Verbal predictions of unexpected stimuli and choice reaction time

In two choice reaction time (RT) experiments, subjects verbally predicted the stimulus alternative that was either most or least likely to be presented on each trial. An expectancy interpretation of prediction effects requires that stimuli matching least likely predictions yield the longest RTs. In Experiment 1, with four stimulus alternatives, RTs to stimuli matching the verbalized stimulus, both most likely and least likely predictions, were shorter than RTs to stimuli that matched neither the most nor the least likely predictions. However, matching most likely predictions produced faster responses with two alternatives. In Experiment 2, multiple predictions of both most and least likely stimuli were compared with joint predictions of first and second most likely alternatives. RTs to stimuli matching least likely predictions were longer than RTs to most likely matches, implicating prediction type as a partial determinant of RT. Matching least likely stimuli were responded to more quickly than unpredicted alternatives, demonstrating the importance of generating a prediction per se over the implied level of expectancy. Results from both experiments were contrasted with nonparametric predictions from an ordered memory scanning model.     

Prediction outcome probabilities as determinants of choice reaction time

In a two-stimulus two-response choice reaction time (RT) task in which Ss made stimulus predictions, the probability of a correct prediction was manipulated between Ss. The magnitude of the difference in RT to correctly and incorrectly predicted stimuli (i.e., the prediction outcome effect) was an increasing function of the probability of a correct prediction This finding was primarily due to a reliable decrease in RT to correctly predicted stimuli as the probability of a correct prediction increased, since RT to incorrectly predicted stimuli was not affected by prediction outcome probability. These results were interpreted as partially supporting a continuous expectancy notion which involves facilitory and inhibitory mechanisms winch are differentially influenced by the probability of a correct prediction.     

A partial repetition effect in choice reaction time for multidimensional stimuli

Bertelson (1963), and others more recently, have observed that when the same stimulus is presented consecutively the reaction time (RT) to the second presentation is faster than the RT to the first presentation. In Experiments 1 and 2, two-dimensional stimuli are used in a discrete four-choice RT task where the stimuli can either be completely repeated, partially repeated, or completely different. In Experiment 3, three-dimensional stimuli were used in a discrete eight-choice RT task where the stimuli can either be completely repeated, partially respeated with respect to two dimensions, partially repeated with respect to one dimension, or completely different. The partial repetition of multidimensional stimuli showed a significant facilitation effect on RT with all sets of stimuli used in the present experiments. This result is discussed in respect to the various possible loci of the repetition effect.     

Prediction outcome and choice reaction time: Inhibition versus facilitation effects

In two-choice RT tasks Ss verbally predicted all stimulus presentations, two-thirds of the presentations, or none of the presentations. Effects of stimulus probability were similar for each type of prediction trial: Correct Prediction Outcome (PO), Incorrect PO, and No-Prediction (NP). When comparisons between Prediction and NP trials were between Ss, reactions on NP trials were significantly faster than reactions POs, but were not slower than reactions to Correct POs. However, when Prediction and NP trials occurred within Ss, reactions on NP trials were not faster than reactions to Incorrect POs, but were significantly slower than reactions to Correct POs. Speculations about Ss' implicit stimulus predictions are offered to interpret differential implications of inhibition and facilitation.     

Estimation of interhemispheric dynamics from simple unimanual reaction time to extrafoveal stimuli

This essay reviews research on interhemispheric transfer time derived from simple unimanual reaction time to hemitachistoscopically presented visual stimuli. Part 1 reviews major theoretical themes including (a) the significance of the eccentricity effect on interhemispheric transfer time in the context of proposed underlying neurohistological constraints; (b) the significance of gender differences in interhemispheric transfer time and findings in dyslexics and left-handers in the context of a fetal brain testosterone model; and (c) the significance of complexity effects on interhemispheric transfer time in a context of dynamic vs. hard-wired concepts of the underlying interhemispheric communication systems. Part 2 consists of a meta-analysis of 49 published behavioral experiments, in view of drawing a portrait of the best set of experimental conditions apt to produce salient, reliable, and statistically significant measures of interhemispheric transfer time, namely (a) index rather than thumb response, (b) low rather than high target luminance, (c) short rather than prolonged target display, and (d) very eccentric rather than near-foveal stimulus location. Part 3 proposes a theoretical model of interhemispheric transfer time, postulating the measurable existence of fast and slow interhemispheric channels. The proposed mechanism's evolutionary adaptive value, the neurophysiological evidence in its support, and favorable functional evidence from studies of callosotomized patients are then presented followed by proposals for critical experimental tests of the model.     

