Blurring vision

Abstract: PURPOSE . To determine the effects of blurring vision on whole-body center-of-mass (CM) dynamics and foot-clearance parameters in elderly individuals performing a single step up to a new level. METHODS . Twelve healthy subjects (mean age, 72.3 +/-4.17 years) performed a single step up to a new level (heights of 73 and 146 mm). Trials were undertaken with vision optimally corrected and with vision diffusively blurred by light-scattering lenses (cataract simulation). CM and foot-clearance parameter data were assessed by analyzing data collected by a five-camera, three-dimensional (3-D) motion analysis system. RESULTS . When vision was blurred, subjects took 11% longer to execute the stepping task (P < 0.05), mediolateral displacement of the point of application of the ground reaction force vector (i.e., weighted average of all pressures over the area in contact with the ground; the so called center of pressure, CP) decreased from 37.6% of stance width to 28.3% (P < 0.01), maximum distance between the mediolateral position of the CM and CP decreased by 9.8 mm (P < 0.01), and toe clearance (distance between tip of shoe and edge of step) increased in both the horizontal (28%) and vertical (19%) direction (P < 0.05). CONCLUSIONS . These findings suggest that when vision was blurred, subjects used a twofold safety-driven adaptation: First, to increase dynamic stability they ensured that the horizontal position of their CM was kept close to the center of the base of support and second, they increased horizontal and vertical toe clearance while swinging their lead limb forward to reduce the risk of tripping.

Abstract: Emotional tears have been shown to enhance the interpretation of sadness that is inferred from facial expressions. The current paper puts emotional tears in an evolutionary context. By using biological signaling theory, it first looks at the distinction between cues and signals, both of which provide information to recipients, except that signals have evolved for that purpose. The conclusion is that a signaling function has yet to be shown. Nevertheless, as emotional tears are likely to function as signals, an analysis of certain inevitable effects of tears on the individual hint at more than a single signaling function, depending on the context in which tears are produced. Emotional tears decrease the perception of gaze direction or of changes in pupil size, and may function as attenuators of intentions. Emotional tears are more likely, however, to function as handicaps. By blurring vision, they handicap aggressive or defensive actions, and may function as reliable signals of appeasement, need or attachment.

Abstract: Three experiments are reported in which subjects were exposed to discrepant visual and haptic form information. Stained glass was used to blur vision and lower its accuracy close to the level of touch. Haptic dominance occurred with the large intersensory conflicts under study. It is proposed that touch may be dominant in form perception when vision is peripheral and blurry.