Probe Stimuli Research Articles

Visual duration bisection in profoundly deaf individuals.

BackgroundPrevious research has been designed to study the effect of hearing loss on supra-second duration estimation in the visual channel and position effect of visual abilities among deaf populations. The current study aimed to investigate the sub-second duration perception of different visual fields in profoundly deaf individuals.MethodsA total of 16 profoundly deaf undergraduates and 16 hearing undergraduates completed a visual duration bisection task in which participants made judgments about whether a series of probe durations that were linearly spaced from 200 ms to 800 ms at 100 ms intervals were more similar to a standard short duration (200 ms) or a standard long duration (800 ms). The probe stimuli were presented in the center, left, or right of the screen. A repeated measure analysis of variance (ANOVA) with a between-participants factor of group and a within-participants factor of position, and a one-sample t-test were conducted.ResultsThe Weber ratio (WR) values of deaf participants were significantly higher than those of hearing participants, regardless of the presented positions of the visual stimulus. The bisection point (BP) value of deaf participants was significantly lower than 500 ms (average mean of 200/800 ms) and the BP value of hearing participants did not significantly differ from 500 ms, although the overall difference of BP values between the deaf group and hearing group did not reach significance. For deaf participants, the BP value in the center condition was significantly lower than 500 ms; however, the difference between the BP value in the left condition and 500 ms did not reach significance, indicating that their duration discrimination accuracy in the left visual field was better than that in the center visual field.ConclusionsHearing loss impaired visual sub-second duration perception, and deaf individuals showed a left visual field advantage of duration discrimination accuracy during the visual duration bisection task.

Distributional Learning of Speech Sounds: An Exploratory Study Into the Effects of Prior Language Experience

AbstractDistributional learning is typically understood as (unattended) tracking of stimulus probabilities. Distributional training with speech yields mixed results and the influencing factors have not yet been fully investigated. This study explored whether prior linguistic experience could have an effect on distributional learning outcomes. Czech and Greek adults, whose native languages contain and lack abstract length categories, respectively, were exposed to novel vowels falling into unimodal or bimodal distributions along the durational dimension. A trending interaction suggested that the Czechs and the Greeks might have been affected differently by the distributional exposure. Improved discrimination of the “trained” contrast was observed in bimodally exposed Czechs (whose prior expectations about length categories could guide learning) and, rather surprisingly, in unimodally exposed Greeks (who, lacking any expectations, might have listened in a noncategorical, auditory mode). Prior linguistic experience could thus affect whether and how experienced language users exploit new distributional speech statistics. This proposal needs to be assessed in future studies.

Neural Oscillations Associated With Auditory Duration Maintenance in Working Memory in Tasks With Controlled Difficulty.

The neural representation of the external events duration in working memory (WM) remains to be understood. It has been reported that there were different neural representations below and above 3 s/2 s for visual/auditory duration, respectively. However, these studies had limitations in experimental design, i.e., the interference of task difficulty was not assessed. Consequently, the results of these studies require verification. In the present study, we eliminated these limitations using an exploratory experiment in which the probe stimulus conditions were reset, while the other settings remained similar to those used in previous studies. In the exploratory experiment, we found that accuracy and reaction times were comparable among all the four duration conditions, suggesting that task difficulty was accurately matched. In the formal experiment, theta and alpha oscillations were examined using electroencephalogram recordings during the maintenance of the auditory duration in working memory, after removing the interference of task difficulty. Electroencephalogram results indicated that there were no significant differences in theta band power among different length of durations retained in working memory, whereas the alpha band power was significantly lower in the 3-s and 4-s duration conditions than in the 1-s and 2-s conditions. The findings suggest that different internal representations of auditory durations above and below the 2-s threshold are maintained in working memory. Also, our study provides evidence that the duration representation segmentation is associated with the length of the auditory duration retained in working memory, but not with task difficulty.

