Reassessing referred sensations following peripheral deafferentation and the role of cortical reorganisation

ABSTRACTBackground and ObjectivesTactile sensations referred to body parts other than those stimulated have been repeatedly described across a wide range of deafferentation and neuropathic pain conditions, including amputation, complex regional pain syndrome, spinal cord injury, and brachial plexus avulsion. Common to all interpretations of referred sensations is the notion that they result from central nervous system (CNS) reorganisation. For example, in amputees, sensations referred to the phantom limb following touches on the face have been classically interpreted as the perceptual correlate of cortical remapping of the face into the neighbouring missing-hand territory in primary somatosensory cortex (S1). Here, using the prominent model of acquired upper-limb amputation, we investigated whether referred sensations reports are associated with cortical remapping or can instead be attributed to demand characteristics (e.g., compliance, expectation, and suggestion), which have been shown to greatly influence self-reports of bodily sensations and were uncontrolled in previous assessments.MethodsUnilateral upper-limb amputees (N=18), congenital one-handers (N=19), and two-handers (N=20) were repeatedly stimulated with PC-controlled vibrations on ten body-parts and asked to report on each trial the occurrence of any concurrent sensations on their hand(s). To further manipulate expectations, we gave participants the suggestion that some of these vibrations had a higher probability to evoke referred sensations. To evaluate remapping, we analysed fMRI data in S1 from two tasks involving movement of facial and whole-body parts, using univariate and multivariate approaches.ResultsThe frequency and distribution of reported referred sensations were similar across groups, with higher frequencies in the high expectancy condition. In amputees, referred sensations were evoked by stimulation of multiple body-parts and reported in both the intact and phantom hand. The group profiles for referred sensations reports were not consistent with the observed patterns of S1 remapping.DiscussionThese findings weaken the interpretation of referred sensations as a perceptual consequence of post-deafferentation CNS reorganisation and reveal the need to account for demand characteristics when evaluating self-reports of anomalous perceptual phenomena for both research and clinical assessments purposes.

Hypothesis awareness confounds asynchronous control conditions in indirect measures of the rubber hand illusion

Reports of changes in experiences of body location and ownership following synchronous tactile and visual stimulation of fake and real hands (rubber hand (RH) effects) are widely attributed to multisensory integration mechanisms. However, existing control methods for subjective report measures (asynchronous stroking and control statements) are confounded by participant hypothesis awareness; the report may reflect response to demand characteristics. Subjective report is often accompanied by indirect (also called ‘objective’ or ‘implicit’) measures. Here, we report tests of expectancies for synchronous ‘illusion’ and asynchronous ‘control’ conditions across two pre-registered studies ( n = 140 and n = 45) for two indirect measures: proprioceptive drift (a change in perceived hand location) and skin conductance response (a measure of physiological arousal). Expectancies for synchronous condition measures were greater than for asynchronous conditions in both studies. Differences between synchronous and asynchronous control condition measures are therefore confounded by hypothesis awareness. This means indirect measures of RH effects may reflect compliance, bias and phenomenological control in response to demand characteristics, just as for subjective measures. Valid control measures are required to support claims of a role of multisensory integration for both direct and indirect measures of RH effects.

Modulating Agency in Hypnosis: Using Suggestion to Induce Self-Tickling

Agency is the subjective sense of control we have over our actions. According to an influential model, this arises when the predicted sensory effects of movements match actual sensory feedback. Consistent with this, previous research found that mechanically manipulating the sensory consequences of actions creates the illusion that they are externally-produced. Across three experiments, we aimed to develop a hypnotic analogue and clarify specific components of hypnosis that contribute to alterations in agency. We compared different suggestions based on clinical impairments whist varying the hypnotisability of subjects and the presence of a hypnotic induction. We found that suggestions designed to model self-monitoring deficits increased perceived involuntariness of actions; these effects were stronger in high hypnotisable participants and after an induction; and could not be explained by demand characteristics alone. These results highlight the capacity of hypnosis to alter sense of agency and model deficits associated with clinical conditions using hypnosis.

Strength Analysis of Single-Symmetry Ratio for Single-Symmetry I-Beam

Double-symmetry I-beams are the most common beam cross-sections in structural building. Because that is simpler to design and analyze steel profiles than single-symmetry I-beams. However, with the advancement of economy, the improvement of the quality of life and the cultural standards, large-scale emergence of various large span bridges, special bridge-type landscapes and viaducts. Single symmetrical I-section is better than Double-symmetry I-section to fairly in line with demand characteristics and material economy. This study chooses different Iyc/Iy ratio sections, 0.229, 0.23, 0.3 and 0.5. Iyc/Iy =0.23 is the change point of the sudden drop of the strength of the compressed airfoil. In study, the section is divided into three sections of plasticity, inelasticity and elasticity for analysis and comparison. Considering the different section sizes. If the value of Lb for a small non-elastic interval is too large, the section with a smaller cross-section will reach the elastic interval. Taking all section conditions Lb into consideration, taking 1.4m as a section will reach the non-elastic interval, if the value of the longer Lb is too small, the section with the larger section does not reach the elastic interval. In study, 10m is taken as the section to reach the elastic interval, orientation the AISC ( 2017 ) specification is used to analyze the I-beam. Symmetrical wing plate cross-sections were increased and reduced. The strength of the cross-sections between the compressed side and the tensioned side was discussed, and a single-symmetric I-section with the best cross-sectional efficiency was proposed.

