Accessory Stimulus Research Articles

Phasic alertness reverses the beneficial effects of accessory stimuli on choice reaction.

Humans respond faster to visual target stimuli when these are accompanied by auditory accessory stimuli. This accessory stimulus effect occurs even though accessory stimuli do not predict which response has to be made. Similar performance benefits occur when auditory stimuli serve as so-called alerting cues by preceding rather than accompanying the visual targets. This latter effect is attributed to phasic alertness, a short-lived increase of the brain's readiness for responding to external information. Phasic alertness and accessory stimulation each have been studied extensively, but it is unclear how the two work in concert. Therefore, the present study investigated how auditory alerting modulates the effects of subsequent accessory stimuli accompanying the targets of a visual choice reaction task. Results showed that accessory stimuli helped performance in the absence of alerting cues but impaired performance when alerting cues had been presented beforehand (Experiment 1). This reversed accessory stimulus effect did not seem due to expectations regarding the combination of accessory stimuli and alerting cues (Experiment 2). Together, the present findings reveal that phasic alertness changes the effects of accessory stimulation in a qualitative fashion: Alerting turns the otherwise helping accessory stimulus into a saboteur of performance.

Exteroceptive stimuli override interoceptive state in reaction time control.

The processing of reaction time (RT) stimulus is modulated by its timing relative to the cardiac cycle. RT stimulus processing is also influenced by task-irrelevant stimuli: a sensory stimulus speeds RT when it accompanies a cue to react in another sensory modality. Different theories have been proposed to explain this accessory stimulus effect (ASE). However, it is unclear whether the ASE interacts with the cardiac timing effect. In the present study, the relationship of the ASE, cardiac timing, and stimulus valence was examined. Fifty-two subjects performed 400 trials of a simple RT task. Images of neutral and fear faces served as visual accessory stimuli; the RT stimulus was a 75 dB tone. Electrocardiography was recorded. Visual and auditory stimuli were presented at either cardiac systole or diastole. The stimulus onset asynchrony between visual and auditory stimuli was either 0 or 75 ms. Repeated measures ANOVAs showed that cardiac timing modulated RT, but only when accessory stimuli were absent. RT was shorter when the accessory stimulus preceded the imperative stimulus with respect to simultaneous presentation. The ASE was not influenced by visual stimulus valence or cardiac timing. Results indicate that the ASE overrides cardiac timing effects, suggesting a dynamic balance between exteroceptive stimuli and interoceptive states, and highlight the importance of embodied information processing.

Accessory stimuli speed reaction times and reduce distraction in a target-distractor task.

Eye movements in a visual search task are drawn towards items irrelevant to the search (distractors). Advance information about the position or features of distractors can reduce this effect, by speeding the resolution of conflict between search target and distractor. The present study investigated whether this can also be achieved by a prime that merely warns of an impending task without providing any other information (an accessory stimulus). We found that accessory stimuli speed the initiation of a saccade to the target, but also speed the resolution of target-distractor conflict. This finding suggests that the oculomotor system can be prepared to counteract distraction in advance of task onset, without requiring information about a specific spatial location or feature.

The accessory stimulus effect is mediated by phasic arousal: A pupillometry study.

People usually respond faster to a visual stimulus when it is immediately preceded by a task-irrelevant, auditory accessory stimulus (AS). This AS effect occurs even in choice reaction time tasks, despite the fact that the AS carries no information about the correct response. Researchers often assume that the AS effect is mediated by a phasic arousal burst evoked by the AS, but direct evidence for that assumption is lacking. We conducted a pupillometry study to directly test the phasic arousal hypothesis. Participants carried out a demanding choice reaction time task with accessory stimuli occurring on 25% of the trials. Pupil diameter, a common index of arousal, was measured throughout the task. Standard analyses of task performance and pupil diameter showed that participants exhibited the typical AS effect, and that accessory stimuli evoked a reliable early pupil dilation on top of the more protracted dilation associated with the imperative stimulus. Moreover, regression analyses at the single-trial level showed that variation in reaction times on AS trials was selectively associated with pupil dilation during the early time window within which the AS had an effect, such that particularly large AS-evoked dilations were associated with especially fast responses. These results provide the first evidence that the AS effect is mediated by AS-evoked phasic arousal.

Accessory stimulus modulates executive function during stepping task.

