in Finland. Exposure to war elevates nightmare prevalence as well as insomnia, depression, and anxiety symptoms even decades after the war; large numbers of war veterans can affect nightmare prevalence on population level.

  • 14.
    Sandman, Nils
    et al.
    National Institute for Health and Welfare, Public Health Genomics Unit and Institute for Molecular Medicine FIMM, Helsinki, Finland / University of Turku, Centre for Cognitive Neuroscience, Turku Brain and Mind Center, Department of Psychology, Turku, Finland.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. University of Turku, Centre for Cognitive Neuroscience, Turku Brain and Mind Center, Department of Psychology, Turku, Finland.
    Kronholm, Erkki
    National Institute for Health and Welfare, Department of Health, Unit of Chronic Disease Prevention, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. University of Turku, Centre for Cognitive Neuroscience, Turku Brain and Mind Center, Department of Psychology, Turku, Finland.
    Laatikainen, Tiina
    National Institute for Health and Welfare, Department of Health, Unit of Chronic Disease Prevention, Turku, Finland / University of Eastern Finland, Institute of Public Health and Clinical Nutrition, Kuopio, Finland / Hospital District of North Karelia, Joensuu, Finland.
    Paunio, Tiina
    National Institute for Health and Welfare, Public Health Genomics Unit and Institute for Molecular Medicine FIMM, Helsinki, Finland / Helsinki University and University Hospital, Department of Psychiatry, Helsinki, Finland.
    Nightmares: Risk factors among the Finnish general adult population2015In: Sleep, ISSN 0161-8105, E-ISSN 1550-9109, Vol. 38, no 4, p. 507-514Article in journal (Refereed)
    Abstract [en]

    STUDY OBJECTIVES: To identify risk factors for experiencing nightmares among the Finnish general adult population. The study aimed to both test whether previously reported correlates of frequent nightmares could be reproduced in a large population sample and to explore previously unreported associations.

    DESIGN: Two independent cross-sectional population surveys of the National FINRISK Study.

    SETTING: Age- and sex-stratified random samples of the Finnish population in 2007 and 2012.

    PARTICIPANTS: A total of 13,922 participants (6,515 men and 7,407 women) aged 25-74 y.

    INTERVENTIONS: N/A.

    MEASUREMENTS AND RESULTS: Nightmare frequency as well as several items related to socioeconomic status, sleep, mental well-being, life satisfaction, alcohol use, medication, and physical well-being were recorded with a questionnaire. In multinomial logistic regression analysis, a depression-related negative attitude toward the self (odds ratio [OR] 1.32 per 1-point increase), insomnia (OR 6.90), and exhaustion and fatigue (OR 6.86) were the strongest risk factors for experiencing frequent nightmares (P < 0.001 for all). Sex, age, a self-reported impaired ability to work, low life satisfaction, the use of antidepressants or hypnotics, and frequent heavy use of alcohol were also strongly associated with frequent nightmares (P < 0.001 for all).

    CONCLUSIONS: Symptoms of depression and insomnia were the strongest predictors of frequent nightmares in this dataset. Additionally, a wide variety of factors related to psychological and physical well-being were associated with nightmare frequency with modest effect sizes. Hence, nightmare frequency appears to have a strong connection with sleep and mood problems, but is also associated with a variety of measures of psychological and physical well-being.

  • 15.
    Sandman, Nils
    et al.
    Center for Cognitive Neuroscience, Turku Brain and Mind Center, Department of Psychology and Speech-Language Pathology, University of Turku, Finland / Genomics and Biomarkers Unit, National Institute for Health and Welfare, Finland.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Center for Cognitive Neuroscience, Turku Brain and Mind Center, Department of Psychology and Speech-Language Pathology, University of Turku, Finland.
    Kronholm, Erkki
    Department of Health, National Institute for Health and Welfare, Turku, Finland.
    Vartiainen, Erkki
    Department of Health, National Institute for Health and Welfare, Helsinki, Finland.
    Laatikainen, Tiina
    Department of Health, National Institute for Health and Welfare, Finland / Institute of Public Health and Clinical Nutrition, University of Eastern Finland / Hospital District of North Karelia, Finland.
    Paunio, Tiina
    Genomics and Biomarkers Unit, National Institute for Health and Welfare, Finland / Department of Psychiatry, University of Helsinki and Helsinki University Central Hospital, Finland.
    Nightmares as predictors of suicide: an extension study including war veterans2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 44756Article in journal (Refereed)
    Abstract [en]

