Comparison of Computerized Dynamic Posturography (CDP) results with subjective visual vertical (SVV) test in patients with and without vestibular dysfunction: effects of horizontal headshaking

The goal of the study was to identify what effect headshaking in the horizontal plane has on Computerized Dynamic Posturography results in normals and patients with unilateral vestibular dysfunction. Additionally, the results were compared to results of the dynamic subjective visual vertical test.

The effects of varying amounts of visual information on telephone intelligibility

This study examines whether similarly reduced amounts of visible articulatory information has potential for increasing speech intelligibility over the telephone to hearing-impaired listeners.

Most comfortable listening levels of hearing impaired people: effects of everyday auditory and visual environments

This paper discusses a study to evaluate the changes that may occur in most comfortable listening levels when hearing aid users encounter a realistic auditory and visual environment.

Objects and positions in visual scenes: effects of perirhinal and postrhinal cortex lesions in the rat

The authors assessed rats' encoding of the appearance or egocentric position of objects within visual scenes containing 3 objects (Experiment 1) or I object (Experiment 2A). Experiment 2B assessed encoding of the shape and fill pattern of single objects, and encoding of configurations (object + position, shape + fill). All were assessed by testing rats' ability to discriminate changes from familiar scenes (constant-negative paradigm). Perirhinal cortex lesions impaired encoding of objects and their shape; postrhinal cortex lesions impaired encoding of egocentric position, but the effect may have been partly due to entorhinal involvement. Neither lesioned group was impaired in detecting configural change. In Experiment 1, both lesion groups were impaired in detecting small changes in relative position of the 3 objects, suggesting that more sensitive tests might reveal configural encoding deficits.

The effects of cross-border and cross-industry mergers and acquisitions on home-region and global multinational enterprises

We examine the effects of international and product diversification through mergers and acquisitions (M&As) on the firm's risk–return profile. We identify the rewards from different types of M&As and investigate whether becoming a global firm is a value-enhancing strategy. Drawing on the theoretical work of Vachani (Journal of International Business Studies, 22 (1991), pp. 307−222) and on Rugman and Verbeke's (Journal of International Business Studies, 35 (2004), pp. 3−18) metrics, we classify firms according to their degree of international and product diversification. To account for the endogeneity of M&As, we develop a panel vector autoregression. We find that global and host-region multinational enterprises benefit from cross-border M&As that reinforce their geographical footprint. Cross-industry M&As enhance the risk–return profile of home-region firms. This effect depends on the degree of product diversification. Hence there is no value-enhancing M&A strategy for home-region and bi-regional firms to become ‘truly global’.

Effects of intensity and positional predictability of a visual stimulus on simple reaction time

The influence of visual stimuli intensity on manual reaction time (RT) was investigated under two different attentional settings: high (Experiment 1) and low (Experiment 2) stimulus location predictability. These two experiments were also run under both binocular and monocular viewing conditions. We observed that RT decreased as stimulus intensity increased. It also decreased as the viewing condition was changed from monocular to binocular as well as the location predictability shifted from low to high. A significant interaction was found between stimulus intensity and viewing condition, but no interaction was observed between neither of these factors and location predictability. These findings support the idea that the stimulus intensity effect arises from purely sensory, pre-attentive mechanisms rather than deriving from more efficient attentional capture. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Effects of approach velocity and foot-target characteristics on the visual regulation of step length

Two questions emerge from the literature concerning the perceptual-motor processes underlying the visual regulation of step length. The first concerns the effects of velocity on the onset of visual control (VCO), when visual regulation of step length begins during goal-directed locomotion. The second concerns the effects of different obstacles such as a target or raised surface on step length regulation. In two separate experiments, participants (Experiment 1 & 2: n=12, 6 female, 6 male) walked, jogged, or sprinted towards an obstacle along a 10 m walkway, consisting of two marker-strips with alternating black and white 0.50 m markings. Each experiment consisted of three targeting or obstacle tasks with the requirement to both negotiate and continue moving (run-through) through the target. Five trials were conducted for each task and approach speed, with trials block randomised between the six participants of each gender. One 50 Hz video camera panned and filmed each trial from an elevated position, adjacent to the walkway. Video footage was digitized to deduce the gait characteristics. Results for the targeting tasks indicate a linear relationship between approach velocity and accuracy of final foot placement (r=0.89). When foot placement was highly constrained by the obstacle step length shortened during the entire approach. VCO was found to occur at an earlier tau-margin for lower approach velocities for both experiments, indicating that the optical variable ‘tau' is affected by approach velocity. A three-phase kinematic profile was found for all tasks, except for the take-off board condition when sprinting. Further research is needed to determine whether this velocity affect on VCO is due to ‘whole-body' approach velocity or whether it is a function of the differences between gait modes.

The effects of target length on the visual control of step length for hard and soft impacts

Adjustments to gait were examined when positioning the foot within a narrow target at the end of an approach for two impact conditions, hard and soft. Participants (6 M, 6 F) ran toward a target of three lengths along a 10-m walkway consisting of two marker strips with alternating black and white 0.5-m markings. Five trials were conducted for each target length and impact task, with trials block randomized between the 6 participants of each gender. A 50-Hz digital video camera panned and filmed each trial from an elevated position adjacent to the walkway. Video footage was digitized to deduce the gait characteristics. A linear speed/accuracy tradeoff between target length and approach time was found for both impact tasks (hard, r = 0.99, p < 0.01; soft, r = 0.96, p < 0.05). For the hard-impact task, visual control time increased linearly (r = 0.99, p < 0.05) when whole-body approach velocity decreased. Visual control time was unaffected by whole-body approach velocity in the soft-impact task. A constant tau-margin of 1.08 describes the onset of visual control when approaching a target while running, with the control of braking during visual control described by a tau-dot of –0.85. Further research is needed to examine the control of braking in different targeting tasks.