When multiple sensory modalities are simultaneously presented, reaction time can be reduced while interference enlarges. The purpose of this research was to examine the effects of task-irrelevant acoustic accessory stimuli simultaneously presented with visual imperative stimuli on executive function during stepping. Executive functions were assessed by analyzing temporal events and errors in the initial weight transfer of the postural responses prior to a step (anticipatory postural adjustment errors). Eleven healthy young adults stepped forward in response to a visual stimulus. We applied a choice reaction time task and the Simon task, which consisted of congruent and incongruent conditions. Accessory stimuli were randomly presented with the visual stimuli. Compared with trials without accessory stimuli, the anticipatory postural adjustment error rates were higher in trials with accessory stimuli in the incongruent condition and the reaction times were shorter in trials with accessory stimuli in all the task conditions. Analyses after division of trials according to whether anticipatory postural adjustment error occurred or not revealed that the reaction times of trials with anticipatory postural adjustment errors were reduced more than those of trials without anticipatory postural adjustment errors in the incongruent condition. These results suggest that accessory stimuli modulate the initial motor programming of stepping by lowering decision threshold and exclusively under spatial incompatibility facilitate automatic response activation. The present findings advance the knowledge of intersensory judgment processes during stepping and may aid in the development of intervention and evaluation tools for individuals at risk of falls.

Noradrenergic and cholinergic effects on speed and sensitivity measures of phasic alerting.

An intense but task-irrelevant auditory accessory stimulus that is presented almost simultaneously with a visual imperative stimulus can reduce reaction times (RTs) to that stimulus. The information-processing locus and neural underpinnings underlying this phasic alerting effect are still poorly understood. The authors investigated a possible noradrenergic or cholinergic basis of the accessory stimulus effect in a double-blind pharmacological study (N = 18), in which healthy participants received a single dose of clonidine (an α2-adrenergic agonist), scopolamine (a muscarinic antagonist), and placebo in separate test sessions. A backward-masking procedure was used to examine, for the first time, the effect of accessory stimuli on perceptual sensitivity. The authors found that accessory stimuli enhanced perceptual sensitivity and decreased RTs to target stimuli, consistent with a recent hypothesis that phasic alerting speeds up stimulus encoding. In contrast to the authors' expectations, clonidine increased the accessory stimulus effect, a finding that seems at odds with earlier proposals that phasic alerting effects are mediated by a phasic noradrenergic response. Furthermore, the accessory stimulus effect was modulated to a similar extent by clonidine and scopolamine, suggesting that the effect of clonidine was not specific to the noradrenergic system. The results instead suggest that clonidine and scopolamine decrease general alertness and that these drug-related reductions in alertness yield room for compensatory performance improvements by phasic alerting.

Effects of a startle stimulus on response speed and inhibition in a go/no-go task.

Two studies examined the interaction of an acoustic startle stimulus and visual go/no-go task stimuli on startle reactivity and task performance. In the first study, an acoustic stimulus (50 ms, 100 dB noise) was presented alone or with a green (go) or red (no-go) circle; in the second study, a prepulse (50 ms, 75 dB noise) was presented alone or 120 ms before the startle stimulus or circle. The startle stimulus speeded responses to the go stimuli and increased the covert false alarm rate in the no-go condition (measured by EMG activity in the hand), although very few overt errors were made in the no-go condition. Startle response magnitude was increased by a circle but decreased by a prepulse. The speeding of go responses caused by a startle stimulus was attenuated by the occurrence of a startle response, suggesting that an intense accessory stimulus can facilitate responding to an imperative stimulus, and that the startle response to that intense stimulus can interfere with that facilitation.

Simon effects in change detection and change blindness.

Responses to centrally presented target stimuli are faster when they are accompanied by a task-irrelevant lateral accessory stimulus that corresponds spatially with the response hand (accessory variant of the Simon effect). In four experiments, we tested whether this effect depends on the awareness of the accessory stimulus. In a change blindness task, participants were asked to respond to a central letter that was accompanied by a lateral background change on some trials. Change blindness describes the phenomenon that even large changes may remain unnoticed when they occur simultaneously with another visual disruption, e.g., a blank screen. In a series of four experiments, a significant Simon effect was observed both when the accessory stimulus reached awareness and when it remained unnoticed. These results indicate that, based on the spatial location of an accessory stimulus, a spatial code is generated. This code interferes with the response code on the response-selection stage.

Fronto-central theta oscillations are related to oscillations in saccadic response times (SRT): an EEG and behavioral data analysis.