Classification of biosonar target echoes based on coarse and fine spectral features in the bottlenose dolphin (Tursiops truncatus)

Previous bottlenose dolphin studies suggest that the coarse envelope of an echo spectrum ("macrostructure") has hierarchical dominance over finer-scale spectral features ("microstructure") during synthetic echo discrimination tasks. In this study, two dolphins listened to and discriminated between underwater sound stimuli consisting of pairs of clicks with different micro- and macrostructures. After conditioning dolphins to reliably discriminate between two "anchor" stimuli with different micro- and macrostructures, probe stimuli, which contained a macrostructure identical to one of the anchor stimuli and the microstructure of the alternate anchor, were infrequently presented. Dolphins responded to probes in a manner consistent with macrostructure primacy.

Identity-Based Crossmodal Negative Priming: Aftereffects of Ignoring in One Sensory Modality on Responding to Another Sensory Modality.

Negative Priming (NP) refers to the phenomenon that responses towards previously ignored stimuli, as compared to new stimuli, are impaired. That is, NP is reflected in the performance on the probe display of a prime-probe sequence. NP is established in vision, audition and touch. In the current study, we presented participants with auditory, visual, and tactile manifestations of the same temporal patterns in order to measure NP across the senses. On each trial, the sensory modality shifted from the prime to the probe. Each prime and probe display consisted of a target and a distractor stimulus, presented to the same sensory modality. On some trials, the prime distractor repeated as probe target (ignored-repetition trials), on other trials the probe stimuli had not been involved in the prime display (control trials). We observed NP between audition and touch (Experiment 1) and between vision and audition (Experiment 2). These findings indicate that the processes underpinning NP can operate at an amodal, postperceptual level.

Uncoupling Sensation and Perception in Human Time Processing.

Timing emerges from a hierarchy of computations ranging from early encoding of physical duration (time sensation) to abstract time representations (time perception) suitable for storage and decisional processes. However, the neural basis of the perceptual experience of time remains elusive. To address this, we dissociate brain activity uniquely related to lower-level sensory and higher-order perceptual timing operations, using event-related fMRI. Participants compared subsecond (500 msec) sinusoidal gratings drifting with constant velocity (standard) against two probe stimuli: (1) control gratings drifting at constant velocity or (2) accelerating gratings, which induced illusory shortening of time. We tested two probe intervals: a 500-msec duration (Short) and a longer duration required for an accelerating probe to be perceived as long as the standard (Long—individually determined). On each trial, participants classified the probe as shorter or longer than the standard. This allowed for comparison of trials with an “Objective” (physical) or “Subjective” (perceived) difference in duration, based on participant classifications. Objective duration revealed responses in bilateral early extrastriate areas, extending to higher visual areas in the fusiform gyrus (at more lenient thresholds). By contrast, Subjective duration was reflected by distributed responses in a cortical/subcortical areas. This comprised the left superior frontal gyrus and the left cerebellum, and a wider set of common timing areas including the BG, parietal cortex, and posterior cingulate cortex. These results suggest two functionally independent timing stages: early extraction of duration information in sensory cortices and Subjective experience of duration in a higher-order cortical–subcortical timing areas.

Electrophysiological correlates of the differential outcomes effect in visual short-term memory

The differential outcomes procedure (DOP) consists in applying a specific outcome after each discriminative stimulus-correct response pairing, leading to improved performance in both memory and learning tasks (faster acquisition and/or higher response accuracy), compared to the non-differential outcomes procedure (NOP). The main aim of this study was to explore the electrophysiological correlates (ERPs) of the DOP in a visual short-term memory task, and to test whether a differential activation pattern would be observed depending on the outcomes condition (DOP vs. NOP). The ERP signals showed differences between both outcomes condition in all three phases of the short-term memory task: encoding, maintenance and retrieval. Our results are in accordance with the view that in the DOP condition the probe stimulus triggers a representation of the unique outcome, which remains active over the maintenance period (prospective process). In the NOP condition, in contrast, a representation of the probe stimulus is maintained (retrospective process). In addition, these results suggested that stimuli associated with unique outcomes captured attention involuntary at retrieval, decreasing the interference from distractor stimuli in the retrieval phase.

