Biomedical subjects

T A Mondor

Publications and source records attributed to T A Mondor.

17 recordsLinked to original sources

PubMed2001

Facilitative and inhibitory effects of cuing sound duration, intensity, and timbre.

Two experiments are reported in which the possibility that auditory attention may be controlled in a stimulus-driven manner by duration, intensity, and timbre cues was examined. In both experiments, listeners were presented with a cue followed, after a variable time period of a 150-, 450-, or 750-msec stimulus onset asynchrony (SOA), by a target. In three different conditions for each experiment, the duration, intensity, or timbre relation between the cue and the target was varied so that, on 50% of the trials, the two sounds were identical and, on 50% of the trials, the two sounds were different in the manipulated feature. The two experiments differed only in the judgment required, with listeners in Experiment 1 identifying the duration, intensity, or timbre of the target and listeners in Experiment 2 indicating whether the target incorporated a brief silent gap. In both experiments, performance was observed to depend on both the similarity of and the time between the cue and the target. Specifically, whereas at the 150-msec SOA performance was best when the target was identical to the preceding cue, at the 750-msec SOA performance was best when the cue and the target differed. This pattern establishes the existence of duration-, intensity-, and timbre-based auditory inhibition of return. The theoretical implications of these results are considered.

Acoustic Stimulation↗

PubMed2000

On the role of eye movements and saccade preparation in generating auditory inhibition of return.

In three experiments, listeners were required to either localize or identify the second of two successive sounds. The first sound (the cue) and the second sound (the target) could originate from either the same or different locations, and the interval between the onsets of the two sounds (Stimulus Onset Asynchrony, SOA) was varied. Sounds were presented out of visual range at 135 azimuth left or right. In Experiment 1, localization responses were made more quickly at 100 ms SOA when the target sounded from the same location as the cue (i.e., a facilitative effect), and at 700 ms SOA when the target and cue sounded from different locations (i.e., an inhibitory effect). In Experiments 2 and 3, listeners were required to monitor visual information presented directly in front of them at the same time as the auditory cue and target were presented behind them. These two experiments differed in that in order to perform the visual task accurately in Experiment 3, eye movements to visual stimuli were required. In both experiments, a transition from facilitation at a brief SOA to inhibition at a longer SOA was observed for the auditory task. Taken together these results suggest that location-based auditory IOR is not dependent on either eye movements or saccade programming to sound locations.

Analysis of Variance↗

PubMed1999

Auditory attention to space and frequency activates similar cerebral systems.

PET was used to test the hypothesis that similar neural systems are involved in attending to spectral and to spatial features of sounds. In each of four conditions subjects heard tones varying randomly in frequency and location and responded to either the low- or the high-frequency stimuli, ignoring location, or to stimuli on the left or right, ignoring frequency. In comparison to a silent baseline, CBF increases were observed in auditory cortex bilaterally and in the right superior parietal, right dorsolateral frontal, and right premotor regions, with no modulation as a function of attentional condition. Analysis of regional covariation indicated a coordinated CBF response between the right parietal region and the right frontal and middle temporal regions. The data imply that auditory attention engages a network of right-hemisphere cortical regions for both spatial location and tonal frequency and support a model whereby auditory attention operates at a level at which separate features have been integrated into a unitary representation.

Adult↗

PubMed1999

Facilitative and inhibitory effects of location and frequency cues: evidence of a modulation in perceptual sensitivity.

The possibility that facilitative and inhibitory effects of auditory cues result because of a modulation in perceptual sensitivity was examined. Listeners were presented with a cue followed by a target, with the time period between the two varied at stimulus onset asynchronies (SOAs) of 150, 450, or 750 msec. In two conditions, the cue and target were either the same or different in location or frequency. In both conditions, listeners were required to identify the rise time of the target. Whereas the cue was presented in isolation, the target was presented in a wide-band noise background such that the required discrimination was made relatively difficult. In both conditions, a facilitative effect was apparent at the 150-msec SOA and an inhibitory effect was apparent at the 750-msec SOA for both accuracy and response time measures of performance. That these results were apparent for a judgment unrelated to the manipulated cue-target relation suggests strongly that both location-based and frequency-based auditory inhibition of return result primarily because of changes in perceptual sensitivity.