The phase reset hypothesis states that the phase of an ongoing neural oscillation, reflecting periodic fluctuations in neural activity between states of high and low excitability, can be shifted by the occurrence of a sensory stimulus so that the phase value become highly constant across trials (Schroeder et al., 2008). From EEG/MEG studies it has been hypothesized that coupled oscillatory activity in primary sensory cortices regulates multi sensory processing (Senkowski et al. 2008). We follow up on a study in which evidence of phase reset was found using a purely behavioral paradigm by including also EEG measures. In this paradigm, presentation of an auditory accessory stimulus was followed by a visual target with a stimulus-onset asynchrony (SOA) across a range from 0 to 404 ms in steps of 4 ms. This fine-grained stimulus presentation allowed us to do a spectral analysis on the mean SRT as a function of the SOA, which revealed distinct peak spectral components within a frequency range of 6 to 11 Hz with a modus of 7 Hz. The EEG analysis showed that the auditory stimulus caused a phase reset in 7-Hz brain oscillations in a widespread set of channels. Moreover, there was a significant difference in the average phase at which the visual target stimulus appeared between slow and fast SRT trials. This effect was evident in three different analyses, and occurred primarily in frontal and central electrodes.

Conflict-Specific Effects of Accessory Stimuli on Cognitive Control in the Stroop Task and the Simon Task

Both the Stroop and the Simon paradigms are often used in research on cognitive control, however, there is evidence that dissociable control processes are involved in these tasks: While conflicts in the Stroop task may be resolved mainly by enhanced task-relevant stimulus processing, conflicts in the Simon task may be resolved rather by suppressing the influence of task-irrelevant information on response selection. In the present study, we show that these control mechanisms interact in different ways with the presentation of accessory stimuli. Accessory stimuli do not affect cognitive control in the Simon task, but they impair the efficiency of cross-trial control processes in the Stroop task. Our findings underline the importance of differentiating between different types of conflicts and mechanisms of cognitive control.

Saccadic Reaction Times to Audiovisual Stimuli Show Effects of Oscillatory Phase Reset

Initiating an eye movement towards a suddenly appearing visual target is faster when an accessory auditory stimulus occurs in close spatiotemporal vicinity. Such facilitation of saccadic reaction time (SRT) is well-documented, but the exact neural mechanisms underlying the crossmodal effect remain to be elucidated. From EEG/MEG studies it has been hypothesized that coupled oscillatory activity in primary sensory cortices regulates multisensory processing. Specifically, it is assumed that the phase of an ongoing neural oscillation is shifted due to the occurrence of a sensory stimulus so that, across trials, phase values become highly consistent (phase reset). If one can identify the phase an oscillation is reset to, it is possible to predict when temporal windows of high and low excitability will occur. However, in behavioral experiments the pre-stimulus phase will be different on successive repetitions of the experimental trial, and average performance over many trials will show no signs of the modulation. Here we circumvent this problem by repeatedly presenting an auditory accessory stimulus followed by a visual target stimulus with a temporal delay varied in steps of 2 ms. Performing a discrete time series analysis on SRT as a function of the delay, we provide statistical evidence for the existence of distinct peak spectral components in the power spectrum. These frequencies, although varying across participants, fall within the beta and gamma range (20 to 40 Hz) of neural oscillatory activity observed in neurophysiological studies of multisensory integration. Some evidence for high-theta/alpha activity was found as well. Our results are consistent with the phase reset hypothesis and demonstrate that it is amenable to testing by purely psychophysical methods. Thus, any theory of multisensory processes that connects specific brain states with patterns of saccadic responses should be able to account for traces of oscillatory activity in observable behavior.

Decomposition of warning effects in Parkinson's disease

ABSTRACT Neutral warning signals speed voluntary reactions by reducing temporal uncertainty and by triggering a brief burst of arousal. We attempted to isolate the phasic arousal mechanism in people with Parkinson's disease (PD) using a clock display to minimize temporal uncertainty. In this condition, the speeding of responses in a color-discrimination task by an accessory stimulus was the fully equivalent to the effect in age-matched control subjects. This indicates preserved phasic arousal in PD. Temporal preparation based on warning cues also appeared to be normal. By contrast, in a condition with high temporal uncertainty, the accessory stimulus (an air puff to the foot) impaired accuracy for the patients but not the neurologically normal subjects. The data are consistent with the view that PD disrupts internal but not external control of alertness.

