A comparison of the mechanical effect of arm swing and countermovement on the lower extremities in vertical jumping

The purposes of this study were to quantify and compare how arm swing and countermovement affect lower extremity torque and work during vertical jumping and to gain insight into the mechanisms that enable the arm swing and countermovement to increase jump height. Five participants maximally performed two types of vertical squat jumps with (SJA) and without (SJ) an arm swing and two types of countermovement vertical jumps with (CJA) and without (CJ) an arm swing. The participants jumped from a force platform and all performances were videotaped with a high-speed video camera (200Hz). Jump heights, joint torques and work were calculated by combining kinematic and kinetic data. It was found that of the four jumping conditions, the participants jumped highest when they used an arm swing with countermovement (i.e., CJA). The increase of the countermovement jump height with an arm swing is the result of the increase of the lower extremity work. In the hip joint, the increase in torque caused by the countermovement predominantly occurred at the beginning of the propulsion phase, while the increase in torque caused by the arm swing occurred in the rest of the propulsion phase. A key finding of our study is that arm swing and countermovement have independent effects on lower extremity work, and their effects are additive in CJA to produce greater jump height.     

Right hemisphere specialization for color detection

Three experiments were carried out to investigate hemispheric asymmetry in color processing among normal participants. In Experiment 1, it was shown that the reaction times (RTs) of the dominant and non-dominant hands assessed using a visual target presented at the central visual field, were not significantly different. In Experiment 2, RTs of ipsilateral hands to lateralized chromatic stimuli revealed that the processing time was 17 ms shorter in the right hemisphere (RH) than that in the left hemisphere among the right-handed participants, whereas no significant difference was found among the left-handed participants. On the other hand, RTs to lateralized achromatic stimuli showed no such asymmetry among both the right- and left-handed participants (Experiment 3). These findings strongly suggest RH superiority for detection of color among right-handed individuals.     

The role of attention during retrieval in working-memory span: a dual-task study

We tested the hypothesis that retrieving target words in operation span (OSpan) involves attention-demanding processes. Participants completed the standard OSpan task and a modified version in which all equations preceded all target words. Recall took place under either full attention or easy versus hard divided-attention conditions. Recall suffered under divided attention with the recall decrement being greater for the hard secondary task. Moreover, secondary-task performance was disrupted more by the standard OSpan task than by the modified version with the hard secondary task showing the larger decrement. Finally, the time taken to start recalling the first word was considerably longer for the standard version than for the modified version. These results are consistent with the proposal that successful OSpan task performance in part involves the attention-demanding retrieval of targets from long-term memory.     

A Psychometric Analysis of the Child Behavior Checklist DSM-Oriented Scales

The Child Behavior Checklist for Ages 6–18 (CBCL/6-18) possesses newly developed DSM-Oriented Scales, constructed through expert clinical judgment to match selected categories for behavioral/emotional problems as described in the DSM-IV. The present investigation examined the basic psychometric properties for all six DSM-Oriented Scales (i.e., Affective, Anxiety, Somatic, Attention-Deficit/Hyperactivity, Oppositional, and Conduct Scales) in a large clinical sample of children and adolescents (N = 673). Findings from the present study provide strong evidence for the reliability, as well as convergent and discriminative validity, of these scales. It appears that the DSM-Oriented Scales may provide accurate supplementary information that may be considered when formulating clinical diagnoses.

Detection of directed gaze in rhesus monkeys (Macaca mulatta).

To examine the ability of monkeys to detect the direction of attention of other individuals, the authors quantitatively investigated the visual scanning pattern of rhesus monkeys (Macaca mulatta) in response to visually presented images of a human frontal face. The present results demonstrated not only that monkeys predominantly gaze at the eyes as compared with other facial areas in terms of duration and number of fixations, but also that they gaze at the eyes for a longer time period and more frequently when a human face, presented as a stimulus, gazed at them than when the gaze was shifted. These results indicate that rhesus monkeys are sensitive to the directed gaze of humans, suggesting that monkeys pay more attention to the human whose attention is directed to them.     

Antiphase flicker induces depth segregation

We examined the influence of the temporal phase of flickering stimuli on perceptual organization. When two regions of a uniform random-dot field are flickered in temporal alternation with the same flicker rate, one of the regions appears to lie in front of the other. Within the range of temporal frequencies used in the present experiments, depth perception was maximal between 5 and 31.3 Hz. Which region of the two is perceived as lying in front is different from person to person and sometimes fluctuates within the same subject, but when two regions are of different sizes, the smaller region tends to be perceived in front for longer than the larger region. The depth segregation was not due to a luminance difference, because the average temporal luminance of the regions was kept equal. Strikingly, the illusory depth segregation is perceived even between two adjacent regions whose densities of dots, sizes, shapes, and flicker rates are identical. This result suggests that a difference of temporal phase between two flickering regions is crucial for this new depth perception.     

Preferred hand and steadiness of reaction time.

RT and its left/right difference of both biceps muscles were measured by electromyogram (EMG) in the bilateral simultaneous flexion of elbows using 11 left- and 13 right-handed subjects under four conditions which were combinations of two factors; warning signal; presence or absence of a fore-period, and position of limbs; elbow 90 degrees or 135 degrees. EMG-RT and its left/right difference were influenced by these factors. The effects of warning and position of limbs were not the same on the preferred and non-preferred hands. It was assumed that EMG-RTs of biceps in the preferred hand were less influenced by these experimental conditions.     

On the size of refutation Kripke models for some linear modal and tense logics

LetL be any modal or tense logic with the finite model property. For eachm, definer _L (m) to be the smallest numberr such that for any formulaA withm modal operators,A is provable inL if and only ifA is valid in everyL-model with at mostr worlds. Thus, the functionr _L determines the size of refutation Kripke models forL. In this paper, we will give an estimation ofr _L (m) for some linear modal and tense logicsL.     

Knowledge-based classification of ill-defined categories

In this paper, I report an exploratory study which investigated the role that prior knowledge plays in influencing classification learning. Under neutral or knowledge-imposing instructions, subjects learned to classify exemplars into categories that either were or were not linearly separable. Linearly separable categories are those categories whose members can be correctly classified based on an additive summation of weighted attribute information. Following category learning, the subjects were given transfer tests. A major finding was that knowledge facilitated the learning of linearly separable categories but interfered with the learning of not linearly separable categories. Quantitative analyses revealed that the knowledge facilitated category learning of the linearly separable categories by influencing the storage and reliance on both prototypical and exemplar information.