Effects of aging on whole body and segmental control while obstacle crossing under impaired sensory conditions

The ability to safely negotiate obstacles is an important component of independent mobility, requiring adaptive locomotor responses to maintain dynamic balance. This study examined the effects of aging and visual–vestibular interactions on whole-body and segmental control during obstacle crossing. Twelve young and 15 older adults walked along a straight pathway and stepped over one obstacle placed in their path. The task was completed under 4 conditions which included intact or blurred vision, and intact or perturbed vestibular information using galvanic vestibular stimulation (GVS). Global task performance significantly increased under suboptimal vision conditions. Vision also significantly influenced medial–lateral center of mass displacement, irrespective of age and GVS. Older adults demonstrated significantly greater trunk pitch and head roll angles under suboptimal vision conditions. Similar to whole-body control, no GVS effect was found for any measures of segmental control. The results indicate a significant reliance on visual but not vestibular information for locomotor control during obstacle crossing. The lack of differences in GVS effects suggests that vestibular information is not up-regulated for obstacle avoidance. This is not differentially affected by aging. In older adults, insufficient visual input appears to affect ability to minimize anterior–posterior trunk movement despite a slower obstacle crossing time and walking speed. Combined with larger medial–lateral deviation of the body COM with insufficient visual information, the older adults may be at a greater risk for imbalance or inability to recover from a possible trip when stepping over an obstacle.     

Utility of center of pressure measures during obstacle crossing in prediction of fall risk in people with Parkinson’s disease

IntroductionPostural instability during walking and tripping over obstacles are the main causes of falls in people with Parkinson’s disease (PD). Preliminary limited evidence suggests that the length of the prospective follow-up period affects falls prediction in PD, with shorter periods leading to more accurate prediction. Thus, the primary aim of the present study was to test the performance of center of pressure (CoP) variables during obstacle crossing to predict fall risk in people with PD during subsequent periods of four, six, and 12 months. We also compared CoP variables during obstacle crossing between fallers and non-fallers.MethodsForty-two individuals with PD, in mild to moderate stages, completed the baseline obstacle crossing assessment and reported falls for 12 months. Participants walked at their self-selected pace and were instructed to cross an obstacle (half knee height) positioned in the middle of an 8-m long pathway. A force platform was used to analyze CoP parameters of the stance phase of the trailing limb (most affected limb). The ability of each outcome measure to predict fall risk at four, six, and 12 months was assessed using receiver operating characteristic curve analyses.ResultsTen individuals (23.8%) were considered fallers at four months, twelve individuals (28.5%) at six months, and twenty-one individuals (50%) at 12 months. CoP amplitude and CoP velocity in the mediolateral direction significantly predicted fall risk at four, six, and 12 months. As judged by the area under the curve, mediolateral CoP velocity showed the best performance at four months, while mediolateral CoP amplitude showed the best performance at six months. Fallers presented greater values of mediolateral CoP velocity and amplitude than non-fallers.ConclusionThese findings suggest that mediolateral CoP velocity and amplitude during obstacle crossing might be useful to predict fall risk in people with PD. Therefore, larger studies are encouraged.     

Pokemon gaming causes pedestrians to run a red light: An observational study of crossing behaviours at a signalised intersection in Taipei City

Since the launch of the smartphone game “Pokemon Go”, the worldwide craze has led to numerous traffic crashes and injuries resulting from falling or tripping. This paper investigates the effects of several smartphone distracting activities (gaming, talking, texting, Web surfing, and listening to music) on the street-crossing behaviours of pedestrians in Taipei City, Taiwan. A field study using video cameras was conducted to observe pedestrian crossing behaviours (e.g., crossing time, sudden movements, running a red light, and walking outside the crosswalk) at a selected signalised intersection. Data such as phone features, distracting activities, and personal attributes of the pedestrians were obtained in interviews conducted after pedestrians had completed crossing the street. In total, 1995 pedestrians engaging in various smartphone activities were observed. Results indicate that unsafe crossing behaviours were more prevalent among those playing “Pokemon Go”. Texting via instant-message apps appeared to be the second-most risk distracting activity. Results of the logistic models reveal that contributing factors to unsafe behaviours include being a student, phone screen of 5 in. or larger, and having an unrestricted 4G Internet data allowance. Two interaction terms (gaming × students, and gaming × unlimited 4G data allowance) in the models appear to be important determinants of unsafe crossing behaviours. The current research suggests that to prevent potential crashes and injuries, smartphone gaming while crossing the street should be prohibited.     