P300 response modulation reflects breaches of non-probabilistic expectations

In oddball paradigms, infrequent stimuli elicit larger P300 event related potentials (ERPs) than frequent ones. One hypothesis is that P300 modulations reflect the degree of “surprise” associated with unexpected stimuli. That is the P300 represents how unlikely the stimulus is and this signal is then used to update the observer’s expectations. It could be hypothesized that P300 is modulated by any factor affecting an observer’s expectations, not only target probability. Alternatively, the P300 may reflect an evaluative process engaged whenever a discrepancy between task context and sensory inputs arises, irrespective of the latter probability. In previous ERP studies, stimulus probability was often the only determinant of task set confounding the effects of stimulus probability and set stimulus discrepancy. In this study, we used a speeded luminance detection task. The target was preceded by a central cue that predicted its location. The probability that the target was valid, i.e. would appear at the cued location was manipulated by varying the reliability of the cue. Reaction times were modulated by probabilistic expectations based on cue reliability and target validity while P300 was affected by target validity only. We conclude that increased P300 amplitude reflects primarily breaches of non-probabilistic expectations, rather than target probability.

설문 기반 대응방안을 사용한 복합시행 프로토콜의 재평가

Traditional deception detection methods had examined the difference of one’s autonomic physiological responses through asking crime-related and crime-unrelated questions. There has been a continuing controversy regarding the accuracy and validity of the test, and thus, many researchers were motivated to explore and develop alternative efficient methods of detection in which one of them is known as P300-based Complex Trial Protocol (CTP). The P300-based CTP detects deception through comparing the P300 amplitudes between probe and irrelevant stimuli and is known as a counterstrategy of countermeasures. However, many previous studies have used countermeasures created from Rosenfeld et al.’s work (2008).The present study initially conducted a survey asking open-ended questions about the countermeasure use to acquire participant-oriented countermeasures for the main experiment. Then, the study aimed to evaluate whether the CTP can accurately detect deception even in the use of survey-based countermeasures. We firstly selected a set of participant-oriented countermeasures through survey questions. Then, a total of 50 participants were divided into three groups (innocent, guilty, and countermeasures) and performed the CTP. Those assigned to the countermeasures group covertly performed mental countermeasures during the CTP. The results of P300 amplitude analysis revealed that the guilty group’s P300 amplitude of probe stimuli was significantly larger than that of irrelevant stimuli. Countermeasures group also had a significantly larger P300 amplitude for probe stimuli compared to irrelevant stimuli, even in the use of countermeasures. The results of bootstrapped amplitude difference (BAD) showed a detection accuracy rate of 81.25%, 82.35%, 82.35% for the innocent, guilty, and countermeasures groups, respectively. These findings demonstrate that the CTP can obtain a high detection rate in participant-oriented countermeasures and suggest the potential use of the CTP in the

Decision Making and Oddball Effects on Pupil Size: Evidence for a Sequential Process.

In our physical environment as well as in many experimental paradigms, we need to decide whether an occurring stimulus is relevant to us or not; further, stimuli have uneven probabilities to emerge. Both, decision making and the difference between rare and frequent stimuli (oddball effect) are described to affect pupil dilation. Surprisingly though, conjoint systematic pupillometric investigations into both factors are still rare. In two experiments, both factors as well as their interplay were investigated. Participants completed a sequential letter matching task. In this task, stimulus probability and letter matching (decision making) were manipulated independently. As dependent variables, pupil dilation and reaction time were assessed. Results suggest a clearly larger pupil dilation for target than for distractor letters, even when targets were frequent and distractors rare. When considering the data structure best, no main effect of stimulus probability was found, instead, oddball effects only emerged when stimuli were goal-relevant to participants. The results are discussed in the light of common theoretical concepts of decision making and stimulus probability. Finally, relating theories of each factor, we propose an integrated framework for effects of decision making and stimulus features on pupil dilation. We assume a sequential mechanism during which incoming stimuli are decided upon regarding their goal relevance and, about 200 ms later, relevant stimuli are appraised regarding their value.

