Vibrotactile frequency discrimination at short durations

This experiment investigated how frequency discrimination of a sinusoidal, mechanical vibration applied to the tip of the right index finger is affected by shortening the duration of the stimuli from 200 ms to 30 ms. Using a standard stimulus of 100 Hz at 30 dB above threshold, seven comparison frequencies (at intervals of 10 Hz) were judged as higher or lower in frequency according to the method of constant differences. Vibrotactile stimuli were matched for subjective intensity across both frequency and duration. Difference limens for vibrotactile frequency were found to decline slightly from 200 ms to 50 ms (attributable to practice) and to increase noticeably at 30 ms. This result is discussed in relation to the seemingly contradictory results for auditory pitch discrimination.     

右侧背外侧前额叶皮质在时间知觉中的作用:基于经颅磁刺激的研究

将10 Hz的重复经颅磁刺激(r TMS)施加于右背外侧前额叶皮质(r DLPFC),探讨该区域在时间加工模型中的作用。实验一采用时间复制任务,通过比较基线和后测条件下时间估计行为的差异,探究高频r TMS离线施加于r DLPFC之后对时间知觉的影响。实验二采用毫秒和秒两种范围的时距,探究r DLPFC在不同范围的时间知觉中的作用。结果发现r TMS施加于r DLPFC导致对1.5 s高估,对600 ms的估计无显著影响,提示r DLPFC在涉及工作记忆加工过程的秒范围的时间知觉中有重要作用。     

振动触觉频率信息的工作记忆容量及存储机制

工作记忆可以同时保存多个信息并且容量有限, 这一内在机制是工作记忆研究的重点问题。视觉和言语等研究领域都发现工作记忆能够存储多个信息单元, 但对振动触觉工作记忆是否能存储多个频率信息目前尚无相关研究。由于振动触觉频率刺激和视觉刺激具有不同的神经编码机制, 以及振动频率信息是通过躯体感觉产生的模拟的、单维的、参数化信息, 振动触觉工作记忆容量及其加工存储机制的研究也必不可少。首先, 本项目将采用新的实验范式, 探究不同的刺激呈现方式以及不同反应报告方式下, 振动触觉工作记忆的容量及其认知机制。其次, 本项目也将同时运用功能磁共振成像(fMRI)技术, 来阐述振动触觉工作记忆加工存储的神经机制。探究基于触觉频率信息的参数工作记忆容量及其神经机制是完善工作记忆模型的重要补充, 将有助于提高我们对工作记忆系统的理解, 并为视觉、听觉、触觉多模态感知觉信息的跨通道研究奠定基础。     

Vibrotactile frequency discrimination

Thresholds for vibrotactile discrimination of pulse interval were determined for pulse frequencies between 1 and 384 Hz. The results point to a temporal resolution significantly more accurate than that demonstrated in earlier studies. Although touch as a vibratory sensor is in general much inferior to audition, the present results show a striking resemblance to those obtained on auditory pitch. The neurophysiological implications for the tactile as well as for the auditory system are discussed.     

Good vibrations: Human interval timing in the vibrotactile modality

This article reports a detailed examination of timing in the vibrotactile modality and comparison with that of visual and auditory modalities. Three experiments investigated human timing in the vibrotactile modality. In Experiment 1, a staircase threshold procedure with a standard duration of 1,000 ms revealed a difference threshold of 160.35 ms for vibrotactile stimuli, which was significantly higher than that for auditory stimuli (103.25 ms) but not significantly lower than that obtained for visual stimuli (196.76 ms). In Experiment 2, verbal estimation revealed a significant slope difference between vibrotactile and auditory timing, but not between vibrotactile and visual timing. That is, both vibrations and lights were judged as shorter than sounds, and this comparative difference was greater at longer durations than at shorter ones. In Experiment 3, performance on a temporal generalization task showed characteristics consistent with the predications of scalar expectancy theory (SET: Gibbon, 1977) with both mean accuracy and scalar variance exhibited. The results were modelled using the modified Church and Gibbon model (MCG; derived by Wearden, 1992, from Church & Gibbon 1982). The model was found to give an excellent fit to the data, and the parameter values obtained were compared with those for visual and auditory temporal generalization. The pattern of results suggest that timing in the vibrotactile modality conforms to SET and that the internal clock speed for vibrotactile stimuli is significantly slower than that for auditory stimuli, which is logically consistent with the significant differences in difference threshold that were obtained.     

