It has been proposed that, in order to enhance sensitivity to novel information, the brain removes predictable components of sensory input. This thesis describes a series of psychophysical and behavioural studies investigating predictive filtering in the perception of touch. Using a novel force-matching paradigm, we demonstrate that self-generated tactile sensations are perceived as weaker than the same stimuli externally imposed. This attenuation is shown to be temporally tuned to the expected time of contact and modulated by the certainty with which a sensation can be attributed to self-action. We confirm experimentally that this attenuation results from a predictive, rather than postdictive, mechanism. Such a mechanism may predict the sensory consequences of action based on an internal model of the environment and an efference copy of the motor command. We investigate how prediction is acquired in a new environment and the coordinate systems in which the new environment is internally represented. Using a novel protocol of transcranial magnetic stimulation, we find evidence to suggest that the efference copy signal underlying the prediction arises upstream of primary motor cortex. Patients with schizophrenia are found to show less attenuation than healthy controls, consistent with models of the disease that propose an underlying deficit in sensory prediction. These experimental findings are discussed in relation to potential neural mechanisms of sensory filtering, and the many proposed roles for predictive mechanisms in human sensory and motor systems are reviewed.

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This portfolio thesis comprises of three parts: a systematic literature review, an empirical report and the appendices. Part one is a systematic review looking at the relationship between infant massage and subsequent parent-infant interactions. The review brings together literature that looks at dyads with and without health problems, and explores whether outcomes differ between dyad types. The review attempts to use the findings to discuss the role of touch in dyadic processes. Part two is an empirical paper that attempts to explore the psychological processes underlying touch through studying the Alexander Technique. Both qualitative interviews and quantitative surveys are used to address how pupils of the technique experience touch, how it changes their psychological wellbeing and how it influences the pupil-teacher relationship. Findings are discussed in terms of implications for the use of touch within psychological therapies. Part three is made up of the appendices, including a reflective statement which discusses the researcher’s experiences of all aspects of the research process.