Simple Reaction Time Situation Research Articles

Investigation of stimulus–response compatibility using a startling acoustic stimulus

We investigated the processes underlying stimulus–response compatibility by using a lateralized auditory stimulus in a simple and choice reaction time (RT) paradigm. Participants were asked to make either a left or right key lift in response to either a control (80 dB) or startling (124 dB) stimulus presented to either the left ear, right ear, or both ears. In the simple RT paradigm, we did not find a compatibility effect for either control or startle trials but did find a right-ear advantage which we attribute to anatomical asymmetry of auditory pathways. In the choice RT paradigm, we found compatibility effects for both startle and control trials as well a high incidence of error for contralateral stimulus–response mapping. We attribute these results to automatic activation of the ipsilateral response, which must then be inhibited prior to initiation of the correct response. The presence of compatibility effects for startle trials also suggest that similar pathways are being used to initiate movements in a choice RT situation, as opposed to involuntary triggering that is thought to occur in a simple RT situation.

Biomechanical analysis of simple jaw movements in Friedreich's ataxia

The jaw movement kinematics in relation to the EMG activity of two antagonistic jaw muscles (the masseter and the digastricus pars anterior) were examined in healthy subjects and patients with Friedreich's disease. Dysarthria and ataxia are the main characteristics of this disease. Jaw movement was monitored with a magnetometer system, and bipolar surface electrodes were used to record EMG activity. Unidirectional opening, unidirectional closing and opening-closing movements of the mandible were performed in a simple reaction time situation. The data were compared with those for normal control subjects. The kinematic and electromyographic characteristics were: (a) prolonged total movement duration resulting from increased acceleration and deceleration durations; (b) decreased maximum velocity, and a secondary peak in the velocity profile; (c) tonic EMG activity in muscles supposedly at rest; (d) prolonged EMG bursts. Premotor reaction time was also increased. These characteristics are similar to those, previously described, of limb movements in subjects with cerebellar dysfunctions and suggest that the alterations of jaw movement in Friedreich's ataxia could be due to a deficit in cerebellar control.

Reaction Times for Fine Discrete Movements

Three experiments (ns = 20, 10, and 20) were conducted in which the reaction times for responses to complexity were investigated for small-scale, discrete, terminated movements. In a choice reaction-time situation, the reaction time for the finger-lift response was longer than that for the finger-lift response followed by the pressing of another key with the same finger. The reaction times for these responses, however, did not differ in a simple reaction-time situation. The difference in reaction times between these responses may have been associated with some differences in allocation of the subjects' internal resources. The subjects' attention might be more attracted to the more complex response.

Contributions of the motor cortex and the cerebellum to a simple learned movement in the monkey

Monkeys were trained to perform isometric plantar flexions of the foot in a simple reaction time situation. In test sessions, the contralateral hindlimb area of the motor cortex was cooled by a cryode placed on the dura until somatosensory evoked potentials disappeared. Movement amplitude decreased to about 70% of initial size; reaction time which was measured on the EMG, and torque signals increased slightly; and the evoked response in the dentate nucleus of the cerebellum remained unchanged. An extensive lesion in the motor cortex by coagulation reduced the movement amplitude to 10% of its preoperational size, but again, did not change reaction time significantly. It is concluded that the motor cortex is not essential for the execution of this overtrained simple movement.

Relation between the specific H reflex facilitation preceding a voluntary movement and movement parameters in man.

