The foreperiod effect revisited

This paper explores four factors which could be important in accounting for the discrepant results which have previously been obtained with respect to the effect of foreperiod duration on reaction time (RT). In some studies a clear effect of foreperiod duration on auditory RT has been found, in contrast to a recent finding that foreperiod duration affected visual RT but not auditory RT. By means of two experiments, the effects of practice, time-on-task, reaction task (a-reaction versus selective reaction) and signal intensity were studied. The latter variable appears to be the principal determinant of the discrepant results in that there is an interaction between signal intensity, foreperiod duration and modality. The results fit the hypothesis that signals beyond a given intensity exert an immediate arousing effect which counteracts the foreperiod effect.     

Conditional probability and components of rt in the variable foreperiod experiment

If the passage of time during the foreperiod in a variable foreperiod experiment is marked by a series of tones, RT decreases with the conditional probability of stimulus occurrence. RTs at short foreperiods, however, are rather slower than would be expected on the basis of a simple conditional probability effect. It is suggested that this is attributable to an independent “initial slow reaction” effect, and it is shown that the degree of this effect is influenced by the duration of the prior foreperiod. The results are related to those of variable foreperiod a-reactions in which no conditional probability effect has been found, and it is argued that in a marked reaction of the kind described above, the initial slow reaction effect behaves like an a-reaction component of RT. It is suggested that the absence of a conditional probability effect in the a-reaction and its presence in the marked reaction are related to the fact that a different type of sensory process is used to identify the signal in each case.     

A suppressing effect of response selection on immediate arousal in a choice reaction task

A clear conflict exists between experiments showing either additive or interactive effects of foreperiod duration and S-R compatibility on choice reaction time. It is hypothesized that in principle S-R compatibility and foreperiod duration have additive effects but that the effect of foreperiod duration is reduced in conditions where a signal is immediately arousing and where the S-R relations are highly compatible. In the case of low S-R compatibility the effect of immediate arousal is supposed to be ineffective.This hypothesis is tested and confirmed in an experiment in which the combined effects of foreperiod duration and S-R compatibility were studied with either loud (85 dBA) or weak (45 dBA) auditory signals. As predicted, additive effects were found in the latter case, while an interaction was observed with 85 dBA signals.     

The relation between physical stimulus properties and the effect of foreperiod duration on reaction time

Seven subjects were used in an experiment on the relation between signal modality and the effect of foreperiod duration (EP) on RT. With visual signals the usually reported systematic increase of RT as a function of FP duration (1, 5 and 15 s) was confirmed; with auditory signals no difference was found between FP's of 1 and 5 s while the effect at 15 s was equivalent to that found at 5 s with the visual signal. The results suggest that besides factors such as time uncertainty the FP effect is also largely dependent on the arousing quality of the signal.     

The relation between response-specificity, S-R compatibility, foreperiod duration and muscle-tension in a target aiming task

Three experiments are reported aiming at a further understanding of the effect of response-specificity, operationalized as the degree of commonality of direction of movements. In a previous study, Spijkers (1987) has claimed that response-specificity affects the readiness of the motor system and is not related to response-selection processes. These suppositions were generally confirmed in experiments 1 and 2 respectively. Common to both experiments were the variables average movement velocity and response-specificity. In experiment 1 the effect of the additional variable foreperiod duration was found to interact with that of response-specificity, hereby confirming its expected relation to the muscular system. The effect of response-specificity did not interact with that of spatial S-R compatibility in the second experiment, but also failed to show a main effect. The third experiment examined the supposed relation of response-specificity more directly through manipulation of the muscle-tension of the responding limb. The predicted form of the interaction between the effect of response-specificity and muscle-tension was confirmed which provided additional evidence for the interpretation of response-specificity effects in terms of differential muscular activation.     

