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.     

Connectionist and diffusion models of reaction time.

Two connectionist frameworks, GRAIN (J. L. McClelland, 1993) and brain-state-in-a-box (J. A. Anderson, 1991), and R. Ratcliff's (1978) diffusion model were evaluated using data from a signal detection task. Dependent variables included response probabilities, reaction times for correct and error responses, and shapes of reaction-time distributions. The diffusion model accounted for all aspects of the data, including error reaction times that had previously been a problem for all response-time models. The connectionist models accounted for many aspects of the data adequately, but each failed to a greater or lesser degree in important ways except for one model that was similar to the diffusion model. The findings advance the development of the diffusion model and show that the long tradition of reaction-time research and theory is a fertile domain for development and testing of connectionist assumptions about how decisions are generated over time.     

Preferred hand and steadiness of reaction time.

RT and its left/right difference of both biceps muscles were measured by electromyogram (EMG) in the bilateral simultaneous flexion of elbows using 11 left- and 13 right-handed subjects under four conditions which were combinations of two factors; warning signal; presence or absence of a fore-period, and position of limbs; elbow 90 degrees or 135 degrees. EMG-RT and its left/right difference were influenced by these factors. The effects of warning and position of limbs were not the same on the preferred and non-preferred hands. It was assumed that EMG-RTs of biceps in the preferred hand were less influenced by these experimental conditions.     

Individual differences in right and left reaction time.

Experiments designed to check the absence of effects for hands and handedness in simple and two-choice reaction time found unexpected individual differences related to stimulus laterality. The majority of subjects responded faster to the stimulus on the left and a substantial minority responded faster to the stimulus on the right in any choice pair. The right index finger was slower than the left index or the middle fingers. Choices tended to be faster between fingers on different hands than on the same hand and same-hand choices were faster with the left hand than the right hand. There were no effects attributable to hand preference or sex.     

Response programming and reaction time

A feature common in the literature is that, prior to responding, subjects have been able to preview the parameters of the movement they are required to make. This introduces the possibility of programming the movement before entering the reaction time period. It is argued that this has contributed to confusion in the literature, making it difficult to detect a consistent relationship between reaction time and motor task demands. Two experiments were conducted to clarify the position. Experiment I concealed the movement parameters prior to subjects responding ("no-preview" model), and this was contrasted with a study in the typical "preview" mode (Experiment II). It was concluded that the no-preview design is more appropriate to detecting changes in reaction time dependent on task parameters, and that the observed effects on reaction time reflect programming difficulty. A third experiment supported this conclusion     

Simple auditory reaction time in blind and sighted adolescents.

This study compared simple auditory reaction times of 20 subjects aged between 11 and 15 yr. (M = 13), 10 born-blind from the Louis Braille Institut (Montréal) and 10 normal sighted subjects of the same age and sex. Their task was to press a telegraph key as fast as possible after presentation of an auditory stimulus. Each subject executed five blocks of 10 trials; the blocks were separated by a rest period of 1 min. The results showed no significant difference (p greater than .05) between born-blind and sighted people of the same sex and chronological age in regard to simple auditory reaction time.     

Rasch-representable reaction time distributions

This article investigates properties of a representation based on the Rasch test model for reaction times (RT) that was proposed by Micko. Necessary and sufficient conditions for a set of RT distributions to be Rasch-representable are derived. It is shown that independent serial and independent parallel processing models cannot be reconciled with the representation. However, random extreme models compatible with the Reasch-representation exist that assume RT is determined by the longest or he shortest processing time of a random number of independent paraloel channels. Nonparametric properties of Rasch-representable distributions are derived that can be used for testing the model and for estimating its parameters. Conditions are presented for Rasch-representable distributions to form a scale family. Finally, Rasch-represent-able distributions are characterized interms of their hazard functions.For helpful discussions, we are grateful to Hans Irtel, Christoph Micko, Hartmann Scheiblechner, and Hans-Henning Schultz.     

Loudness and reaction time: I

It is widely assumed, based on Chocholle’s (1940) research, that stimuli that appear equal in loudness will generate the same reaction times. In Experiment 1, we first obtained equal-loudness functions for five stimulus frequencies at four different intensity levels. It was found that equal loudness produced equal RT at 80 phons and 60 phons, but not at 40 phons and 20 phons. It is likely that Chocholle obtained equivalence between loudness and RT at all intensity levels because of relay-click transients in his RT signals. One main conclusion drawn from Experiment 1 is that signal detection (in reaction time) and stimulus discrimination (in loudness estimation) require different perceptual processes. In the second phase of this investigation, the RT-intensity functions from six different experiments were used to generate scales of auditory intensity. Our analyses indicate that when the nonsensory or “residual” component is removed from auditory RT measures, the remaining sensory-detection component is inversely related to sound pressure according to a power function whose exponent is about — 3. The absolute value of this exponent is the same as the .3 exponent for loudness when interval-scaling procedures are used, and is one-half the size of the .6 exponent which is commonly assumed for loudness scaling.     

Paced and self-paced continuous reaction time

Studies of the effect of pacing in continuous RT tasks are inconclusive. They have failed to (1) compare paced and self-paced RT at matched error rates and (2) examine RT distributions as well as mean or median RT. In the present experiment RTs were corrected for error rate by relating them to the speed-accuracy tradeoff function, which was measured in each experimental session. In this way deciles of the RT distributions of paced and self-paced conditions were compared, for eight subjects and four successive sessions. The task was a four-choice continuous RT task, employing visual stimuli. The results show that RT distributions are wider in the paced conditions. RTs of the first deciles are faster for pacing whereas medians in paced and self-paced conditions are about equal. The results can be explained when it is assumed that the variable R-S intervals in paced conditions lead to a larger variability of RT.     

Non-aging fore-periods and simple reaction time

This study deals with the relationship between the momentary objective probability of the delivery of a stimulus and the reaction time in a simple reaction-time task. The hypothesis was that the reaction time is closely related to the objective probability via expectancy i.e., the momentary probability of the delivery of the stimulus as experienced by the subject. This problem was experimentally approached from two directions: (1) by varying the objective probability, in which case the reaction times should change inversely with the objective probability, and (2) by keeping the objective probability constant (by using the Bernoulli process), in which case the reaction times should not change. Eight male subjects were used. The first assumption proved to be correct, whereas the second held only when certain mean inter-stimulus intervals were used.     

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.