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PubMed1980

Children's understanding of some temporal terms denoting order, duration, and simultaneity.

This study examined the comprehension by children of the concepts of order, duration, and simultaneity as reflected in certain linguistic structures. The children in the study were 3, 5, and 7 years old. Temporal order was examined through children's comprehension of two-clause sentences containing the conjunctions "after," "before," "since," and "until." Temporal duration was examined through children's understanding of one-clause sentences containing the progressive aspect and two-clause sentences containing the conjunctions "since" and "until." These two conjunctions signal duration in the main clause when they conjoin two clauses. Simultaneity was studied through children's comprehension of two-clause sentences containing "while." The results revealed that the order sentence structures ("before" and "after") were generally comprehended by the children before the duration or simultaneous sentence structures, although at 7 years of age children were still not performing above chance on the order relation in "since" and "until" sentences. The duration sentence structures were comprehended by the children before the simultaneous sentence structures. The results support the literature in cognitive psychology and in philosophy which argues that order is simpler than duration is simpler than simultaneity.

Child↗
PubMed1981

Elicited imitation in lexical development: evidence from a study of temporal reference.

This study examined the use of elicited imitation in investigating lexical development within a semantic domain. For this purpose the acquisition of reference to sequence and simultaneity by 3-5 year old children was examined. Three factors were proposed to account for the older in which lexical items within a semantic field are acquired: restrictedness of a lexical item, congruence with perceptual strategies, and conceptual simplicity. A significantly greater number of correct responses was found in sentences describing sequential events than in simultaneous events. Furthermore, imitations of sentences referring to simultaneity were more degraded than imitations of sentences referring to sequence. The children seemed to begin acquiring reference to temporally related events by learning about words describing serially ordered events. A three stage developmental model is proposed to account for the results.

Child, Preschool↗
PubMed1982

Acoustical correlates of the perception of speech rate: an experimental investigation.

The purpose of the study was to investigate the influence of vocal frequency and vocal intensity upon the perception of speech rate at three levels of actual speech rate. A single sample of spontaneous speech was electronically varied to produce nine stimulus segments that factorially combined three levels each of vocal frequency and intensity. The nine stimuli were recorded such that preceding each was the original segment that served as the standard with which each of the nine stimuli was to be compared. The speech rate of the set of nine stimulus pairs was then electronically altered to obtain a slow set, a moderate set, and a fast set, although the duration of every segment in the three sets was 20 seconds. The sets were rated by different groups of judges in terms of four 7-point scales that measured perceived speech rate, pitch, loudness, and perceived duration. The results indicate that the perception of speech rate is positively related to vocal frequency and intensity at each of the three actual speech rates, and suggest that these relationships are a function of the repeated experience of almost always hearing such covariation in spontaneously occurring speech.

Adolescent↗
PubMed1994

Modeling human motion perception. I. Classical stimuli.

Motion perception is one of the most prominent tasks of the visual system and therefore has been extensively investigated both experimentally and theoretically. A classical model describing the mechanism of motion detection originally developed in the context of insect orientation behavior, the elementary motion detector (EMD) of the correlation type, turned out to be very powerful in explaining many basic aspects of human motion perception. For more complex visual tasks, like the discrimination of a figure from its background by relative motion, on the other hand, further processing of motion information is required. In the first part of this review it will be illustrated by means of a few examples, what kind of motion information can be derived from the mere correlation-type model, and what perceptual phenomena can be accounted for by the EMD. In the second part, more recently developed stimuli will be introduced to answer the question what further processing steps, or more sophisticated mechanisms than the EMD, have to be assumed in order to understand "higher" aspects of human motion perception.

Cybernetics↗
PubMed1999

The role of phonological awareness, speech perception, and auditory temporal processing for dyslexia.

There is strong evidence that auditory processing plays a major role in the etiology of dyslexia. Auditory temporal processing of non-speech stimuli, speech perception, and phonological awareness have been shown to be influential in reading and spelling development. However, the relationship between these variables remains unclear. In order to analyze the influence of these three auditory processing levels on spelling, 19 dyslexic and 15 control children were examined. Significant group differences were found for all speech variables, but not for any non-speech variable. Structural equation modeling resulted in a fairly simple model with direct paths to the respective next lower level. One additional path from preattentive speech processing to spelling had to be included in order to improve the model fit. These results strengthen the role of speech and phonological processing for the etiology in dyslexia.

Attention↗
PubMed2002

Temporal information for spatially constrained locomotion.

