State-dependent corrective reactions for backward balance losses during human walking

We investigated corrective reactions for backward balance losses during walking. Several biomechanical studies have suggested that backward falling can be predicted from the horizontal position and velocity of the body center of mass (COM) related to the stance foot. Our hypothesis was that corrective reactions for backward balance losses depend on whether the body moves forward or backward after a perturbation. Using a split-belt treadmill, backward balance losses during walking were induced by rapid decreases of belt speed from 3.5 km/h to 2.5, 2.0, 1.5 and 1.0 km/h. We measured kinematic data and surface electromyography (EMG) during corrective reactions while walking on the treadmill. Phase portrait analysis of COM trajectories revealed that backward balance stability was decreased by the perturbations. When the perturbed belt speed was 1.0 km/h, the COM states at toe-off were significantly lower than the stability limit; a rapid touch-down of the swing foot posterior to the stance foot then occurred, and the gait rhythm was modulated so that the phase advanced. EMG recordings during perturbed steps revealed a bilateral response, including modulation of the swing leg during the recovery. For weaker perturbations, the swing foot placements were anterior to the stance foot and there was a phase delay. In contrast to the bilateral responses for stronger perturbations, unilateral EMG responses were observed for weaker perturbations. The differences in joint kinematics and EMG patterns in the unperturbed swing leg depended on the COM states at toe-off, suggesting the existence of different responses consisting of ongoing swing movements and rapid touch-down. Thus, we conclude that corrective reactions for backward balance losses are not only phase-dependent but also state-dependent. In addition, the control system for backward balance losses predicts the feasibility of forward progression and modulates swing movement and walking rhythm according to backward balance stability.     

Sensory Processing Sensitivity and its association with personality traits and affect: A meta-analysis

In two Bayesian meta-analyses, we investigated associations between Sensory Processing Sensitivity (SPS) and the Big Five personality traits (MA1) as well as both Positive and Negative Affect (MA2). Moderators were age and the three SPS subscales. In MA1 (8 papers, 6790 subjects), SPS in children correlated with Neuroticism (r = 0.42) but did not with Extraversion, Openness, Agreeableness or Conscientiousness. In adults, SPS correlated with Openness (r = 0.14) and Neuroticism (r = 0.40) but did not with Extraversion, Agreeableness or Conscientiousness. In MA2 (19 papers, 5326 subjects), SPS in children correlated with Negative (r = 0.29) and Positive Affect (r = 0.21), but only with Negative Affect (r = 0.34) in adults. Developmental and measurement aspects are discussed.     

A comparison of AME and CR100 for scaling perceived exertion

In psychophysical studies of the relation between perceived magnitude and physical stimulus, interest has focused on the preciseness of growth functions. Very little interest has been devoted to natural levels of an "absolute" character and to the validity of direct measurements. In this article, the Category (C)-Ratio (R) (CR) scaling methodology, developed by Borg (1973, 1977, 1982) is presented together with a new CR scale: the CR100 scale. In an experiment on perceived exertion, CR100 was compared with Absolute Magnitude Estimation (AME). Perceived exertion has the advantage of having easily measured physiological variables that can function as validity criteria. 32 persons (16 men and 16 women) participated as subjects on two different occasions, and the presentation order was counterbalanced. Results from CR100 and AME could be described equally well with psychophysical functions. The exponents obtained with CR100 were n = 1.60 for women and n = 1.69 for men, and the corresponding exponents for AME were n = 1.60 for women and n = 1.46 for men (with a "noise" constant included in the function). ANOVA showed that CR100 could make the predicted differentiation between sexes, whereas AME could not. This drawback with AME was also found when using the methods to predict working capacity.     

Influence of vestibular signals on bodily self-consciousness: Different sensory weighting strategies based on visual dependency

Previous studies showed that the vestibular system is crucial for multisensory integration, however, its contribution to bodily self-consciousness more specifically on full-body illusions is not well understood. Thus, the current study examined the role of visuo-vestibular conflict on a full-body illusion (FBI) experiment that was induced during a supine body position. In a mixed design experiment, 56 participants underwent through a full-body illusion protocol. During the experiment, half of the participants received synchronous visuo-tactile stimulation, and the other half received asynchronous visuo-tactile stimulation, while their physical body was lying in a supine position, but the virtual body was standing. Additionally, the contribution of individual sensory weighting strategies was investigated via the Rod and Frame task (RFT), which was applied both before (pre-FBI standing and pre-FBI supine) and after the full-body illusion (post-FBI supine) protocol. Subjective reports of the participants confirmed previous findings suggesting that there was a significant increase in ownership over a virtual body during synchronous visuo-tactile stimulation. Additionally, further categorization of participants based on their visual dependency (by RFT) showed that those participants who rely more on visual information (visual field dependents) perceived the full-body illusion more strongly than non-visual field dependents during the synchronous visuo-tactile stimulation condition. Further analysis provided not only a quantitative demonstration of full-body illusion but also revealed changes in perceived self-orientation based on their field dependency. Altogether, findings of the current study make further contributions to our understanding of the vestibular system and brought new insight for individual sensory weighting strategies during a full-body illusion.     

