Investigating misperceptions of visuotactile information, somatosensory amplification and illusory tactile sensations

Lakhlani, Vrushant (2019) Investigating misperceptions of visuotactile information, somatosensory amplification and illusory tactile sensations. PhD thesis, University of Nottingham.

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Abstract

This thesis investigated the underlying mechanisms of illusory tactile sensations that are generated by visuotactile cross-modal manipulations in healthy individuals using the Somatic Signal Detection Task (SSDT) as well as a modified version of the task known as Somatic Signal Discrimination Task (SSDiT). To investigate how the presence of light can result in an illusory report of tactile intensity (i.e., False Alarms), a series of behavioural experiments were conducted using the SSDT and SSDiT paradigms. Further experiments measured the underlying neural processing using EEG and MIRAGE augmented reality system. Behavioural findings indicate that simultaneous presentation of light with a tactile pulse created an illusory tactile enhancement effect (greater false alarms). EEG results indicate that there are two underlying mechanisms that are present during the SSDiT, an early sensory mechanism (EEG components P120 and P160) and a later discrimination mechanism (P360 and P400). Additionally, the SSDiT MIRAGE investigation found that participants were affected by bottom-up visual information they perceived, as fewer false alarms were observed during light present trials during the visual manipulated conditions (no sight and pixilated view). This implies that the level of external focus participants have can affect their susceptibility to experience these illusory sensations; more specifically, bottom-up sensory information can be affected by top-down expectations.

The findings from the current investigations suggest that these illusory mechanisms occur as a result of hyper awareness to ambiguous extra-bodily stimulus that is misinterpreted subjectively as being an actual stimulus sensation when it is not. The individual’s ability to ‘filter’ out non-essential sensory noise causes disruptions to the mechanisms that mediate sensory information processing (e.g., the ability to distinguish threatening stimulus from non-threatening). The findings of this thesis can be used to help improve the treatment of patients with Medically Unexplained Symptoms (MUS) by focusing on improving patients’ interpretation and perception of sensory signals.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Price, Jessica
Newport, Roger
Keywords: Neurobiology, brain, visuotactile information, somatosensory amplification, illusory tactile sensations
Subjects: Q Science > QP Physiology
Faculties/Schools: UNMC Malaysia Campus > Faculty of Science > School of Psychology
Item ID: 53038
Depositing User: LAKHLANI, VRUSHANT
Date Deposited: 25 Feb 2019 07:03
Last Modified: 23 Nov 2020 05:48
URI: http://eprints.nottingham.ac.uk/id/eprint/53038

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