Probability effects in choice reaction time tasks

This paper contains a short review of the main results that were obtained by the author in a series of experiments that constituted a study of the effects of signal probability on choice reaction time. The effects of stimulus probability are shown to be influenced by the following variables: (1) differences in the method of varying stimulus probability, (2) differences in task complexity, (3) differences in S-R code, and (4) differences in Ss’ motivation. The data that are considered here are the overall mean RT for particular signals and the mean RT for sequential repetitions. Two questions, related to the psychological “nature” of the probability effects in choice RT are discussed: (1) The question of the relationship between the relative frequency and the number of alternatives as two different ways of determining the probability effect in choice RT; and (2) the question of identifying the main determinants of the trial-to-trial variability of RT in such experiments.

     

Sequential effects of catch-trials on choice reaction time

The aim of the study was to examine whether or not choice reaction time (RT) depends on catch-trial frequency. The results show a significant increase of mean RT as the catch-trial frequency increases from zero to 0.77. A similar effect has been shown previously in simple RT experiments. The interpretation of these effects on simple RT supposes the existence of an inverse relationship between catch-trial frequency and anticipated response frequency. This cannot be extended to a choice RT task since the subject must wait for the stimulus to arrive before deciding which is the appropriate response. The interpretation of the present results proposes preparatory adjustments prior to the arrival of the stimulus. Sequential effects found suggest that (1) the tendency to prepare for a stimulus at a trial was stronger when a stimulus was presented at the preceding trial than after a catch-trial, and (2) the frequency effects of catch-trials can be explained completely in terms of sequential effects.     

Acute aerobic exercise and information processing: energizing motor processes during a choice reaction time task

The immediate and short-term after effects of a bout of aerobic exercise on young adults’ information processing were investigated. Seventeen participants performed an auditory two-choice reaction time (RT) task before, during, and after 40 min of ergometer cycling. In a separate session, the same sequence of testing was completed while seated on an ergometer without pedalling. Results indicate that exercise (1) improves the speed of reactions by energizing motor outputs; (2) interacts with the arousing effect of a loud auditory signal suggesting a direct link between arousal and activation; (3) gradually reduces RT and peaks between 15 and 20 min; (4) effects on RT disappear very quickly after exercise cessation; and (5) effects on motor processes cannot be explained by increases in body temperature caused by exercise. Taken together, these results support a selective influence of acute aerobic exercise on motor adjustment stage.     

Sequential effects in auditory choice reaction time tasks

This paper concerns sequential effects in choice reaction time tasks. Performance in two interleaved auditory tasks was examined, and two general types of sequential effects were revealed. First, a response repetition effect occurred: Subjects were facilitated in responding when both the stimulus and the response were immediately repeated. Generally, it appeared that subjects were operating according to the bypass rule—that is, repeat the response if the stimulus or some aspect thereof is repeated from the preceding trial; otherwise, change the response. In addition, the experiment also revealed a second type of sequential effect, known as a task-switching effect. Subjects were overall slower to respond when the task changed between adjacent trials than when there was no task change. A final result was that subjects were markedly impaired when the stimulus changed but the same response had to be repeated. This finding has been reported elsewhere when purely visual tasks have been used. Hence, it seems that particular difficulties arise, in such sequential testing situations, when type-distinct stimuli are grouped into the same response categories.     

On the predictor variable for choice reaction time

A survey of published research using the Sternberg task was made for the period 1966 to early 1973. A majority of the data are better described by a linear equation involving log positive set size than by one involving set size per se as the scale of the predictor variable.     

Confidence ill stimulus predictions and choice reaction time

In two choice reaction time (RT) experiments, a stimulus prediction and a confidence judgment in the prediction preceded each occurrence of one of two stimulus alternatives. Ss identified each stimulus presentation by pressing a left-hand or right-hand telegraph key. In Experiment I the source of the stimulus predictions and confidence estimates was varied between groups of 20 Ss. For each condition, RT to correctly predicted stimuli was an inverse function of prediction confidence. Following incorrectly predicted stimuli, RT was not reliably influenced by confidence when S gave both predictions and confidence judgments; but RT to incorrectly predicted stimuli was an increasing function of confidence when E verbalized the predictions and confidence estimates or when S predicted and E indicated confidence. In Experiment II Ss made predictions and the validity of Es confidence estimate was manipulated between Ss. When Es confidence was perfectly related to the probability of a correct prediction, choice RT to nonpredicted stimuli was inversely related to confidence. However, choice RT to nonpredicted stimuli was not affected by prediction confidence when Es judgments were random.     

Stimulus proba]bility and choice reaction time

Two experiments, in which three stimuli were paired with two responses in a 2∶1, 1∶1 arrangement, showed choice RT to be a decreasing function of the relative frequency of stimulus occurrence when response frequencies are equated. The size of effect varied significantly with stimulus type (Experiment 1), being larger for circular light patches of differing diameter than for sets of colors, letters, and spatially distributed light sources, but was independent of differences in the similarity of stimulus alternatives within a set (Experiment 2). The results are discussed in terms of various strategies of stimulus identification.