Alcohol and vigilance performance: effect of small doses of alcohol on simple visual reaction time

The effects of small doses of alcohol were tested in a vigilance setting. Subjects were repeatedly tested during three 30-min. sessions. The stimulus event was a visual light located in front of subjects. The average intersignal interval was 3.75 sec., and the dependent measure was simple reaction time. Analysis indicates that alcohol produced a skewness in the RT-distribution with time on task; the longer reactions increased more than the shorter ones. Especially the extremely long reactions (blockings) increased markedly with time on task under alcohol. Results were discussed in relation to other studies reporting divergent results in similar test situations.     

Alcohol and vigilance performance: effect of small doses of alcohol on simple auditory reaction time

This study explored whether a small dose of alcohol (0.67 ml/kg) would affect simple auditory RT as developed with time on task in a vigilance setting. Analysis indicated that absolute levels were not affected and no interaction with time on task was evident. Alcohol did, however, increase both number and mean duration of the extreme long reactions but this effect was not related to time on task. It was concluded that in many applied situations this effect of small alcohol doses may be critical.     

Effects of graded doses of alcohol on speed-accuracy tradeoff in choice reaction time

The inconsistency of previous results concerning the effects of alcohol on reaction time (RT) may be related to possible tradeoffs between speed and accuracy. In the present experiment, complete speed-accuracy tradeoff functions were generated for each of five doses of alcohol (0-1.33 ml/kg) in a choice RT task. Such functions permit RT differences resulting from changes in performance efficiency to be distinguished from those due to changes in subjects’ speed accuracy criteria. Increasing doses of alcohol produced a progressive decrease in the slope parameter of linear equations fit to the speed-accuracy data, but did not significantly alter the intercept of the functions with the RT axis. Thus, alcohol reduced performance efficiency by decreasing the rate of growth of accuracy per unit time. A change in speed-accuracy criterion was combined with the decrease in efficiency at the highest alcohol dose.     

Chromatic information processing

The investigation of visual processing mediated solely by chromatic information requires conditions preventing a subject's use of the luminance differences normally accompanying a chromatic change. In Experiment 1, which involved a discriminative reaction time (RT) task, chromatic and white stimuli of the same luminance were presented on a dimmer achromatic background. Subjects were instructed to respond only to the chromatic stimuli. RT was slowest at 570 nm and somewhat faster to short wavelengths than to long wavelengths. In Experiment 2, which compared two discriminative RT tasks, RT was faster when subjects responded to color than when they responded to white. Experiments 3 and 4 demonstrated that a brighter white surround decreased the perceived brightness of chromatic stimuli as well as their perceptual similarity to white, but did not affect RT. The results are discussed in terms of the response strength of the chromatic processing channel.     

Anticipatory and event related changes in heart rate as indicators of attention processes

The present study was concerned with the question of whether phasic event-related heart rate (HR) changes under easy intake conditions account for the association between anticipatory HR deceleration and task performance in a choice reaction time (RT) task with a fixed foreperiod. The task employed differed from simple RT tasks especially with regard to processing and attention demands. Subjects were required to determine as quickly and accurately as possible whether a probe, presented for 80 ms, was identical or not to one of two distinct memory items, presented at the onset of each trial. Reaction times as well as accuracy of responses were determined. The results of the present study were indicative of a reliable anticipatory HR deceleration which was related to latency of responses to the probe stimulus. Subjects with stronger decelerations reacted faster than subjects with diminished or missing decelerations. Furthermore a relation was found between this association and the heart rate changes to repeated presentations of a non-signal auditory stimulus under habituation conditions. Results were discussed in terms of differences in the regulation or control of attentional processes.     

Noise annoyance during the performance of different nonauditory tasks

Three experiments were performed to study the effects of an ongoing task on the annoyance response to noise. In the first two experiments a total of five tasks were used: three versions of a proofreading task, a finger-dexterity task, and a complex reaction time (RT) task. Subjects performed the tasks during exposure to two levels of a continuous broadband noise. Task was of no consequence for rated annoyance. Four tasks were used in Experiment 3: proofreading, complex RT, grammatical reasoning, and simple RT. A third type of noise, irrelevant speech, was added to the broadband noises. Rated annoyance was lower during simple RT than during the reasoning and proofreading tasks, especially in the irrelevant speech condition. The difference corresponded to a 6-dB difference in noise level. It was concluded that task differences probably only explain a small part of the widely differing noise tolerance levels at different work places.     

Effects of alcohol, practice, and task complexity on reaction time distributions.