Effects of stimulus order on discrimination processes in comparative and equality judgements: Data and models

In typical discrimination experiments, participants are presented with a constant standard and a variable comparison stimulus and their task is to judge which of these two stimuli is larger (comparative judgement). In these experiments, discrimination sensitivity depends on the temporal order of these stimuli (Type B effect) and is usually higher when the standard precedes rather than follows the comparison. Here, we outline how two models of stimulus discrimination can account for the Type B effect, namely the weighted difference model (or basic Sensation Weighting model) and the Internal Reference Model. For both models, the predicted psychometric functions for comparative judgements as well as for equality judgements, in which participants indicate whether they perceived the two stimuli to be equal or not equal, are derived and it is shown that the models also predict a Type B effect for equality judgements. In the empirical part, the models' predictions are evaluated. To this end, participants performed a duration discrimination task with comparative judgements and with equality judgements. In line with the models' predictions, a Type B effect was observed for both judgement types. In addition, a time-order error, as indicated by shifts of the psychometric functions, and differences in response times were observed only for the equality judgement. Since both models entail distinct additional predictions, it seems worthwhile for future research to unite the two models into one conceptual framework.     

Spatio-temporal dynamics of face recognition in a flash: it’s in the eyes

We adapted the Bubbles procedure [Vis. Res. 41 (2001) 2261] to examine the effective use of information during the first 282 ms of face identification. Ten participants each viewed a total of 5100 faces sub‐sampled in space–time. We obtained a clear pattern of effective use of information: the eye on the left side of the image became diagnostic between 47 and 94 ms after the onset of the stimulus; after 94 ms, both eyes were used effectively. This preference for the eyes increased with practice, and was not solely due to the informativeness of the eyes for the task at hand. The bias for the eye on the left side of the image is explained in terms of hemispheric specialization. Although there were individual differences, most participants exhibited this pattern of effective use of information. An intriguing finding is that most participants displayed a clear sinusoidal modulation of effective use of attention through time with a frequency of about 10.6 Hz.     

The effects of type of interval,sensory modality,base duration,and psychophysical task on the discrimination of brief time intervals

The present study was designed to investigate the influences of type of psychophysical task (two-alternative forced-choice [2AFC] and reminder tasks), type of interval (filled vs. empty), sensory modality (auditory vs. visual), and base duration (ranging from 100 through 1,000 ms) on performance on duration discrimination. All of these factors were systematically varied in an experiment comprising 192 participants. This approach allowed for obtaining information not only on the general (main) effect of each factor alone, but also on the functional interplay and mutual interactions of some or all of these factors combined. Temporal sensitivity was markedly higher for auditory than for visual intervals, as well as for the reminder relative to the 2AFC task. With regard to base duration, discrimination performance deteriorated with decreasing base durations for intervals below 400 ms, whereas longer intervals were not affected. No indication emerged that overall performance on duration discrimination was influenced by the type of interval, and only two significant interactions were apparent: Base Duration × Type of Interval and Base Duration × Sensory Modality. With filled intervals, the deteriorating effect of base duration was limited to very brief base durations, not exceeding 100 ms, whereas with empty intervals, temporal discriminability was also affected for the 200-ms base duration. Similarly, the performance decrement observed with visual relative to auditory intervals increased with decreasing base durations. These findings suggest that type of task, sensory modality, and base duration represent largely independent sources of variance for performance on duration discrimination that can be accounted for by distinct nontemporal mechanisms.     

Perception of the duration of auditory and visual stimuli in children and adults

This experiment investigated the effect of modality on temporal discrimination in children aged 5 and 8 years and adults using a bisection task with visual and auditory stimuli ranging from 200 to 800 ms. In the first session, participants were required to compare stimulus durations with standard durations presented in the same modality (within-modality session), and in the second session in different modalities (cross-modal session). Psychophysical functions were orderly in all age groups, with the proportion of long responses (judgement that a duration was more similar to the long than to the short standard) increasing with the stimulus duration, although functions were flatter in the 5-year-olds than in the 8-year-olds and adults. Auditory stimuli were judged to be longer than visual stimuli in all age groups. The statistical results and a theoretical model suggested that this modality effect was due to differences in the pacemaker speed of the internal clock. The 5-year-olds also judged visual stimuli as more variable than auditory ones, indicating that their temporal sensitivity was lower in the visual than in the auditory modality.     