Attention↗

PubMed1999

Predictability of the cue-target relation and the time-course of auditory inhibition of return.

The possibility that the time-course of auditory inhibition of return (IOR) might depend on the temporal or spatial predictability of the cue-target relation was investigated. In all the experiments, a location cue was followed by a target that was to be localized. An inhibitory effect became apparent at a longer stimulus onset asynchrony (SOA) when either the temporal or the spatial relation was predictable, rather than when either was unpredictable. A facilitative effect was apparent at a 100-msec SOA, irrespective of the predictability of the cue-target relation. These results establish that the time-course of the inhibitory component of location-based auditory IOR depends on the predictability of the temporal and spatial relations of cue and target. The theoretical implications of these results are considered, and a dual-process model of auditory selective attention is offered.

Adult↗

PubMed1998

Effect of same- and different-modality spatial cues on auditory and visual target identification.

A target identification paradigm was used to study cross-modal spatial cuing effects on auditory and visual target identification. Each trial consisted of an auditory or visual spatial cue followed by an auditory or visual target. The cue and target could be either of the same modality (within-modality conditions) or of different modalities (between-modalities conditions). In 3 experiments, a larger cue validity effect was apparent on within-modality trials than on between-modalities trials. In addition, the likelihood of identifying a significant cross-modal cuing effect was observed to depend on the predictability of the cue-target relation. These effects are interpreted as evidence (a) of separate auditory and visual spatial attention mechanisms and (b) that target identification may be influenced by spatial cues of another modality but that this effect is primarily dependent on the engagement of endogenous attentional mechanisms.

Analysis of Variance↗

PubMed1998

Inhibitory processes in auditory selective attention: evidence of location-based and frequency-based inhibition of return.

The possibility that there is an inhibitory component to auditory covert orienting was addressed. Each trial consisted of a cue followed by a target, and listeners were required to detect, localize, or identify the frequency of the target. At 150-msec stimulus onset asynchrony (SOA), performance was best when stimuli sounded from the same location or were of the same frequency. However, at 750-msec SOA, performance was best when stimuli differed in location or were of different frequencies. These results document the existence of both location-based and frequency-based auditory inhibition of return.

Attention↗

PubMed1995

Shifting and focusing auditory spatial attention.

Auditory spatial attention was investigated by manipulating spatial and temporal relations between an auditory spatial cue and an auditory target. The principal findings were that performance improved as time available to shift attention to a cued spatial position increased, accurate spatial cues facilitated performance more than inaccurate cues, performance was virtually identical for shifts of attention ranging from 0 degrees and 180 degrees, and performance declined as the distance of an unexpected target from a cued spatial location increased. The experiments provided evidence that auditory attention may be allocated to a specific location in response to an auditory spatial cue and that the time required to shift attention does not appear to depend on the distance of the shift. Furthermore, the findings suggest that the spatial distribution of auditory attention may be described most accurately by a gradient model in which attentional resources decline gradually with distance from a focal point.

Attention↗

PubMed1994

Interaction between handedness and the attentional bias during tests of dichotic listening performance.

Perceptual advantages are typically interpreted as direct expressions of underlying hemispheric functional asymmetries. However, many other confounding factors including the asymmetric distribution of attention may also contribute to either the magnitude or direction of any of these advantages. In a series of experiments, Mondor and Bryden (1991, 1992a, 1992b) found that right-handed subjects bias their attention toward the right ear when faced with a difficult dichotic listening task. The present study was undertaken to determine whether the direction of the attentional bias is associated with handedness. The focus of auditory spatial attention was manipulated in a dichotic listening paradigm by presenting a pretrial tone cue to the ear from which the subject was required to report. The time period between the onset of the cue and the onset of the dichotic trial (Stimulus Onset Asynchrony--SOA) was varied in order to control the time available to orient attention to the cued ear. Whereas performance for the right ear improved substantially with SOA, that for the left ear improved only marginally. In addition, because of this differential effect of the cue on right ear and left ear performance, the magnitude of the right ear advantage was inflated at 450 ms SOA from that apparent at 150 ms and 750 ms SOA. These findings are interpreted as evidence that, in contrast to right-handers, left-handers bias their attention toward the left ear. This relation between handedness and the direction of the attentional bias is shown to have important implications for the interpretation of perceptual asymmetries.