Dissociative patterns of foreperiod effects in temporal discrimination and reaction time tasks

This study examined whether the process of temporal preparation for a target stimulus is the same regardless of the task required by the target stimulus. To this end, the same variable-foreperiod design was used in a temporal discrimination task (Experiment 1) and a reaction time task (Experiment 2). In Experiment 1, both temporal sensitivity and perceived duration increased as a function of foreperiod, whereas in Experiment 2, foreperiod did not influence reaction time. Furthermore, both temporal sensitivity and perceived duration revealed an asymmetric sequential effect of foreperiod, but the pattern of this effect was opposite to the pattern observed in the reaction time task. Together these dissociative patterns of foreperiod effects suggest that the mechanism of temporal preparation depends on the task required by the target stimulus.     

Lengthening fixed preparatory foreperiod durations within a digit magnitude classification task serves mainly to shift distributions of response times upwards

In this study, the effect of lengthening foreperiod duration (i.e. the time between the presentation of a warning signal and a subsequent target stimulus) on choice RTs is examined. The foreperiod durations used were either 2 or 8 s and were fixed within pure blocks of trials. The task was to determine whether a single-digit target stimulus was either smaller or larger than 5 and responses were provided manually. An additive relation between foreperiod duration length and numerical distance from 5 was present in the mean RTs. Subsequent ex-Gaussian analyses of the shapes of the RT distributions indicated that they become shifted upwards as the foreperiod increased with relatively smaller increases in the sizes of their tails. It is argued mainly that the latter finding is incompatible with the strategic time estimation view of the fixed foreperiod duration effect.     

Dissociative patterns of foreperiod effects in temporal discrimination and reaction time tasks

This study examined whether the process of temporal preparation for a target stimulus is the same regardless of the task required by the target stimulus. To this end, the same variable-foreperiod design was used in a temporal discrimination task (Experiment 1) and a reaction time task (Experiment 2). In Experiment 1, both temporal sensitivity and perceived duration increased as a function of foreperiod, whereas in Experiment 2, foreperiod did not influence reaction time. Furthermore, both temporal sensitivity and perceived duration revealed an asymmetric sequential effect of foreperiod, but the pattern of this effect was opposite to the pattern observed in the reaction time task. Together these dissociative patterns of foreperiod effects suggest that the mechanism of temporal preparation depends on the task required by the target stimulus.     

Variable foreperiods and temporal discrimination

Temporal judgements are often accounted for by a single-clock hypothesis. The output of such a clock is reported to depend on the allocation of attention. In the present series of experiments, the influence of attention on temporal information processing is investigated by systematic variations of the period preceding brief empty intervals to be judged. Two indicators of timing performance, temporal sensitivity, reflecting discrimination performance, and perceived duration served as dependent variables. Foreperiods ranged from 0.3 to 0.6 s in Experiments 1 to 4. When the foreperiod varied randomly from trial to trial, perceived duration was longer with increasing length of foreperiod (Experiments 1 and 3 with brief auditory markers and Experiment 4 with brief visual markers), an effect that disappeared with no trial-to-trial variations (Experiment 2). Longer foreperiods also enhanced performance on temporal discrimination of auditory empty intervals with a base duration of 100 ms (Experiments 1 and 5), whereas discrimination performance was unaffected for auditory intervals with a base duration of 500 ms (Experiment 3). The variable-foreperiod effect on perceived duration also held when foreperiods ranged from 0.6 to 1.5 s (Experiments 5-7). Findings suggest that foreperiods appear to effectively modulate attention mechanisms necessary for temporal information processing. However, alternative explanations such as assimilation or compatibility effects cannot be totally discarded.     

Planning of saccadic eye movements

Most theories of the programming of saccadic eye movements (SEM) agree that direction and amplitude are the two basic dimensions that are under control when an intended movement is planned. But they disagree over whether these two basic parameters are specified separately or in conjunction. We measured saccadic reaction time (SRT) in a situation where information about amplitude and direction of the required movement became available at different moments in time. The delivery of information about either direction or amplitude prior to another reduced duration of SRT demonstrated that direction and amplitude were specified separately rather than in conjunction or in a fixed serial order. All changes in SRT were quantitatively explained by a simple growth-process (accumulator) model according to which a movement starts when two separate neural activities, embodying the direction and amplitude programming, have both reached a constant threshold level of activity. Although, in isolation, the amplitude programming was faster than the direction programming, the situation reversed when two dimensions had to be specified at the same time. We conclude that beside the motor maps representing the desired final position of the eye or a fixed movement vector, another processing stage is required in which the basic parameters of SEM, direction and amplitude, are clearly separable.     

