Engineering data compendium. Human perception and performance. User's guide

The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use

Tongue-placed tactile biofeedback suppresses the deleterious effects of muscle fatigue on joint position sense at the ankle

Whereas the acuity of the position sense at the ankle can be disturbed by muscle fatigue, it recently also has been shown to be improved, under normal ankle neuromuscular state, through the use of an artificial tongue-placed tactile biofeedback. The underlying principle of this biofeedback consisted of supplying individuals with supplementary information about the position of their matching ankle position relative to their reference ankle position through electrotactile stimulation of the tongue. Within this context, the purpose of the present experiment was to investigate whether this biofeedback could mitigate the deleterious effect of muscle fatigue on joint position sense at the ankle. To address this objective, sixteen young healthy university students were asked to perform an active ankle-matching task in two conditions of No-fatigue and Fatigue of the ankle muscles and two conditions of No-biofeedback and Biofeedback. Measures of the overall accuracy and the variability of the positioning were determined using the absolute error and the variable error, respectively. Results showed that the availability of the biofeedback allowed the subjects to suppress the deleterious effects of muscle fatigue on joint position sense at the ankle. In the context of sensory re-weighting process, these findings suggested that the central nervous system was able to integrate and increase the relative contribution of the artificial tongue-placed tactile biofeedback to compensate for a proprioceptive degradation at the ankle

The Effect of Oral Tactile Sensitivity on Texture Discrimination and Mastication

Texture perception is one of the most important factors in food acceptance. Individual differences between consumers for perception and oral processing techniques makes research on related topics difficult to find overall effects. It is thought that individual differences in texture perception could be caused by oral sensitivity or mastication behavior. The first hypothesis is that the variation in texture perception across populations is dependent on oral tactile sensitivity and masticatory performance. To address this hypothesis, the study was aimed to measure tactile acuity with a battery of tests and quantitate the relationship to masticatory performance. In general, sensitivity and masticatory performance in the younger age groups was superior to that of older adults (p \u3c 0.0001). A positive linear trend was also found between bite force sensitivity and masticatory performance with younger participants, a trend not found in older participants. No significant relationship between age groups for bite force sensitivity and masticatory performance was found, suggesting that age-related declines in bite force sensitivity are not a significant cause of altered masticatory performance. The second hypothesis is that as oral sensitivity decreases so will a participant’s ability to discriminate texture differences, since there will be less feedback from the oral cavity. We noted that oral sensitivity was not a significant factor when looking at differences in discrimination ability between high and low sensitivity groups. However, the study found that multiple masticatory behaviors were being modulated by oral sensitivity, including overall chewing patterns used (p \u3c 0.0001). More specifically, those in the high sensitivity group used more stochastic chewing movements, while those in the low sensitivity group were found to use crescent and crossed-shaped chewing cycles. It was also noted that in the high sensitivity group the jaw moved further distances (p \u3c 0.0001) in all phases (opening and closing) and moved at a higher velocity when opening (p \u3c 0.0001) but not when closing, when compared to the low sensitivity group. These results help bolster evidence that sensitivity and masticatory performance are related and, as previously reported, both decline as people age (Calhoun, Gibson, Hartley, Minton, & Hokanson, 1992)

Seeing with ears: how we create an auditory representation of space with echoes and its relation with other senses

Spatial perception is the capability that allows us to learn about the environment. All our senses are involved in creating a representation of the external world. When we create the representation of space we rely primarily on visual information, but it is the integration with the other senses that allows us a more global and truthful representation of it. While the influence of vision and the integration of different senses among each other in spatial perception has been widely investigated, many questions remain about the role of the acoustic system in space perception and how it can be influenced by the other senses. Give an answer to these questions on healthy people can help to better understand whether the same \u201crules\u201d can be applied to, for example, people that have lost vision in the early stages of development. Understanding how spatial perception works in blind people from birth is essential to then develop rehabilitative methodologies or technologies to help these people to provide for lack of vision, since vision is the main source of spatial information. For this reason, one of the main scientific objective of this thesis is to increase knowledge about auditory spatial perception in sighted and visually impaired people, thanks to the development of new tasks to assess spatial abilities. Moreover, I focus my attention on a recent investigative topic in humans, i.e. echolocation. Echolocation has a great potential in terms of improvement regarding space and navigation skills for people with visual disabilities. Several studies demonstrate how the use of this technique can be favorable in the absence of vision, both on the level perceptual level and also at the social level. Based in the importance of echolocation, we developed some tasks to test the ability of novice people and we undergo the participants to an echolocation training to see how long does it take to manage this technique (in simple task). Instead of using blind individuals, we decide to test the ability of novice sighted people to see whether technique is blind related or not and whether it is possible to create a representation of space using echolocatio

