Response Selection and the Processing of Auditory Intensity

S-R Compatibility Effects without Response Uncertainty

Five experiments investigated whether cognitively based spatial S-R correspondence effects or “compatibility” effects can occur in simple reaction time (SRT) tasks and if so, which factors might be responsible for their occurrence and size. In Experiment 1, responses were cued before each trial, but made only after presentation of a Go signal. There were considerably faster responses with spatial correspondence of Go signal and response, demonstrating that response certainty does not prevent a compatibility effect. Experiment 2, a SRT task with “extra” trials requiring responses with the same or the opposite hand, indicated a major determinant of this effect to be the keeping of two task-relevant responses in a state of readiness. Experiment 3 provided preliminary evidence for “inertia” effects—that is, for stronger correspondence effects with frequent than with infrequent alternations between left-hand and right-hand blocks. Experiment 4 showed that correspondence effects can be obtained by using a within-hand response repertoire. Experiment 5, a replication of Experiment 3 with within-hand responses, found further evidence for inertia effects. For all experiments, reaction time distribution analyses were carried out to gain insight into the temporal dynamics of correspondence effects. Altogether the results strongly suggest that most if not all correspondence effects had a cognitive rather than an anatomical origin. This raises some doubts about conclusions from prior attempts to measure interhemispheric transmission costs by means of SRT tasks.

Polarity correspondence effect between loudness and lateralized response set

Performance is better when a high pitch tone is associated with an up or right response and a low pitch tone with a down or left response compared to the opposite pairs, which is called the spatial-musical association of response codes effect. The current study examined whether polarity codes are formed in terms of the variation in loudness. In Experiments 1 and 2, in which participants performed a loudness-judgment task and a timbre-judgment task respectively, the correspondence effect was obtained between loudness and response side regardless of whether loudness was relevant to the task or not. In Experiments 3 and 4, in which the identical loudness- and timbre-judgment tasks were conducted while the auditory stimulus was presented only to the left or right ear, the correspondence effect was modulated by the ear to which the stimulus was presented, even though the effect was marginally significant in Experiment 4. The results suggest that loudness produced polarity codes that influenced response selection (Experiments 1 and 2), and additional spatial codes provided by stimulus position modulated the effect, generating the stimulus eccentricity effect (Experiments 3 and 4), which is consistent with the polarity correspondence principle.

Functional Locus of Intensity Effects in Choice Reaction Time Tasks

Long reaction times (RT) paradoxically occur with extremely loud auditory stimuli ( Van der Molen & Keuss, 1979 , 1981 ) or with ultrabright and large visual stimuli ( Jaśkowski & Włodarczyk, 2006 ) when the task requires a response choice. Van der Molen and Keuss (1981 ) hypothesized that this effect results from an arousal-driven elongation of response-selection processes. We tested this hypothesis using visual stimuli and chronopsychophysiological markers. The results showed that the latency of both early (P1 recorded at Oz) and late (P300) evoked potentials decreased monotonically with intensity. In contrast, the latency of stimulus-locked lateralized readiness potentials (LRP) abruptly increased for the most intense stimuli, thus mirroring the reaction time–intensity relationship. Response-locked LRPs revealed no dependency on intensity. These findings suggest that the processes responsible for the van der Molen-Keuss effect influence processing stages that are completed before the onset of LRP. The van der Molen-Keuss effect likely occurs later than those represented by early sensory potentials. This is in keeping with the hypothesis of van der Molen-Keuss.

Effect of loudness on reaction time and response force in different motor tasks

Van der Molen and Keuss, in 1979 and 1981, showed that paradoxically long reaction times occur with extremely strong auditory stimuli when the task is difficult, e.g., choice-by-location or Simon paradigm. It was argued that this paradoxical behavior of RT is due to active inhibition of an arousal-dependent bypassing mechanism to prevent false responses. As the peak force, i.e., maximal force exerted by participants on a response key, is considered to be related to immediate arousal, we predicted that for extremely loud stimuli and for difficult tasks, lengthening of RT should be associated with reduction of peak force. Moreover, these effects should be enhanced when emphasis is on accuracy rather than speed. Although the relation between RT and intensity depended on task difficulty, no increase in RT was found for the loudest tones. Moreover, peak force increased monotonically with loudness, showing no tendency to be suppressed for loudest tones and difficult tasks.