Orienting Under Load: Intrinsic Dynamics and Postural Affordances for Visual Perception

Orientation toward one's surroundings is necessary for prospective control of action, and constraints on orienting activity have consequences for animal survival. Physically coupled load is a constraint for humans wearing protective equipment (firefighters, soldiers, etc.). The consequences of load on postural affordances while transitioning to upright stance was used to quantify the impact of different soldier configurations. Eight participants established upright posture in 4 relevant load configurations (5.0 to 79.2 lb). Load affected the accessibility of optical information at a distance as evidenced by increasing downward head angles and reductions in postural coordination. Reductions in the variability of time to establish upright stance with load suggests a loss of functional adaptability. Load asymmetries played a significant role as the most asymmetric configuration (not the heaviest) had the most detrimental effect on postural affordances. Center of Pressure (CoP) dynamics reflected the consequences of asymmetric loading on postural regulation as greater power and fluctuations across frequencies were observed. Physically coupled load induces significant constraints on orienting activity, and load asymmetry contributes significantly to the detrimental effects of protective equipment on action-perception coupling during whole-body movements.     

Obstacle Crossing Differences Between Blind and Blindfolded Subjects After Haptic Exploration

Little is known about the ability of blind people to cross obstacles after they have explored haptically their size and position. Long-term absence of vision may affect spatial cognition in the blind while their extensive experience with the use of haptic information for guidance may lead to compensation strategies. Seven blind and 7 sighted participants (with vision available and blindfolded) walked along a flat pathway and crossed an obstacle after a haptic exploration. Blind and blindfolded subjects used different strategies to cross the obstacle. After the first 20 trials the blindfolded subjects reduced the distance between the foot and the obstacle at the toe-off instant, while the blind behaved as the subjects with full vision. Blind and blindfolded participants showed larger foot clearance than participants with vision. At foot landing the hip was more behind the foot in the blindfolded condition, while there were no differences between the blind and the vision conditions. For several parameters of the obstacle crossing task, blind people were more similar to subjects with full vision indicating that the blind subjects were able to compensate for the lack of vision.     

The road user behaviour of New Zealand adolescents

The present study aimed to describe the road user behaviour of New Zealand adolescents and to investigate the applicability of the Adolescent Road user Behaviour Questionnaire (ARBQ) to New Zealand adolescents. In total 944 adolescents were surveyed in the North and South islands of New Zealand. Factor analysis of the scale produced three factors which had acceptable internal reliability and were very similar to those found in the original research. The three factors were “unsafe crossing behaviour”, “playing on the road” and “planned protective behaviour”. This research also found that males and those who were at least part Maori were more likely to put themselves at risk by playing on the road. Furthermore, those who identified themselves as being part Maori also engaged in unsafe road crossing behaviour more often than Caucasian and Asian adolescents. Interestingly, only the interaction effect between age and sex was significantly related to engagement in planned protective behaviour. However, despite differences between New Zealand and England, and differences in the sample characteristics, the scale appeared to be measuring the same latent variables. Therefore, this research confirmed that the ARBQ is a useful tool for investigating the behaviour of adolescents on the road.     

A method for sensation scaling based on an analogy between perception and judgment

Two techniques for studying judgment are discussed. In the first of these one assumes invariance of perception over different judgment processes and conceives of the properties of one judgment process as known. Then, perceptions may be estimated under this process and utilized in the study of other judgment processes of interest. A second technique disposes of the reliance up on a basic, “known” process and instead suggests that perception be treated as free parameters to be estimated from data. The paper then proceeds to show how this second technique may be used under certain conditions on perception themselves. A concept of sensation is introduced which is thought of as generating percepts in formally the same manner as percepts are thought of as generating judgments. The idea is tried out on the perception of movement time. A simple perception process appears to give a good fit to data.     

Introducing human factors in pedestrian crossing behaviour models

The objective of this research is the development of pedestrian crossing choice models on the basis of road, traffic and human factors. For that purpose, a field survey was carried out, in which a panel of 75 pedestrians were asked to take 8 short walking trips (each one corresponding to a different walking and crossing scenario) in the Athens city centre in Greece, allowing to record their crossing behaviour in different road and traffic conditions. The same individuals were asked to fill in a questionnaire on their travel motivations, their mobility characteristics, their risk perceptions and preferences with respect to walking and road crossing, their opinion on drivers, etc. The walking and crossing scenarios’ data were used to develop mixed sequential logit models of pedestrian behaviour on the basis of road and traffic characteristics. The modelling results showed that pedestrian crossing choices are significantly affected by road type, traffic flow and traffic control. The questionnaire data were used to estimate human factors (components) of pedestrian crossing behaviour by means of principal component analysis. The results showed that three components of pedestrian crossing behaviour emerge, namely a “risk-taking and optimisation” component reflecting the tendency to cross at mid-block in order to save time, etc., a “conservative” component, concerning individuals with increased perceived risk of mid-block crossing, who also appear to be frequent public transport users, and a “pedestrian for pleasure” component, bringing together frequent pedestrians, walking for health or pleasure, etc. The introduction of these components as explanatory variables into the choice models resulted in improvement of the modelling results, indicating that human factors have additional explanatory power over road and traffic factors of pedestrian behaviour. Therefore, the development of integrated choice and latent variables models appears to be an appropriate field for further research.     