    Nightmares are intensive dreams with negative emotional tone. Frequent nightmares can pose a serious clinical problem and in 2001, Tanskanen et al. found that nightmares increase the risk of suicide. However, the dataset used by these authors included war veterans in whom nightmare frequency -and possibly also suicide risk -is elevated. Therefore, re-examination of the association between nightmares and suicide in these data is warranted. We investigated the relationship between nightmares and suicide both in the general population and war veterans in Finnish National FINRISK Study from the years 1972 to 2012, a dataset overlapping with the one used in the study by Tanskanen et al. Our data comprise 71,068 participants of whom 3139 are war veterans. Participants were followed from their survey participation until the end of 2014 or death. Suicides (N = 398) were identified from the National Causes of Death Register. Frequent nightmares increase the risk of suicide: The result of Tanskanen et al. holds even when war experiences are controlled for. Actually nightmares are not significantly associated with suicides among war veterans. These results support the role of nightmares as an independent risk factor for suicide instead of just being proxy for history of traumatic experiences.

  • 16.
    Scheinin, Annalotta
    et al.
    University of Turku, Finland / Hospital District of Southwest Finland, Turku, Finland / Turku University Hospital, Finland.
    Kallionpää, Roosa E.
    Turku University Hospital, Finland / University of Turku, Finland.
    Li, Duan
    University of Michigan Medical School, Ann Arbor, Michigan.
    Kallioinen, Minna
    Turku University Hospital, Finland.
    Kaisti, Kaike
    University of Turku, Finland / Hospital District of Southwest Finland, Turku, Finland / Oulu University Hospital, Finland.
    Långsjö, Jaakko
    University of Turku, Finland / Hospital District of Southwest Finland, Turku, Finland / Tampere University Hospital, Finland.
    Maksimow, Anu
    University of Turku, Finland / Hospital District of Southwest Finland, Turku, Finland / Turku University Hospital, Finland.
    Vahlberg, Tero
    University of Turku, Finland / Turku University Hospital, Finland.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. University of Turku, Finland.
    Mashour, George A.
    University of Michigan Medical School, Ann Arbor, Michigan.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. University of Turku, Finland.
    Scheinin, Harry
    University of Turku, Finland / Hospital District of Southwest Finland, Turku, Finland / Turku University Hospital, Finland.
    Differentiating Drug-related and State-related Effects of Dexmedetomidine and Propofol on the Electroencephalogram2018In: Anesthesiology, ISSN 0003-3022, E-ISSN 1528-1175, Vol. 129, no 1, p. 22-36Article in journal (Refereed)
    Abstract [en]

    BACKGROUND

    Differentiating drug-related changes and state-related changes on the electroencephalogram during anesthetic-induced unconsciousness has remained a challenge. To distinguish these, we designed a rigorous experimental protocol with two drugs known to have distinct molecular mechanisms of action. We hypothesized that drug- and state-related changes can be separated.

    METHODS: 

    Forty-seven healthy participants were randomized to receive dexmedetomidine (n = 23) or propofol (n = 24) as target-controlled infusions until loss of responsiveness. Then, an attempt was made to arouse the participant to regain responsiveness while keeping the drug infusion constant. Finally, the concentration was increased 1.5-fold to achieve presumable loss of consciousness. We conducted statistical comparisons between the drugs and different states of consciousness for spectral bandwidths, and observed how drug-induced electroencephalogram patterns reversed upon awakening. Cross-frequency coupling was also analyzed between slow-wave phase and alpha power.

    RESULTS: 

    Eighteen (78%) and 10 (42%) subjects were arousable during the constant drug infusion in the dexmedetomidine and propofol groups, respectively (P = 0.011 between the drugs). Corresponding with deepening anesthetic level, slow-wave power increased, and a state-dependent alpha anteriorization was detected with both drugs, especially with propofol. Negative phase-amplitude coupling before and during loss of responsiveness frontally and positive coupling during the highest drug concentration posteriorly were observed in the propofol but not in the dexmedetomidine group.