Tactile encoding of directions and temporal distances to safety hazards supports drivers in overtaking and intersection scenarios

Safe traffic participation requires continuous monitoring of the environment for potential safety hazards. Here we investigate, to what extent an interface using directed tactile stimuli to communicate temporal distances to approaching objects can make drivers feel supported and influence their driving safety. In contrast to previous studies, we focus on conditions in which the driver has relatively high levels of control over the criticality of evolving hazards as well as on scenarios with laterally approaching hazards. In a dynamic driving simulator experiment, 33 participants completed a selection of overtaking and intersection scenarios with and without sensory support. Furthermore, two novel variants of the interface which differed in the resolution of the temporal distance encoding were utilized. We measured safety, quantified as minimum time-to-contact (mTTC) and rate of critical situations, and assessed the participants’ subjective understanding, acceptance and perceived helpfulness of the support functions. Participants understood the system in both variants after brief exposure. The subjective evaluation was positive with regard to helpfulness, acceptance, and custom questionnaire responses. While mTTC values did not differ between supported and baseline drives, the availability of the system reduced the occurrence of safety–critical situations in intersection scenarios. Driving statistics further reveal that the availability of the system increased the likelihood for entering system-relevant signaling ranges in overtaking scenarios. In sum, the presented work extends previous findings by showing that the subjective utility of the investigated tactile interface applies beyond critical situations and that it can also provide a safety advantage at intersections.     

Beyond Beauty: Design Symmetry and Brand Personality

Our research explores connections between a fundamental element of visual design, namely symmetry, and consumer inferences regarding brand personality. In contrast to prior work focused on broad affective responses, we propose that symmetry plays an additional, nuanced role in the communication of brand personality. Results of four experiments reveal that asymmetry in visual brand elements is associated by consumers with brand excitement, and that the effect is driven in part by the experience of subjective arousal. These findings contribute to growing interest in visual design and consumer processing, while extending current understanding regarding the communication of brand personality.     

A teleological account of Cartesian sensations?

Alison Simmons, in Simmons (1999), argues that Descartes in Meditation Six offered a teleological account of sensory representation. According to Simmons, Descartes’ view is that the biological function of sensations explains both why sensations represent what they do (i.e., their referential content) and why they represent their objects the way they do (i.e., their presentational content). Moreover, Simmons claims that her account has several advantages over other currently available interpretations of Cartesian sensations. In this paper, I argue that Simmons’ teleological account cannot be sustained for both theoretical and textual reasons and that it does not have the advantages it is claimed to have.     

Crossmodal change blindness between vision and touch

Change blindness is the name given to people's inability to detect changes introduced between two consecutively-presented scenes when they are separated by a distractor that masks the transients that are typically associated with change. Change blindness has been reported within vision, audition, and touch, but has never before been investigated when successive patterns are presented to different sensory modalities. In the study reported here, we investigated change detection performance when the two to-be-compared stimulus patterns were presented in the same sensory modality (i.e., both visual or both tactile) and when one stimulus pattern was tactile while the other was presented visually or vice versa. The two to-be-compared patterns were presented consecutively, separated by an empty interval, or else separated by a masked interval. In the latter case, the masked interval could either be tactile or visual. The first experiment investigated visual-tactile and tactile-visual change detection performance. The results showed that in the absence of masking, participants detected changes in position accurately, despite the fact that the two to-be-compared displays were presented in different sensory modalities. Furthermore, when a mask was presented between the two to-be-compared displays, crossmodal change blindness was elicited no matter whether the mask was visual or tactile. The results of two further experiments showed that performance was better overall in the unimodal (visual or tactile) conditions than in the crossmodal conditions. These results suggest that certain of the processes underlying change blindness are multisensory in nature. We discuss these findings in relation to recent claims regarding the crossmodal nature of spatial attention.     

Representation recovers information

Early agreement within cognitive science on the topic of representation has now given way to a combination of positions. Some question the significance of representation in cognition. Others continue to argue in favor, but the case has not been demonstrated in any formal way. The present paper sets out a framework in which the value of representation use can be mathematically measured, albeit in a broadly sensory context rather than a specifically cognitive one. Key to the approach is the use of Bayesian networks for modeling the distal dimension of sensory processes. More relevant to cognitive science is the theoretical result obtained, which is that a certain type of representational architecture is necessary for achievement of sensory efficiency. While exhibiting few of the characteristics of traditional, symbolic encoding, this architecture corresponds quite closely to the forms of embedded representation now being explored in some embedded/embodied approaches. It becomes meaningful to view that type of representation use as a form of information recovery. A formal basis then exists for viewing representation not so much as the substrate of reasoning and thought, but rather as a general medium for efficient, interpretive processing.