Auditory Warning Signal Research Articles

Reduced excitability of the cortico-spinal system during the warning period of a reaction time task

Seven subjects made a wrist flexion movement as rapidly as possible in response to a cutaneous shock on the opposite hand. In some trials, an auditory warning signal was given 0.5s beforehand. In random trials, transcranial magnetic stimulation (TMS) was used to elicit EMG responses (MEPs) in forearm flexor and extensor muscles 0–500ms before the cutaneous shock. H-reflexes were elicited in flexor muscles at the same intervals. The warning stimulus reduced reaction time from about 400ms to 200ms. MEPs in the flexor muscles were significantly suppressed from 125ms after the warning stimulus until the time of the cutaneous shock whilst MEPs in the extensors, and H-reflexes in the flexor were either unaffected, or reduced by a smaller amount at a later time. Responses in relaxed contralateral muscles were unchanged. If the task was changed to a choice reaction, in which the imperative stimulus (but not the warning signal) indicated whether to flex or extend the wrist, then there was no change in the MEPs or H-reflex in the warning period. A similar effect was seen if the duration of the warning period was extended from 0.5 to 2s in a simple reaction (flexion) task. We conclude that increased excitability of the corticospinal output is not required to speed up reaction times. The time taken to discharge cortical output elements is relatively unimportant compared with the time needed to process the sensory input and link it to the motor output.

The Use of Advance Information for Motor Preparation in Parkinson's Disease: Effects of Cueing and Compatibility between Warning and Imperative Stimuli

The ability of 13 Parkinsonian patients and 11 age-matched control subjects to process and use two components of the information given prior to a voluntary movement was studied using reaction time (RT) tasks. This advance information about the direction of a pointing movement was given using a double stimulation paradigm with an auditory warning signal (WS) which occurred prior to a visual imperative signal (IS). The first component of the information was given by the WS at the beginning of each trial, and the second component was the WS–IS compatibility during series of trials. The subjects were tested with three RT paradigms: a cued simple (CS) task, a cued choice (NC) task, and a priming choice (P) task. The results show that the normal subjects used both the lateral cue and the WS–IS compatibility to shorten their RTs, whereas the Parkinsonian patients were able to use the lateral warning signal, but their ability to use the degree of compatibility stimuli was impaired. These data suggest that when dealing with lateral cues in a RT task, Parkinsonian patients have no difficulty in identifying a stimulus and selecting the appropriate response, but that this is no longer so in the case of stimulus compatibility. This impairment may be due to attentional disorders involving a dysfunction affecting the medial premotor system, which includes the basal ganglia and may be responsible for the feedforward movement control deficits associated with Parkinson's disease.

The disappearance of foveal and nonfoveal stimuli: Decomposing the gap effect.

