Physiological evidence for response inhibition in choice reaction time tasks

Inhibition is a widely used notion proposed to account for data obtained in choice reaction time (RT) tasks. However, this concept is weakly supported by empirical facts. In this paper, we review a series of experiments using Hoffman reflex, transcranial magnetic stimulation and electroencephalography to study inhibition in choice RT tasks. We provide empirical support for the idea that inhibition does occur during choice RT, and the implications of those findings for various classes of choice RT models are discussed.     

Stimulus and response prediction in choice reaction time: Free vs. forced reactions

Verbal predictions were combined in a 1:many mapping in order to analyze the contribution of response preparation to both stimulus and response prediction effects in choice reaction time (RT). Using a three-stimulus, two-response task in which two of the stimuli were mapped 1:1 to separate responses (forced-choice) and the third stimulus was mapped to both responses (free-choice), response frequencies and latencies were compared in two experiments. The results indicated that (1) free-choice response selections were not influenced by forced-choice stimulus predictions; (2) free-choice RTs were reduced only when the free-choice stimulus was correctly predicted; (3) free-choice responses were generally consistent with the response predicted, but RT did not depend on response prediction; (4) on forced-choice trials, the RT difference between correct and incorrect predictions was similar for stimulus and response predictions; and (5) under no-prediction conditions, no difference was found between free and forced RTs. A stimulus anticipation component was the only apparent contribution to the stimulus prediction effect, while the response prediction data suggest some prior response selection with no associated decrease in latency     

Cross-sex comparisons: A word of caution

A cross-sex difference on one variable is often hypothesized to be related to a gender difference on a second variable. However, caution should be exercised in making such comparative hypotheses. We gathered the expected and actual examination grades for 168 female and 163 male college students. As in prior research, males had higher expectancies than females (p<.05). But analysis of the intrasex regression equations indicated that the relationship of expectancies to performance was different for women than it was for men. Thus, a cross-sex difference in expectancies did not correspond to a parallel difference in grades. This finding highlights the potential hazards of making certain cross-sex comparisons, and we argue for more caution in their application.     

Response selection in choice reaction time: Test of a buffer model

Two experiments were conducted to test a buffer model of response selection. Subjects reacted to the onset of one of six possible visual stimuli by pressing either a left- or a right-hand key. Two stimuli were assigned to one key Itwo-item set) and four stimuli were assigned to the other key flour-item set). An irrelevant monaural tone accompanied the visual stimulus in Experiment 1 but not in Experiment 2. Results of Experiment 1 showed that reactions were faster when the location of the tone corresponded with the response than when it did not, and the difference between these corresponding and noncorresponding conditions was greater for the two-item set than for the four-item set. Results supported the notion that the response selection process involved a serial self-terminating search of response buffers and that the tone determined the buffer searched first. In both experiments, reactions were faster to stimuli from the twoitem set than to stimuli from the four-item set     

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.

     

The additivity of stimulus-response compatibility with perceptual and motor factors in a visual choice reaction time task

One hundred and four participants performed a two-choice reaction time task requiring button-press responses to visual stimuli. Two levels of stimulus-response compatibility were factorially combined with two levels of stimulus discriminability and two levels of response repertoire. Results showed that the effects of these three variables were additive both in terms of mean reaction time as in terms of reaction time variances. The implication of this outcome is discussed in terms of the underlying information processing stage structure.     

The point of no return in choice reaction time: controlled and ballistic stages of response preparation

A countermanding procedure and race model are used to assess separately the effects of experimental factors before and after the "point of no return" in response preparation. The results reveal details about processes that so closely precede the initiation of movement that they cannot be inhibited. These processes appear to be affected by the repetition of stimulus-response pairs, but not by the physical or semantic properties of the stimuli. A model of response preparation is supported in which response inhibition depends upon the outcome of a race between independent excitatory and inhibitory processes, and reaction time is the sum of the durations of at least two stages, separated by the point of no return.     

Useful visual field in patients with schizophrenia: a choice reaction time study

This study examined the size of the useful visual field in patients (9 men, 6 women) with schizophrenia. A choice reaction task was conducted, and performances at 2.5, 5, 7, 10, and 25 degrees in both visual fields were measured. Three key findings were shown. First, patients had slower choice reaction times (choice RTs) than normal controls. Second, patients had slower choice RTs in the right visual field than in the left visual field. Third, patients and normal controls showed the same U-shaped choice RT pattern. The first and second findings were consistent with those of other studies. The third finding was a clear indication of the patients' performance in peripheral vision, and a comparison with normal controls suggested that there was no difference in the size of the useful visual field, at least within     

Binary choice reaction time as a criterion of motor equivalence

In a binary choice situation the two alternative movements may vary in the degree in which they are equivalent in respect to controlling processes and/or structures. With a higher degree of motor equivalence a shorter RT is to be expected. A series of five experiments shows that a movement of a finger of one hand has a shorter latency if the alternative movement with the other hand is of the same form than in case of different forms. There is no evidence of corrsponding effect of using the same or different fingers with both hands. These results indicate that programming of the form of a movement is at least partly independent of the muscles involved in movement execution.     

