Cardiac and behavioral responses to rocking stimulations in one- and three-month-old infants

Cardiac and behavioral reactions to lateral rocking stimulations were analysed at two different ages (1 and 3 months) and at two speeds of motion for the younger infants. Sixteen 1- and 3-mo.-old infants received 12 10-sec. trials of four complete cycles of vestibulokinesthetic stimulation (rapid rocking) and another group of 10 1-mo.-olds received one complete cycle in the same time period (slow rocking) provided by a motorized cradle. Stimulations were given when infants were in an alert state. Rapid and slow rocking induced similar cardiac responses in younger infants; these responses varied according to the type of motor reaction observed at stimulus onset. Cardiac acceleration was shown with motor activation and cardiac deceleration with motor quieting. In 3-mo.-olds, cardiac deceleration appeared with both types of motor reaction. A strong link between cardiac and behavioral responses in younger infants may prevent the occurrence of the usual simple cardiac index of orienting (heart-rate deceleration). In older infants, cardiac deceleration to rocking stimulation appeared even when it produced concomitant behavioral arousal. Vestibulokinesthetic stimulation is interpreted as having an important homeostatic effect on the young organism.     

A note on constant error shifts in post-perturbation responses

Response biasing was examined in the production of well-learned discrete timing responses. Interpolated movements consisted of trials which were briefly perturbed by an accelerating or decelerating force with subjects requested to amend the response in order to complete the trial successfully. Movement time analysis indicated that the response immediately following the perturbation trial demonstrated large biasing effects with the direction of the constant error shift a function of the direction of the perturbation. Responses following deceleration perturbations were produced too rapidly and those following acceleration perturbations were produced too slowly. Analysis of kinematic variables associated with these responses showed that post perturbation trials were characterized by systematic changes in peak acceleration and peak deceleration as well as the timing of these parameters. The biasing effects were temporary and showed other similarities to findings from short-term motor memory investigations. A number of differences were also noted along with methodological considerations for perturbation paradigms.     

A Note on Constant Error Shifts in Post-Perturbation Responses

Response biasing was examined in the production of well-learned discrete timing responses. Interpolated movements consisted of trials which were briefly perturbed by an accelerating or decelerating force with subjects requested to amend the response in order to complete the trial successfully. Movement time analysis indicated that the response immediately following the perturbation trial demonstrated large biasing effects with the direction of the constant error shift a function of the direction of the perturbation. Responses following deceleration perturbations were produced too rapidly and those following acceleration perturbations were produced too slowly. Analysis of kinematic variables associated with these responses showed that post perturbation trials were characterized by systematic changes in peak acceleration and peak deceleration as well as the timing of these parameters. The biasing effects were temporary and showed other similarities to findings from short-term motor memory investigations. A number of differences were also noted along with methodological considerations for perturbation paradigms.     

The development of attention regulation in the Wisconsin Card Sorting Task

The present study examined performance on a computerized version of the Wisconsin Card Sorting Test (WCST) in participants between 6 and 18 years. Test trials were presented upon request, without time constraints, and with a direct coupling between the participant's response and the onset of the feedback. The pattern of findings that emerged from the self-controlled computerized WCST permitted unique insights into the developmental changes in reasoning and attention regulation during childhood and adolescence. The number of WCST categories achieved developed linearly between 6 and 11 years and asymptoted beyond this age, whereas attentional responses continued to develop. More specifically, a decrease in distractive attention to correct feedback predicted performance in the younger group. In contrast, an increase in attention to error feedback predicted the number of WCST categories achieved by the older children. This pattern of findings indicates that, although trial-by-trial feedback monitoring is crucial for the successful detection of WCST categories in both younger and older children, the specifics of attention regulation differ greatly between children and adolescents.     

Cardiac activity and information processing: the effects of stimulus significance, and detection and response requirements.