    CONCLUSIONS: 

    Electroencephalogram effects of dexmedetomidine and propofol are strongly drug- and state-dependent. Changes in slow-wave and alpha activity seemed to best detect different states of consciousness.

  • 17.
    Sikka, Pilleriin
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Feilhauer, Diana
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    How You Measure Is What You Get: Differences in Self- and External Ratings of Emotional Experiences in Home Dreams2017In: American Journal of Psychology, ISSN 0002-9556, E-ISSN 1939-8298, Vol. 130, no 3, p. 367-384Article in journal (Refereed)
    Abstract [en]

    This study demonstrates that different methods for measuring emotional experiences in dreams — self-ratings of dreams using emotion rating scales versus external ratings in the form of content analysis of narrative dream reports — can lead to strikingly different results and contradicting conclusions about the emotional content of home dreams. During 3 consecutive weeks, every morning upon awakening, 44 participants (16 men, 28 women, average age 26.9± 5.1 years) reported their dreams and rated their emotional experiences in those dreams using the modified Differential Emotions Scale. Two external judges rated emotional experiences inthe same 552 (M = 12.55 ± 5.72) home dream reports using the same scale. Comparison of the 2 methods showed that with self-ratings dreams were rated as more emotional and more positive than with external ratings. Moreover, whereas with self-ratings the majority of dreams was rated as positively valenced, with external ratings the majority of dream reports was rated as negatively valenced. Although self- and external ratings converge, at least partially, in the measurement of negative emotional experiences, they diverge greatly in the measurement of positive emotional experiences. On one hand, this discrepancy may result from different biases inherent in the 2 measurement methods highlighting the need to develop better methods for measuring emotional experiences. On the other hand, self- and external ratings may capture different phenomena and should thus be considered complementary and used concurrently. Nevertheless, results suggest that negative emotional experiences can be measured in a more valid and reliable manner than positive emotional experiences.

  • 18.
    Sikka, Pilleriin
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Sandman, Nils
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland / The Genomics and Biomarkers Unit, National Institute for Health and Welfare, Finland.
    Tuominen, Jarno
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Dream emotions: a comparison of home dream reports with laboratory early and late REM dream reports2018In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 27, no 2, p. 206-214Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to compare the emotional content of dream reports collected at home upon morning awakenings with those collectedin the laboratory upon early and late rapid eye movement (REM) sleep awakenings. Eighteen adults (11 women, seven men; mean age = 25.89 ± 4.85) wrote down their home dreams every morning immediately upon awakening during a 7-day period. Participants also spent two non-consecutive nights in the sleep laboratory where they were awoken 5 min into each continuous REM sleep stage, upon which they gave a verbal dream report. The content of a total of 151 home and 120 laboratory dream reports was analysed by two blind judges using the modified Differential Emotions Scale. It was found that: (1) home dream reports were more emotional than laboratory early REM dream reports, but not more emotional than laboratory late REM dream reports; (2) home dream reports contained a higher density of emotions than laboratory (early or late REM) dream reports; and (3) home dream reports were more negative than laboratory dream reports, but differences between home and early REM reports were larger than those between home and late REM reports. The results suggest that differences between home and laboratory dream reports in overall emotionality may be due to the time of night effect. Whether differences in the density of emotions and negative emotionality are due to sleep environment or due to different reporting procedures and time spent in a sleep stage, respectively, remains to be determined in future studies.

  • 19.
    Sikka, Pilleriin
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. University of Turku, Finland.
    Valli, Katja
    Methodological Issues in Measuring Dream Emotions2016Conference paper (Refereed)
    Abstract [en]

    Emotions are central in dreams, specifically in rapid eye movement sleep dreams. Despite a wealth of research on the emotional content of dreams, there is little consensus about the overall emotionality and predominant valence of dreams or about the prevailing specific emotions in dreams. Previous contradictory findings are arguably due to unresolved methodological issues. However, studies that have directly investigated these methodological issues are scarce. In this presentation three studies that investigated the effect of study methodology on the frequency, valence and phenomenological content of dream emotions are discussed. The studies demonstrate that the use of different methods for rating dream emotions (participants who experience the dream vs external judges who analysed the respective dream report) and for collecting dream reports (home vs laboratory setting) leads to very different results and conclusions about the emotional content of dreams. As such, these studies highlight the importance of carefully considering study methodology when conducting and interpreting dream (emotional) content studies.

