Accessory stimulation in the time course of visuomotor information processing: stimulus intensity effects on reaction time and response force

A series of three visual choice-reaction time experiments were performed to systematically investigate the effects of accessory auditory stimulation on response time (RT) and response force (RF). In Experiment 1, the effect of accessory auditory stimulation on early visual information processing was investigated. Experiments 2 and 3 were designed to examine the effects of accessory intensity on RT and RF across the entire time course of sensorimotor processing. Accessory stimulation accelerated response speed only when presented within 100 ms after onset of the visual response signal. An enhancing effect of accessory stimulation on RF, however, was found as late as 220 ms after onset of the response signal. These findings support the notion that response speed and response dynamics represent functionally independent sensorimotor phenomena.     

Effect of stimulus intensity on manual and saccadic reaction time

Reaction time (RT) decreases with stimulus intensity. Hughes and Kesley (1984) demonstrated, however, that the effect of stimulus intensity on simple RT is larger for manual than for saccadic responses. We reexamined this relation under various conditions. The dissociation occurred when the task enabled the generation of exogenous saccades. We found, however, no dissociation if endogenous saccades had to be executed. It is hypothesized that the different effects of intensity result from the simplified neuronal processing of exogenous saccades performed in the direct route from the retina to the superior colliculus.     

Effect of locus of warning tone on auditory choice reaction time

Forty Ss pressed a left- or right-hand key depending on the ear in which they heard a 500-Hz stimulus tone. Half of the Ss were instructed to press the key on the same side as the ear stimulated (corresponding condition), while the other half pressed the key on the opposite side (noncorresponding condition). A 200-Hz warning tone preceded the stimulus tone by either 200 or 400 msec. The warning tone was presented to the left ear, the right ear, or to both ears in a predetermined random sequence. The locus of the warning tone affected RT on noncorresponding trials but not on corresponding trials. The effect consisted of a significant slowing of information processing on trials where the warning tone was contralateral to the response. Results were explained in terms of an initial tendency to respond toward the source of the warning tone.     

Effect of directional response variables on eye-hand reaction times and decision time

To determine if direction of response affects reaction time, we measured the time for hand response to a visual stimulus, using a sensitive, microprocessor-based testing device to determine simple reaction time (RT), choice RT, and decision time. Mean simple RT was 207 +/- 3.7 msec. (mean +/- SEM); mean choice RT was 268 +/- 4.2 msec; and mean decision time was 61 msec. No differences were noted for leftward versus rightward movements, or midline versus lateral movements. Choice RT increased by 1.49 msec./yr. of age. Simple RT increased significantly with age for the nondominant hand, but not for the dominant hand. Right-handed subjects were more rapid with the dominant hand for choice RT. We conclude that dominance of hand tested and test initiation mechanism have major effects, but direction of movement in the lateral plane has little effect on reaction time.     

Effect of visuomotor calibration and uncertainty on the perception of peripersonal space

Target selection for action depends not only on the egocentric location of objects estimated from retinal and extraretinal variables, but also on the assessment of current action possibilities. In the present study, we investigated the effect of altering sensorimotor anticipation processes on subsequent perceptual estimates of reachability. To do so, we conducted two experiments in which we changed the relation between visual distance and movement amplitude. Experiment 1 showed that iterative visuomotor adaptation to distorted visual feedback (in steps of ±15?mm, up to a total adaptation of ±75?mm) led to a congruent variation of perceived reachable space, although the first introduction of the shifted visual feedback produced a reduction of perceived reachable space whatever the direction of the feedback shift. Experiment 2 showed that increasing uncertainty about visuomotor performances, by providing a visual feedback randomly shifted in depth (±7.5?mm), produced the same reduction of perceived reachable space in the absence of visuomotor adaptation. Taken together, these data suggest that the visual perception of reachable space depends on a motor-related perceptual system, which is affected by both visuomotor recalibration and reliability of the visuomotor system.     

Effect of protective eyewear on reaction time in the horizontal field of vision

This study determined the effect of various models of protective eyewear on the reaction time in the horizontal field of vision. Five protective eye devices for racquet sports were selected based on design characteristics. Eyewear was presented to 64 subjects in a random order along with no eyewear. Each subject's reaction time was measured for the random presentation of the visual stimuli by releasing a depressed telegraphic key wired to a digital clock. Stimulus anticipation was controlled using an interval timer generating random time intervals. Significant differences were noted between lights, eyewear, and the interaction of lights by eyewear. No differences were found between dominant and nondominant sides or between trials. Reaction time was unaffected in the central portion of the horizontal field and affected with some of the eyewear in the peripheral portion. It was concluded that the configuration of the protective eyewear was a significant factor affecting reaction time in the horizontal field of vision.     

Effect of loudness on reaction time and response force in different motor tasks

Van der Molen and Keuss, in 1979 and 1981, showed that paradoxically long reaction times occur with extremely strong auditory stimuli when the task is difficult, e.g., choice-by-location or Simon paradigm. It was argued that this paradoxical behavior of RT is due to active inhibition of an arousal-dependent bypassing mechanism to prevent false responses. As the peak force, i.e., maximal force exerted by participants on a response key, is considered to be related to immediate arousal, we predicted that for extremely loud stimuli and for difficult tasks, lengthening of RT should be associated with reduction of peak force. Moreover, these effects should be enhanced when emphasis is on accuracy rather than speed. Although the relation between RT and intensity depended on task difficulty, no increase in RT was found for the loudest tones. Moreover, peak force increased monotonically with loudness, showing no tendency to be suppressed for loudest tones and difficult tasks.     