In two experiments, measures of heart rate and electromyographic activity were obtained from 40 male undergraduates while they performed two series of trials involving a sequential information processing task. Each trial consisted of a warning light, three successive tones, and a responded light, separated by 6-sec intervals. In Experiment 1, subjects responded only if the three tones were of different frequencies. Acclerative heart-rate responses to the last tone increased as a function of the significance of that tone. Subsequent cardiac decelerations were only observed if the subject was preparing to make a response. These results were replicated in Experiment 2, in which subjects responded only if two of the preceding tones were of the same frequency. Electromyographic activity was not significantly affected by stimulus significance or response anticipation. The data indicate that cardiac acceleration and deceleration reflect two independent psychological processes, associated with information-processing and decision-making activity on the one hand, and preparatory activity on the other.     

Postnatal development of heart rate patterns elicited by an aversive CS and US in cats

Heart rate and motor responses were recorded in cats of different ages during classical conditioning. A deceleratory-acceleratory heart rate pattern observed during the CS-US interval in one and four-week-old kittens is an alpha conditioned response, a potentiated original response to the CS. At eight weeks of age two new distinct patterns of pure acceleration or pure deceleration are acquired during conditioning and in the absence of motor learning. At 12 weeks of age and in adult subjects, heart rate patterns during the CS-US interval become more complex and conditioned motor responses can be observed. A covariance of HR acceleration and motor responses during the CS-US interval is absent in eight-week-old subjects, but quite high in 12-week-old subjects and adult cats. The data are interpreted as suggesting separate elicitatory mechanisms of HR and motor responses which may show synchrony later in ontogeny.     

The visual cliff: cardiac and behavioral responses on the deep and shallow sides at five and nine months of age

Cardiac and behavioral reactions of 5- and 9-month-old infants placed directly atop the two sides of the visual cliff were studied. Evidence of a developmental shift in infant responses on the deep side of the cliff was obtained in heart rate, which shifted from the deceleration previously obtained with younger subjects, to the acceleration obtained with the 9-month-olds of the present study. Behaviorally, visual attention on the two sides was similar at 5 months, but differed at 9 months, being significantly greater on the deep side. Limb movement showed less of an increase on the deep side than on the shallow at both ages tested. Negative vocalization and positive vocalization recordings failed to show any significant effects. The cardiac data are interpreted as indicating a possible shift from attentiveness to fearfulness on the deep side with age.     

Mechanisms underlying accuracy in fast goal-directed arm movements in man

This study investigated how accuracy is attained in fast goal-directed arm movements. Subjects were instructed to make arm extension movements over three different distances in random order, with and without visual feedback. Target width was varied proportionally with distance. Movement time was kept as short as possible, but there were well-defined limits with respect to accuracy. There appeared to be a large relative variability (variation coefficient [VC]) in the initial acceleration. The VC in the distance the hand moved during the acceleration phase was much smaller. This reduction was accompanied by a strong negative correlation between the initial acceleration and the duration of the acceleration phase. Further, the VC in the total distance moved was less than the VC in the distance moved during acceleration. This result indicates asymmetry between the acceleration and the deceleration phase. This is confirmed by the negative correlation between the distance the hand moved during acceleration and the distance it moved during deceleration. Withdrawal of visual feedback had a significant effect on movement accuracy. No differences were found in the parameters of the acceleration phase in the two feedback conditions, however. our results point to the existence of a powerful variability compensating mechanism within the acceleration phase. This mechanism seems to be independent of visual feedback; this suggests that efferent information (efference copies) and/or proprioceptive information is/are responsible for the timing of agonist and antagonist activation. The asymmetry between the acceleration and deceleration phase contributes to a reduction in the relative variability in the total distance moved. The fact that the withdrawal of visual feedback affected movement variability only during the deceleration phase indicates that visual information is used in the adjustment of antagonist activity.     