Accessory Stimuli Affect the Emergence of Conflict, Not Conflict Control

Accessory signals that precede stimuli in interference tasks lead to faster overall responses while conflict increases. Two opposing accounts exist for the latter finding: one is based on dual-route frameworks of response preparation and proposes amplification of both direct response activation and indirect response selection processes; the other refers to attentional networks and suggests inhibition of executive attention, thereby hampering conflict control. The present study replicated previous behavioral findings in a Simon task and extended them by electrophysiological evidence. Accessory tones facilitated stimulus classification and attentional allocation in the Simon task as reflected by an increased N1 amplitude and an overall decrease of the N2 amplitude, respectively. The conflict-related N2 amplitude, which is larger in conflict trials compared with nonconflict trials, was not modulated by accessory tones. Moreover, accessory tones did not affect sequence-dependent conflict adaptation. In terms of a dual-route framework present results suggest amplification of both response preparation routes by accessory stimuli. An executive attention approach proposing accessory stimuli to hamper control of conflict is not supported.

DO THE MATERIAL PROPERTIES OF CUTLERY AFFECT THE PERCEPTION OF THE FOOD YOU EAT? AN EXPLORATORY STUDY

ABSTRACTOur perception of food depends both on the contextual conditions in which it is presented and on the way the food is consumed; hence, the current trend toward investigating these contextual variables in empirical research. In most meal situations, people interact with the food that they consume by means of a variety of accessories, such as dishes and cutlery that fulfill the consumers' functional requirements. However, despite the important role that these accessory stimuli play during the consumption of food, little research has been carried out in order to investigate how they may affect food perception. The present preliminary study was therefore undertaken in order to explore how the cutlery, specifically two teaspoons (a plastic one with metallic finish and a stainless steel one), affected consumers' sensory and hedonic perception of yoghurt. Consumers' quality and liking judgments concerning identical yoghurt samples differed significantly when tasted either with a metallic plastic spoon or else with a stainless steel spoon, the latter resulting in significantly higher scores.PRACTICAL APPLICATIONSThese results contribute to our knowledge of how contextual variables affect a consumer's perception of food. These findings open up new research directions emphasizing the potential importance of the properties of cutlery and its influence on consumers' perception of food. These results are relevant to product development and to caterers and restaurateurs because different dishes (i.e., foodstuffs/flavors) could be matched with different types of cutlery in order to increase convenience and, at the same, time potentially enhance the consumers' eating experience.

Cost–benefit and distributional analyses of accessory stimuli

Accessory stimuli (AS) are task-irrelevant events (typically an auditory tone) that speed reaction time (RT). With two conditions (AS-present, AS-absent) it is unclear whether AS-presence causes benefits or AS-absence causes costs, possibly due to the expectancy violations. The current study added a third condition where AS were absent in blocks and not expected (pure blocks); in other blocks, AS occurred with a probability of 0.5 (mixed blocks), allowing cost-benefit analysis comparing AS-absent RTs in pure and mixed blocks. Results demonstrated RTs were slower when AS were absent, regardless of whether the absence occurred in a mixed block or a pure block, suggesting AS do provide a benefit to RT. Additionally, AS-facilitation across the RT distribution was analysed using cumulative distribution frequencies and ex-Gaussian parameter estimation. Both provided converging evidence that AS-facilitation increases towards the slower end of the RT distribution. The implications for the utility of AS paradigms are discussed.

Auditory Warning Signals Affect Mechanisms of Response Selection

Irrelevant tone (accessory) stimuli facilitate performance in simple and choice reaction time tasks. In the present study, we combined accessory stimulation with a selective attention paradigm in order to investigate its influence on mechanisms of response selection. In the framework of a spatial stimulus-response compatibility task (Simon task), we tested whether accessory stimuli selectively affect bottom up triggered response activation processes (e.g., direct route processing), processing of task-relevant stimulus features (indirect route processing), or both/none. Results suggest a two-component effect of accessory stimuli within this selective attention task. First, accessory stimuli increased the Simon effect due to beneficial direct route processing. Second, accessory stimuli generally decreased reaction times indicating facilitation of indirect route processing.