How is locomotion adapted to spatial environmental constraints? The control of this everyday behavior is claimed to be based on information that specifies either spatial or temporal properties of the actor-environment system. Although studies on open-loop locomotor pointing (i.e., the positioning of a foot on a target on the floor while walking) agree on the use of spatial information, studies on closed-loop locomotor pointing propose the use of temporal information. Here, we test the hypothesis of closed-loop locomotor pointing based on temporal information, by dissociating spatial and temporal information in a virtual reality setup (virtual environment connected to a treadmill). The results support this hypothesis and shed some light on the type of temporal information that is used. The performed dissociation between spatial and temporal information, however, does not rule out a control based on a continuous updating of spatial information. Therefore, our conclusion on the use of temporal information was moderated.

Adaptation, Physiological↗
PubMed2003

Audiovisual temporal order judgments.

In two experiments, we examined the extent to which audiovisual temporal order judgments (TOJs) were affected by spatial factors and by the dimension along which TOJs were made. Pairs of auditory and visual stimuli were presented from either the left and/or right of fixation at varying stimulus onset asynchronies (SOAs), and participants made unspeeded TOJs regarding either "Which modality was presented first?" (experiment 1), or "Which side was presented first?" (experiment 2). Modality TOJs were more accurate (i.e. just-noticeable differences, JNDs, were smaller) when the auditory and visual stimuli were presented from different spatial positions rather than from the same position, highlighting an important potential confound inherent in previous research. By contrast, spatial TOJs were unaffected by whether or not the two stimuli were presented in different modalities. A between-experiments comparison revealed more accurate performance (i.e. smaller JNDs) when people reported which modality came first than when they reported which side came first for identical bimodal stimulus pairs. These results demonstrate that multisensory TOJs are critically dependent on both the relative spatial position from which stimuli are presented and on the particular dimension being judged.

Acoustic Stimulation↗
PubMed2005

Differential effects of mental load on proximal and distal arm muscle activity.

Work-related upper extremity disorders (WRUEDs) that result from keyboarding tasks are prevalent and costly. Although the precise mechanisms causing the disorder are not yet fully understood, several risk factors have been proposed. These include the repetitive nature of the motor task and the associated sustained static working postures, but also more psychological factors such as mental load. Epidemiological surveys have shown that WRUEDs are more prone to develop in the postural muscles of the neck/shoulder area than in the executive muscles controlling the hand. The present study investigated whether the activation patterns of these two muscle types are differentially affected by an additional mental load during the performance of a repetitive tapping task. Participants tapped various keying patterns with their dominant index finger at two prescribed tempi. Mental load was manipulated by means of an auditory short-term memory task. We recorded the EMG activity of two neck/shoulder muscles (trapezius and deltoid), two upper arm muscles (biceps and triceps), and four forearm muscles (flexor digitorum superficialis, extensor digitorum, extensor carpi radialis longus and extensor carpi ulnaris) and analyzed the kinematics and impact forces of the index finger. The results confirmed that the upper limb has two functions. Specifically, activity of the executive distal musculature was increased during tapping at the higher pace, while the activity of the postural upper limb musculature was elevated due to the memory task. We argue that continuously increased muscular activity can lead to fatigue and thus eventually cause musculoskeletal complaints. The results are discussed with respect to biomechanical adaptation strategies that deal with the consequences of increased noise in the neuromotor system due to enhanced mental processing.

Adult↗
PubMed2005

The role of spatial disparity and hemifields in audio-visual temporal order judgments.

We explored whether sensitivity to audio-visual temporal order judgments (TOJs) was affected by the amount of spatial separation between a sound and light, and by whether the sound and light were presented in the same or in different hemifields. Participants made TOJs about noise bursts and light flashes, and judged whether the stimuli came from the same location or not. Flashes were presented either in the left or right hemifield (at +/-10 degrees from central fixation), and sounds either came from the same location as the lights, or at small or large disparities (20 or 40 degrees from the light, respectively), thereby crossing the hemifields or not. TOJs became more accurate (i.e., the just noticeable difference, JND, became smaller) when spatial disparity increased and when hemifields were crossed. Location discrimination of the sound and light was affected similarly. These results demonstrate that audio-visual TOJs are critically dependent on both the relative position from which stimuli are presented and on whether stimuli cross hemifields or not.

Acoustic Stimulation↗
PubMed2005

Three dimensional spatial-temporal convergence of otolith related signals in vestibular only neurons in squirrel monkeys.