Inhibition of c-Kit signaling is associated with reduced heat and cold pain sensitivity in humans

The tyrosine kinase receptor c-Kit is critically involved in the modulation of nociceptive sensitivity in mice. Ablation of the c-Kit gene results in hyposensitivity to thermal pain, while c-Kit activation produces hypersensitivity to the noxious heat, without altering sensitivity to innocuous mechanical stimuli. In this study we investigated the role of c-Kit signalling in human pain perception. We hypothesized that subjects treated with Imatinib or Nilotinib, potent inhibitors of tyrosine kinases including c-Kit, but also Abl1, PDFGFR{alpha}, and PDFGFR{beta}, that are used to treat chronic myeloid leukemia (CML), would experience changes in thermal pain sensitivity. We examined 31 asymptomatic CML patients (14 male, 17 female) under Imatinib/Nilotinib treatment and compared them to 39 age- and sex-matched healthy controls (12 male, 27 female). We used cutaneous heat and cold stimulation to test normal and noxious thermal sensitivity, and a grating orientation task to assess tactile acuity. Thermal pain thresholds were significantly increased in the Imatinib/Nilotinib-treated group, while innocuous thermal and tactile thresholds were unchanged compared to the control group. In conclusion, our findings suggest that the biological effects of c-Kit inhibition are comparable in mice and humans in that c-Kit activity is required to regulate thermal pain sensitivity, but does not affect innocuous thermal and mechanical sensation. The effect on experimental heat pain observed in our study is comparable to that of several common analgesics, thus modulation of the c-Kit pathway can be used to specifically modulate noxious heat and cold sensitivity in humans

Body perception and brain plasticity in blind and sighted individuals

Lack of vision is associated with large-scale brain plasticity. Vision, touch, proprioception, interoception, and other sensory modalities are thought to play a vital role in developing and maintaining bodily awareness. How do blind people perceive their bodies, and what kind of compensatory neuroplasticity processes are involved? This thesis comprises a series of experiments focused on a profoundly understudied topic – the perception of one’s body following blindness. Study I shows that blind individuals are significantly better at perceiving their heartbeats than sighted individuals. The results indicate that blind individuals experience signals from inner organs differently than sighted individuals, which has implications for further research on emotional processing and bodily awareness. Study II provides a broader insight into tactile perception following blindness by studying discriminative and affective touch plasticity in blind and sighted groups. A key novel finding is changed pleasantness sensation due to affective touch, that is, slow, gentle, caress-like stroking of the skin, especially on the palm, in blind participants compared to sighted participants. The results have implications for understanding social and physical interactions in blind individuals. Study III re-examines a classic paradigm to study multisensory bodily awareness, the somatic rubber hand illusion, in a large sample of blind participants with a well-matched sighted control group. The results present strong evidence that blind individuals are “immune” to this illusion which suggests that they rely more on unisensory processing rather than multimodal integration of sensory signals, compared to sighted individuals. Study IV investigates the effect of short-term visual deprivation by a two-hour blindfolding procedure on the bodily senses of cardiac interoception, thermosensation, and discriminative touch in sighted participants. The results show no effect on these senses, which suggests that the changes observed in blind individuals on these sensory functions relate to their long-term lack of visual experience and associated brain plasticity changes. Finally, Study V uses structural magnetic resonance imaging to analyze cortical thickness in a group of blind individuals and a matched sighted control group and relate the cortical thickness measure to the behaviorally registered changes in cardiac interoceptive accuracy. The key finding is that blind individuals with thicker occipital cortices are better at sensing their heartbeats; this finding advances our understanding of the limits of cross-modal plasticity following blindness and suggests that the visual cortex supports the awareness of inner bodily sensations in blind individuals. Overall, this thesis is the first systematic characterization of differences and similarities between blind and sighted individuals in body perception and functioning of the bodily senses, opening a line of research with important links to mental health