  • 20.
    Sikka, Pilleriin
    et al.
    University of Skövde, The Systems Biology Research Centre. University of Skövde, School of Bioscience. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Virta, Tiina
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    I know how you felt last night, or do I?: Self- and external ratings of emotions in REM dreams2014In: Consciousness and Cognition, ISSN 1053-8100, E-ISSN 1090-2376, Vol. 25, p. 51-66Article in journal (Refereed)
    Abstract [en]

    We investigated whether inconsistencies in previous studies regarding emotional experiencesin dreams derive from whether dream emotions are self-rated or externally evaluated.Seventeen subjects were monitored with polysomnography in the sleep laboratoryand awakened from every rapid eye movement (REM) sleep stage 5 min after the onsetof the stage. Upon awakening, participants gave an oral dream report and rated their dreamemotions using the modified Differential Emotions Scale, whereas external judges rated theparticipants’ emotions expressed in the dream reports, using the same scale. The twoapproaches produced diverging results. Self-ratings, as compared to external ratings,resulted in greater estimates of (a) emotional dreams; (b) positively valenced dreams;(c) positive and negative emotions per dream; and (d) various discrete emotions representedin dreams. The results suggest that this is mostly due to the underrepresentationof positive emotions in dream reports. Possible reasons for this discrepancy are discussed.

  • 21.
    Sikka, Pilleriin
    et al.
    University of Skövde, School of Humanities and Informatics. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Virta, Tiina
    Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics. Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, Finland.
    Subjective and objective measures of affective states in REM sleep dreams2012Conference paper (Refereed)
  • 22.
    Valli, Katja
    University of Skövde, School of Humanities and Informatics.
    Dreaming in the multilevel framework2011In: Consciousness and Cognition, ISSN 1053-8100, E-ISSN 1090-2376, Vol. 20, no 4, p. 1084-1090Article in journal (Refereed)
    Abstract [en]

    Biological realism (Revonsuo, 2001, 2006) states that dreaming is a biological phenomenon and therefore explainable in naturalistic terms, similar to the explanation of other biological phenomena. In the biological sciences, the structure of explanations can be described with the help of a framework called ‘multilevel explanation’. The multilevel model provides a context that assists to clarify what needs to be explained and how, and how to place different theories into the same model. Here, I will argue that the multilevel framework would be useful when we try to construct scientific explanations of dreaming.

  • 23.
    Valli, Katja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Dreams2016In: The SAGE Encyclopedia of Theory in Psychology / [ed] Harold L. Miller, Thousand Oaks: Sage Publications, 2016Chapter in book (Other academic)
  • 24.
    Valli, Katja
    et al.
    University of Skövde, School of Humanities and Informatics.
    Frauscher, Birgit
    Innsbruck Med Univ, Dept Neurol, A-6020 Innsbruck, Austria .
    Gschliesser, Viola
    Innsbruck Med Univ, Dept Neurol, A-6020 Innsbruck, Austria .
    Wolf, Elisabeth
    Innsbruck Med Univ, Dept Neurol, A-6020 Innsbruck, Austria .
    Falkenstetter, Tina
    Innsbruck Med Univ, Dept Neurol, A-6020 Innsbruck, Austria .
    Schönwald, Suzana V.
    Hosp Clin Porto Alegre, Dept Neurol, Porto Alegre, RS, Brazil.
    Ehrmann, Laura
    Innsbruck Med Univ, Dept Neurol, A-6020 Innsbruck, Austria .
    Zangerl, Anja
    Innsbruck Med Univ, Dept Neurol, A-6020 Innsbruck, Austria .
    Marti, Isabelle
    Innsbruck Med Univ, Dept Neurol, A-6020 Innsbruck, Austria .
    Boesch, Sylvia M.
    Innsbruck Med Univ, Dept Neurol, A-6020 Innsbruck, Austria .
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Poewe, Werner
    Innsbruck Med Univ, Dept Neurol, A-6020 Innsbruck, Austria .
    Högl, Birgit
    Innsbruck Med Univ, Dept Neurol, A-6020 Innsbruck, Austria .
    Can observers link dream content to behaviours in rapid eye movement sleep behaviour disorder?: A cross-sectional experimental pilot study2012In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 21, no 1, p. 21-29Article in journal (Refereed)
    Abstract [en]