Adult↗

PubMed1994

Allocating attention to frequency regions.

Three experiments were conducted to determine whether attention may be allocated to a specific frequency region. On each trial, a frequency cue was presented and was followed by a target tone. The cue indicated the most likely frequency of the forthcoming target about which the listeners were required to make a duration judgment. It was reasoned that if listeners are able to allocate attention to the cued frequency region, then judgments of any characteristic of a tone of the cued frequency should be facilitated relative to tones of different frequencies. Results indicated that duration judgements were made more quickly and accurately when the cue provided accurate frequency information than when it did not. In addition, performance generally declined as the frequency separation between cue and target increased. These effects are interpreted as an indication that listeners may use a frequency cue to allocate attention to a specific frequency region and that, under these conditions, the shape of the attentional focus conforms to a gradient. The possible similarities of covert orienting mechanisms in vision and audition are discussed.

Acoustic Stimulation↗

PubMed1993

The influence of attention on the dichotic REA with normal and learning disabled children.

Recently, Mondor and Bryden (Neuropsychologia, 29, 1179-1190, 1991; Percept. Psychophys. 52, 393-402, 1992) developed a lateralized cueing technique which appears to be a more powerful method than is the forced-attention technique (Bryden, 1978) of controlling the contribution of attentional biases to auditory perceptual asymmetries. This lateralized cueing technique was used to determine the influence of attentional biases on perceptual asymmetries obtained for normal and specific learning disabled (LD) children. Subjects were instructed to attend to, and report from, only the ear in which the cue sounded. The interval between the onset of the cue and the onset of the dichotic trial is varied so as to control the amount of time available to subjects to allocate attention to the cued ear. Results indicated that, for normal children capable of performing the task at a better than chance level, a large REA apparent at 150 msec Stimulus Onset Asynchromy (SOA) was attenuated at longer cueing intervals (450 and 750 msec SOA). For LD children, the magnitude of the initial REA appeared to be attenuated at 450 msec SOA. Thus, these data demonstrate that for normal children as well as for children with specific learning disabilities, attentional factors may contribute to the magnitude of the REA.

Attention↗

PubMed1992

Orienting of auditory spatial attention: effects of a lateralized tone cue.

Mondor and Bryden [8] (Neuropsychologia 29, 1179-1190, 1991) reported that the normal Right Ear Advantage for the identification of verbal material presented dichotically could be largely eliminated if subjects were cued to attend to and report from only one ear on each trial. In these experiments, the ear to be attended was cued by presentation of a tone to that ear only prior to each dichotic trial. The present series of studies were undertaken to determine whether this lateralized tone cue exerted its effect by orienting attention or by alerting the subject of the forthcoming trial. Results revealed that for both the right and left ears the facilitating effect of the cue was dependent on the accuracy of the location information it conveyed. Thus, the precueing technique originally employed by Mondor and Bryden as a means of controlling the contribution of attention to ear advantages was validated. It is concluded that the precueing technique provides a powerful means for specification of the extent to which attentional factors and hemispheric functional capabilities contribute to ear asymmetries.

Acoustic Stimulation↗

PubMed1992

On the relation between visual spatial attention and visual field asymmetries.

In the typical visual laterality experiment, words and letters are more rapidly and accurately identified in the right visual field than in the left. However, while such studies usually control fixation, the deployment of visual attention is rarely restricted. The present studies investigated the influence of visual attention on the visual field asymmetries normally observed in single-letter identification and lexical decision tasks. Attention was controlled using a peripheral cue that provided advance knowledge of the location of the forthcoming stimulus. The time period between the onset of the cue and the onset of the stimulus (Stimulus Onset Asynchrony--SOA) was varied, such that the time available for attention to focus upon the location was controlled. At short SOAs a right visual field advantage for identifying single letters and for making lexical decisions was apparent. However, at longer SOAs letters and words presented in the two visual fields were identified equally well. It is concluded that visual field advantages arise from an interaction of attentional and structural factors and that the attentional component in visual field asymmetries must be controlled in order to approximate more closely a true assessment of the relative functional capabilities of the right and left cerebral hemispheres.

