A novel approach to mechanical foot stimulation during human locomotion under body weight support

Input from the foot plays an essential part in perceiving support surfaces and determining kinematic events in human walking. To simulate adequate tactile pressure inputs under body weight support (BWS) conditions that represent an effective form of locomotion training, we here developed a new method of phasic mechanical foot stimulation using light-weight pneumatic insoles placed inside the shoes (under the heel and metatarsus). To test the system, we asked healthy participants to walk on a treadmill with different levels of BWS. The pressure under the stimulated areas of the feet and subjective sensations were higher at high levels of BWS and when applied to the ball and toes rather than heels. Foot stimulation did not disturb significantly the normal motor pattern, and in all participants we evoked a reliable step-synchronized triggering of stimuli for each leg separately. This approach has been performed in a general framework looking for “afferent templates” of human locomotion that could be used for functional sensory stimulation. The proposed technique can be used to imitate or partially restore surrogate contact forces under body weight support conditions.     

The similarity heuristic

Decision makers often make snap judgments using fast‐and‐frugal decision rules called cognitive heuristics. Research into cognitive heuristics has been divided into two camps. One camp has emphasized the limitations and biases produced by the heuristics; another has focused on the accuracy of heuristics and their ecological validity. In this paper we investigate a heuristic proposed by the first camp, using the methods of the second. We investigate a subset of the representativeness heuristic we call the “similarity” heuristic, whereby decision makers who use it judge the likelihood that an instance is a member of one category rather than another by the degree to which it is similar to others in that category. We provide a mathematical model of the heuristic and test it experimentally in a trinomial environment. In this environment, the similarity heuristic turns out to be a reliable and accurate choice rule and both choice and response time data suggest it is also how choices are made. We conclude with a theoretical discussion of how our work fits in the broader “fast‐and‐frugal” heuristics program, and of the boundary conditions for the similarity heuristic. Copyright © 2009 John Wiley & Sons, Ltd.     

Effect of Sensory Deprivation on Maximal Force Abilities from Local to Non-local Digits

Abstract

The present study investigates the effect of sensory deprivation of the index and middle finger on motor function of all digits during maximal voluntary force production tasks. A total of 27 subjects performed maximal isometric pressing tasks by using different instructed finger combinations. Subjects completed the same tasks in two visits: a control visit when they had normal sensory feedback in all fingers, and an anesthesia visit when digital nerve blocks were performed on their right index and middle fingers. We evaluated three aspects of motor adaptation on both local (anesthetized) and non-local (non-anesthetized) digits during maximal force production: (1) task-relevant and overall force magnitude, (2) force directional application, and (3) digital individuation and force sharing. Our results indicate that selective digital anesthesia resulted in decreased maximal force magnitude, changed direction of force production, and significant changes extended to non-local digits. The motor weakness and inefficiency revealed in the non-local digits implies that sensory information from each digit can be shared across the digits to assist motor execution within the same hand.     

Making Sense of Their World: Sensory Reactivity and Novelty Awareness as Aspects of Temperament and Correlates of Social Behaviours in Early Childhood

This study examines the early emergence of sensory reactivity and novelty awareness and their relations to children's behaviours with peers. A total of 260 parents (242 mothers, 18 fathers) and 10 teachers of 260 children (131 male, 129 female; M = 63 months; SD = 8.80; range = 39–81) participated. Structural equation models indicate that sensory reactive children appear to be less social (i.e. prosocial and friendly), more likely to engage in solitary‐active play behaviour, and more prone to utilize instrumental aggression in peer interactions. Children scoring high on novelty awareness tend to be more social (i.e. prosocial, friendly, and control impulses), better able to appropriately and punctually comply with tasks given by teacher, less likely to engage in a number of solitary play behaviours (i.e. solitary passive and solitary active), less likely to utilize instrumental or reactive aggressive strategies, and more likely to dodge negative peer interactions by avoiding bullies. Furthermore, the associations between sensory reactivity/novelty awareness and children's behaviours differ from those of other dimensions of temperament (i.e. activity level and emotionality). This suggests that novelty awareness and sensory reactivity uniquely contribute to our overall understanding of children's temperament and its correlates. Copyright © 2012 John Wiley & Sons, Ltd.     

Spatial probability cuing and right hemisphere damage

In this experiment we studied statistical learning, inter-trial priming, and visual attention. We assessed healthy controls and right brain damaged (RBD) patients with and without neglect, on a simple visual discrimination task designed to measure priming effects and probability learning. All participants showed a preserved priming effect for item color. Contrary to healthy controls and RBD participants without neglect, RBD participants with neglect did not show positional priming and both RBD groups learned the underlying spatial probability distribution of target locations to a lesser degree. To see if the latter deficiency could be improved, we tested a patient with long standing chronic spatial neglect on three separate days and observed improved identification times for left sided, high probability, targets. In summary, we found preservation of priming per se in people with spatial neglect. However, this was only clearly demonstrable for color priming and not for positional priming. Associated with this impairment was a difficulty in learning the overall statistical structure of target locations. In a patient with severe persistent neglect we were able to demonstrate that the deficit in statistical learning was not absolute, as this subject improved his identification times for targets appearing in high probability regions of the test display.     

First‐hand sensory experience plays a limited role in children's early understanding of seeing and hearing as sources of knowledge: Evidence from typically hearing and deaf children

One early‐developing component of theory of mind is an understanding of the link between sensory perception and knowledge formation. We know little about the extent to which children's first‐hand sensory experiences drive the development of this understanding, as most tasks capturing this early understanding target vision, with less attention paid to the other senses. In this study, 64 typically hearing children (M_age = 4.0 years) and 21 orally educated deaf children (M_age = 5.44 years) were asked to identify which of two informants knew the identity of a toy animal when each had differing perceptual access to the animal. In the ‘seeing’ condition, one informant saw the animal and the other did not; in the ‘hearing’ condition, one informant heard the animal and the other did not. For both hearing and deaf children, there was no difference between performance on hearing and seeing trials, but deaf children were delayed in both conditions. Further, within both the hearing and deaf groups, older children outperformed younger children on these tasks, indicating that there is a developmental progression. Taken together, the pattern of results suggests that experiences other than first‐hand sensory experiences drive children's developing understanding that sensory perception is associated with knowledge.     

Modality-specific effects in bilingual language perception

ABSTRACT

Language switching typically leads to language switch costs. Previous studies demonstrated that production-based language switching often results in reduced costs when the languages are assigned to distinct modalities (i.e. bimodal language switching) compared to switching within a modality (i.e. unimodal switching). In Experiment 1–3, we compared unimodal to bimodal switching in language perception. In Experiment 4, unimodal switching was compared to bivocal switching (i.e. languages were assigned to different voices). Experiment 1–3 revealed significantly higher switch costs for bimodal than for unimodal switching, indicating fundamental differences to language production studies. While bimodal switching leads to no (additional) costs but – under specific conditions – even to advantage in production, it increases switch costs in language perception. Moreover, Experiment 4 indicates that this is more a modality-specific rather than a general perception-based effect. Different voices instead of different modalities evoked no similar increase in switch costs.