The attentional cost of amplitude and directional requirements when pointing to targets

The aim of this study was to investigate the comparative cost of accuracy constraints in direction or amplitude for movement regulation. The attentional cost is operationally defined as the amount of disturbance created in a secondary task by the simultaneous execution of a pointing task in direction or amplitude. The cost is expressed in terms of modifications in response to a secondary task, consisting of a foot-pedal release in response to an auditory stimulus (probe). The probe was introduced during the programming portion or the first, middle, or last portion of the pointing movement. The independent variables were the requirements of the task: direction or amplitude, and the moments of occurrence of the probe. Subjects were submitted to eight experimental conditions: (1) simple foot reaction time to a buzzer; (2) single directional task; (3) single amplitude task; (4) dual directional task (i.e. directional task with probe); (5) dual amplitude task (i.e. amplitude task with probe); (6) retest of foot simple reaction time; (7) retest of single directional task; and (8) retest of single amplitude task. Regulation in direction was more attention-demanding than regulation in distance in terms of programming. During pointing in amplitude, probe RT increased monotonically from start to end of movement execution, whereas directional pointing did not lead to any significant probe RT changes. These results emphasize the specific attentional loads for directional and amplitude pointing tasks, hence the involvement of different central nervous system mechanisms for the programming and regulation of the directional and amplitude parameters of pointing movements.     

Mutual interactions between speech and finger movements

Speech output and finger movements were recorded as right-handed males repeated a syllable while making cyclical finger movements in three experimental conditions: (2) maintaining constant amplitude in both response systems; (b) alternating speech amplitude while attempting to maintain constant finger movement amplitude; and (c) alternating finger movement amplitude while attempting to maintain constant speech amplitude. Observations showed that output of the two response systems was coupled (one syllable was uttered with each finger movement) and entrained in amplitude (the amplitude pattern of the response that the subject attempted to keep constant followed that of the concurrently-active amplitude-modulated response). These interactions were bidirectional and were present with both left-handed and right-handed finger movements. The interactions are more extensive and subtle than mere interference wtih one response system by the other, and apparently do not depend on anatomical overlap of the responding neural systems.     

Mutual Interactions Between Speech and Finger Movements

Speech output and finger movements were recorded as right-handed males repeated a syllable while making cyclical finger movements in three experimental conditions: (a) maintaining constant amplitude in both response systems; (b) alternating speech amplitude while attempting to maintain constant finger movement amplitude; and (c) alternating finger movement amplitude while attempting to maintain constant speech amplitude. Observations showed that output of the two response systems was coupled (one syllable was uttered with each finger movement) and entrained in amplitude (the amplitude pattern of the response that the subject attempted to keep constant followed that of the concurrently-active amplitude-modulated response).

These interactions were bidirectional and were present with both left-handed and right-handed finger movements. The interactions are more extensive and subtle than mere interference with one response system by the other, and apparently do not depend on anatomical overlap of the responding neural systems.     

About the role of bottom-up and top-down processes on perception–action interaction in sensorimotor transformations

Theories of common-coding propose that feature codes of perceived and to-be-produced events are likely to interact with each other when they overlap. We investigated the impact of bottom-up and top-down processes on cross talk in a motor replication task. Participants moved a pen on a covered digitizer tablet while a gain varied the relation between hand and cursor amplitude. Then, participants replicated the hand amplitude (intra-modal) or the cursor amplitude (intermodal) without visual feedback. We replicated that, when the not-to-be-replicated amplitude was longer (shorter) than the to-be-replicated amplitude, replications significantly overshot (undershot) (= after-effects). Importantly, after-effects were remarkably smaller in the experimental groups which wore gloves (thin and thick rubber) or goggles (clear and tinted lenses) than in a control group. Our results provide evidence that top-down attention modulated perception–action interaction.     