Visual and auditory accessory stimulus offset and the Simon effect

We investigated the effect on the right and left responses of the disappearance of a task-irrelevant stimulus located on the right or left side. Participants pressed a right or left response key on the basis of the color of a centrally located visual target. Visual (Experiment 1) or auditory (Experiment 2) task-irrelevant accessory stimuli appeared or disappeared at locations to the right or left of the central target. In Experiment 1, responses were faster when onset or offset of the visual accessory stimulus was spatially congruent with the response. In Experiment 2, responses were again faster when onset of the auditory accessory stimulus and the response were on the same side. However, responses were slightly slower when offset of the auditory accessory stimulus and the response were on the same side than when they were on opposite sides. These findings indicate that transient change information is crucial for a visual Simon effect, whereas sustained stimulation from an ongoing stimulus also contributes to an auditory Simon effect.

TLR4 Promotes B Cell Maturation: Independence and Cooperation with B Lymphocyte-Activating Factor

We have previously shown that TLR4 triggering promotes the generation of CD23(+)CD93(+) transitional T2-like cells in vitro from mouse B cell precursors, suggesting a possible role for this receptor in B cell maturation. In this study, we perform an extensive study of cell surface markers and functional properties of B cells matured in vitro with LPS, comparatively with the well-known B cell maturation factor B lymphocyte-activating factor (BAFF). LPS increased generation of CD23(+) transitional B cells in a TLR4-dependent way, upregulating IgD and CD21 and downregulating CD93, without inducing cell proliferation, in a manner essentially equivalent to BAFF. For both BAFF and LPS, functional maturation of the IgM(+)CD23(+)CD93(+) cells was confirmed by their higher proliferative response to anti-CD40 plus IL-4 compared with IgM(+)CD23(neg)CD93(+) cells. BAFF-R-Fc-mediated neutralization experiments showed that TLR4-induced B cell maturation was independent of BAFF. Distinct from BAFF, maturation by LPS relied on the activation of canonical NF-kappaB pathway, and the two factors together had complementary effects, leading to higher numbers of IgM(+)CD23(+)CD93(+) cells with their simultaneous addition. Importantly, BCR cross-linking abrogated the generation of CD23(+) B cells by LPS or BAFF, indicating that signals mimicking central tolerance act on both systems. Addition of cyclosporin A reverted BCR-mediated inhibition, both for BAFF and LPS, suggesting similar regulation of signaling pathways by calcineurin. Finally, LPS-injected mice showed a rapid increase of mature B cells in the bone marrow, suggesting that TLR4 signaling may effectively stimulate B cell maturation in vivo, acting as an accessory stimulus in B cell development, complementary to the BAFF physiological pathway.

Visuo‐spatial processing and the N1 component of the ERP

Asymmetries in posterior ERP components, such as the N1, are generally taken to reflect the visual processing of spatial information in absolute (fixation-based) coordinates. Yet, it is also well established that the position of an object can be coded relative to the position of other objects. To examine the ERP correlates of relative spatial coding, two experiments were conducted in which spatially neutral target stimuli were preceded, accompanied, or followed by laterally presented, task-irrelevant accessory stimuli. Targets presented simultaneously with a lateral accessory evoked, despite physical asymmetry, a bilateral, symmetric N1. Targets that followed the accessory evoked, despite physical symmetry, an asymmetric N1, with a maximum contralateral to the accessory N1. Thus, lateralizations in the N1 range already reflect relative spatial coding rather than just the processing of the absolute location of incoming information.

Flanker and Simon effects interact at the response selection stage

The present study aimed at investigating the processing stage underlying stimulus-stimulus (S-S) congruency effects by examining the relation of a particular type of congruency effect (i.e., the flanker effect) with a stimulus-response (S-R) spatial correspondence effect (i.e., the Simon effect). Experiment 1 used a unilateral flanker task in which the flanker also acted as a Simon-like accessory stimulus. Results showed a significant S-S Congruency x S-R Correspondence interaction: An advantage for flanker-response spatially corresponding trials was observed in target-flanker congruent conditions, whereas, in incongruent conditions, there was a noncorresponding trials' advantage. The analysis of the temporal trend of the correspondence effects ruled out a temporal-overlap account for the observed interaction. Moreover, results of Experiment 2, in which the flanker did not belong to the target set, demonstrated that this interaction cannot be attributed to perceptual grouping of the target-flanker pairs and referential coding of the target with respect to the flanker in the congruent and incongruent conditions, respectively. Taken together, these findings are consistent with a response selection account of congruency effects: Both the position and the task-related attribute of the flanker would activate the associated responses. In noncorresponding-congruent trials and corresponding-incongruent trials, this would cause a conflict at the response selection stage.