The effect of foreperiod duration on reaction time and its relation to interval schedules of reinforcement

Two groups of pigeons were exposed to a simple reaction-time procedure in which mean foreperiod duration was 5, 10, or 20 seconds. For one group, the foreperiods had an arithmetic, or rectangular, distribution; for the second group, they had a constant-probability, or Bernoulli, distribution. Under both distributions, mean response latency was an increasing, negatively accelerated function of mean foreperiod duration. On a given trial, response latency was a function of its associated foreperiod duration: latency was a decreasing function of foreperiod duration in the arithmetic distribution, and an increasing function of foreperiod duration in the constant-probability distribution. Examination of the distribution of latencies revealed a harmonic structure reminiscent of distributions of interresponse times under variable-interval schedules of reinforcement. Taken together, the results confirm and extend previous findings with human subjects, and also suggest numerous similarities to behavior maintained by variable-interval schedules.     

Tactical skills and ball speed during a field simulation of penalty kick strategies in soccer

This study investigates the efficacy of intermediate penalty kickers by comparing the effect of applying an automated WiFi system on the field of play to simulate a strategy that takes account of goalkeeper action (dependent) with another for which goalkeeper strategy is irrelevant (independent). Intermediate penalty kickers (n=12) took a pretreatment test of 32 kicks in a "real-play" situation with intermediate goalkeepers (n=3). Two groups of kickers underwent 11 treatment sessions using different strategies and then were administered a posttreatment test. The variables measured were the number of goals scored, whether the direction of the shot was the same or different from the direction of the goalkeeper's move (DDG), ball speed, and the duration of the kicking movement. Data suggested the goalkeepers had a greater capacity to identify advance cues when faced with independent strategy kickers and that dependent strategy kickers achieved lower ball speeds.     

Sequential effects of foreperiod duration and conditional probability of the signal in a choice reaction time task

The aim of the present study was to determine whether the negative relationship usually found between reaction time and foreperiod duration in the variable foreperiod paradigm is entirely due to sequential foreperiod effects. It has been shown that when a particular foreperiod has been preceded by a longer one on the previous trial, reaction time is longer than when the preceding foreperiod was equal or shorter. This may be sufficient to explain the increase in reaction time observed for short foreperiods in variable foreperiod conditions.The present results show that, when sequential effects were controlled by the elimination of all trials where the foreperiod was shorter than the preceding one, the negative slope of the reaction time-foreperiod function diminished but did not disappear. The results suggest an interpretation of the role of conditional probability of stimulus arrival in terms of variation in the tendency to reprepare when the moment initially chosen for preparation appears to fall short of the moment at which the stimulus is actually presented.     

Perceptual and motor components of performance in three different reaction time experiments

Three reaction time experiments were conducted to examine the effects of time of day, stimulus intensity, stimulus modality, and constant and variable foreperiod on the perceptual and motor components of performance. These variables are all supposed to generate changes in arousal level. All the independent variables affected the perceptual component, while the motor component was significantly influenced only by foreperiod and modality. The results are discussed in relation to aspects of dependency/independency of the perceptual and motor components of human performance in reaction time experiments.     

Delay of stimulus presentation after the saccade in visual search

Delay of stimulus onset after each saccade in visual search decreased oculomotor and manual reaction times, with a greater effect occurring for the oculomotor response. The saccadic oculomotor reaction might have been facilitated in three ways: by the facilitation of reaction with a foreperiod warning stimulus, by the attenuation of saccadic suppression effects due to the stimulus onset delay, or by the use of a strategy of preprogramming fixation durations. The results support a model of visual search using preprogrammed control of visual fixation durations.     