前瞻记忆的字形、语音TAP效应研究

本研究采用单因素实验设计,以30名大学生为被试,基于双重任务范式,考察了前瞻任务为材料驱动的情况下,前瞻记忆语音、字形适当迁移加工(transfer—appropriate processing,TAP)效应。结果发现：TAP效应对前瞻记忆的辨别力指标和传递效率的影响达到了显著性水平,而对于前瞻记忆判断标准的影响未达到显著水平。     

Lingual vibrotactile threshold alterations in response to varying stimulation levels of intensity and duration.

Lingual vibrotactile thresholds were obtained at a frequency of 250 Hz by using an ascending-continuous series of stimulation during five sessions. Each of three adult male Ss attended a control session which included a prescribed period of constant tongue positioning, a pre-experimental session where the mean of six thresholds was obtained as a basis of further testing, and three experimental sessions. In the experimental sessions vibrotactile thresholds after exposure to vibratory stimulation of varying levels of intensity and duration were obtained. The findings of the control session reflected a slight pattern of decreased lingual sensitivity indicative of the influential factor of constant maintenance of tongue positioning. Results from the experimental sessions demonstrated shifts toward progressively decreased lingual sensitivity after exposure to vibratory signals of increased levels of intensity and duration. A recovery phase to near-normal sensitivity followed each stimulus presentation.     

Auditory/visual duration bisection in patients with left or right medial-temporal lobe resection

Patients with unilateral (left or right) medial temporal lobe lesions and normal control (NC) volunteers participated in two experiments, both using a duration bisection procedure. Experiment 1 assessed discrimination of auditory and visual signal durations ranging from 2 to 8 s, in the same test session. Patients and NC participants judged auditory signals as longer than equivalent duration visual signals. The difference between auditory and visual time discrimination was equivalent for the three groups, suggesting that a unilateral temporal lobe resection does not modulate the modality effect. To document interval-timing abilities after temporal lobe resection for different duration ranges, Experiment 2 investigated the discrimination of brief, 50-200 ms, auditory durations in the same patients. Overall, patients with right temporal lobe resection were found to have more variable duration judgments across both signal modality and duration range. These findings suggest the involvement of the right temporal lobe at the level of the decision process in temporal discriminations.     

Spatial constraints on visual-tactile cross-modal distractor congruency effects

Across three experiments, participants made speeded elevation discrimination responses to vibrotactile targets presented to the thumb (held in a lower position) or the index finger (upper position) of either hand, while simultaneously trying to ignore visual distractors presented independently from either the same or a different elevation. Performance on the vibrotactile elevation discrimination task was slower and less accurate when the visual distractor was incongruent with the elevation of the vibrotactile target (e.g., a lower light during the presentation of an upper vibrotactile target to the index finger) than when they were congruent, showing that people cannot completely ignore vision when selectively attending to vibrotactile information. We investigated the attentional, temporal, and spatial modulation of these cross-modal congruency effects by manipulating the direction of endogenous tactile spatial attention, the stimulus onset asynchrony between target and distractor, and the spatial separation between the vibrotactile target, any visual distractors, and the participant’s two hands within and across hemifields. Our results provide new insights into the spatiotemporal modulation of crossmodal congruency effects and highlight the utility of this paradigm for investigating the contributions of visual, tactile, and proprioceptive inputs to the multisensory representation of peripersonal space.     

Intermittency of visual information and the frequency of rhythmical force production

The authors examined the influence of intermittent (40-5,000 ms) visual information on the control of rhythmical isometric force output (0.5, 2.0, and 4.0 Hz) in 10 participants. Force variability decreased as a function of less intermittent visual information only in the 0.5- and 2.0-Hz tasks. Vision influenced the frequency structure of force output through 0-12 Hz in the 0.5-Hz task, but in only the 10.0- to 12.0-Hz range in the 2.0-Hz task and not in the 4.0-Hz task. The effective use of intermittent visual information in force output was mediated by task frequency, and that mediation was reflected in the differential emphasis of feedback and feedforward processes over multiple timescales of control.     