    Motor activity in rapid eye movement (REM) sleep behaviour disorder (RBD) has been linked to dream content. Systematic and controlled sleep laboratory studies directly assessing the relation between RBD behaviours and experienced dream content are, however, largely lacking. We aimed to investigate whether a link can be established between RBD behaviours and dream content when both are systematically sampled in a controlled setting. We investigated six patients with Parkinson syndrome and RBD who underwent 23 nights of videopolysomnographic recording during which they were awakened from REM sleep (10 min after the onset of the second and successive REM periods). Spontaneous free-worded dream reports and a structured dream questionnaire were obtained. Video recordings of motor manifestations were each combined with four dream reports, and seven judges had to match the video clip with the correctly reported dream content from a choice of four possibilities. Of the 35 REM sleep awakenings performed, a total of 17 (48.6%) motor-behavioural episodes with recalled dream content were obtained. The mean of correctly identified video-dream pairs was 39.5% (range 0100%). Our data showed that reported dream content can be linked to motor behaviours above chance level. Matching accuracy was affected mainly by the clarity of dream reports and the specific nature of movements manifest in video recordings.

  • 25.
    Valli, Katja
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Centre for Cognitive Neuroscience, Turku Brain and Mind Center, Department of Psychology, University of Turku, Turku, Finland.
    Frauscher, Birgit
    Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria.
    Peltomaa, Taina
    Centre for Cognitive Neuroscience, Turku Brain and Mind Center, Department of Psychology, University of Turku, Turku, Finland.
    Gschliesser, Viola
    Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria.
    Revonsuo, Antti
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Centre for Cognitive Neuroscience, Turku Brain and Mind Center, Department of Psychology, University of Turku, Turku, Finland.
    Högl, Birgit
    Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria.
    Dreaming furiously?: A sleep laboratory study on the dream content of people with Parkinson's disease and with or without rapid eye movement sleep behavior disorder2015In: Sleep Medicine, ISSN 1389-9457, E-ISSN 1878-5506, Vol. 16, no 3, p. 419-427Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: Rapid eye movement (REM) sleep behavior disorder (RBD) has been related to altered, action-filled, vivid, and aggressive dream content, but research comparing the possible differences in dreams of Parkinson's disease (PD) patients with and without RBD is scarce. The dream content of PD patients with and without RBD was analyzed with specific focus on action-filledness, vividness, emotional valence, and threats.

    METHODS: A total of 69 REM and NREM dream reports were collected in the sleep laboratory, 37 from nine PD patients with RBD and 32 from six PD patients without RBD. A content analysis of (1) action-filledness (actions and environmental events); (2) vividness (emotions and cognitive activity); (3) intensity of actions, events and emotions; (4) emotional valence, and (5) threatening events was performed on the transcripts.

    RESULTS: Altogether 563 dream elements expressing action-filledness and vividness were found. There were no significant between-group differences in the number or distribution of elements reflecting action-filledness or vividness, emotional valence or threats. In within-group analyses, PD patients with RBD had significantly more negative compared to positive dreams (p = 0.012) and compared to PD patients without RBD, a tendency to have more intense actions in their dreams (p = 0.066).

    CONCLUSIONS: Based on the results of this study, there are no major between-group differences in the action-filledness, vividness, or threat content of dreams of PD patients with and without RBD. However, within-group analyses revealed that dreams were more often negatively than positively toned in PD patients with RBD.