Abstract When a foveal stimulus disappears prior to the appearance of a peripheral target, saccadic reaction times (RTs) are reduced. We compared this gap ef%ect for foveal and nonfoveal stimuli when a highly predictive auditory warning signal was or was not presented. Without a tone, there was a gap effect for both foveal and nonfoveal stimuli; with a tone, there was a gap effect for foveal but not for nonfoveal stimuli. Highly predictive warning tones also modulated the gap effect in a manner that seemed to reflect top-down release of ocular inhibition. We argue that the gap effect therefore consists of three components: (a) warning effects; (b) release of ocular inhibition due to the disappearance of a foveal stimulus; and (c) release of ocular inhibition due to top-down processes. In a gap paradigm, participants are required to maintain gaze on a foveal stimulus until the onset of a peripheral saccade target. On some (overlap) trials, the foveal stimulus remains present; on other (gap) trials, the foveal stimulus is extinguished at some interval prior to the appearance of the target. Saccadic reaction times (RTs) are reduced on gap versus overlap trials (Saslow, 1967). Known as the gap effect, several explanations for this relative facilitation of RTs have been tested and rejected. The longer saccadic RTs on overlap versus gap trials do not result from refractoriness of the saccadic system following fixation-maintaining microsaccades (Kingstone, Fendrich, Wessinger, & Reuter-Lorenz, 1995). The facilitation of saccadic RTs on gap versus overlap trials is not the result of improved visual processing of the target (cf. Reulen, 1984a, 1984b; see Kingstone & Klein, 1993a; ReuterLorenz, Hughes, & Fendrich, 1991). In addition, the gap effect does not reflect the anticipatory execution of preprogrammed saccades on gap trials (cf. Juttner & Wolf, 1992; Kalesnykas & Hallett, 1987; see Kingstone & Klein, 1993a; Reuter-Lorenz et al., 1991). Fischer and colleagues proposed that the facilitation of saccadic RTs following the disappearance of a foveal stimulus may be related to the disengagement of visual attention: When attention is engaged, the saccadic system is inhibited; when attention is disengaged, the saccadic system is released from this inhibition (see Fischer & Weber, 1993 for a review). According to this account, RT facilitation in the typical gap paradigm occurs because the foveal stimulus is also the attended stimulus. It is possible to test this hypothesis by removing attention from the foveal stimulus. If participants are asked to maintain gaze on a foveal stimulus but to attend to a nonfoveal stimulus, the effects of extinguishing the unattended foveal stimulus can be distinguished from the effects of extinguishing the attended nonfoveal stimulus. Unfortunately, early studies that used this strategy to test the attentional disengagement hypothesis were compromised by a failure to assess whether attention was actually allocated to the nonfoveal stimulus (Braun & Breitmeyer,1987; Mayfrank, Mobashery, Kimmig, & Fischer,1986). When Kingstone and Klein (1993a) corrected this methodological weakness, they found that the facilitation of RTs depended on the location of the extinguished stimulus and not on the locus of covert attention. Kingstone and Klein (1993a) presented participants with three stimuli along the vertical meridian. Attention was directed on a trial-by-trial basis to one of the two nonfoveal stimuli on the vertical meridian. This was accomplished via a symbolic cue (Experiments 1 and 3) or via a brightening in the periphery (Experiment 2). On the majority of trials, participants were required to maintain central fixation and to make a speeded manual (button-press) response to report the detection of a target that appeared at one of the two locations on the vertical meridian. To the extent that attention was allocated to the cued location, manual detection RTs were expected to be faster at the cued nonfoveal location than at the uncued nonfoveal location (cf. …

Auditory collision warning signals for crane operation

This study examined the effect that an auditory collision warning signal's pulse rate, pulse pattern, and onset distance had on subject braking responses in a simulated crane/overhead power line collision scenario. The experimental warning signal alerted subjects of their proximity to overhead power lines. The experimental task required subjects to monitor a simulated auditory collision warning signal while simultaneously operating a single-axis driving simulation task. The driving task simulated an actual crane operator's mental workload required to navigate a crane and manipulate various loads. Subjects were required to initiate braking responses based on the information conveyed solely through the auditory collision warning system. No visual information was provided to the subjects to isolate the effects of the warning signal. Subjective ratings of the auditory warning signals were obtained to compare subjects' actual performance using the warning signal versus their subjective preferences. Results indicate that subjects were able to initiate appropriate braking responses while using an auditory collision warning signal with moderate onset distances and low pulse rates. The auditory pulse pattern did not have a large impact on subjects' braking responses except at extremely short onset distances. Overall, it was concluded that a pulsing auditory warning signal comprised of a moderate onset distance and low pulse rate could work effectively as a proximity warning device for mobile cranes.

Does Immediate Arousal Enhance Response Force in Simple Reaction Time?

Three experiments assessed the hypothesis that immediate arousal enhances response force in speeded reaction-time tasks. Immediate arousal was manipulated via the physical characteristics of a warning signal that closely preceded the imperative response signal. The first experiment revealed that responses were more forceful and faster for a loud than for a soft warning signal. The second experiment manipulated the duration of an auditory warning signal; more forceful but slower responses were obtained for longer durations of the warning signal. The third experiment employed a visual warning signal, and its intensity was either rather weak or moderately bright; more forceful responses and slightly faster responses were observed for the brighter warning signal. Although the results of Experiment 1 and 2 may agree with an arousal account, the findings of Experiment 3 argue against such an account. A stimulus-response compatibility hypothesis is suggested as one possible alternative account.