The effects of alcohol (1.0 ml/kg body weight) and practice (2 sessions) were investigated in 2-, 4-, and 8-choice reaction time (RT) tasks with 24 male subjects. The number of errors increased with alcohol, practice, and increasing task complexity (choice). Mean RT decreased with practice, but increased with alcohol and complexity. Both the alcohol and practice effects on mean RT increased as complexity increased. The effects of alcohol, practice, and complexity were all larger for the higher percentiles of the RT distributions than for the lower percentiles. RT distributions were further analysed at each level of choice by plotting percentiles (5th, 10th, ... , 95th) for alcohol conditions against corresponding percentiles for no-alcohol conditions, and percentiles obtained early in practice (Session 1) against those obtained later in practice (Session 2). These plots revealed that whereas at all levels of choice the effect of alcohol could be expressed as a simple linear transformation of all RTs, the effect of practice required a more complex curvilinear transformation. Thus, alcohol produces a general slowing of all RTs, whereas practice produces a disproportionate improvement at the slower end of the RT distribution.     

Perceived control

Permitting subjects to choose materials to be learned on a task enhances performance on that task. These results support the idea that choice increases the learner's perception of control, thereby enhancing motivation and performance. The purpose of the present experiments was to determine whether choosing responses to be learned on a paired-associate task would also benefit performance on a reaction-time task. Half of the subjects selected their responses to be learned on a paired-associate task while the remaining subjects were assigned responses. In one experiment, subjects then performed both the PA and RT tasks simultaneously, while in the second experiment the RT task was performed following the choice/force procedure. Providing the learner with the opportunity to choose produced a generalized increase in motivation, which resulted in significantly faster responding on the nonchosen RT task. Also discussed are the limitations of the effects of perceived control.     

The effect of directed forgetting on the time to remember

A recognition memory task was used to determine whether the search set is reduced by cueing subject to forget a part of the input. Correct recognition reaction time was used to infer the size of the search set. The principal results were that RT on forget trials was faster than RT on remember trials and that RT was fastest when the forget cue was presented at the outset of the trial rather than after the material had been presented. These findings are generally consistent with the hypothesis that selective search is responsible for the enhancement of recall produced by forget instructions in earlier studies.     

Beyond drug effects and dependent variables: the use of the Poisson-Erlang model to assess the effects of D-amphetamine on information processing

Several studies have shown that d-amphetamine (DAMP) speeds mean reaction time (RT). However, the use of mean RT may obscure important aspects of the drug response. Therefore we applied the Poisson-Erlang (PE) stochastic model of choice reaction time proposed by Pieters (1985) to the RT distribution. This model proposes that the RT distribution is generated by two states: Processing (P) and Distraction (D). RT represents the sum of the time spent in each of these states. P is the time taken to complete a set of cognitive operations which are required to give a correct response. D represents the time taken by all other activities. RTs were collected using a task (SERS) in which stimulus and response complexity each had two levels, easy and hard. Subjects were tested pre- and postdrug. Drug conditions were: placebo, 10 mg d-amphetamine (DAMP), 4 mg of the dopamine agonist, pimozide, and a combination of DAMP and pimozide (COMBO). Parameters of the model were derived using methods described by Pieters. Four measures were analyzed: Processing Time (PT); Mean Time per distraction (XTD); Distraction Rate (DR); and Total Distraction Time per trial (TDT). Mean RT is also presented. Analyses of the effects of task conditions on the parameters of the model were made using the predrug sessions. Mean RT was increased by both stimulus and response complexities as was PT. TDT was increased by the task conditions. The PE measures did not change over days. DAMP speeded mean RT. However, this effect did not interact with the task factors. DAMP speeded processing and reduced distraction. Processing was speeded only in the hard response condition, distraction time was reduced only in the easy response condition. The results indicate that the PE model can be successfully applied to fast RT tasks. More importantly, the parameters of the model revealed important pharmacological effects that were not apparent in mean RT. DAMP speeds cognitive operations related to motor preparation and reduces the effects of distraction. Consistent with past studies there are no indications that DAMP interacted with stimulus processing. The distraction effect appears to be mediated by an increase in the rate of distraction and a decrease in the average time of these distractions.     

Physical activity and cognitive function in a cross-section of younger and older community-dwelling individuals.

