Illusory touch and tactile perception in somatoform dissociators

Brown, Richard J.; Brunt, Natalie; Poliakoff, Ellen; Lloyd, David T.

doi:10.1016/j.jpsychores.2009.11.010

Cited by 50 publications

(58 citation statements)

References 35 publications

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“…In this previous study (Katzer et al, 2011), the level of response bias liberalization was significantly associated with the level of somatoform symptoms in a college student population. The result is also in line with Brown et al (2010), who reported that individuals with high scores for pseudoneurological symptoms are characterized particularly by a more liberal response bias. Given that pseudoneurological symptoms might represent a special marker of functional somatization (Brown, 2004), the observed correlations between SSDT parameters and the Pseudoneurological scale of the SOMS-2 are worth a closer look.…”

Section: Ssdt Resultssupporting

confidence: 90%

“…On average, in the first test half more false alarms (i.e., illusory perceptions of the tactile stimuli) were registered than in the second test half, whereas the expected effect of the light stimulus on the false-alarm rate was not found. As in Katzer et al (2011), a significant increase in false alarms in the light-present condition without an actual tactile stimulation could not be registered, although other studies found such a manipulation of illusory tactile perceptions (e.g., Brown et al, 2010;Lloyd et al, 2008). More important, the rate of false alarms was independent of group membership.…”

Section: Ssdt Resultsmentioning

confidence: 62%

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Tactile perceptual processes and their relationship to somatoform disorders.

Katzer

Oberfeld

Hiller

et al. 2012

Journal of Abnormal Psychology

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The Somatic Signal Detection Task (SSDT) is a recent paradigm serving to examine perceptual processes likely relevant for somatoform disorders. We tested whether touch illusions are more easily induced in individuals suffering from somatoform disorders (SFD) and whether their perceptual threshold for tactile stimuli is lower compared to healthy controls. Thirty-three participants with SFD and 32 healthy controls reported whether they recognized near-threshold tactile stimuli at their fingertip, which were presented in half of the test trials. With a probability of 0.5, an auxiliary visual stimulus was additionally presented. Tactile detection thresholds, tactile sensitivity, response bias, and the rate of false-positive perceptions of the tactile stimulus were assessed. In both groups, the light stimulus led to an amelioration of tactile sensitivity as well as to a more liberal response style. The SFD group was characterized by a more liberal response bias in the first half of the light-absent condition compared to the healthy controls. Within the SFD group, the report of somatoform (especially pseudoneurological) symptoms correlated positively with illusory tactile perceptions in the SSDT. Tactile thresholds in the SSDT were measured reliably (r tt ϭ .86) and were significantly lower in the SFD group. The notion that general perceptual dispositions influence the formation of symptom perception may thus complement cognitive models of SFD.Keywords: Somatic Signal Detection Task, somatoform disorders, medically unexplained symptoms, tactile detection threshold, response bias Somatoform symptoms, also called "medically unexplained symptoms" (MUS), are a common phenomenon in primary health care settings (De Waal, Arnold, Eckhof, & van Hemert, 2004). Afflicted persons suffer from bodily complaints that cannot be explained sufficiently by medical conditions. Various models of somatoform disorders (SFD) have been developed, but the precise etiology of MUS and SFD is still unknown (Brown, 2004;Witthöft & Hiller, 2010). Most of the current models assume an interaction of cognitive and perceptual somatosensory processes that lead to behavioral, affective, and biological consequences. Cognitivebehavioral models emphasize factors like catastrophizing, bodyfocused attentional styles, and excessive illness behavior, for example, "doctor shopping," leading in combination to vicious circles that amplify symptom perception (Barsky, Wyshak, & Klerman, 1990;Rief, Hiller, & Margraf, 1998).According to a recently proposed filter model (Rief & Barsky, 2005), the perception of MUS is determined by factors that increase the likelihood of bodily signals (e.g., overarousal, sensitization), on the one hand, and factors that decrease activity of filter systems, on the other hand (e.g., selective attention, lack of distraction). The combination of these two factors could result in the perception of symptoms, which most individuals normally would not experience.Brown (2004) proposed an integrative, conceptual model of MUS focusing on cogniti...

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Section: Ssdt Resultssupporting

confidence: 90%

Section: Ssdt Resultsmentioning

confidence: 62%

Tactile perceptual processes and their relationship to somatoform disorders.