Attention↗

PubMed1992

On the relation between auditory spatial attention and auditory perceptual asymmetries.

Laterality investigators have typically interpreted any perceptual asymmetry as a direct expression of the functional organization of the brain. However, many other confounding factors, including the asymmetric distribution of attention, may also contribute to either the magnitude or the direction of any of these advantages. In two experiments, attention was manipulated in a dichotic listening paradigm by presenting a preexposural tone cue to the ear from which the subject was required to report. The time available to orient attention was manipulated by varying the time period between the onset of the cue and the onset of the trial (stimulus onset asynchrony, or SOA). Results indicated that a right ear advantage for the identification of verbal material obtained at a 150-msec SOA was almost completely eliminated at an SOA of 450 msec. In addition, the direction of the ear advantage for emotion identification was found to depend on task difficulty. A left ear advantage, apparent when task difficulty was minimal, was reversed to a right ear advantage when difficulty was increased. These data are taken as evidence that, when subjects are faced with a difficult dichotic task, there is a general tendency for right-handed subjects to bias their attention toward the right ear. Such a tendency is shown not only to have likely seriously compromised the results of past investigations of functional perceptual asymmetries but also to be inconsistent with previously proposed theories of dichotic listening performance.

Adult↗

PubMed1991

The influence of attention on the dichotic REA.

Laterality researchers have frequently neglected to control for possible attentional components of perceptual asymmetries. Attention was manipulated in a dichotic listening paradigm by presenting a pre-exposural tone cue to the ear from which the subject was required to report. The time period between the onset of the cue and the onset of the trial (Stimulus Onset Asynchrony--SOA) was varied such that the time available to orient attention was manipulated. In two experiments, sizeable REAs were apparent at the shortest SOA (150 msec) but were substantially attenuated at longer intervals (450 and 750 msec SOA). In addition, a much larger effect of SOA on left-ear than on right-ear performance was observed. These effects were taken as evidence of an attentional bias to the right ear in the typical dichotic listening situation.

Adult↗

PubMed1991

Attentional factors in visual field asymmetries.

Over the past 30 years, numerous studies have reported left/right asymmetries in visual field performance, with performance generally superior in the right visual field for verbal tasks and in the left visual field for spatial tasks. These asymmetries parallel those found in neurological studies of hemispheric specialization. Consequently, many investigators have concluded that visual hemifield differences are primarily a reflection of the functional differences between the two cerebral hemispheres. However, alternative explanations proposing that visual field effects are dependent on other factors such as inadequate fixation, eye movements during presentation, postexposural scanning, and attentional biases have been offered. The potential impact of each of these factors on visual field differences are reviewed and discussed. Evidence is provided suggesting that attention and hemispheric functional differences interact to produce the magnitude and direction of visual field differences.

Attention↗

PubMed1990

Locus of information in words and the right visual field effect.

The right visual field (RVF) advantage found for the identification or classification of words has usually been interpreted as evidence for left hemisphere language functions. It has more recently been explained as the result of the fact that the most informative part of the word, presumably the beginning, is in a region of better visual acuity. It is not clear from existing evidence that the beginnings of words are in fact more informative. The present study assessed the locus of information in words by deleting either the initial or terminal one or two letters. Subjects were required to generate a completion. Regardless of whether subjects were scored as correct for generating the original target word (as would be appropriate in a naming study) or for producing any legitimate word (as would be appropriate for a lexical decision study), the results indicated that most words have more information in the initial letters. Nevertheless, there are exceptions to this rule, and some words have more terminal information. Equal numbers of words with more initial information and with more terminal information were selected for two visual field studies in order to assess the effect of the locus of information on visual laterality. In neither a lexical decision study nor a naming study did locus of information affect the commonly observed right visual field superiority. Thus the distribution of information is not likely to be a major confounding variable in laterality studies employing horizontally presented words.

Adolescent↗