The effect of unilateral hand contractions on psychophysiological activity during motor performance: Evidence of verbal-analytical engagement

ObjectivesConscious engagement in movement control can influence motor performance. In most cases, the left hemisphere of the brain plays an important role in verbal-analytical processing and reasoning, so changes in the balance of hemispheric activation may influence conscious engagement in movement. Evidence suggests that unilateral hand contractions influence hemispheric activation, but no study has investigated whether there is an associated effect of hand contractions on verbal-analytical processing during motor performance. This study utilized psychophysiological (and behavioural) measures to examine whether pre-performance unilateral hand contraction protocols change verbal-analytical engagement during motor performance.DesignA repeated measures crossover design was employed.MethodsTwenty-eight participants completed three hand contraction protocols in a randomised order: left-, right- and no-hand contractions. Electroencephalography (EEG) measures of hemispheric asymmetry were computed during hand contractions. A golf putting task was conducted after each protocol. EEG connectivity between sites overlying the left verbal-analytical temporal region (T7) and the motor planning region (Fz) was computed for the 3 sec prior to movement initiation. Additionally, electrocardiography (ECG) and electromyography (EMG) signals were analysed 6 sec prior to movement initiation until 6 sec after. Golf putting performance (distance from the target) and putter swing kinematics were measured.ResultsContralateral hemisphere activity was revealed for the left-hand and right-hand contraction conditions. During motor planning, the left-hand contraction protocol led to significantly lower T7-Fz connectivity, and the right-hand contraction protocol led to significantly higher T7-Fz connectivity than the other conditions. EMG, ECG and kinematic measures did not differ as a function of condition. Importantly, T7-Fz connectivity mediated the relationship between hand squeezing and motor performance (distance from the target).ConclusionThe EEG results suggest that pre-performance unilateral hand contractions influence the extent of verbal-analytical engagement during motor planning, which in turn influences motor performance. However, the hand contractions did not influence cardiac activity, muscle activity or kinematics.     

Toward a social psychophysiology of vagally mediated heart rate variability: Concepts and methods in self‐regulation,emotion, and interpersonal processes

Theory and research on self‐regulation, emotional adjustment, and interpersonal processes focus increasingly on parasympathetic functioning, using measures of vagally mediated heart rate variability (vmHRV) or respiratory sinus arrhythmia (RSA). This review describes models of vmHRV in these areas, and issues in measurement and analysis. We propose a framework organizing theory and research as examining (a) vmHRV as an individual difference or a situational response, and (b) resting, reactive, or recovery levels. Evidence supports interpretation of individual differences in resting vmHRV as a broad biomarker for adaptive functioning, but its specificity and underlying mechanisms require elaboration. Individual differences in vagal reactivity (i.e., trait‐like differences in vmHRV decreases during challenge or stress) are less commonly studied in adults and results are mixed. Many stressors and challenges evoke temporary decreases in vmHRV, and in some research self‐regulatory effort evokes increases. In a smaller literature, positive interpersonal experiences and some restorative processes increase resting vmHRV, whereas depletion of self‐regulatory capacity through related effort decreases it. Greater attention to conceptual distinctions regarding vmHRV constructs and several methodological issues will strengthen future research. Importantly, researchers should exercise caution in equating vmHRV with specific psychosocial constructs, especially in the absence of converging assessments and precise experimental manipulations.     

Molecular analyses of the principal components of response strength

Killeen and Hall (2001) showed that a common factor called strength underlies the key dependent variables of response probability, latency, and rate, and that overall response rate is a good predictor of strength. In a search for the mechanisms that underlie those correlations, this article shows that (a) the probability of responding on a trial is a two-state Markov process; (b) latency and rate of responding can be described in terms of the probability and period of stochastic machines called clocked Bernoulli modules, and (c) one such machine, the refractory Poisson process, provides a functional relation between the probability of observing a response during any epoch and the rate of responding. This relation is one of proportionality at low rates and curvilinearity at higher rates.     

Progressive-ratio schedules: effects of later schedule requirements on earlier performances

Four rats were studied with variants of a progressive-ratio schedule with a step size of 6 in which different terminal components followed completion of the 20th ratio: (a) a reversal of the progression, (b) a fixed-ratio 6 schedule, or (c) extinction. Responding in the progressive-ratio components of these schedules was compared to performances under conventional progressive-ratio baselines. Under baseline conditions, postreinforcement pauses increased exponentially as a function of increasing ratio size, whereas running rates showed modest declines. The procedure of linking the progressive-ratio schedule to the reversed progression or to the fixed-ratio component resulted in decreased pausing. Linking the progressive-ratio schedule to the extinction component had the opposite effect, that of producing weakened progressive-ratio performances as evidenced by increased pausing. Subjects whose responses were reinforced on half of the ratios also showed exponential increases; however, pauses were substantially shorter following ratios on which the reinforcer was omitted. The results suggested that progressive-ratio pausing reflects the influence of remote as well as local contingencies.     

