Quantitative analysis of human movement synergies: constructive pattern analysis for gait

To record three-dimensional coordinates of the joints from normal human subjects during locomotion, we used a digital motion analysis system (ELITE). Recordings were obtained under several different conditions, which included normal walking and stepping over obstacles. Principal component analysis was used to analyze coordinate data after conversion of the data to segmental angles. This technique gave a stable summary of the redundancy in gait kinematic data in the form of reduced variables (principal components). By modeling the shapes of the phase plots of reduced variables (distortion analysis) and using a limited number of model parameters, good resolution was obtained between subtly different conditions. Hence, it was possible to accurately resolve small distributed changes in gait patterns within subjects. These methods seem particularly suited to longitudinal studies in which relevant movement features are not known a priori. Assumptions and neurophysiological applications are discussed.     

Cognitive reference points in judgments of symbolic magnitude

Research on speeded symbolic magnitude comparisons indicates that decisions are made more quickly when the magnitudes of the stimuli being compared are relatively close to an explicit or implicit reference point. Alternative explanations of this phenomenon are tested by seeking similar effects in nonspeeded rating tasks. In accord with the predictions of discriminability models, rated magnitude differences between stimuli in the vicinity of a reference point are expanded relative to differences between stimuli far from it. The inferred locations of cities along a west-east axis varies systematically depending on which coast, Pacific or Atlantic, is specified as the reference point. Scales derived from the rating data are correlated with the pattern of reaction times obtained in a comparable speeded comparison task. In addition, the distance between the cities nearest the locale of our subjects is subjectively stretched. Reference point effects are also observed when the form of the comparative specifies an implicit reference point at either end of a continuum of subjective size; however, these effects are very small and do not clearly support a discriminability interpretation. Stronger evidence for discriminability effects is obtained when an explicit reference point is established at an arbitrary size value. An implicit scaling model, related to range-frequency theory, is proposed to account for the influence of reference points on relative discriminability of stimulus magnitudes. The implicit scaling model is used to develop an account of how symbolic magnitudes may be learned and of how habitual reference points can produce asymmetries in distance judgments.     

Assessing Parenting Behaviors in Euro–Canadian and East Asian Immigrant Mothers: Limitations to Observations of Responsiveness

The use of parenting measures that are developed for use with Western families without testing their validity among families from non-Western cultural backgrounds may not be appropriate. Similar parenting behaviors may affect child outcomes in different ways across different cultures. This study examined the cross-cultural validity of an observational Maternal Responsiveness coding system and of self-reports of lax/inconsistent parenting in Euro–Canadian (n = 23) and East Asian immigrant mothers (n = 23) of 4- to 7-year-old sons. In Euro–Canadian mothers, observed parenting responsiveness was associated with less lax/inconsistent parenting and fewer child behavior problems. In East Asian immigrant mothers, however, observations of greater responsiveness were not related to reports of lax/inconsistent parenting, and were associated with greater child behavior problems. Implications for the use of these parenting measures across culture groups are discussed.     

Cognitive aging and flight performances in general aviation pilots

ABSTRACT

Unlike professional pilots who are limited by the FAA's age rule, no age limit is defined in general aviation. Our overall goal was to examine how age-related cognitive decline impacts piloting performance and weather-related decision-making. This study relied on three components: cognitive assessment (in particular executive functioning), pilot characteristics (age and flight experience), and flight performance. The results suggest that in comparison to chronological age, cognitive assessment is a better criterion to predict the flight performance, in particular because of the inter-individual variability of aging impact on cognitive abilities and the beneficial effect of flight experience.     

Hydrocortisone infusion exerts dose- and sex-dependent effects on attention to emotional stimuli

Glucocorticoid administration has been shown to exert complex effects on cognitive and emotional processing. In the current study we investigated the effects of glucocorticoid administration on attention towards emotional words, using an Affective Go/No-go task on which healthy humans have shown an attentional bias towards positive as compared to negative words. Healthy volunteers received placebo and either low-dose (0.15 mg/kg) or high-dose (0.45 mg/kg) hydrocortisone intravenously during two separate visits in a double-blind, randomized design. Seventy-five minutes post-infusion, the subjects performed tests of attention (Rapid Visual Information Processing [RVIP]), spatial working memory (Spatial Span) and emotional processing (Affective Go/No-go task [AGNG]). On the attention task, performance was impaired under both hydrocortisone doses relative to placebo, though the effect on error rate was not significant after controlling for age; Spatial Span performance was unaffected by hydrocortisone administration. On the AGNG task, relative to the placebo condition the low-dose hydrocortisone infusion decreased response time to emotional words while high-dose hydrocortisone increased response time. In the females specifically, both high and low dose hydrocortisone administration attenuated the normal attentional bias toward positively valenced words. These data suggest that, in healthy women, the modulation of attention by the emotional salience of stimuli is influenced by glucocorticoid hormone concentrations.     

Photograph method fosters direct access to second-language word meaning: Direct evidence from a word-picture matching task

This experiment was designed to investigate conceptual links directly through a word–picture matching task in children. Participants were asked to indicate between two pictures the one depicting the same concept as the newly learned L2 word (target). One of the two pictures was the target, while the other was either semantically related to it or was unrelated. To investigate whether learning methods modulate L2 word processing, two learning methods were compared: an L2-photograph method and an L1-L2 method. Results showed a semantic interference effect only with the L2-photograph method: Children responded more slowly in the related condition than in the unrelated one. The learning method modulated L2 word processing and L2 word meaning was not necessarily accessed through L1 mediation in the first steps of learning. The method used paves the way for the direct investigation of conceptual links.     

Semantic congruity in symbolic comparisons: Evidence against an expectancy hypothesis

A previously proposed expectancy hypothesis predicts that the semantic congruity effect typically observed in symbolic comparison tasks will be eliminated when the items to be compared are presented prior to the comparative. Previous studies testing this hypothesis have been inconclusive. The present experiments demonstrate that a semantic congruity effect can be obtained when the comparative follows the pair after a 1-sec (Experiment 1) or 4-sec (Experiment 2) delay. Lexical markedness effects were also obtained. The key to producing a “comparative-after” congruity effect is to intermix questions about several different dimensions, so that when the pair is presented, subjects will be unable to anticipate the question. The results disconfirm the expectancy hypothesis.     

Cognitive aging and flight performances in general aviation pilots

Unlike professional pilots who are limited by the FAA's age rule, no age limit is defined in general aviation. Our overall goal was to examine how age-related cognitive decline impacts piloting performance and weather-related decision-making. This study relied on three components: cognitive assessment (in particular executive functioning), pilot characteristics (age and flight experience), and flight performance. The results suggest that in comparison to chronological age, cognitive assessment is a better criterion to predict the flight performance, in particular because of the inter-individual variability of aging impact on cognitive abilities and the beneficial effect of flight experience.