  • 26.
    Valli, Katja
    et al.
    Centre for Cognitive Neuroscience, University of Turku, Assistentinkatu 7, FI-20014 Turku, Finland.
    Lenasdotter, Sophie
    University of Skövde, School of Humanities and Informatics.
    MacGregor, Oskar
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics. Department of Philosophy, University of Helsinki, Helsinki, Finland.
    A Test of the Threat Simulation Theory: Replication of Results and Independent Sample2007In: Sleep and Hypnosis: A Journal of Clinical Neuroscience and Psychopathology, ISSN 1302-1192, Vol. 9, no 1, p. 30-46Article in journal (Refereed)
    Abstract [en]

    The Threat Simulation Theory (TST) postulates that dreaming evolved as a mental simulation for the rehearsal of the neurocognitive mechanisms essential for threat recognition and avoidance behaviors. In the present study, we tested the predictions of the TST that dreams are specialized in the frequent simulation of realistic and severe threatening events targeted against the dream self, and that the dream self is likely to take appropriate defensive actions against the threat. The subjects were 50 Swedish university students who kept home-based dream diaries for a period of two or four weeks. The dreams were analyzed with a content analysis method specifically designed for identifying and classifying threatening events in dreams, the Dream Threat Scale. Our results show that in the dreams of ordinary young adults threatening events are frequent, severe, realistic and targeted against the self and significant others. Appropriate defensive actions are frequently undertaken when the situation allows active participation. The present study replicates earlier findings but in an independent sample, collected in a different country and language area, and analyzed by judges different from the original study. Our findings thus offer further support for the predictions of the TST

  • 27.
    Valli, Katja
    et al.
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Evolutionary Psychological Approaches to Dream Content2007In: The New Science of Dreaming: volume III, Praeger, 2007Chapter in book (Other academic)
  • 28.
    Valli, Katja
    et al.
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Sleep: Dreaming Data and Theories2009In: Encyclopedia of Consciousness / [ed] William P. Banks, London: Academic Press, 2009, p. 341-355Chapter in book (Other academic)
  • 29.
    Valli, Katja
    et al.
    University of Skövde, School of Humanities and Informatics.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Pälkäs, Outi
    Punamäki, Raija-Leena
    The effect of trauma on dream content: A field study of Palestinian children2006In: Dreaming (New York, N.Y.), ISSN 1053-0797, E-ISSN 1573-3351, Vol. 16, no 2, p. 63-87Article in journal (Refereed)
    Abstract [en]

    In the present study, we compared the frequency and intensity of threatening events in the dreams of traumatized and nontraumatized Palestinian children. The aim of the study was to test some of the predictions and hypotheses derived from the Threat Simulation Theory proposing an evolutionary function for dreaming. Most, but not all, of our hypotheses were supported by the findings. We discuss the results in the light of the Threat Simulation Theory, and we also consider whether alternative theories of dream function are able to account for them

  • 30.
    Valli, Katja
    et al.
    University of Skövde, School of Humanities and Informatics.
    Strandholm, Thea
    Univ Helsinki, Cent Hosp, Helsinki, Finland.
    Sillanmäki, Lauri
    University of Turku, Turku, Finland.
    Revonsuo, Antti
    University of Skövde, School of Humanities and Informatics.
    Dreams are more negative than real life: Implicaitons for the function of dreaming2008In: Cognition & Emotion, ISSN 0269-9931, E-ISSN 1464-0600, Vol. 22, no 5, p. 833-861Article in journal (Refereed)
    Abstract [en]

    Dream content studies have revealed that dream experiences are negatively biased; negative dream contents are more frequent than corresponding positive dream contents. It is unclear, however, whether the bias is real or due to biased sampling, i.e., selective memory for intense negative emotions. The threat simulation theory (TST) claims that the negativity bias is real and reflects the evolved biolgical function of dreaming. In the present study, we tested the hypothesis of the TST that threatening events are overrepresented in dreams, i.e., more frequent and more severe in dreams than in real life. To control for biased sampling, we used as a baseline the corresponding negative events in real life rather than the corresponding positive events in dreams. We collected dream reports (N = 419) and daily event logs (N = 490) from 39 university students during a two-week period, and interviewed them about real threat experiences retrievable from autobiographical memory (N = 714). Threat experiences proved to be much more frequent and severe in dreams than in real life, and Current Dream Threats more closely resembled Past than Current Real Threats. we conclude that the TST´s predictions hold, and that the negativity bias is real.

1 - 30 of 30
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