Effect of inter-aural modulation depth difference on interaural time difference thresholds for speech: An observational study

Background: The temporal envelope (ENV) plays a vital role in conveying inter-aural time difference (ITD) in many clinical populations. However, the presence of background noise and electronic features, such as compression, reduces the modulation depth of ENV to a different degree in both ears. The effect of ENV modulation depth differences between the ears on ITD thresholds is unknown; therefore, this was the aim of the current study’s investigation. Methods: Six normally hearing young adults (age range 20-30 years) participated in the current study. Six vowel-consonant-vowel (VCV) (/aka/, /aga/, /apa/, /aba/, /ata/, /ada/) tokens were used as the probe stimuli. ENV depth of VCV tokens was smeared by 0%, 29%, and 50%, which results in 100%, 71%, and 50% of the original modulation depth. ITD thresholds were estimated as a function of the difference in temporal ENV depth between the ears, wherein in one ear the modulation depth was retained at 100% and in the other ear, the modulation depth was changed to 100%, 71%, and 50%. Results: Repeated measures of ANOVA revealed a significant main effect of interaural modulation depth differences on the ITD threshold (F(2,10)= 9.04, p= 0.006). ITD thresholds increased with an increase in the inter-aural modulation depth difference. Conclusion: Inter-aural ENV depth is critical for ITD perception.

The influence of cognitive load on susceptibility to audio

In this study we evaluate how cognitive load affects susceptibility to auditory signals. Previous research has used the frontal P3 (fP3) event related potential response to auditory novel stimuli as an index for susceptibility to auditory signals. This work demonstrated that tasks that induce cognitive load such as visual and manual tasks, reduced susceptibility. It is however unknown whether cognitive load without visual or manual components also reduces susceptibility. To investigate this, we induced cognitive load by means of the verb generation task, in which participants need to think about a verb that matches a noun. The susceptibility to auditory signals was measured by recording the event related potential in response to a successively presented oddball probe stimulus at 3 different inter-stimulus intervals, 0 ms, 200 ms or 400 ms after the offset of the noun from the verb generation task. An additional control baseline condition, in which oddball response was probed without a verb generation task, was also included. Results show that the cognitive load associated with the verb task reduces fP3 response (and associated auditory signal susceptibility) compared to baseline, independent of presentation interval. This suggests that not only visual and motor processing, but also cognitive load without visual or manual components, can reduce susceptibility to auditory signals and alerts.

The First 250\u2009ms of Auditory Processing: No Evidence of Early Processing Negativity in the Go/NoGo Task

Past evidence of an early Processing Negativity in auditory Go/NoGo event-related potential (ERP) data suggests that young adults proactively process sensory information in two-choice tasks. This study aimed to clarify the occurrence of Go/NoGo Processing Negativity and investigate the ERP component series related to the first 250 ms of auditory processing in two Go/NoGo tasks differing in target probability. ERP data related to each task were acquired from 60 healthy young adults (M = 20.4, SD = 3.1 years). Temporal principal components analyses were used to decompose ERP data in each task. Statistical analyses compared component amplitudes between stimulus type (Go vs. NoGo) and probability (High vs. Low). Neuronal source localisation was also conducted for each component. Processing Negativity was not evident; however, P1, N1a, N1b, and N1c were identified in each task, with Go P2 and NoGo N2b. The absence of Processing Negativity in this study indicated that young adults do not proactively process targets to complete the Go/NoGo task and/or questioned Processing Negativity’s conceptualisation. Additional analyses revealed stimulus-specific processing as early as P1, and outlined a complex network of active neuronal sources underlying each component, providing useful insight into Go and NoGo information processing in young adults.

Necessity of the target discrimination in the P300-based complex trial protocol test for concealed information.

The two most common types of ERP-based protocols to detect concealed information are the 3-stimulus protocol (3SP) and Complex Trial Protocol (CTP). Both protocols traditionally include presentation of a target (a stimulus with assigned significance requiring a unique behavioral response). The intention of the target presentation is forcing subjects to pay attention to all stimuli, especially to guilty knowledge stimuli, called probes. It was unclear though, how the presence of a targets influences probe recognition, and thus, the concealed information test (CIT) effect-the difference in P300 response to the probe and Irrelevant (crime-unrelated) stimuli. The question of target necessity was first raised in relation to the 3SP, and it was found that although omitting target stimuli reduced P300 amplitudes for all probe and irrelevant stimuli, the CIT effect was not reduced. The current study investigated how the presence or absence of the target/nontarget discrimination in the CTP affects the CIT effect, by comparing two CTP groups both with (T) and without (NT) the target/nontarget discrimination. The results demonstrated that this discrimination significantly increases the P300 effect. We found a greater P300 CIT effect in the T group than in the NT group, suggesting that for field use, it is better to retain the target discrimination in the CTP. CIT effects were also seen with P300 latency, but not reaction time.