Planning of saccadic eye movements

Most theories of the programming of saccadic eye movements (SEM) agree that direction and amplitude are the two basic dimensions that are under control when an intended movement is planned. But they disagree over whether these two basic parameters are specified separately or in conjunction. We measured saccadic reaction time (SRT) in a situation where information about amplitude and direction of the required movement became available at different moments in time. The delivery of information about either direction or amplitude prior to another reduced duration of SRT demonstrated that direction and amplitude were specified separately rather than in conjunction or in a fixed serial order. All changes in SRT were quantitatively explained by a simple growth-process (accumulator) model according to which a movement starts when two separate neural activities, embodying the direction and amplitude programming, have both reached a constant threshold level of activity. Although, in isolation, the amplitude programming was faster than the direction programming, the situation reversed when two dimensions had to be specified at the same time. We conclude that beside the motor maps representing the desired final position of the eye or a fixed movement vector, another processing stage is required in which the basic parameters of SEM, direction and amplitude, are clearly separable.     

Controlling velocity in rapid movements

It has often been reported that subjects prefer to use a strategy in which they vary movement velocity and peak amplitude in a linear fashion. In this study, control of velocity and amplitude in rapid reciprocating movements of the interphalangeal joint of the thumb was investigated by examining movement trajectories and patterns of activity in the extensor pollicis longus (EPL) and flexor pollicis longus (FPL) muscles. In controlling either amplitude or peak flexion velocity without constraint, subjects always used a strategy in which peak extension velocity and peak flexion velocity had strong linear correlations with movement amplitude. When they were required to keep either amplitude or peak flexion velocity fixed their movements were still biased toward a strategy in which peak velocity and movement amplitude covaried. It is suggested that the preferred strategy is related to a basic principle of scaling the magnitude and duration of a velocity profile in order to achieve different movement amplitudes.     

Nature reversed: Diminishing intensity of the maternal call affects approach behaviour of chicks

Skinner (1974) suggested that ducklings could be taught to move away from an imprinting object provided the natural consequences of approach behaviour was reversed. We constructed an apparatus in which approach behaviour toward an audio-visual stimulus caused reduced amplitude of a maternal call, whereas movement away caused an increase in amplitude. Chicks (Experiment 1) trained in this apparatus approached the training stimulus, but to a lesser degree than chicks exposed to calls of constant amplitude. Highly active experimental chicks kept a larger distance to the stimulus than passive chicks. Thus the reversal of the natural consequences of approaching influenced filial behaviour. However, a training period of three hours did not influence approach behaviour in the direction predicted by Skinner (1974). A second group of chicks (Experiment 2) which could increase the call amplitude by moving in one direction without being able to localize the sound source was more influenced by the amplitude gradient than Experiment I-chicks.     

An on-line program to calculate respiratory sinus arrhythmia amplitude

A variety of evidence shows that the amplitude of respiratory sinus arrhythmia (RSA)—the peak-to-peak variations in heart rate caused by respiration—is a valid and reliable index of para-sympathetic cardiac control. An on-line program to calculate RSA amplitude on a breath-by-breath basis is described. The validity of the RSA amplitude values obtained through the computer pro-gram were tested in two studies. From the first one, the correlations between RSA amplitude and a set of cardiorespiratory variables, under both rest and auditory stimulation conditions, are reported. In the second study, the effect of atropine administration on the RSA amplitude, under both rest and mental load conditions, was examined. The results of both studies are con-gruent with predictions and suggest the usefulness of the software.     

GSR amplitude instead of GSR magnitude: Caveat emptor!

Size of GSR made by 300 Ss to 20 repetitions of a visual stimulus is presented as mean magnitude and mean amplitude, illustrating that the amplitude method (averaging only those responses which are greater than zero) is susceptible to distortion resulting from a systematic elimination of Ss who initially make small responses. From trial to trial, the amplitude function comes more and more to be due to the behavior of Ss who initially make large responses. Even though the latter Ss’ responses actually reduce across trials, the amplitude function rises. Magnitude (including zeroes) docs not suffer from this distortion. It is suggested that the definition of a zero response is the source of the problem.     