Obstacle Avoidance Increases Asymmetry of Crossing Step in Individuals With Parkinson's Disease and Neurologically Healthy Individuals

The authors' aim was to investigate gait asymmetry of crossing step during obstacle avoidance while walking in people with Parkinson's disease (PD) under and without the effects of dopaminergic medication. Thirteen individuals with PD and 13 neurologically healthy individuals performed 5 trials of unobstructed gait and 10 trials of obstacle crossing during gait (5 trials with each leg) and spatiotemporal parameters were analyzed. Obstacle crossing increased step duration of the crossing step for the most-affected or nondominant limb compared to the crossing step with the least-affected or dominant limb. Individuals with PD without the effects of medication increased step duration for the step with the least-affected limb compared to the step with the most-affected limb during obstacle crossing.     

A TEST OF NONVERBAL RECEIVING ABILITY: PRELIMINARY STUDIES1

This paper describes the development and preliminary studies of a test of the ability to decode affect in others. Items are videotaped sequences showing spontaneous unposed facial expressions and gestures of college student “senders” to emotionally-loaded color slides. Subjects make judgments about what kind of slide elicited the affect and how pleasant or unpleasant the sender's subjective response was. Satisfactory test-retest reliability was demonstrated for the former kind of judgment but not the latter. There was evidence that females are slightly better receivers than males, and business and fine arts majors are relatively good receivers while science majors are relatively poor.     

When an Object Appears Unexpectedly: Object Circumvention in Adults

Obstacles often appear unexpectedly in our pathway and these require us to make immediate adjustments. Despite how regularly we encounter such situations only few studies have considered how we adjust to unexpected obstacles in the pathway that require us to walk around them. The authors considered how adults adjust to the possibility of an obstacle appearing and then also how foot placement is adjusted to circumvent an obstacle. Fifteen healthy adults walked down an 11-m walkway, initially they were told this was a clear pathway and nothing in the environment would change (no gate), they then performed a series of trials in which a gate may (gate close) or may not (gate open) partially obstruct their pathway. The authors found that mediolateral trunk velocity and acceleration was significantly increased when there was the possibility of an obstacle but before the obstacle appeared. This demonstrates an adaptive walking strategy that seems to enable healthy young adults to successfully circumvent obstacles. The authors also categorized foot placement adjustments and found that adults favored making shorter and wider steps away from the obstacle. They suggest this combination of adjustments allows participants to maintain stability while successfully circumventing the obstacle.     

Evaluating the Acute Contributions of Dopaminergic Replacement to Gait With Obstacles in Parkinson's Disease

The influence of dopaminergic replacement (DR) on gait in people with Parkinson's disease (PD) is well documented. However, little is known about the acute effects of dopamine on more complex locomotor tasks that require visual guidance to avoid obstacles during gait. The authors investigated the influence of DR on locomotor behavior in a task where movement planning and control might be challenged by the height of the obstacle. The PD group included patients diagnosed with idiopathic PD (n = 12), as well as healthy controls (n = 12). Patients walked and stepped over obstacles of different heights before (OFF) and after (ON) levodopa intake. Spatial adjustments were not modulated by DR, but the step time to perform these anticipatory gait adjustments was longer only in PD-OFF (compared with healthy controls) when approaching the highest obstacle, but not PD-ON. During the crossing phase, trail limb toe clearance of PD patients was shorter than healthy controls only during the OFF state. ON-OFF comparisons were significantly different only for the time to reach the lead foot clearance over the highest obstacle. In summary, DR partially improved movement slowness but did not directly affect movement amplitude of lower limb regulation in this gait task.     

Knowing Your Ability

In this article, we present an attempt to reconcile intellectualism and the anti‐intellectualist ability account of knowledge‐how by reducing “S knows how to F” to, roughly speaking, “S knows that she has the ability to F demonstrated by a concrete way w.” More precisely, “S has a certain ability” is further formalized as the proposition that S can guarantee a certain goal by a concrete way w of some method under some precondition. Having the knowledge of our own ability, we can plan our future actions accordingly, which would not be possible by merely having the ability without knowing it, and this pinpoints the crucial difference between knowledge‐how and ability. Our semi‐formal account avoids most of the objections to both intellectualism and the anti‐intellectualist ability account, and provides a multistage learning process of knowledge‐how, which reveals various subtleties.     