Effect of inter-aural modulation depth difference on interaural time difference thresholds for speech: An observational study.

Background: The temporal envelope (ENV) plays a vital role in conveying inter-aural time difference (ITD) in many clinical populations. However, the presence of background noise and electronic features, such as compression, reduces the modulation depth of ENV to a different degree in both ears. The effect of ENV modulation depth differences between the ears on ITD thresholds is unknown; therefore, this was the aim of the current study's investigation. Methods: Six normally hearing young adults (age range 20-30 years) participated in the current study. Six vowel-consonant-vowel (VCV) (/aka/, /aga/, /apa/, /aba/, /ata/, /ada/) tokens were used as the probe stimuli. ENV depth of VCV tokens was smeared by 0%, 29%, and 50%, which results in 100%, 71%, and 50% of the original modulation depth. ITD thresholds were estimated as a function of the difference in temporal ENV depth between the ears, wherein in one ear the modulation depth was retained at 100% and in the other ear, the modulation depth was changed to 100%, 71%, and 50%. Results: Repeated measures of ANOVA revealed a significant main effect of interaural modulation depth differences on the ITD threshold (F(2,10)= 9.04, p= 0.006). ITD thresholds increased with an increase in the inter-aural modulation depth difference. Conclusion: Inter-aural ENV depth is critical for ITD perception.

A New Technique to Measure the Level of Interest Using Heartbeat-Evoked Brain Potential

Abstract. Interest is a positive emotion related to attention. The event-related brain potential (ERP) probe technique is a useful method to evaluate the level of interest in dynamic stimuli. However, even in the irrelevant probe technique, the probe is presented as a physical stimulus and steals the observer’s attentional resources, although no overt response is required. Therefore, the probe might become a problematic distractor, preventing deep immersion of participants. Heartbeat-evoked brain potential (HEP) is a brain activity, time-locked to a cardiac event. No probe is required to obtain HEP data. Thus, we aimed to investigate whether the HEP can be used to evaluate the level of interest. Twenty-four participants (12 males and 12 females) watched attractive and unattractive individuals of the opposite sex in interesting and uninteresting videos (7 min each), respectively. We performed two techniques each for both the interesting and the uninteresting videos: the ERP probe and the HEP techniques. In the former, somatosensory stimuli were presented as task-irrelevant probes while participants watched videos: frequent (80%) and infrequent (20%) stimuli were presented at each wrist in random order. In the latter, participants watched videos without the probe. The P2 amplitude in response to the somatosensory probe was smaller and the positive wave amplitudes of HEP were larger while watching the videos of attractive individuals than while watching the videos of unattractive ones. These results indicate that the HEP technique is a useful method to evaluate the level of interest without an external probe stimulus.

Electric-acoustic interaction measurements in cochlear-implant users with ipsilateral residual hearing using electrocochleography.

Cochlear implantation is increasingly being used as a hearing-loss treatment for patients with residual hearing in the low acoustic frequencies. These patients obtain combined electric-acoustic stimulation (EAS). Substantial residual hearing and relatively long electrode arrays can lead to interactions between the electric and acoustic stimulation. This work investigated EAS interaction through psychophysical and electrophysiological measures. Moreover, cone-beam computed-tomography data was used to characterize the interaction along spatial cochlear locations. Psychophysical EAS interaction was estimated based on the threshold of audibility of an acoustic probe stimulus in the presence of a simultaneously presented electric masker stimulus. Intracochlear electrocochleography was used to estimate electrophysiological EAS interaction via the telemetry capability of the cochlear implant. EAS interaction was observed using psychophysical and electrophysiological measurements. While psychoacoustic EAS interaction was most pronounced close to the electrical stimulation site, electrophysiological EAS interaction was observed over a wider range of spatial cochlear locations. Psychophysical EAS interaction was significantly larger than electrophysiological EAS interaction for acoustic probes close to the electrode position.