Wearing a mint-scented face mask reduces appetite

Previous studies have shown that mint scents reduce chocolate craving. However, two questions remain: whether the effect is an artifact of demand characteristics in which participants were aware that the study aimed to examine the effect of mint scent, and whether mint scent reduces appetite for foods generally other than chocolate. The present study took advantage of the fact that wearing face masks in public is becoming a standard norm because of the COVID-19 pandemic, to manipulate scent presentation to participants. We investigated the potential application of mint-scented masks for appetite control. Participants who were deceived that wearing masks were for consumer testing to eliminate demand characteristics rated their perceived wanting to eat for a variety of food images that had been preliminarily rated for perceived wanting while wearing a mint-scented mask (or an unscented control mask). The results showed that wearing a mint-scented compared to an unscented mask reduced perceived wanting for foods regardless of base wanting. The results demonstrate a novel potential application of mint-scented masks, namely appetite control, and replicates and extends the generalizability of past findings by excluding artifacts of demand characteristics.

Improving Utilization Efficiency and Drivers’ Degree of Satisfaction in Urban Complex Parking Lot through Modelling the Dynamic Allocation of Parking Spaces

There are significant differences in the utilization efficiency of parking spaces in different spatial locations within the complex parking lots, which reduces the utilization efficiency of parking resources. For the above problem, a parking spaces supply demand characteristics indexes system was constructed. The Metro City complex was taken as an example, and its parking demand utilization characteristics were analyzed to judge the problem of parking spaces utilization. On this basis, a model of the dynamic allocation of parking spaces for parking spaces was constructed to improve drivers’ degree of degree of satisfaction and balance the occupancy rates for parking spaces in different zones. The simulation results show that after the implementation of the dynamic allocation of parking spaces, the differences of the parking spaces’ demand characteristic indexes between two different parking zones are significantly reduced. It was specifically observed that the differences between parking zones A and B in terms of turnover number, total parking time and average parking time were reduced from 2.24 times to 0.03 times, 1.3 h to 0.6 h and 2.2 h to 0.1 h, respectively, and the average interval time of parking spaces became smaller and more evenly distributed. It can be seen that this model can improve the overall utilization efficiency of the complex parking lot and drivers’ degrees of satisfaction.

Experimental manipulation of muscularity preferences through visual diet and associative learning

Body preferences are somewhat flexible and this variability may be the result of one’s visual diet (whereby mere exposure to certain bodies shifts preferences), associative learning mechanisms (whereby cues to health and status within the population are internalised and affect body preferences), or a mixture of both visual diet and associative learning effects. We tested how these factors may drive changes in preferences for muscularity in male bodies across a male and female sample. Three studies were conducted where participants viewed manipulation images of high and/or low muscle mass males which were either aspirational (high status clothing and posture) and/or neutral (no obvious cues to status). Preferences for muscularity were recorded before and after exposure to such manipulation images to assess whether body preferences had changed following manipulation. We found evidence for both the visual diet and associative learning hypotheses. Exposure to non-muscular male bodies decreased preferences for muscular bodies irrespective of image valence. Exposure to aspirational non-muscular male bodies alongside neutral muscular male bodies also led to a decrease in muscularity preferences. Further, when manipulation conditions are less obviously skewed towards a particular body type, preferences still shifted in the direction of the most prevalent body type, suggesting that demand characteristics are unlikely to have confounded results of previous adaptation experiments with more obvious manipulations.

Order effects in the rubber hand illusion

Seeing a fake hand brushed in synchrony with brushstrokes to a participant’s hand (the rubber hand illusion; RHI) prompts reports of referred touch, illusory ownership and that the real hand has drifted toward the fake hand (proprioceptive drift). According to one theory, RHI effects are attributable to multisensory integration mechanisms, but they may alternatively (or additionally) reflect the generation of experience to meet expectancies arising from demand characteristics (phenomenological control). Multisensory integration accounts are supported by contrasting synchronous and asynchronous brush stroking conditions, typically presented in counter-balanced order. This contrast is known to be confounded by demand characteristics, but to date there has been no exploration of the role of demand characteristics relating to condition-order. In an exploratory study, existing data from a rubber hand study (n = 124) were analysed to test order effects. Synchronous condition illusion report and the difference between synchronous and asynchronous conditions in both report and proprioceptive drift were greater when the asynchronous condition was performed first (and therefore participants were exposed to the questionnaire materials). These order effects have implications for interpretation of reports of ownership experience: in particular, there was no mean ownership agreement in the synchronous-first group. These data support the theory that reports of ownership of a rubber hand are at least partially attributable to phenomenological control in response to demand characteristics.