Target-size influences on reaction time with movement time controlled

The variable that affect motor programming time may be studied by changing the nature of the response and measuring the subsequent changes in reaction time (RT). One notion of motor programming suggests that aiming responses with reduced target size and/or increased target amplitude require more "complex" motor programs that require longer RTs. In a series of five experiments which movement time (MT) was experimentally varied target size neither influences RT when the movement amplitude was 2 or 30 cm nor when the target sizes differed by as much as a factor of 16:1. Increasing the movement amplitude from 15 to 30 cm also had no influence on RT. Movement time, however, did affect RT, with 200-msec movements having longer RTs than 120-msec movements. Target size and movement amplitude did not appear to be factors that influence programming time or program complexity.     

Effects of electromyographic biofeedback on reaction time and movement time

The effects of electromyographic (EMG) biofeedback on reaction time (RT) and movement time (MT) were investigated utilizing 42 right-handed, male subjects from a university population. Subjects were randomly divided into three groups, a control group and two experimental groups. Both experimental groups were exposed to their EMG signals from their triceps brachii during the task, one experimental group received written information explaining the purpose of the EMG was to improve performance through biofeedback. Reaction times of the first block of 25 trials were significantly faster than those on the subsequent three blocks of trials for all groups. This provided evidence of learning. No other significant effects for reaction times were observed. Mean movement time for the EMG-only group was significantly slower than the means of either the Control group or EMG-Biofeedback group, with no difference between the latter two. The differences between experimental groups may have been related to alteration of strategy, anxiety, motivation.     

Effect of visuomotor rehearsal with videotaped modeling on racquetball performance of beginning players

This investigation was designed to assess the effect of visuomotor behavior rehearsal (VMBR) with videotaped modeling on racquetball performance of beginning players. 24 male students in beginning racquetball class were randomly assigned to either VMBR with videotape modeling or relaxation and imagery (no modeling) condition for a 2-wk. training period. All subjects were pre- and posttested on forehand and backhand racquetball skill tests. Analysis indicated an effect for forehand shooting, with those given visuomotor behavior rehearsal with videotaped model exhibiting better performance than the relaxation and imagery group, but no effect for backhand shooting.     

Wavelength effects on simple reaction time

Simple reaction time was measured to spectral lights matched photometrically in luminance. When these lights were presented on a dimmer achromatic background, reaction time did not vary as a function of wavelength. Moreover, reaction times to white and chromatic lights were the same. When the luminance of the background was the same as that of the chromatic lights, reaction time increased and showed a strong effect of wavelength. Reaction time in this condition appeared to follow a saturation function. The results are described in terms of the operation of achromatic and chromatic processing channels.     

Modelling the influence of time pressure on reaction time of drivers

Speeding is a major traffic violation and time pressure is one of the leading contributors to speeding. High-speed driving requires an immediate response to perilous events from the driver to avoid a crash. Reaction time is one of the important driving performance measures to assess the driver’s response to the event. Therefore, the current study examined the influence of time pressure on reaction times of the drivers measured for two different perilous events (pedestrians crossing and obstacle overtaking). Eighty-five Indian licensed drivers participated in a driving simulation study designed for three different time pressure conditions: No Time Pressure (NTP), Low Time Pressure (LTP), and High Time Pressure (HTP). The survival analysis technique was used to model the effect of time pressure and driver characteristics with reaction times of the drivers. It was observed that drivers’ reaction times decreased by 18% and 9% in LTP and 28% and 16% in HTP during the pedestrians crossing and obstacle overtaking events, respectively. Further, 1 m/second increase in approach speed resulted in 2% and 4% reduction in reaction times of the drivers in pedestrians crossing and obstacle overtaking events, respectively. Young drivers responded 21% faster than mature drivers during the pedestrians crossing event. Interestingly, sleeping hours and physical fitness played an important role in driver’s reaction to the events. The drivers performing regular physical exercise and having minimum eight-hours of overnight sleep reacted 16% and 17% earlier in pedestrians crossing and obstacle overtaking events, respectively. The overall findings from this study showed enhanced stimulus-response behaviour of the drivers under time pressure driving conditions. The results obtained from the study can give new insight into various safety-related ITS applications.     

Effect of moderate doses of alcohol on simple auditory reaction time in a vigilance setting

An experiment was performed with 11 voluntary male subjects to test the effects of moderate doses of alcohol on simple auditory RT in a vigilance setting. Subjects were tested during a 30-min. session, during which signals were presented with an average intersignal interval of 3.75 sec. Subjects responded by pressing a microswitch held in the preferred hand. Analysis indicated that absolute means increased as a function of alcohol dose. With time-on-task alcohol produced a faster increase in RT and especially affected the longest RTs. Number of extreme long reactions (blockings) and mean duration of these reactions increased under alcohol and were directly related to time on task; alcohol produced a much faster increase in number of blockings with time on task. Results were discussed in terms of attentional processes and habituation theory. Some practical implications of the results were pointed out.