儿童青少年大脑认知功能事件相关电位P_（300）的年龄特征

从发展心理学的角度．对幼儿到大学六个年龄组的儿童青少年进行了事件相关电位Ｐ_（３００）测定．结果发现：反映大脑认知功能的事件相关电位Ｐ_（３００）各成分随着年龄增长而发展的趋势十分明显,从而进一步说明了认知发展的特点与大脑高级神经系统活动功能发展特点的密切关系。     

Three-dimensional movement trajectories in Fitts' task: Implications for control

According to Fitts (1954), movement time (MT) is a function of the combined effects of movement amplitude and target width (index of difficulty). Aiming movements with the same index of difficulty and MT may have different planning and control processes depending on the specific combination of movement amplitude and target size. Trajectories were evaluated for a broad range of amplitudes and target sizes. A three-dimensional motion recording system (WATSMART) monitored the position of a stylus during aiming movements. MT results replicated Fitts' Law. Analysis of the resultant velocity profiles indicated the following significant effects: As amplitude of movement increased, so did the time to peak resultant velocity; peak resultant velocity increased slightly with target size, and to a greater extent with increases in the amplitude of movement; the time after peak resultant velocity was a function of both amplitude and target size. Resultant velocity profiles were normalized in the time domain to look for scalar relation in the trajectory shape. This revealed that: the resultant velocity profiles were not symmetrical; the proportion of time spent prior to and after peak speed was sensitive to target size only, i.e. as target size decreased, the profiles became more skewed to the right, indicating a longer decelerative phase; for a given target size, a family of curves might be defined and scaled on movement amplitude. These results suggest that a generalized program (base trajectory representation) exists for a given target width and is parameterized or scaled according to the amplitude of movement.     

Spontaneous covariations of movement parameters in 5- to 7-year-old boys

The kinematic parameters of to and fro forearm movements in the horizontal plane were investigated in 5- to 7-year-old boys. In one condition, the period of the movements was induced by an acoustic stimulus, while the amplitude was left free. In a second condition, the amplitude of the swing was suggested by a visual frame, but the movement was self-paced. In both conditions, the unconstrained variable (amplitude and period, respectively) was found to covary spontaneously with the constrained variable. The results suggest that, within the age range considered here, motor control processes do not conceive of amplitude and velocity as two independent variables.     

移动支付对大学生冲动性消费行为的影响——来自ERP的实验证据

为寻找移动支付影响冲动性消费的电生理证据,实验采用两难选择的虚拟购物任务,通过2(支付方式)×2(产品类型)被试内实验设计,结合ERP技术比较移动支付和现金支付下的冲动消费及相关电生理指标。实验数据显示:(1)移动支付下参与者的购买意愿高于现金条件;(2)对享乐品的购买,移动支付下的购买意愿、购买率高于现金支付,而对实用品两种支付下无差异;(3)决策阶段头皮左侧发现,移动支付下享乐品的LPP波幅正于实用品,而现金支付下二者LPP波幅无差异;(4)N2波幅上存在Buy/No Buy效应。结果表明:移动支付促进了享乐品的冲动性消费,决策阶段左侧脑区的LPP波幅可作为其电生理指标,N2波幅表征买与不买。     

Affective valence and P300 when stimulus arousal level is controlled

Visual stimuli from the International Affective Picture System (IAPS) were employed in a modified oddball paradigm to elicit the P300 event-related brain potential (ERP) in young adult females (N=12). The pictures varied on valence (negative, neutral, positive) ratings but had the same medium arousal level ratings. The images were presented as targets with a standard stimulus composed of red/white triangles designed to mimic the spatial frequency of the pictures. P300 amplitude from negative relative to neutral stimuli was smaller over frontal areas, whereas amplitude from positive relative to neutral stimuli did not differ. P300 amplitude differences among valence categories were consistent across the midline electrodes, and did not change over the parietal area where arousal effects are typically observed. The findings suggest that valence affects P300 frontal amplitude, and arousal level should be controlled when using emotional stimuli to elicit ERPs. Theoretical implications are discussed.     

Influence of the movement parameter to be controlled on manual RT asymmetries in right-handers

In this experiment we test whether the effects of manual asymmetries on movement preparation depend on the parameter (amplitude or direction) to be programmed. In two experiments, only the amplitude, or the direction, of aiming movements was constrained. Reaction and movement times were measured. Results show that RTs are always shorter for left-hand than for right-hand movements. There is an effect of target extent in the amplitude condition, but not in the direction one. RTs for ipsilateral movements are shorter than RTs for contralateral movements. These results are discussed in the light of the processes involved in setting the amplitude or direction of the movement and with regard to the competency of the two hemispheres regarding these processes.     