Response timing variability: coherence of kinematic and EMG parameters

A detailed kinematic and electromyographic (EMG) analysis of single degree of freedom timing responses is reported to (a) determine the coherence of kinematic and EMG variability to the reduced timing error variability exhibited with amplitude increments within a given criterion movement time and (b) understand the temporal organization of various movement parameters in simple responses. The data reveal that the variability of kinematic (time to peak acceleration, duration of acceleration phase, time to peak deceleration) and EMG (duration of agonist burst, duration of antagonist burst, time to antagonist burst) timing parameters decreased with increments of average velocity in a manner consistent with the variable timing error. In addition, the coefficient of variation for peak acceleration, peak deceleration, and integrated EMG of the agonist burst followed the same trend. Increasing average movement velocity also led to decreases in premotor and motor reaction times. Overall, the findings suggest a strong coherence between the variability of response outcome, kinematic, and EMG parameters.     

Response Timing Variability

A detailed kinematic and electromyographic (EMG) analysis of single degree of freedom timing responses is reported to (a) determine the coherence of kinematic and EMG variability to the reduced timing error variability exhibited with amplitude increments within a given criterion movement time and (b) understand the temporal organization of various movement parameters in simple responses. The data reveal that the variability of kinematic (time to peak acceleration, duration of acceleration phase, time to peak deceleration) and EMG (duration of agonist burst, duration of antagonist burst, time to antagonist burst) timing parameters decreased with increments of average velocity in a manner consistent with the variable timing error. In addition, the coefficient of variation for peak acceleration, peak deceleration, and integrated EMG of the agonist burst followed the same trend. Increasing average movement velocity also led to decreases in premotor and motor reaction times. Overall, the findings suggest a strong coherence between the variability of response outcome, kinematic, and EMG parameters.     

Error processing in pointing at randomly feedback-induced double-step stimuli

Two experiments were conducted to determine the spatial and temporal organization of the arm trajectory in human subjects as they pointed to single- and double-step target displacements. Subjects pointed either without (Experiment 1) or with (Experiment 2) vision of their moving hand throughout the trial. In both experiments, target perturbation occurring in double-step trials was clearly perceived by the subjects and was randomly introduced either at the onset or at peak velocity of hand movement. Regardless of whether or not visual reafference from the pointing hand was available, subjects corrected the trajectory of their moving hand to accommodate the double-step. Moreover, asymmetrical velocity profiles were observed for responses to both types of target, with or without vision of the moving hand. The acceleration phase was a fixed pattern independent of the type of step stimulation. However, a clear dissociation, both in the deceleration phase and accuracy of responses to double-step targets, emerged according to the timing of target perturbation. When targets were perturbed at the onset of hand movement, subjects modulated the deceleration phase of their response to compensate for 88 to 100% of the second target displacement. In contrast, when targets were perturbed at peak velocity of hand movement, subjects were unable to modulate the deceleration phase adequately and compensated for only 20 to 40% of the perturbation. These results suggest that motor error is dynamically evaluated during the acceleration phase of a movement toward a perturbed target, allowing amendments to the trajectory to be performed during the deceleration phase. This main corrective process appears to be basically independent of visual reafference from the moving hand.     

Self-report and physiological changes accompanying repeated imagining of a phobic scene.

Twenty female subjects were selected from a larger subject pool on the basis of their scores to the ‘snakes’ item on the Geer (1965) Fear Survey Schedule. Ten of the subjects were selected as phobic; the other ten were non-phobic controls. Heart rate, skin conductance and self-reports of fear and imagery vividness were continuously monitored while subjects repeatedly imagined a prescribed snake scene for a total of 15 trials. The phobic group reported more overall fear to the images. Further, while the nonphobic subjects reported progressively less fear over trials, the phobic subjects reported progressively more fear. The groups did not differ in rated imagery vividness. However, heart rate responses to the image differentiated the two groups. The non-phobic subjects showed a progression from cardiac acceleration in the early trials to a biphasic response pattern, deceleration preceding acceleration, in the later trials. In contrast, the phobic subjects demonstrated sustained acceleration in the later trials. The groups did not differ in skin conductance response amplitude.     