Previous reports have indicated a small, positive relationship between physical activity and cognition. However, the majority of research has focused on older adults, with few studies examining this relationship during earlier periods of the life span. This study examined the relationship of physical activity to cognition in a cross-section of 241 community-dwelling individuals 15-71 years of age with a task requiring variable amounts of executive control. Data were analyzed with multiple regression, which controlled for age, sex, and IQ. Participants reported their physical activity behavior and were tested for reaction time (RT) and response accuracy on congruent and incongruent conditions of a flanker task, which manipulates interference control. After controlling for confounding variables, an age-related slowing of RT was observed during both congruent and incongruent flanker conditions. However, physical activity was associated with faster RT during these conditions, regardless of age. Response accuracy findings indicated that increased physical activity was associated with better performance only during the incongruent condition for the older cohort. Findings suggest that physical activity may be beneficial to both general and selective aspects of cognition, particularly among older adults.     

The effect of prediction accuracy on choice reaction time

In this study, we examined the effect of prediction accuracy on reaction time (RT). Subjects performed on three blocks of choice RT trials, all of which involved the mapping of four stimuli (red, green, 1, or 0) onto two response keys. The subjects were told that the four stimuli were equally probable and that their task was to respond to each stimulus onset by pressing the correct key. In one block (stimulus-prediction), the subjects predicted, prior to each trial, the precise stimulus that would appear. In a second block (category-prediction), the subjects predicted the category of the stimulus (i.e., color or digit) that would appear. In a third block (no-prediction), the subjects simply responded to each stimulus without making a prior prediction. In the stimulus-prediction block, RT was faster for correct predictions than for incorrect predictions. In addition, RT was faster on trials in which an incorrect prediction involved the correct category than on trials in which it involved the incorrect category: that is, a "half-wrong" prediction was better than an "all-wrong" prediction. In the category-prediction block, RT was faster when the stimulus category was predicted correctly than when it was not. There was little evidence of a response-facilitation contribution to the correct-prediction effect. These results permit inferences concerning the encoding and organization of information in memory.     

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.     

Biasing power law exponents by magnitude estimation instructions

This study investigates the influence of attention loading on the established intersensory effects of passive bodily rotation on choice reaction time (RT) to visual motion. Subjects sat at the center of rotation in an enclosed rotating chamber and observed an oscilloscope on which were, in the center, a tracking display and, 10° left of center, a RT line. Three tracking tasks and a no-tracking control condition were presented to all subjects in combination with the RT task, which occurred with and without concurrent cab rotations. Choice RT to. line motions was inhibited (p < .001) both when there was simultaneous vestibular stimulation and when there was a tracking task; response latencies lengthened progressively with increased similarity between the RT and tracking tasks. However, the attention conditions did not affect the intersensory effect; the significance of this for the nature of the sensory interaction is discussed.     

Motor preparation of manual aiming at a visual target manipulated in size, luminance contrast, and location

We conducted two experiments to investigate whether the motor preparation of manual aiming to a visual target is affected by either the physical characteristics (size or luminance contrast) or spatial characteristics (location) of the target. Reaction time (RT) of both finger lifting (ie stimulus-detection time) and manual aiming (ie movement-triggering time) to the onset of the target was measured. The difference of RT (DRT) between two tasks (ie the difference of task complexity) was examined to clarify the temporal characteristics of manual aiming per se during visuomotor integration. Results show classical characteristics: RT decreased as either the target size or luminance contrast increased. Furthermore, the task-complexity and target-location factors significantly interacted with each other, where the aiming RT was longer than the finger-lifting RT and the effects of target location on RT differed for each task. However, the task factor did not interact with either the size or luminance-contrast factor, implying that the motor preparation of manual aiming is associated with the spatial characteristics rather than the physical characteristics of the target. Inspection of DRT revealed that the time needed for motor preparation for an ipsilateral target was significantly shorter than that for a contralateral target. This was the case both for the left and for the right hand. Foveal targets required longer processing time, implying a disadvantageous function of motor preparation for the gazed target. The left-hand superiority for the target appearing in the left visual field was also observed. Such lateralised effect and left-hand advantage to the left visual field in manual aiming suggest that visuospatial information processing is activated during the preparation of aiming action, with faster processing in the right hemisphere.     

Fractioned Reaction Ttme in Power-Trained and Endurance-Trained Athletes under Conditions of Fatiguing Isometric Exercise

Fractionated knee extensor and plantar flexor reaction time (RT) components were assessed in a group of eight weightlifters and eight long distance runners. Following a 4-day period of baseline stabilization for each muscle group, a 50% maximal voluntary contraction (MVC) holding-time exercise was administered. Results showed that the runners had longer premotor times (PMT) than the weightlifters in the knee extensors, but had much faster PMTs than the lifters in the plantar flexor condition. Compared to previously reported investigations using non-athletes, the data for the present sample of athletes indicated faster total reaction times (TRT) in both the knee extensors and the plantar flexors. A resistance of 15% MVC applied during the RT task resulted in a lengthening of the motor time (MT) component in both groups prior to exercise. However, while knee extensor resisted motor time was lengthened by the exercise task, no such lengthening occurred in plantar flexor resisted RT. It is concluded that power-trained and endurance-trained athletes exhibit differences in response to a fractionated RT task, under both baseline and fatiguing exercise conditions.     