Event-related potential correlates of non-motor anticipation

A slow negative shift called “stimulus-preceding negativity” (SPN) has been observed preceding feedback. The aim of the present study is to investigate whether the SPN is related to perceptual or conceptual anticipation. Event-related potentials (ERPs) were recorded in an S1–S2–S3 sequence with intervals of 3 s. S1 was an auditory warning signal; the task stimulus presented at S2 consisted of two digits on which subjects ( n=8) performed an arithmetic task. They had to match their solution with a probe stimulus presented at S3. Perceptual anticipation was manipulated by varying the discriminability of S2 (intact vs. degraded). Conceptual anticipation was manipulated by varying the amount of information processing required at S2 (easy vs. difficult arithmetic). Motor preparation was varied by requiring a speeded versus a delayed response. No negativity was found before the task stimulus (S2), whereas the probe stimulus (S3) was always preceded by a negative shift. The amplitude of this negative shift was larger under the speed than under the delayed instruction. Its amplitude showed a left-hemisphere preponderance and was larger for the difficult than for the easy condition. ERPs preceding task stimuli seem to reflect functionally different processes from ERPs preceding probe and feedback stimuli. The difference is explained in terms of motivational factors that come into play with feedback and probably play a role in the anticipation of the probe stimulus.

The additive factor logic applied to the personality trait disinhibition

Thirteen subjects scoring high on Disinhibition (one of the sub dimensions of Sensation Seeking and measurable with a questionnaire) and 16 subjects scoring low on this personality dimension (HD and LD respectively) carried out a choice reaction time task, each trial consisting of an auditory warning signal (S1) followed by a visual imperative signal (S2). The design was aimed at finding an interaction of Disinhibition with one of several task parameters, supposed to affect a particular stage of information processing. Results support the conclusion that Disinhibition is significantly connected to the decision stage of processing. The absence of a relation with the early processing stage of encoding is ascribed to the fact that stimulus intensity was not manipulated in the present experiment.

Effects of age, brain damage, and task complexity on the sensitivity of reaction time to the delay between the warning signal and the stimulus.

Four age groups of normal subjects were given a visual reaction time task with three levels of uncertainty. The speed of response improved when the interval between the auditory warning signal and the imperative visual stimulus increased in the range from 1 to 3 s. This delay effect decreased when the level of uncertainty was increased, irrespective of the age. This phenomenon was globally reiterated in two control experiments. A set of 21 brain-injured subjects with clinical complaints concerning attention was also given the test. These subjects were also able to benefit from the delay. The benefit was affected neither by the task complexity nor by the slowness of the reaction times.

Perceptual aberration and brain hemisphere reversal of foreperiod effect on time estimation.

An auditory warning signal of 3 seconds' duration was followed by tachistoscopic presentation of a single dark dot to either the left or the right visual field (N = 18). The warning signal was presented monaurally to the left or to the right ear. The duration of the warning signal constituted foreperiod. The task was verbal estimation of the duration of the dot. For those who showed little or no sign of aberration of personal body image, as detected by Chapman's Perceptual Aberration Scale, time estimation of dot duration tended to be longer when the warning signal was presented to the left ear than to the right ear. For those who showed substantial sign of such aberration, the laterality of foreperiod effect was reversed, so that time estimation of dot duration was longer for the right ear than for the left ear. There was no such hemispheric reversal in terms of visual field.

Influence of auditory or visual warning on visual reaction time with variations of subjects' alertness.

The purpose of the study was to determine the effect of visual and auditory warning on visual reaction time with variations of subjects' alertness. An experimental group of 30 subjects was tested with an auditory or visual warning signal; foreperiods lasted 3, 2, and 4 sec. Reaction time was shorter as alertness improved and with an auditory warning signal. Comparable measures in a control group showed that visual reaction time was shorter when an auditory warning signal was used.

Binocular locus of brain hemisphere reversal of time information effect in schizophrenia

Investigated brain hemisphere laterality of time information among 60 schizophrenics and 60 nonschizophrenics. Duration estimation of a single dark dot presented to the left, center and right visual fields was studied with respect to an auditory warning signal of variable duration. Three conclusions were drawn: First, the relation between posterior and prior time information was shown to be that of inverse variation, and this relation was intact among schizophrenics. Second, time information was lateralized toward the left hemisphere among nonschizophrenics and toward the right hemisphere among schizophrenics, which indicates hemispheric reversal of time information as a characteristic of schizophrenia. Third, such hemispheric reversal of time information was confined to binocular, therefore, bilateral, stimulus input.

On ego regression and prior time information effect in schizophrenia.