The relationship between estimates of foreperiod duration and simple time reaction

The relationship between estimates of foreperiod length and simple reaction time (RT) was examined using constant foreperiods. It was learned that neither the average accuracy nor the variability of the foreperiod estimates necessarily manifested themselves in appropriate simple RT change. Of secondary interest was the discovery that the average accuracy of foreperiod duration estimations differed greatly from that obtained for similar time lengths in a time-estimation task. Finally, an attempt was made to determine whether subjects actually utilized the directional knowledge of results inherent in the imperative stimulus to influence their foreperiod duration judgments. Unfortunately, the evidence obtained did not permit a definite answer regarding this possibility.     

Modification of muscle activation patterns during fast goal-directed arm movements

The motor programming of fast goal-directed arm movements was studied in a tracking task. A target jumped once or twice randomly to the left or right direction with an interstimulus interval (ISI) in a range between 50 and 125 msec. Double step stimuli were either two steps in the same direction (C-trial) or in opposite direction (R-trial). Tracking results show that at the beginning average EMG-activity is the same for responses to single step trials, R-trials and C-trials. Differences set in after some time equal to or somewhat shorter than ISI. It was concluded that muscle activation patterns of fast goal-directed movements are not preprogrammed but that they can be modified during the movement. The time interval between second target step and the moment when EMG activity of the double step response deviates from the EMG activity of a single step (RT2) could be smaller than the time interval between first target displacement and EMG onset. (RT1). If modification of the muscle activation pattern required a longer or larger activation of the active muscle, RT2 tended to be smaller than RT1, whereas RT2 was about equal to RT1 if the new muscle activation required a termination of the ongoing muscle activation pattern and the activation of another muscle.     

The acquisition of conditioned emotional response as a function of intertrial interval

The effects of intertrial interval (ITI) and foreperiod duration on the acquisition of a conditioned emotional response were investigated using a four-trial conditioning procedure. The optimum ITI was found to be 60 s with a bidirectional gradient for conditioned suppression above and below 60 s. Conditioned supression was found to be directly related to foreperiod duration.     

An effect of spatial-temporal association of response codes: understanding the cognitive representations of time

The present study addresses the question of how such an abstract concept as time is represented by our cognitive system. Specifically, the aim was to assess whether temporal information is cognitively represented through left-to-right spatial coordinates, as already shown for other ordered sequences (e.g., numbers). In Experiment 1, the task-relevant information was the temporal duration of a cross. RTs were shorter when short and long durations had to be responded to with left and right hands, respectively, than with the opposite stimulus-response mapping. The possible explanation that the foreperiod effect (i.e., shorter RTs for longer durations) is greater with right than with left hand responses is discarded by results of Experiment 2, in which right and left hand responses alternated block-wise in a variable foreperiod paradigm. Other explanations concerning manual or hemispheric asymmetries may be excluded based on the results of control experiments, which show that the compatibility effect between response side and cross duration occurs for accuracy when responses are given with crossed hands (Experiment 3), and for RTs when responses are given within one hand (Experiment 4). This pattern suggests that elapsing time, similarly to other ordered information, is represented in some circumstances through an internal spatial reference frame, in a way that may influence motor performance. Finally, in Experiment 5, the temporal duration was parametrically varied using different values for each response category (i.e., 3 short and 3 long durations). The compatibility effect between hand and duration was replicated, but followed a rectangular function of the duration. The shape of this function is discussed in relation to the specific task demands.     

Distribution of Programming in a Rapid Aimed Sequential Movement

Studies indicate that rapid sequential movements are preprogrammed and that preprogramming increases with complexity, but more complex sequences that require on-line programming have seldom been studied. The purpose of this investigation was to determine whether on-line programming occurs in a 7-target sequence in which there is a unique target constraint and if so, to determine how different task constraints affect the distribution of additional programming. Subjects contacted seven targets with a hand-held stylus as quickly as possible while maintaining a 90% hit rate. Initiation- and execution-timing patterns and movement kinematics were measured to determine when the additional programming took place. Results indicated that additional programming occurred before initiation and during movement to the first target when the constraint required more spatial accuracy (small target). A different type of unique target (a triple hit of one target) caused the additional programming to occur on-line one or two segments before its execution. Different positions of the unique target also affected timing patterns. Results were discussed in terms of: (1) capacity of processing; (2) control of movement variance; and (3) mean velocity as a programmed parameter in sequential aiming movements.