Fractioned reaction time in power-trained and endurance-trained athletes under conditions of fatiguing isometric exercise

Fractionated knee extensor and plantar flexor reaction time (RT) components were assessed in a group of eight weightlifters and eight long distance runners. Following a 4-day period of baseline stabilization for each muscle group, a 50% maximal voluntary contraction (MVC) holding-time exercise was administered. Results showed that the runners had longer premotor times (PMT) than the weightlifters in the knee extensors, but had much faster PMTs than the lifters in the plantar flexor condition. Compared to previously reported investigations using non-athletes, the data for the present sample of athletes indicated faster total reaction times(TRT) in both the knee extensors and the plantar flexors. A resistance of 15% MVC applied during the RT task resulted in a lengthening of the motor time (MT) component in both groups prior to exercise. However, while knee extensor resisted motor time was lengthened by the exercise task, no such lengthening occurred in plantar flexor resisted RT. It is concluded that power-trained and endurance-trained athletes exhibit difference in response to a fractionated RT task, under both baseline and fatiguing exercise conditions.     

Effects of a timing signal on simple reaction time with a rectangular distribution of foreperiods

It was hypothesized that the time course of preparation during a variable interstimulus interval (ISI) of a simple reaction time (RT) experiment was partly determined by the subjective distribution of conditional probabilities of the executive signal (ES). Sixty subjects performed a simple auditory RT task with various ranges of six ISI durations organized in rectangular frequency distributions. In order to give the subjects information about elapsed time during ISI, a recurring time-marking click, the periodicity of which was varied, was introduced during the ISI in one of the three series of trials each subject performed. A strong decreasing RT--ISI relationship was observed supporting the main hypothesis. However, a clear increase of mean RT over all ISIs combined, was also found. Because these two mixed effects were greatest when the click intervened at the possible times of ES occurrence only, three functions of time-information given by the click are discussed: (a) a reduction of the usual increase of time estimation error with increased ISI; (b) an increase of the subjects knowledge of the ISI range resulting from the discontinuity of the time-marking click which makes easier a discrete time-intervals numbering process; (c) a change of the simple-RT task into a discrimination task.     

Influence of extended practice on programming time, movement time, and transfer in simple target-striking responses

Two experiments describe the effects of extended practice on the development of motor control programs for simple target-striking responses. In Experiment 1,400 right-hand trials of simple one-target and two-target striking tasks were performed. In Experiment 2,600 practice trials were given. Overall reaction time (RT) was faster for the one-target condition in both experiments, supporting a response complexity effect. Movement time (MT) for both conditions improved linearly with practice, suggesting that development of the motor control programs was still occurring. Subjects then transferred to a three-target condition for 50 trials, performing the transfer task with the right hand in Experiment 1, and with right and left hands in Experiment 2. Transfer to the three-target conditions produced execution errors in the form of failure to contact the second target and repetitive tapping on the third target. These results suggest that extensive practice may serve to firmly entrench a response sequence, making it difficult to implement a similar, but unique, motor control program. An interpretation in terms of automaticity and enhanced priming of behavioral and neural pathways is offered to account for these results.     

Programming strategies for rapid aiming movements under simple and choice reaction time conditions

Increases in reaction time (RT) as a function of response complexity have been shown to differ between simple and choice RT tasks. Of interest in the present study was whether the influence of response complexity on RT depends on the extent to which movements are programmed in advance of movement initiation versus during execution (i.e., online). The task consisted of manual aiming movements to one or two targets (one- vs. two-element responses) under simple and choice RT conditions. The probe RT technique was employed to assess attention demands during RT and movement execution. Simple RT was greater for the two- than for the single-target responses but choice RT was not influenced by the number of elements. In both RT tasks, reaction times to the probe increased as a function of number of elements when the probe occurred during movement execution. The presence of the probe also caused an increase in aiming errors in the simple but not choice RT task. These findings indicated that online programming was occurring in both RT tasks. In the simple RT task, increased executive control mediated the integration between response elements through the utilization of visual feedback to facilitate the implementation of the second element.