Kinematic Analyses of Manual Asymmetries in Visual Aiming Movements

The right hand advantage has been thought to arise from the greater efficiency of the right hand/left hemisphere system in processing visual feedback information. This hypothesis was examined using kinematic analyses of aiming performance, focusing particularly on time after peak velocity which has been shown to be sensitive to visual feedback processing demands. Eight right-handed subjects pointed at two targets with their left and right hands with or without vision available and either as accurately or as fast as possible. Pointing errors and movement time were found to be smaller with the right hand. Analyses of the temporal componenets of movement time revealed that the hands differed only in time after peak velocity (in deceleration), with the right hand spending significantly less time. This advantage for the right hand, however, was apparent whether or not vision was available and only when accuracy was emphasized in performance. These findings suggest that the right hand system may be more efficient at processing feedback information whether this be visual or nonvisual (e.g., proprioceptive).     

Amending movements: the relationship between degree of mechanical disturbance and outcome accuracy

This paper examines the relationship between the degree of a mechanical disturbance, outcome accuracy, and amendment times to produce response corrections. Movement time error and amendment times were generated by systematically increasing the duration of acceleration and deceleration perturbations. Subjects produced discrete timing responses (700 msec-70 degrees) during which perturbations were interjected into the ongoing movement on random trials. Amendment times were generated from acceleration curves along with a number of related kinematic parameters (e.g., Movement Time, Peak Acceleration). The results showed that as the degree of the mechanical disturbance increased, timing error and amendment times to the perturbations also increased. At low force levels, the percentage of accurate responses to a decelerating perturbation was approximately equal to the percentage of accurate responses for control trials. As force level increased, however, timing error increased and the percentage of accurate responses decreased. in addition, as the magnitude of the disturbance increased, changes occurred in the kinematic properties of the perturbed movements which contributed toward the degree of outcome accuracy of the response. Collectively, the results are discussed in relation to an error correction system that operates in an interactive fashion based on the characteristics of the error and the constraints of the task.     

Switching between spatial stimulus-response mappings: a developmental study of cognitive flexibility

Four different age groups (8-9-year-olds, 11-12-year-olds, 13-15-year-olds and young adults) performed a spatial rule-switch task in which the sorting rule had to be detected on the basis of feedback or on the basis of switch cues. Performance errors were examined on the basis of a recently introduced method of error scoring for the Wisconsin Card Sorting Task (WCST; Barcelo & Knight, 2002). This method allowed us to differentiate between errors due to failure-to-maintain-set (distraction errors) and errors due to failure-to-switch-set (perseverative errors). The anticipated age differences in performance errors were most pronounced for perseverative errors between 8-9 years and 11-12 years, but for distraction errors adult levels were not reached until 13-15 years. These findings were interpreted to support the notion that set switching and set maintenance follow distinct developmental trajectories.     

Form and characteristics of the cardiovascular conditional response in Rhesus monkeys

Three Rhesus monkeys restrained in primate chairs were exposed to several Pavlovian control procedures, followed by 13 sessions of cardiac conditioning under a delay paradigm. The conditional stimulus (CS) was a vertical line and the unconditional stimulus (US) was electric foot shock. Heart rate (HR) was analyzed in successive fivesecond intervals beginning five seconds before CS onset. The major finding was that the conditional response was consistently biphasic and consisted of an initial acceleration followed by deceleration toward the baseline, but rarely reaching it before onset of US. The subjects differed in magnitude of acceleration and subsequent deceleration as well as the location of the maximum rate in the CS-US interval. A breakdown of trials on the basis of the pre-CS HR revealed that the magnitude of effect was inversely related to the pre-CS rate.     

The Effects of Objectives and Constraints on Motor Control Strategy in Reciprocal Aiming Movements