Assessment of distance to potential mates by female barking treefrogs (Hyla gratiosa)

This study investigated the cues used by female barking treefrogs, Hyla gratiosa, to assess distances to potential mates. Eight-speaker playback experiments were used to demonstrate that distance affects female choice in complex acoustic environments and to test 3 possible cues that females might use to assess distance: (a) degradation in spectral and temporal cues of calls, (b) relative call amplitude at the female's location, and (c) the rate at which the amplitude of calls increases as a female approaches a calling male. All 3 hypotheses were refuted, suggesting that females use a more complex mechanism, such as triangulation, to assess distance. Females preferred speakers with greater source amplitudes even when they had to travel further to reach those speakers. Determination of source amplitude is possible only if females can assess independently both the distance to sound sources and the amplitude of calls at the females' location. Hence, anuran amphibians may possess greater cognitive abilities than are generally attributed to them.     

Amplitude and phase spectra as indices of infants' pattern preferences

This study examined whether the linear systems model of infants' visual preferences (Banks & Salapatek, 1981) could predict neonates' preferences, among facelike and abstract patterns. To do so, the study assessed the relative importance of stimulus energy (as measured by the amplitude spectrum) and stimulus structure (as measured by the phase spectrum) in determining early preferences. Forty-eight neonates viewed six pairings of four stimuli: (a) a schematic face, (b) a lattice, (c) a pattern composed of the amplitude spectrum of the lattice and the phase spectrum of the face, and (d) a pattern composed of the amplitude spectrum of the face and the phase spectrum of the lattice. The linear systems model predicted the observed preferences quite accurately. That is, the infants' preferences could be predicted from knowledge of the amplitude spectrum but not the phase spectrum. These results are interpreted as showing that neonates' preferences for facelike patterns are governed primarily by simulus energy and not by the familiarity or social significance of such patterns.     

Phase- or energy-based face discrimination: some problems

Fourier analysis may be used to obtain the amplitude and phase spectra of images. Spectra from two images can then be recombined in an attempt to produce images with identical phase spectra but different amplitude spectra or with identical amplitude but different phase spectra. Kleiner and Banks (1987) and Kleiner (1987) used this technique to determine if the amplitude (energy) or phase characteristics of images form the basis for infant face preferences. This article describes how some of the procedures used by these researchers, for example, luminance normalization and photographic production of transparencies of images, probably prevented the images from having the desired characteristics, thus making interpretation of their studies very difficult. Additional potentially confounding issues to be addressed when repeating these or similar experiments are also discussed. These difficulties arise from the distinction between the numerical phase values obtained through the mathematical process and those that are visually effective.     

Speed-accuracy trade-offs in myocontrol

Myoelectric (EMG) signals are used in assistive technology for prostheses, computer and domestic control. However, little is known about the capacity of controlling these signals. Specifically, it is unclear whether myocontrol, i.e., the control of myoelectric signals, obeys the same laws as motor control. Neurologically intact adult participants performed pointing tasks with EMG signals captured from the forehead or the hand in two modalities (sustained: stabilize the signal amplitude in the target; impulsion: produce an impulse and return to resting level). In the sustained modality, the time to reach the target (reach time) increased logarithmically with target amplitude, which is compatible with the predictions of Fitts' law. The rate of failure was not significantly affected by target amplitude. In the impulsion modality, the reach time and the rate of failure followed a bow-shaped pattern as a function of target amplitude. Stabilization time in the sustained modality followed a convex (bow-shaped) pattern for the forehead and a concave pattern for the hand. This was the only significant effect of electrode placement in this study. These findings suggest that myocontrol obeys laws that are distinct from those determining motor control, and that the muscular and intra-muscular synergies that produce EMG signals are specific of each pointing modality and target amplitude.     

Neurofeedback Training Reduces Frontal Midline Theta and Improves Putting Performance in Expert Golfers

A single-subject design was used to examine the influence of one session of neurofeedback training (NFT) on reducing frontal midline theta (Fmθ) amplitude and enhancing golf putting performance. Posttraining, three highly skilled golfers improved in putting score or score stability. Although the Fmθ amplitude during the pre-putt period inconsistently decreased across participants, all golfers exhibited lower Fmθ amplitude during the resting condition following NFT, suggesting that the tonic reduction of Fmθ may play a role in subsequent performance improvement. Overall, these results indicate that a short session of NFT may be an effective method of performance enhancement in some sports.