Assessment of sexual preference using a choice reaction time task

The purpose of this study was to investigate the use of a choice reaction time task, during which slides of sexually explicit and neutral stimuli were used as an interference task, to differentiate between groups of individuals on the basis of their sexual preference. Twenty subjects, in each of the four groups (heterosexual males, heterosexual females, homosexual males, and homosexual females), participated in this study. Sexual orientation was determined by self-report. Subjects were given a choice reaction time with interference task, followed by a recall incidental learning task. A significant higher-order interaction was found among gender, orientation, and stimulus type for all four groups. This interaction indicated a longer reaction time to slides depicting preferred sexual partners than to nonpreferred sexual partners or neutral scenes. These results indicate that sexual arousal does interfere with cognitive processing. A main effect for gender was found for the incidental learning task, with males having the fewest errors.     

Central processing uncertainty as a determinant of choice reaction time

It was demonstrated that central processing uncertainty (Hc) can be derived to provide a single valued statement of the information hypothesis RT=a+b (Hc) across test stimulus sets and across several levels of test stimulus probability in an information reduction task. The derivation procedure assumes successive tests of stimulus hypotheses with Bayesian revision of stimulus probabilities after failure of an initial test. It was shown that the procedure can be generalized to data from single test stimuli in an information conservation task. Stimulus and response repetition effects were estimated for the information reduction task data.     

Manipulating response set in a choice reaction task: evidence for anatomical coding in response selection

Accurate motor performance requires a process of response selection that chooses the correct response out of a set of possible ones. Most theories of response selection assume that this selection process operates on spatial codes, which define the location of stimuli and responses in environmental coordinates, with little or no role for the anatomical codes of the effectors involved. In this study, I systematically manipulated the anatomical identities of the response fingers in a four-choice reaction task, while keeping the stimulus and response locations constant. Results showed that homologous fingers on different hands modulated the reaction time profiles and error patterns in a mirror-symmetrical way. This finding indicates that anatomical factors may play a more substantial role in response selection than often assumed.     

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.     

Incremental exercise, plasma concentrations of catecholamines, reaction time, and motor time during performance of a noncompatible choice response time task

The primary purpose was to examine the effect of incremental exercise on a noncompatible response time task. Participants (N=9) undertook a 4-choice noncompatible response time task under 3 conditions, following rest and during exercise at 70% and 100% of their maximum power output. Reaction and movement times were the dependent variables. Maximum power output had been previously established on an incremental test to exhaustion. A repeated-measures multivariate analysis of variance yielded a significant effect of exercise intensity on the task, observation of the separate univariate repeated-measures analyses of variance showed that only movement time was significantly affected. Post hoc Tukey tests indicated movement time during maximal intensity exercise was significantly faster than in the other two conditions. The secondary purpose of the study was to assess whether increases in plasma concentrations of adrenaline and nor-adrenaline during exercise and power output would act as predictor variables of reaction and movement times during exercise. Catecholamine concentrations were based on venous blood samples taken during the maximum power output test. None of the variables were significant predictors of reaction time. Only power output was a significant predictor of movement time (R2 = .24). There was little support for the notion that peripheral concentrations of catecholamines directly induce a central nervous system response.     

Binary choice reaction time as a criterion of motor equivalence: Further evidence

In a previous study Heuer (1982) found shorter binary choice RTs for finger movements of the right hand when the alternative movement with the left hand was of the same form that in case of different forms. Contrary to expectation there was no corresponding effect if the fingers used were the same of different ones. This result was replicated for right hand RTs as well as left hand RTs and for male and female subjects, using a different experimental design. It is discussed in respect to different preparatory processes in the foreperiod.     

A ballistic model of choice response time

Almost all models of response time (RT) use a stochastic accumulation process. To account for the benchmark RT phenomena, researchers have found it necessary to include between-trial variability in the starting point and/or the rate of accumulation, both in linear (R. Ratcliff & J. N. Rouder, 1998) and nonlinear (M. Usher & J. L. McClelland, 2001) models. The authors show that a ballistic (deterministic within-trial) model using a simplified version of M. Usher and J. L. McClelland's (2001) nonlinear accumulation process with between-trial variability in accumulation rate and starting point is capable of accounting for the benchmark behavioral phenomena. The authors successfully fit their model to R. Ratcliff and J. N. Rouder's (1998) data, which exhibit many of the benchmark phenomena.