The goal of this study was to examine how the kinematics of reciprocal aiming movements were affected by both the objective of the movement and the constraints operating on that movement. In Experiment 1, the objective of the movement was indirectly manipulated by capitalizing on the fact that subjects determine their own accuracy and speed limits, despite uniform task instructions to move as quickly and accurately as possible. A Fitts' type reciprocal aiming paradigm was employed, in which 69 subjects were asked to move a stylus repetitively between two spatially separated targets. Four target widths were orthogonally combined with four movement amplitudes, resulting in 16 conditions. Movements were made on an X-Y digitizing tablet. Based on the mean variable error produced on both targets, subjects were differentiated post hoc into three movement objective groups: speed, accuracy, and speed-plus-accuracy. Kinematic analyses revealed that the programming and execution of movements were systematically influenced by both the movement objective and the movement constraints. That is, movement time, peak velocity, dwell time, acceleration and deceleration time, normalized acceleration and normalized deceleration varied systematically as a function of both the speed-accuracy movement objective and the movement constraints of target size and movement distance. Moreover, the consequences of changing the constraints of the movement were affected by an interaction with the objective of the movement. In Experiment 2, the objective of the movement was directly manipulated by varying speed and/or accuracy instructions to subjects. The basic results of Experiment 1 were substantiated. Overall, the results were consistent with the view that motor control is dependent upon sensory consequences.     

Cognitive demands of error processing

This study used a dual-task methodology to assess attention demands associated with error processing during an anticipation-timing task. A difference was predicted in attention demands during feedback on trials with correct responses and errors. This was addressed by requiring participants to respond to a probe reaction-time stimulus after augmented feedback presentation. 16 participants (8 men, 8 women) completed two phases, the reaction time task only and the anticipation-timing task with the probe RT task. False feedback indicating error and a financial reward manipulation were used to increase relevance of errors. Data supported the hypothesis that error processing is associated with higher cognitive demands than processing feedback denoting a correct response. Individuals responded with quicker probe reaction times during presentation of feedback on correct trials than on error trials. These results are discussed with respect to the cognitive processes which might occur during error processing and their role in motor learning.     

Thumbs up or thumbs down? Effects of neuroticism and depressive symptoms on psychophysiological responses to social evaluation in healthy students

The effects of neuroticism and depressive symptoms on psychophysiological responses in a social judgment task were examined in a sample of 101 healthy young adults. Participants performed a social judgment task in which they had to predict whether or not a virtual peer presented on a computer screen liked them. After the prediction, the actual judgment was shown, and behavioral, electrocortical, and cardiac responses to this judgment were measured. The feedback-related negativity (FRN) was largest after unexpected feedback. The largest P3 was found after the expected “like” judgments, and cardiac deceleration was largest following unexpected “do not like” judgments. Both the P3 and cardiac deceleration were affected by gender—that is, only males showed differential P3 responses to social judgments, and males showed stronger cardiac decelerations. Time–frequency analyses were performed to explore theta and delta oscillations. Theta oscillations were largest following unexpected outcomes and correlated with FRN amplitudes. Delta oscillations were largest following expected “like” judgments and correlated with P3 amplitudes. Self-reported trait neuroticism was significantly related to social evaluative predictions and cardiac reactivity to social feedback, but not to the electrocortical responses. That is, higher neuroticism scores were associated with a more negative prediction bias and with smaller cardiac responses to judgments for which a positive outcome was predicted. Depressive symptoms did not affect the behavioral and psychophysiological responses in this study. The results confirmed the differential sensitivities of various outcome measures to different psychological processes, but the found individual differences could only partly be ascribed to the collected subjective measures.     

Directional errors of movement and their correction in a discrete tracking task

Many studies have shown that subjects can correct their own errors of movement more quickly than they can react to external stimuli. In the control of movements, three general categories of feedback have been defined as follows: (a) knowledge of results, primarily visually mediated, (b) proprioceptive or kinesthetic, such as from muscle spindles and joint receptors, and (c) corollary discharge or efference copy within the central nervous system. Experiments were conducted on eight normal human subjects to study the effects of these feedbacks on simple RT, choice RT, and error correction time. The movement used was plantarflexion and dorsiflexion of the ankle joint. The feedback loops were modified (a) by inverting the visual display to alter the subject's perception of results and (b) by applying a 100-Hz vibration simultaneously to both flexor and extensor muscles of the ankle joint. Central processing was altered by giving the subjects moderated doses of alcohol (blood-alcohol concentration levels of up to.10%). Vibration and alcohol increased both simple and choice RT but not the error correction time. These data reinforce the concept that there is a central pathway which can mediate error correcting responses.