Process schizophrenics, reactive schizophrenics, neurotics, and alcoholics (N = 80) estimated the duration of a dark dot that followed an auditory warning signal of variable duration. The duration of the warning signal constituted foreperiod (FP). The effect of FP duration on time estimation (TE) was an increasing one for all Ss, and schizophrenics were indistinguishable from nonschizophrenics. Similarly, there was no group difference with respect to the effect of preceding foreperiod (PFP). Prior time information (TI) in terms of the correlation between the pitch of the warning signal and FP duration eliminated the effects of FP and FP change for schizophrenics. As for neurotics, such prior TI accentuated the effect of decrease of FP duration and attenuated the effect of increase of FP duration. The multi-level conceptualization of time is proposed in order to establish the distinction between regression in time and regression of time. Neurosis is regarded as involving regression in time; schizophrenia is regarded as involving regression on time.

Extensionality of information accompanying effect of numerosity on estimation of time duration.

60 subjects estimated the duration of the stimulus consisting of 1, 3, or 5 dark dots, following the auditory warning signal. The duration of the warning signal constituted duration of foreperiod which was either 1 or 5 sec. For the correlated groups, pitch of the warning signal weas perfectly correlated with numerosity of dots. For the uncorrelated group, there was no such correlation. For the constant group, pitch of the warning signal was constant. The increasing effect of numerosity of stimulus elements was reduced for the 5-sec foreperiod but not for the 1-sec. foreperiod in the correlated group. Such effect was present for both durations for foreperiod in the uncorrelated group and was absent for both durations of foreperiod in the constant group.

Diurnal differences between morning-type and evening-type subjects in self-rated alertness, body temperature and the visual and auditory evoked potential

On the basis of their score on a morningness/eveningness questionnaire 9 extreme morning-type (M-type) and 9 extreme evening-type (E-type) subjects were selected. During a morning and an evening session both groups performed a reaction-time task with a visual and an auditory warning signal. The results showed that (i) M-types have a higher self-rated activation level in the morning than in the evening, while E-types show the reverse; (ii) M-types do not differ in oral temperature between the two sessions, while E-types show an increased temperature in the evening; (iii) M-types have a larger N1-P2 amplitude of the visual and auditory AEP in the morning than in the evening, while E-types show the reverse.

Differential effect of prior event information on reaction time with respect to paranoid vs nonparanoid symptomatology

The effect on reaction time, of prior information concerning the imperative stimulus, was investigated with respect to the dimension of paranoid vs nonparanoid symptomatology of schizophrenia. In the first experiment, the auditory warning signal was followed by the imperative stimulus, which was a straight line, a triangle or a rectangle. Prior information was provided by means of correlation between pitch of the warning signal and shape of the imperative stimulus. The task was to depress the telegraph key promptly at the onset of the imperative stimulus. Twenty chronic undifferentiated schizophrenics, 20 paranoid schizophrenics and 20 alcoholics participated in the experiment. Reaction time of the chronic undifferentiated schizophrenics increased, and reaction time of the paranoid schizophrenics decreased, when the prior event information was provided. In the second experiment, the imperative stimulus consisted of not only different shapes but also different colors. Reaction times of 20 chronic undifferentiated and 20 paranoid schizophrenics were again affected in opposite directions by prior information. In the third experiment, the imperative stimulus was either 1, 3 or 5 dark dots. Twenty each of the chronic undifferentiated and paranoid schizophrenics participated in the experiment. The opposite effects of prior information on reaction time with respect to the dimension of paranoid vs nonparanoid symptomatology, were again demonstrated. It was concluded that paranoid vs nonparanoid symptomatology is based on two elementary processes which are dichotomous and characteristically different from each other.

Binocular locus of prior time information effect in schizophrenia.

Schizophrenics and alcoholic controls estimated the duration of a single dark dot, which followed an auditory warning signal of variable duration that functioned as foreperiod duration. The effect of foreperiod duration on time estimation was an increasing one for both schizophrenics and alcoholics alike. Elimination of such foreperiod effect by prior time information in terms of correlation between pitch of the warning signal and foreperiod duration, was shown to be unique to schizophrenics. However, this prior time information effect was demonstrated only when the dot was viewed binocularly, not when viewed monocularly. This binocular locus of time expectancy in schizophrenia reflects the tendency toward spatialization of prior time information.