Functional dissociation of multiple-object tracking mechanisms based on hemispheric asymmetries.

A number of theoretical accounts have been put forward to explain the ability to simultaneously track multiple visually indistinguishable objects over a period of time. Serial processing models of visual tracking focus on the maintenance of the spatial locations of every single item over time. A more recent mechanism describes multiple object tracking as the ability to maintain a higher order representation of an abstract spatial configuration built by the illusory connection of the tracked items through their transition. The current study investigates the correspondence between these serial and parallel tracking accounts and the right hemispheric specialization for the space-based vs. left hemispheric for object-based attentional processing. Electrophysiological brain responses were recorded in two groups of patients with right- and left hemispheric lesions while performing in a multiple object tracking task. The results suggest a failure to distinguish single item information for the right hemispheric patients accompanied by the absence of a known electrophysiological marker associated with single item tracking. Importantly, left hemispheric patients showed a graded behavioral and electrophysiological response to probe stimuli as a function of the congruence of the probe with the relevant target stimuli. The current data suggest that the differential contribution of serial and parallel tracking mechanisms during object tracking can partly be explained by the different functional contributions of the right and left brain hemispheres.

Stimulus probability affects the visual N700 component of the event-related potential

ObjectiveTo examine whether the occipito-temporal visual N700 component of the event-related potential is sensitive to stimulus probabilities. MethodsP1, N1, P3, and, in particular, the occipito-temporal N700 component of the event-related potential were analysed in response to frequent and rare non-target letters of a continuous performance task in 200 healthy adolescents. Additionally, amplitude habituation with time was examined for the occipito-temporal N700 and N1 components. ResultsThe visual P1, N1, and occipito-temporal N700 components were significantly larger in response to rare letters than to frequent letters, whereas the P3 component demonstrated no amplitude difference. Over time, the occipito-temporal N700 amplitude decreased in response to the rare letters, while the N1 amplitude increased, to both, frequent and rare letters. ConclusionsThis study provides first evidence that the visual occipito-temporal N700 is sensitive to stimulus probabilities, suggesting an enhanced post-processing of rare stimuli in secondary visual areas. The distinct habituation patterns of occipito-temporal N700 and N1 amplitudes distinguish repetition effects on stimulus post-processing (N700) from those on perception (N1). SignificanceThe enhanced N700 component to rare stimuli might reflect an orienting response and underlying attentional processes. The N700 sensitivity to stimulus probabilities should be examined in patient groups with attentional deficits.

Fixation related shifts of perceptual localization counter to saccade direction.

Perisaccadic compression of the perceived location of flashed visual stimuli toward a saccade target occurs from about 50 ms before a saccade. Here we show that between 150 and 80 ms before a saccade, perceived locations are shifted toward the fixation point. To establish the cause of the "reverse" presaccadic perceptual distortion, participants completed several versions of a saccade task. After a cue to saccade, a probe bar stimulus was briefly presented within the saccade trajectory. In Experiment 1 participants made (a) overlap saccades with immediate return saccades, (b) overlap saccades, and (c) step saccades. In Experiment 2 participants made gap saccades in complete darkness. In Experiment 3 participants maintained fixation with the probe stimuli masked at various interstimulus intervals. Participants indicated the bar's location using a mouse cursor. In all conditions in Experiment 1 presaccadic compression was preceded by compression toward the initial fixation. In Experiment 2, saccadic compression was maintained but the preceding countercompression was not observed. Stimuli masked at fixation were not compressed. This suggests the two opposing compression effects are related to the act of executing an eye movement. They are also not caused by the requirement to make two sequential saccades ending at the initial fixation location and are not caused by continuous presence of the fixation markers. We propose that countercompression is related to fixation activity and is part of the sequence of motor preparations to execute a cued saccade.