Color,Externalism, and Switch Cases

I defend externalism about color experiences and color thoughts, which I argue color objectivism requires. Externalists face the following question: would a subject's wearing inverting lenses eventually change the color content of, for instance, those visual experiences the subject reports with “red”? From the work of Ned Block, David Velleman, Paul Boghossian, Michael Tye, and Fiona Macpherson, I extract problems facing those who answer “Yes” and problems facing those who answer “No.” I show how these problems can be overcome, leaving externalism available to the color objectivist.     

Individual Differences in Risk Taking1

Risk taking behavior in civilian and military settings often results in unnecessary loss of life and equipment. The present research investigates the contribution of three cognitive styles (Type A., Cognitive Complexity, and GIAL) to risky behavior under varying task load conditions. The research is further concerned with uncovering possible relationships between these cognitive styles and physiological arousal (cardiovascular response) as interactive sources of risky actions. A variety of diverse and combined effects of styles on the propensity to take risks was obtained. These relationships were not generally reflected in arousal levels. In addition, the present findings support the conclusions of Streufert et al. (1983) who suggested that risk taking is primarily an effect of cognitive error. In the absence of an arousal based “thrill” finding, specific “educational” programs, based on a person's stylistic characteristics, may be possible to reduce the propensity for risky actions.     

审美的测量:美术能力倾向测验的回顾与展望

美术能力倾向测验对美术人才的识别和选拔具有重要意义。现有测验可分为审美能力测量和艺术创作能力测量两种,其中审美能力测量的测验又可以分为审美判断测验和判断后选择判断理由的两种形式。但以往研究缺乏对审美知觉能力维度的实证研究、没有区分“主观美”和“客观美”,以及缺乏对各类型美术能力倾向测验效度的比较研究。未来可加深对审美知觉能力维度的实证研究,开发多类型美术能力判断测验并比较其效度,开发适用于小学生的美术能力倾向测验,以及开发适合我国国情的美术能力倾向测验。     

Acquiescing to intuition: Believing what we know isn't so

When people identify an error in their initial judgment, they typically try to correct it. But, in some cases, they choose not to—even when they know, in the moment, that they are being irrational or making a mistake. A baseball fan may know that he cannot affect the pitcher from his living room but still be reluctant to say “no‐hitter.” A person may learn that flying in an airplane is statistically safer than driving a car and still refuse to fly. Dual‐process models of judgment and decision making often implicitly assume that if an error is detected, it will be corrected. Recent work suggests, however, that models should decouple error detection and correction. Indeed, people can explicitly recognize that their intuitive judgment is wrong but, nevertheless, stick with it, a phenomenon known as acquiescence. My goals are to offer criteria for identifying acquiescence, consider why people acquiesce even when it incurs a cost, discuss how lessons that are learned in cases when acquiescence is clearly identified can be exported to cases when acquiescence may be harder to establish, and, more broadly, describe the implications of a model that decouples error detection and error correction.     

Reflective judgment: Concepts of justification and their relationship to age and education

This paper describes a seven-stage model of post-adolescent reasoning styles, the most advanced of which is called “Reflective Judgment.” The model outlines a sequence of increasingly complex methods of justification of beliefs. This model demonstrates how people's conceptions of the nature of knowledge, the nature of reality, and their concepts of justification change over age/educational levels. Sixty subjects from three age/educational levels (high school, college, and graduate school) were administered the Reflective Judgment Interview. In addition, subjects were tested on four other factors hypothesized to affect reflective judgment scores. Two were competing theoretical constructs: verbal ability (using Terman's Concept Mastery Test) and Piagetian formal operations (chemicals and pendulum tasks); and two were potentially confounding factors: socio-economic status (using Hollingshead's two-factor index) and verbal fluency (number of words spoken during the interview). Highly significant differences (p < .001) were found on reflective judgment level between the three age/educational groups, and could not be statistically accounted for by scores earned on measures of the other four factors. Whereas verbal ability was found to be closely related to reflective judgment level, the differences between groups on reflective judgment could not be solely attributed to this factor.     

Repeated magnitude estimations with a variable standard: Sequential effects and other properties

Twelve Ss made magnitude estimations of the loudness of each one of a sequence of pure tones according to the rule R(N) = R(N - 1) · [S(N)/S(N - 1)], where R(N) is the response on Trial N, R(N - 1) is the response on Trial N - 1, and S(N)/S(N - 1) is the judged ratio of the “loudness” of the pure tone presented on Trial N to that of the pure tone presented on Trial N - 1. It was found that these magnitude estimations were assimilated toward the immediately preceding stimuli as far as five trials back in the sequence of stimuli. In addition, ratio judgments were consistently asymmetric and the data displayed a form of “time order error.” In all cases, there are similar effects displayed in category judgment data. These and other data imply that at least some kinds of magnitude estimations may involve a judgment of the “difference” or “distance” between pairs of stimuli as a first step in the production of the response required by the judgment situation.