Spatio-temporal convergence (STC) properties of 19 vestibular only neurons' responses to translational head movements were examined in an alert, behaving squirrel monkey. In addition to standard tests that included 1.2 Hz yaw/pitch/roll rotations and inter-aural/naso-occipital/dorso-ventral translations, we also observed responses to translations along multiple directions in several orthogonal planes. Neural responses were fitted first by a model that permitted STC in all planes, characterized by a non-zero minimum and a gradual shift of phase. We then evaluated statistically whether models with fewer independent dynamic parameters yielded equally satisfactory results. The responses of 13 neurons were adequately fit by simple cosine models (1-D) as well as models that allowed complex STC behavior. Of the six neurons exhibiting STC, five could be modeled with two independent phase parameters (2-D) while the remaining neuron required a model with three independent phase parameters (3-D). The maximum translation sensitivity and phase, Smax and varphimax, and minimum translation sensitivity and phase, Smin and varphimin, were estimated from the reconstructed sensitivity and phase surfaces. The tuning ratio, Smin/Smax, in STC neurons was>0.40 while in 1-D neurons it was <0.25. Furthermore, the maximum response vectors of most 1-D neurons lay within 20 degrees of either the horizontal or sagittal plane while those of STC neurons lay >20 degrees from both planes. No difference in other response properties, such as varphimax or rotational responses, was found between neurons exhibiting STC and the simple cosine tuning. Our results suggest that the STC behavior observed in otolith-related vestibular neurons probably arises from summing inputs from afferents, with diverse response dynamics, innervating different otolith macula.

Acoustic Stimulation↗
PubMed2005

Spatiotemporal interactions between audition and touch depend on hand posture.

We report two experiments designed to assess the consequences of posture change on audiotactile spatiotemporal interactions. In Experiment 1, participants had to discriminate the direction of an auditory stream (consisting of the sequential presentation of two tones from different spatial positions) while attempting to ignore a task-irrelevant tactile stream (consisting of the sequential presentation of two vibrations, one to each of the participant's hands). The tactile stream presented to the participants' hands was either spatiotemporally congruent or incongruent with respect to the sounds. A significant decrease in performance in incongruent trials compared with congruent trials was demonstrated when the participants adopted an uncrossed-hands posture but not when their hands were crossed over the midline. In Experiment 2, we investigated the ability of participants to discriminate the direction of two sequentially presented tactile stimuli (one presented to each hand) as a function of the presence of congruent vs incongruent auditory distractors. Here, the crossmodal effect was stronger in the crossed-hands posture than in the uncrossed-hands posture. These results demonstrate the reciprocal nature of audiotactile interactions in spatiotemporal processing, and highlight the important role played by body posture in modulating such crossmodal interactions.

Acoustic Stimulation↗
PubMed2000

Modulation of cutaneous reflexes by load receptor input during human walking.

To investigate the influence of load on the modulation of cutaneous reflexes, evoked by sural nerve stimulation, electromyographic activity in different leg muscles (tibialis anterior, gastrocnemius medialis (GM), biceps femoris, and soleus muscles (SO)) was recorded in healthy humans during treadmill walking with different body loads. Sural nerve stimulation was applied at two times perception threshold during different phases of the step cycle. Reflex amplitudes increased with body unloading and decreased with body loading. The reflex responses were not a simple function of the level of background activity. For example, in GM and SO, the largest reflex responses occurred during walking with body unloading, when background activity was decreased. Hence, stable ground conditions (body loading) yielded smaller reflexes. It is proposed that load receptors are involved in the regulation of cutaneous reflex responses in order to adapt the locomotor pattern to the environmental conditions.

Adult↗
PubMed2000

Neural substrates of spatial and temporal disorientation in Alzheimer's disease.

To examine the neuroanatomical correlates of spatial and temporal disorientation in Alzheimer's disease (AD), we performed an anterograde clinicopathological study of 29 patients with clinically and neuropathologically confirmed AD. Spatial and temporal disorientation was assessed using the locational orientation subtests of the Mini Mental State Examination and the Benton's test for temporal orientation. Quantitative analysis of neurofibrillary tangles and senile plaques were performed in the CA1 field of the hippocampus, layers II and V of the entorhinal cortex, and layers II-III and V-VI of areas 9, 7, 39, 19, 37, 20 and 23 in the right hemisphere. Forward stepwise logistic regression was used to assess the relationship between lesion densities and the presence of either spatial or temporal disorientation; severity scores and brain weight were included as covariants. A statistically significant relationship was found between neurofibrillary tangle densities in Brodmann's areas 7, 23 and the CA1 field of hippocampus and both spatial and temporal disorientation. Senile plaque counts did not correlate with any of the neuropsychological parameters. Both temporal and spatial disorientation in AD are related to the degeneration of the same pathways linking the hippocampus with the superior parietal and posterior cingulate cortex in the right hemisphere. These observations are discussed with respect to the notion of global corticocortical disconnection in AD.

Aged↗