In a reaction-time situation, the monosynaptic spinal reflex (H reflex) is facilitated before the onset of an electromyographic (e.m.g.) response. The aim of the present investigation was to study aspects of this facilitation. Human subjects were required to perform isometric plantarflexions of the foot in response to a visual stimulus. The movement was always on the same side in the simple reaction-time situation, and randomly with the right or left foot in the choice reaction-time situation. Stimuli to evoke H reflexes were applied bilaterally 40-400 ms after the onset of the visual stimulus. Pre-motor time, i.e. the interval between the onset of the visual stimulus and the e.m.g. response, and reaction time, i.e. the interval between the onset of the visual stimulus and the response on the torque recording, were computed. In both reaction-time situations, there was a significant facilitation of the ipsilateral H reflex 100-160 ms before e.m.g. onset and, in some subjects, a small facilitation of the contralateral H reflex. The specific facilitation, i.e. the difference between the facilitation on the ipsi- and contralateral side relative to the movement, was not significantly different on the right and left side. Pre-motor time was divided into the interval from the light onset until the onset of the specific facilitation, and the interval from the onset of the facilitation until the onset of the voluntary response. Both intervals increased, and the slope and the amplitude of the facilitation decreased with increasing pre-motor time and reaction time. The specificity of the H reflex facilitation in a choice reaction-time situation implies that the interval from light onset until the onset of the facilitation includes stimulus identification and response selection, and the interval from the onset of the facilitation until the e.m.g. response preparation of the motor system for the required movement. The present results suggest that the specific facilitation of the H reflex before a movement is caused by removal of presynaptic inhibition at I a terminals or by activation of interneurones intercalated in polysynaptic components of the H reflex rather than by a subthreshold activation of motoneurones.

Incentive contrast effects in humans with monetary reinforcement and reaction time

In experiment 1, a reduction in amount of monetary reinforcement with humans produced a negative incentive contrast effect in a simple reaction time situation. In experiment 2, positive contrast occurred in human subjects following an increment in magnitude of monetary incentive in the same reaction time task. The results demonstrate the generality of human incentive contrast effects.

Reaction Times and Derived Information Processing Measures: Limitations of Their Practical Use in Vehicle Operator Screening

The use of information processing rate (difference between the amount of uncertainty in a choice and simple reaction time situation, in bits, divided by the difference of the corresponding reaction time averages, in seconds) as a driver screening measure from a relevance point of view has been suggested by Fergenson (1971).

Timing of expectancy peak in simple reaction time situation

The present study attempted to determine the moment of the peak expectancy of the imperative stimulus in a simple reaction-time situation with constant foreperiods of 0.25, 0.5, 1, 2 and 4 sec. Four Ss were instructed to indicate the expected moment of the presentation of the imperative stimulus by a key press, i.e., to try to synchronize the key press with the onset of the imperative stimulus. Also a parallel simple reaction-time task was given using these foreperiods. It was found that when the foreperiod was prolonged from 0.5 sec on, the accuracy of prediction of the moment of the imperative stimulus as well as the reaction speed were continuously decreased. The present method was not considered suitable for determining the expectancy peak under the condition involving the shortest FP.

Some data on neurophysiological processes involved in the preparatory motor activity to reaction time performance

This study is concerned with an analysis of monosynaptic reflexes during the foreperiod in a simple reaction time situation. There is a dissociation in direction, time course and correlation with motor efficiency of the changes of excitability of the spinal structures controlling the muscles involved and not involved in the motor response respectively: the inhibition of reflexes observed in the involved muscle is more predictive for the performance level and more sensitive to the effect of probability of occurrence of the signal to respond to than the augmentation of reflexes observed in the non-involved muscle. The significance and the neurophysiological mechanism of this inhibition are discussed.

Stimulus probability and simple reaction time.

SIMPLE reaction time tasks usually contain procedures designed to reduce or eliminate the frequency with which subjects anticipate the onset of the stimulus. These measures include varying the interval or foreperiod between the warning stimulus and the subsequent stimulus, and introducing a number of “catch trials” on which the stimulus does not follow the warning. Obviously, one effect of including catch trials is to lower the overall probability that the stimulus will follow the warning stimulus. In view of the known importance of stimulus probability in choice reaction time situations, it is perhaps surprising that, although there have been several studies (for example, refs. 3–5) of the effects of changes in the range and variability of foreperiods, there appears to have been only a single study in which the effect of changing the frequency of catch trials has received systematic investigation. Drazin2 introduced catch trials to produce three levels of probability of occurrence of the stimulus (s): P(s) = 1.0, 0.9 and 0.5. These levels were allowed to interact with mean fore-period, so that Drazin's results regarding the effects of P(s) on reaction time are limited to the demonstration of (1) an inverse relationship between P(s) and reaction time, and (2) an interaction between P(s) and the reaction time–foreperiod relationship. The study reported here was designed to examine the relationship of the P(s) and reaction time over a wide range of P(s) values in a sequential, simple reaction time situation.

Remote action potentials at the moment of response in a simple reaction-time situation.

Remote action potentials at the moment of response in a simple reaction-time situation.