社会因素对剖宫产率的影响

近二三十年来,剖宫产率在世界范围内不断升高。究其原因,除了医学因素外,社会因素起着重要作用,从社会经济发展,社会科学文化水平、社会习俗观念、法律、医疗道德、国家计划生育政策、医学教育等多个角度分析了社会因素对剖宫产率的影响,并就如何发挥社会因素的积极作用,消除和避免其消极作用,使剖部率维持在合理的范围内进行了讨论。     

Global processing speed as a mediator of developmental changes in children's auditory memory span

This study examined the role of global processing speed in mediating age increases in auditory memory span in 5- to 13-year-olds. Children were tested on measures of memory span, processing speed, single-word speech rate, phonological sensitivity, and vocabulary. Structural equation modeling supported a model in which age-associated increases in processing speed predicted the availability of long-term memory phonological representations for redintegration processes. The availability of long-term phonological representations, in turn, explained variance in memory span. Maximum speech rate did not predict independent variance in memory span.     

Rate of conditioned reinforcement affects observing rate but not resistance to change

The effects of rate of conditioned reinforcement on the resistance to change of operant behavior have not been examined. In addition, the effects of rate of conditioned reinforcement on the rate of observing have not been adequately examined. In two experiments, a multiple schedule of observing-response procedures was used to examine the effects of rate of conditioned reinforcement on observing rates and resistance to change. In a rich component, observing responses produced a higher frequency of stimuli correlated with alternating periods of random-interval schedule primary reinforcement or extinction. In a lean component, observing responses produced similar schedule-correlated stimuli but at a lower frequency. The rate of primary reinforcement in both components was the same. In Experiment 1, a 4:1 ratio of stimulus production was arranged by the rich and lean components. In Experiment 2, the ratio of stimulus production rates was increased to 6:1. In both experiments, observing rates were higher in the rich component than in the lean component. Disruptions in observing produced by presession feeding, extinction of observing responses, and response-independent food deliveries during intercomponent intervals usually were similar in the rich and lean components. When differences in resistance to change did occur, observing tended to be more resistant to change in the lean component. If resistance to change is accepted as a more appropriate measure of response strength than absolute response rates, then the present results provide no evidence that higher rates of stimuli generally considered to function as conditioned reinforcers engender greater response strength.     

Steps and pips in the history of the cumulative recorder

From its inception in the 1930s until very recent times, the cumulative recorder was the most widely used measurement instrument in the experimental analysis of behavior. It was an essential instrument in the discovery and analysis of schedules of reinforcement, providing the first real-time analysis of operant response rates and patterns. This review traces the evolution of the cumulative recorder from Skinner's early modified kymographs through various models developed by Skinner and his colleagues to its perfection in the 1950s, and then into the 1960s when it proliferated as different scientific instrument companies began marketing their own models of the cumulative recorder. With the rise of digital computers, the demise of the cumulative recorder as a scientific instrument was inevitable; however, the value of the cumulative record as a monitoring device to assess schedule control of behavior continues. The cumulative recorder remains, along with the operant conditioning chamber, an icon of Skinner's approach to psychology.     

An evaluation of the ability to voluntarily reduce the heart rate after a month of yoga practice

The study aimed at determining whether novices to yoga would be able to reduce their heart rate voluntarily and whether the magnitude of reduction would be more after 30 days of yoga training. Two groups (yoga and control,n=12 each) were assessed on Day 1 and on Day 30. During the intervening 30 days, the yoga group received training in yoga techniques while the control group carried on with their routine. At each assessment the baseline heart rate was recorded for one minute, this was followed by a six-minute period during which participants were asked to attempt to voluntarily reduce their heart rate, using any strategy. Both the baseline heart rate and the lowest heart rate achieved voluntarily during the six-minute period were significantly lower in the yoga group on Day 30 compared to Day 1 by a group average of 10.7 beats per minute (i.e., bpm) and 6.8 bpm, respectively (p<.05, Wilcoxon paired signed ranks test). In contrast, there was no significant change in either the baseline heart rate or the lowest heart rate achieved voluntarily in the control group on Day 30 compared to Day 1. The results suggest that yoga training can enable practitioners to use their own strategies to reduce the heart rate, which has possible therapeutic applications.