Temporal generalization under time pressure in humans

In two experiments, participants performed a temporal generalization task in which they were asked to decide whether or not the durations of comparison stimuli were different from those of standard stimuli (750 ms, 1,000 ms, or 1,250 ms). One half of the participants was instructed to respond as quickly as possible, while the other half received no instruction concerning the speed of response. The relationship between stimulus duration and the time of response and the effect of time pressure on duration discrimination were examined. Response time increased as a linear function of the duration of the to-be-judged stimuli until a certain instant, which was defined as T₂ = s/(1 - b), where s refers to the internal representation of the standard duration and b to the decision threshold. Moreover, the participants systematically overestimated the presented intervals if they were asked to respond as fast as possible when the standard duration was either 1,000 ms or 1,250 ms, but not when the standard duration was 750 ms.     

The effect of marker frequency disparity on the discrimination of gap duration in monkeys

Duration-discrimination thresholds of the silent interval (gap) between two successive tones (markers) were measured in four Japanese monkeys. The task was serial discrimination, and monkeys were required to release the lever when the gap duration decreased from 200 ms. Monkeys successfully acquired the task, and gap thresholds of monkeys were revealed to be larger than previous data with human subjects. Gap thresholds were not affected by marker frequency when the two markers were identical in frequency, though the thresholds increased when large frequency differences existed between markers. The effect of marker frequency disparity on gap thresholds in monkeys is discussed in terms of the difficulty in integrating information from discrete frequency channels.     

空间推理的脑机制：一项ERP研究

记录14名正常成人完成四种空间推理及一种基线任务（记忆任务）时的事件相关电位,对空间推理的脑电活动情况进行考察。研究结果表明,在200ms-900ms窗口,推理任务比基线任务诱发更大的正成分。对不同推理任务的比较表明,具体与抽象材料的单模型推理诱发相似的波形;单模型与有效的双模型任务诱发的ERP成分明显不同,在300ms-600ms窗口,后者比前者诱发更大的正波;在200-600ms时间窗口,存在有效结论与无有效结论的双模型问题也诱发明显不同的ERP波形。研究的结果表明,推理与记忆涉及不同的加工要求,推理需要整合前提的信息,而记忆只需要储存前提信息。在解决双模型推理问题时,从200ms开始,被试就对刺激材料进行初步的加工与判断,随后对双模型问题采用有注解的单模型加工策略。另外,不同材料的空间推理任务之间的波形较为一致,表明视觉表象并未明显影响空间推理过程。     

疼痛表情对秒下及秒上时距知觉的影响

采用二分法和泛化法范式,在秒下及秒上呈现时距探究疼痛表情对时距知觉的影响。结果发现,使用二分法,疼痛表情在秒上秒下都显著延长了个体的主观时距,但使用泛化法,疼痛表情仅在秒上产生影响。根据时间分段综合模型和范式特点,该实验结果反映疼痛表情对时距知觉的影响在秒上秒下的作用机制可能不同,在秒下主要是通过唤醒影响,在秒上则可能由唤醒和注意共同调节。     

Time Perception: Modality and Duration Effects in Attention-Deficit/Hyperactivity Disorder (ADHD)

Time perception performance was systematically investigated in adolescents with and without attention-deficit/hyperactivity disorder (ADHD). Specifically, the effects of manipulating modality (auditory and visual) and length of duration (200 and 1000 ms) were examined. Forty-six adolescents with ADHD and 44 controls were administered four duration discrimination tasks and two control tasks, and a set of standardized measures. Participants with ADHD had higher thresholds than controls on all of the duration discrimination tasks, with the largest effect size obtained on the visual 1000 ms duration discrimination task. No group differences were observed on the control tasks. Visual–spatial memory was found to be a significant predictor of visual and auditory duration discrimination at longer intervals (1000 ms) in the ADHD sample, whereas auditory verbal working memory predicted auditory discrimination at longer intervals (1000 ms) in the control sample. These group differences suggest impairments in basic timing mechanisms in ADHD.     

Temporal generalization under time pressure in humans

In two experiments, participants performed a temporal generalization task in which they were asked to decide whether or not the durations of comparison stimuli were different from those of standard stimuli (750 ms, 1,000 ms, or 1,250 ms). One half of the participants was instructed to respond as quickly as possible, while the other half received no instruction concerning the speed of response. The relationship between stimulus duration and the time of response and the effect of time pressure on duration discrimination were examined. Response time increased as a linear function of the duration of the to-be-judged stimuli until a certain instant, which was defined as T ₂ = s/(1 – b), where s refers to the internal representation of the standard duration and b to the decision threshold. Moreover, the participants systematically overestimated the presented intervals if they were asked to respond as fast as possible when the standard duration was either 1,000 ms or 1,250 ms, but not when the standard duration was 750 ms.