People’s awareness of tactile stimuli has been investigated in far less detail than their awareness of stimuli in other sensory modalities. In an attempt to fill this gap, we provide an overview of studies that are pertinent to the topic of tactile consciousness. We discuss the results of research that has investigated phenomena such as “change blindness”, phantom limb sensations, and numerosity judgments in tactile perception, together with the results obtained from the study of patients affected by deficits that can (...) adversely affect tactile perception such as neglect, extinction, and numbsense. The similarities as well as some of the important differences that have emerged when visual and tactile conscious information processing have been compared using similar experimental procedures are highlighted. We suggest that conscious information processing in the tactile modality cannot be separated completely from the more general processing of spatial information in the brain. Finally, the importance of considering tactile consciousness within the larger framework of multisensory information processing is also discussed. (shrink)

People can maintain accurate representations of visual changes without necessarily being aware of them. Here, we investigate whether a similar phenomenon also exists in touch. In Experiments 1 and 2, participants detected the presence of a change between two consecutively-presented tactile displays. Tactile change blindness was observed, with participants failing to report the presence of tactile change. Critically, however, when participants had to make a forced choice response regarding the number of stimuli presented in the two displays, their performance was (...) significantly better than chance . Experiment 3 demonstrated that tactile change detection does not necessarily involve a shift of spatial attention toward the location of change, regardless of whether the change is explicitly detected. We conclude that tactile change detection likely results from comparing representations of the two displays, rather than by directing spatial attention to the location of the change. (shrink)

What is the primary function of consciousness in the nervous system? The answer to this question remains enigmatic, not so much because of a lack of relevant data, but because of the lack of a conceptual framework with which to interpret the data. To this end, we have developed Passive Frame Theory, an internally coherent framework that, from an action-based perspective, synthesizes empirically supported hypotheses from diverse fields of investigation. The theory proposes that the primary function of consciousness is well-circumscribed, (...) serving the 'somatic nervous system[. For this system, consciousness serves as a frame that constrains and directs skeletal muscle output, thereby yielding adaptive behavior. The mechanism by which consciousness achieves this is more counterintuitive, passive, and “low level” than the kinds of functions that theorists have previously attributed to consciousness. Passive frame theory begins to illuminate (a) what consciousness contributes to nervous function, (b) how consciousness achieves this function, and (c) the neuroanatomical substrates of conscious processes. Our untraditional, action-based perspective focuses on olfaction instead of on vision and is 'descriptive' (describing the products of nature as they evolved to be) rather than 'normative' (construing processes in terms of how they should function). Passive frame theory begins to isolate the neuroanatomical, cognitive-mechanistic, and representational (e.g., conscious contents) processes associated with consciousness. (shrink)

Everyone has felt those tingling, tickly sensations occurring spontaneously all over the body in the absence of stimuli. But does anyone know where they come from? Here, right-handed subjects were asked to focus on one hand while looking at it and while looking away and subsequently to map and describe the spatial and qualitative attributes of sensations arising spontaneously. The spatial distribution of spontaneous sensations followed a proximo-distal gradient, similar to the one previously described for the density of receptive units. (...) The intensity and spatial extent of the reported sensations were modulated by the focusing condition, especially in respect of the left hand. Convergent focusing acted upon the conscious perception of sensations by enhancing or suppressing them. To our knowledge, this is the first ever study of spontaneous sensations, and it offers considerable insight into their sources. The presence of the proximo-distal distributional gradient is a clear sign that receptive units are involved. The enhancement/suppression effects also confirm the involvement of attention. Finally, left-hand dominance suggests several right-hemisphere processes may be involved, such as spatial and tactile perception, and probably interoception. (shrink)

BackgroundReconciling results obtained using different types of sensory measures is a challenge for autism sensory research. The present study used questionnaire, psychophysical, and neurophysiological measures to characterize autistic sensory processing in different measurement modalities.MethodsParticipants were 46 autistic and 21 typically developing 11- to 14-year-olds. Participants and their caregivers completed questionnaires regarding sensory experiences and behaviors. Auditory and somatosensory event-related potentials were recorded as part of a multisensory ERP task. Auditory detection, tactile static detection, and tactile spatial resolution psychophysical thresholds were (...) measured.ResultsSensory questionnaires strongly differentiated between autistic and typically developing individuals, while little evidence of group differences was observed in psychophysical thresholds. Crucially, the different types of measures appeared to be largely independent of one another. However, we unexpectedly found autistic participants with larger auditory Tb ERP amplitudes had reduced hearing acuity, even though all participants had hearing acuity in the non-clinical range.LimitationsThe autistic and typically developing groups were not matched on cognitive ability, although this limitation does not affect our main analyses regarding convergence of measures within autism.ConclusionOverall, based on these results, measures in different sensory modalities appear to capture distinct aspects of sensory processing in autism, with relatively limited convergence between questionnaires and laboratory-based tasks. Generally, this might reflect the reality that laboratory tasks are often carried out in controlled environments without background stimuli to compete for attention, a context which may not closely resemble the busier and more complex environments in which autistic people’s atypical sensory experiences commonly occur. Sensory questionnaires and more naturalistic laboratory tasks may be better suited to explore autistic people’s real-world sensory challenges. Further research is needed to replicate and investigate the drivers of the unexpected association we observed between auditory Tb ERP amplitudes and hearing acuity, which could represent an important confound for ERP researchers to consider in their studies. (shrink)

This PhD thesis concerns introspective approaches to the study of the mind. Across three standalone papers, I examine the significance of introspective data and advise on appropriate kinds of training for the production of such data. An overview document first introduces major themes, methods and arguments of the thesis. Paper 1 then begins the argumentative work, interrogating the constraining function of introspection in cognitive science. Here, I evaluate “enactivist” claims about the significance of introspection, clarifying central enactivist suggestions to draw (...) out the broader importance of introspection in science and philosophy. Paper 2 then examines the proposed employment of Buddhist meditation practices in the production of rigorous introspective data. I defend such proposals against concerns that meditators yield ungeneralizable data, given the transformative character of these attention-training techniques. I argue that some meditation-trained transformations are actually epistemically-beneficial, undermining popular associations between transformation and “distortion”. Paper 3 then reviews difficulties involved in integrating meditative training into research. I emphasise the importance of specific contextual supports to meditation as critical ingredients of introspective proficiency, showing how difficulties replicating these threaten to limit the scope of meditation’s scientific benefits. I layout methodological responses to this that can maximise meditation’s positive impact going forwards. (shrink)

This review addresses the role of early sensory areas in the awareness of tactile information in humans. The results of recent studies dealing with this important topic are critically discussed: In particular, we report on evidence from neuropsychology, neurophysiology, neuroimaging, and behavioral experiments that have highlighted the crucial role played by the primary somatosensory cortex in mediating our awareness of tactile information. Phenomena, such as tactile hallucinations, tactile illusions, the perception of supernumerary limbs, and synaesthesia are also discussed. The research (...) reviewed here clearly shows that the activation of SI is necessary, but not sufficient, for the awareness of touch. On the basis of the evidence outlined here, we propose a neurocognitive model that provides a conceptual framework in which to interpret the results of the literature regarding tactile consciousness. (shrink)