Effects of stop signal modality, stop signal intensity and tracking method on inhibitory performance as determined by use of the stop signal paradigm

In Experiment 1, the effects of stop signal modality on the speed and efficiency of the inhibition process were examined. Stop signal reaction time (SSRT) and inhibition function slope in an auditory stop signal condition were compared to SSRT and inhibition function slope in a visual stop signal condition. It was found that auditory stop signals compared to visual stop signals enhanced both the speed and efficiency of stopping. The modality effects were attributed to differences in the neurophysiological processes underlying perception. However, Experiment 2 demonstrated that the modality difference was larger for 80 dB(A) auditory stop signals than 60 dB(A) auditory stop signals. This effect was reconciled with the suggestion that loud tones are more capable of eliciting immediate arousing effects on motor processes than weak tones and visual stimuli. The second purpose of the present investigation was to explore the utility (and potential advantages) of an alternative way of setting stop signal delay relative to mean reaction time (MRT). The method that was suggested compensates for inter-individual differences in primary task reaction speed by setting stop signal delays as proportions of the subjects' MRT.

Task modulation of the effects of brightness on reaction time and response force

Van der Molen and Keuss [van der Molen, M.W., Keuss, P.J.G., 1979. The relationship between reaction time and intensity in discrete auditory tasks. Quarterly Journal of Experimental Psychology 31, 95-102; van der Molen, M.W., Keuss, P.J.G., 1981. Response selection and the processing of auditory intensity. Quarterly Journal of Experimental Psychology 33, 177-184] showed that paradoxically long reaction times (RT) occur with extremely loud auditory stimuli when the task is difficult (e.g. needs a response choice). It was argued that this paradoxical behavior of RT is due to active suppression of response prompting to prevent false responses. In the present experiments, we demonstrated that such an effect can also occur for visual stimuli provided that they are large enough. Additionally, we showed that response force exerted by participants on response keys monotonically grew with intensity for large stimuli but was independent of intensity for small visual stimuli. Bearing in mind that only large stimuli are believed to be arousing this pattern of results supports the arousal interpretation of the negative effect of loud stimuli on RT given by van der Molen and Keuss.

Accessory stimulation in the time course of visuomotor information processing: stimulus intensity effects on reaction time and response force

A series of three visual choice-reaction time experiments were performed to systematically investigate the effects of accessory auditory stimulation on response time (RT) and response force (RF). In Experiment 1, the effect of accessory auditory stimulation on early visual information processing was investigated. Experiments 2 and 3 were designed to examine the effects of accessory intensity on RT and RF across the entire time course of sensorimotor processing. Accessory stimulation accelerated response speed only when presented within 100 ms after onset of the visual response signal. An enhancing effect of accessory stimulation on RF, however, was found as late as 220 ms after onset of the response signal. These findings support the notion that response speed and response dynamics represent functionally independent sensorimotor phenomena.

Influence of sleep deprivation and auditory intensity on reaction time and response force

Arousal and activation are two variables supposed to underlie change in response force. This study was undertaken to explain these roles, specifically, for strong auditory stimuli and sleep deficit. Loud auditory stimuli can evoke phasic overarousal whereas sleep deficit leads to general underarousal. Moreover, Van der Molen and Keuss (1979, 1981) showed that paradoxically long reaction times occurred with extremely strong auditory stimuli when the task was difficult, e.g., choice reaction or Simon paradigm. It was argued that this paradoxical behavior related to reaction time is due to active disconnecting of the coupling between arousal and activation to prevent false responses. If so, we predicted that for extremely loud stimuli and for difficult tasks, the lengthening of reaction time should be associated with reduction of response force. The effects of loudness and sleep deficit on response time and force were investigated in three different tasks: simple response, choice response, and Simon paradigm. According to our expectation, we found a detrimental effect of sleep deficit on reaction time and on response force. In contrast to Van der Molen and Keuss, we found no increase in reaction time for loud stimuli (up to 110 dB) even on the Simon task.