Prior time uncertainty reduction of foreperiod duration under two different levels of event uncertainty in process and reactive schizophrenia.

Process and reactive schizophrenic Ss judged stimulus durations of .50 and .55 seconds. Stimulus was 1, 3 or 5 dark dots and was preceded by variable foreperiod duration of 1, 3 or 5 seconds. Judgment of stimulus duration was found to be a monotonically increasing function of foreperiod duration. When pitch of the auditory warning signal was correlated with foreperiod duration so that it functioned as prior time information, such monotonic function was eliminated for process schizophrenics only when the numerosity of dots was constant from trial to trial. The effect of prior time information that concerned foreperiod duration was negligible for both process and reactive schizophrenics when the numerosity of dots was variable from trial to trial. Uniqueness of process schizophrenia was shown to be associated with prior time uncertainty reduction of foreperiod duration in the context of minimal event uncertainty of stimulus.

Effets de la Durée du Stimulus et de la Nature de la Réponse Sur L’Amplitude de la CNV Enregistrée Chez L’Homme Dans des Tâches de Temps de Réaction et D’Estimation Temporelle

[Effects of Stimulus Duration and Response Nature on CNV Amplitude. STUDIED in Man Performing Reaction Time and Time Estimation Tasks] The effects of several factors upon CNV amplitude were examined. Subjects were proposed two types of situations: 1. A simple reaction time taskwith a fixed preparatory period. An auditory warning signal (s1) was followed 2 seconds later by a visual signal (s2). The subject had to press or release the button as rapidly as possible when s2 commenced. 2. A time estimation task (DRL schedule). The subject had to press or release the button between 2 and 2.5 seconds following the onset of s1. Two types of s1 were used in each task: a short lone of 100 msec, or a long tone of 2.5 sec. Two types of responses were required: a brief button press, or a button release after a sustained button press. The type of task did not affect cnv amplitude, while the type of response had a slight influence according to time. The type of stimulus significantly affected CNV amplitude, which was higher when s1 was a long tone. Three points are mainly discussed: the possible relation between CNV and the temporal component of preparatory processes, the relation between CNV and slow positive waves associated with sustained motor activity, and the role of activation as a determinant of CNV amplitude.

The contingent negative variation related to preparatory set in a reaction time situation with variable foreperiod

It is well established that when the foreperiod varies over a short range from trial to trial, simple reaction time decreases as foreperiod duration increases. An experiment was conducted to relate this development of preparatory set to the slow change of cortical potential known as the contingent negative variation (CNV). Ten subjects were presented with an auditory warning signal and a visual reaction signal, with interstimulus intervals of 500, 600, 700, 800 and 900 msec arranged in random order. The hypotheses that reaction time decreases and CNV amplitude increases as monotonic functions of foreperiod duration were upheld. These data combine with those already in the literature to suggest that the form of the CNV reflects the development of preparatory set.

Evoked potentials in reaction time with a variable foreperiod.

The reaction times (RTs) of 12 subjects were recorded in a design where a visual or auditory warning signal preceded an auditory RT signal by one of four short foreperiods 500, 750, 1000 or 1250 ms long, which occured in a random sequence. For the 16 trials at each foreperiod, with each modality of warning signal, the average of the 2-s long EEG samples following the warning signal was computed so that the record showed the scalp recorded (vertex–-left mastoid) evoked potentials (EPs) to both warning and RT signals, and also the contingent negative variation or expectancy wave occurring during the foreperiod. Differences between RTs with different foreperiods were not reflected in negatively correlated differences in the amplitude of the RT signal EPs, taking the major positive going deflection between peaks N1 and P2 at mean latencies of 126 and 231 msec after the RT signal. Furthermore RT signal EPs preceded by a warning signal were highly attenuated in amplitude relative to control EPs which were not preceded by a warning signal, whether or not an RT response was required. This was despite the fact that alerted RTs were slightly faster than non-alerted RTs, so that these findings contradict previous findings associating augmented EPs with responding versus not responding and with speeded RTs. However, it was also found that RT signal EP amplitudes were greater with the more effective modality of warning signal than the less effective, which was consistent with previous findings. The divergence from previous findings when comparing EPs preceded by a warning with those having no prior warning is tentatively accounted for in terms of persisting physiological refractoriness following the warning signal EP.