Katzer

Oberfeld

Hiller

et al. 2012

Journal of Abnormal Psychology

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“…Further research is needed in order to understand the role of hypervigilance in the elicitation of vicarious experiences in healthy controls and chronic pain patients. The results are also not in line with those of Brown et al (2010), who suggested that there might be an interrelation between illusory tactile perceptions and the degree of pseudoneurological symptoms, nor with Katzer et al (2011) who suggested medically unexplained symptoms might be related to touch illusions, because both groups in the present study reported a comparable number of vicarious somatosensory experiences. Some previous studies have demonstrated that patients with FM have a hypersensitivity for mechanical, cold and heat pain perception (Kosek et al, 1996;Smith et al, 2008) and mixed results exist for non-painful sensations such as cold, warm and touch (Desmeules et al, 2003;Klauenberg et al, 2008).…”

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confidence: 99%

Fibromyalgia patients and controls are equally accurate in detecting tactile stimuli while observing another in pain: an experimental study

Vandenbroucke

Crombez

Harrar

et al. 2014

Atten Percept Psychophys

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Objective: This study investigated the effects of observing pain in others upon vicarious somatosensory experiences and the detection of somatosensory stimuli in both fibromyalgia patients (FM) and controls. The putative modulatory role of dispositional empathy, hypervigilance to pain, and central sensitization was examined.Methods: FM patients (N=39) and controls (N=38) saw videos depicting pain-related (hands being pricked) and non-pain-related scenes, whilst occasionally experiencing vibrotactile stimuli themselves on the left, right, or both hands. Participants reported the location at which they felt a somatosensory stimulus. Tactile and visual scenes were presented in the same spatial location (congruent, e.g., left-left) or from opposite locations (incongruent, e.g., left-right). We calculated the proportion of correct responses, vicarious somatosensory experiences (i.e., trials on which an illusory somatosensory experience was reported while observing pain-related scenes), and neglect errors (i.e., only reporting the site congruent to the visual painrelated information when both hands had been stimulated).Results: Observing another in pain resulted in an equal numbers of vicarious somatosensory experiences in both groups and facilitated the detection of tactile stimuli, especially during spatially congruent trials.Counter to our expectations, this facilitation was not moderated by group. FM patients made fewer neglect errors. Hypervigilance for pain, dispositional empathy, and central sensitization did not exert a modulatory role.Conclusion: Observing pain facilitates the detection of tactile stimuli in FM patients and controls. Overall, a low incidence of vicarious experiences was observed. Further research is needed to understand the role of attentional body focus in the elicitation of vicarious experiences.

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“…The response on each trial was coded as "reported-yes" if the participants responded "definitely yes" or "maybe yes", or "reported-no" if the participant responded "definitely no" or "maybe no". The primary purpose of the "maybe" options was to encourage false alarms (Brown et al, 2010;Lloyd et al, 2008), and thus we chose to collapse across these options for analytical simplicity.…”

Section: Single-trial Analysis Of Somatosensory Alpha Powermentioning

confidence: 99%

“…In addition, an LED placed close to the non-dominant hand flashes during the SSDT, sometimes simultaneous with the tactile stimulus and sometimes on its own. The presence of the LED has previously been shown to increase false alarm rates (Brown, Brunt, Poliakoff, & Lloyd, 2010;Lloyd et al, 2008;Lloyd, McKenzie, Brown, & Poliakoff, 2011). A common impediment to examining the relationship between alpha power and false alarms is the relative lack of false alarm trials to examine.…”

Section: Introductionmentioning

confidence: 99%

Pre-stimulus alpha oscillations over somatosensory cortex predict tactile misperceptions

et al. 2017

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Cite this article as: Matt Craddock, Ellen Poliakoff, Wael El-deredy, Ekaterini Klepousniotou and Donna M. Lloyd, Pre-stimulus alpha oscillations over somatosensory cortex predict tactile misperceptions, Neuropsychologia, http://dx.doi.org/10. 1016/j.neuropsychologia.2016.12.030 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractFluctuations of pre-stimulus oscillatory activity in the somatosensory alpha band (8-14 Hz) observed using human EEG and MEG have been shown to influence the detection of supraand peri-threshold somatosensory stimuli. However, some reports of touch occur even without a stimulus. We investigated the possibility that pre-stimulus alpha oscillations might also influence these false reports of touch -known as tactile misperceptions. We recorded EEG while participants performed the Somatic Signal Detection Task (SSDT), in which participants must detect brief, peri-threshold somatosensory targets. We found that prestimulus oscillatory power in the somatosensory alpha range exhibited a negative linear 2 relationship with reporting of touch at electrode clusters over both contralateral and ipsilateral somatosensory regions. As pre-stimulus alpha power increased, the probability of reporting a touch declined; as it decreased, the probability of reporting a touch increased. This relationship was stronger on trials without a somatosensory stimulus than on trials with a somatosensory stimulus, although was present for both trial types. Spatio-temporal clusterbased permutation analysis also found that pre-stimulus alpha was lower on trials when touch was reported -irrespective of whether it was present -over contralateral and ipsilateral somatosensory cortices, as well as left frontocentral areas. We argue that alpha power may reflect changes in response criterion rather than sensitivity alone. Low alpha power relates to a low barrier to reporting a touch even when one is not present, while high alpha power is linked to less frequent reporting of touch overall.

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Illusory touch and tactile perception in somatoform dissociators

Cited by 50 publications

References 35 publications

Tactile perceptual processes and their relationship to somatoform disorders.

Tactile perceptual processes and their relationship to somatoform disorders.

Fibromyalgia patients and controls are equally accurate in detecting tactile stimuli while observing another in pain: an experimental study

Pre-stimulus alpha oscillations over somatosensory cortex predict tactile misperceptions

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