Procedural differences in processing intact and degraded stimuli

In three experiments, the extent to which the processing of a visual stimulus profits from equal processing demands of a preceding stimulus was examined. Subjects identified two subsequently presented digits (S1 and S2) that were either intact or degraded by noise, yielding four combinations of stimulus quality. In Experiments 1 and 2, S1 and S2 differed with respect to the values of the digits, so that stimulus quality was the only dimension of possible agreement. The results revealed a faster response to S2 when the stimulus pairs were homogeneous (both intact or both degraded stimuli) than when they were not homogeneous (degraded-intact pairs and intact-degraded pairs, respectively). The occurrence of equal values of S1 and S2 (Experiment 3) tended to magnify this homogeneous-stimulus effect, but was not a prerequisite for its occurrence. Relative to conditions considered to be neutral, the homogeneous-stimulus effect proved to be due to deviant behavior following the processing of a degraded S1. The suggestion that this reflects the involvement of controlled processing is discussed.

Parsing attentional components during a simple reaction time task using sleep deprivation and amphetamine intervention

To examine the independent contributions of the attentional components of arousal and activation in performance, sleep deprivation was used as the attentional manipulation in a reaction time (RT) task. The subjects were 18 men who underwent 63 hr. of sleep deprivation during which time they periodically performed a simple auditory RT task with manipulations of temporal uncertainty and intensity. After 48 hr. sleep deprivation, subjects ingested either 20 mg d-amphetamine or placebo, then continued testing throughout Day 3. During sleep deprivation, performance was more impaired on trials associated with low temporal uncertainty (arousal) and high preparation (activation) than on trials associated with high temporal uncertainty and low preparation. Analysis indicated that sleep deprivation perturbed activation, leaving arousal relatively unimpaired and that amphetamine had a restorative effect on the sleep deprivation-impaired activation system. The stimulus of high intensity was disruptive on Day 1 but facilitative on Day 3, a result which was interpreted as an initial inhibition, then disinhibition of arousal. Results were interpreted to indicate that, in some instances, alterations in the less specific arousal and activation systems may underlie impairment or changes in the more specific information processing and motor output stages.

Auditory accessory effects on visual processing

A series of experiments on intersensory facilitation demonstrates that non-informative sound of low to moderate intensity (30/80 dB) facilitates the reaction to a visual stimulus. By manipulating the preprocessing and perceptual stages of the visual signals, it appears that auditory intensity reduces choice reaction time independently from the positive influence of the intensity and duration of the visual imperative signal, but interacts with the effect of stimulus degradation. Degraded stimuli take more profit of the sound than intact stimuli. Besides a short-term activation effect, originated by accessories of the auditory modality, on the motor adjustment stage (cf. Sanders 1983), the results suggest that the accessory influences the stage of feature extraction.

Effect of conflicting cues on information processing: the 'Stroop effect' vs. the 'Simon effect'

This study examined the relationship between two sources of interference in human information processing: the Stroop effect and the Simon effect. Forty subjects pressed a left- or right-hand key in response to a Stroop color word located on the left or right side of a screen. For one group, ink color was the relevant cue and, for another group, word meaning was the relevant cue. Independent variables were: congruence, i.e., agreement or lack thereof between the ink color and meaning of the Stroop word; spatial correspondence, i.e., agreement or lack thereof between the location of the Stroop word and the location of the key used to make the response; and stimulus duration, i.e., 400 or 100 ms. Each of these variables had a significant effect on RT, and there were no significant interactions. According to Sternberg's additive-factor logic, these findings suggest that the Stroop effect (congruence) and the Simon effect (spatial correspondence) involve separate stages of processing. If one assumes that manipulation of stimulus duration effects the encoding stage, then results also suggest that neither the Stroop effect nor the Simon effect involves the stimulus encoding stage.

Attention to auditory and peripheral visual stimuli: effects of arousal and predictability

Changes in the distribution of attention among auditory and peripheral visual stimuli were examined in a choice reaction time paradigm. Two variables were manipulated: predictability of stimulus locations and arousal state of subjects. The arousal level of some subjects was raised by occasionally exposing them to brief, mild electric shocks. On most trials either a tone or a light was presented alone (single-stimulus trials). However, on 20% of the trials both a tone and light were presented simultaneously (dual trials). Two dependent variables were used to assess dominance of attention: reaction time (on all trials) and percentage of time each modality was chosen on dual trials. Neither modality was dominant when subjects were in a nonaroused state and stimulus locations were unpredictable. However, peripheral vision dominated when stimulus locations were predictable or when the subjects' level of arousal was raised. The results are discussed with reference to previous research on sensory dominance and on the facilitating or inhibiting effects of auditory stimuli on reaction time.