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At least 19 recordsLinked to original sources
PubMed2003

The effect of otitis media with effusion on perceptual masking.

OBJECTIVE: To determine the effect of otitis media with effusion (OME) on perceptual masking (a phenomenon in which spondee threshold for a 2-talker masker is poorer than for a speech-shaped noise masker). DESIGN: Longitudinal testing over a 1-year period following insertion of tympanostomy tubes, using clinical and normal-hearing control groups. SUBJECTS: Forty-seven children having a history of OME were tested. Possible testing intervals were just before the placement of tympanostomy tubes, and up to 3 separate occasions after the placement of the tubes. An age-matched control group of 19 children was tested. METHODS: A perceptual masking paradigm was used to measure the ability of the listener to recognize a spondee in either a speech-shaped noise or a 2-talker masker background. The masker was either continuous or gated on and off with the target spondee. RESULTS: In gated masking conditions, children with a history of normal hearing showed only slight perceptual masking, but the children with a history of OME showed relatively great perceptual masking before surgery and up to 6 months following surgery. In continuous masking conditions, both groups of children showed relatively great perceptual masking and did not differ significantly from each other in this respect either before or after surgery. However, before surgery, the OME group showed higher thresholds in both the 2-talker and speech-shaped noise maskers. CONCLUSIONS: In agreement with previous psychoacoustical findings, the relatively great perceptual masking in gated conditions shown by children with OME history may reflect a general deficit in complex auditory processing.

Age Factors↗
PubMed2006

Discriminative stimulus effects of flumazenil: perceptual masking by baclofen, and lack of substitution with gamma-hydroxybutyrate and its precursors 1,4-butanediol and gamma-butyrolactone.

Pigeons trained to discriminate 0.1 mg/kg flumazenil, proposed as an in-vivo model to study interactions with diazepam-insensitive gamma-aminobutyric acid (GABA)A receptors, were tested with various GABAergic and non-GABAergic compounds. As a result of its pharmacological selectivity, the model was suitable for further examining previously reported flumazenil-like effects of gamma-hydroxybutyrate (GHB). Flumazenil and the GABAA negative modulator Ro 15-4513 produced 82-100% flumazenil-appropriate responding. Diazepam and the direct-acting GABAA agonists muscimol and 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridine-3-ol (THIP) produced 38-64% flumazenil-appropriate responding. GHB, its precursors 1,4-butanediol (1,4-BD) and gamma-butyrolactone (GBL), and the GABAB agonists baclofen and SKF97541 produced 0-24% flumazenil-appropriate responding. Baclofen shifted the flumazenil dose-response curve to the right and down, possibly involving perceptual masking of the discriminative stimulus effects of flumazenil by agonist activity at GABAB receptors. These masking effects of baclofen were blocked by the GABAB antagonist CGP35348. When CGP35348 was given together with GHB to block its GABAB agonist effects, GHB did not produce flumazenil-appropriate responding. Conceivably, effects of GHB at non-GABAB receptors (e.g. diazepam-sensitive GABAA receptors and GHB receptors) may interfere with the expression of its flumazenil-like discriminative stimulus effects. The asymmetric substitution between GHB and flumazenil is consistent with the hypothesis that the discriminative stimulus effects of GHB consist of several components, not all of which are mimicked by flumazenil.

4-Butyrolactone↗
PubMed1989

Evidence for perceptual masking of the discriminative morphine stimulus.

Morphine-amphetamine and morphine-naltrexone interactions were examined in three groups of White Carneaux pigeons (n = 3), which were trained in a two-choice drug discrimination procedure under a FR-30 schedule of food reinforcement using 3.2 mg/kg morphine and saline as discriminative stimuli. Once stimulus control was acquired by these initial training stimuli, the training doses of morphine were gradually changed to 1.0 mg/kg for group A and to 10 mg/kg for group C. The three groups differed in the minimum dose required for stimulus control and the drugs to which the training stimulus generalized. Stimulus generalization to amphetamine was inversely related to training dose. Amphetamine potentiated the discriminative stimulus properties of morphine. Naltrexone blocked the discriminative stimulus properties of morphine to varying degrees, which appeared to be limited by the training dose and the rate-suppressing effects of naltrexone when administered alone. Challenging the morphine stimulus with amphetamine resulted in a qualitatively similar blockade. This blockade was a direct function of the morphine training dose. It is argued that MS-AMP interactions result in perceptual masking of the MS stimulus, which can be differentiated from pharmacological antagonism by NTX. Two other challenge drugs, ketamine and sodium pentobarbital, did not alter stimulus control by morphine.

Animals↗
PubMed1994

Perceptual masking of the chlordiazepoxide discriminative cue by both caffeine and buspirone.

Twelve male Sprague-Dawley rats were trained to discriminate between the interoceptive stimulus attributes of 5 mg/kg chlordiazepoxide (CDP) and saline in a two-lever operant task under a fixed-ratio 10 (FR-10) schedule of food reinforcement. Caffeine, buspirone, and Ro 15-1788 failed to engender complete generalization when tested in combination with saline. In drug interaction test sessions caffeine (56 mg/kg) blocked the discriminative stimulus properties of the training dose of CDP and shifted the CDP discriminative dose-response function to the right. This rightward shift in CDP discriminative function was paralleled by a concomitant downward shift in the rate-of-responding dose-response function. Drug interaction test sessions conducted with 3.2 mg/kg of buspirone in combination with various doses of CDP engendered a downward shift in both the discriminative and rate-of-responding dose-response functions. Because 3.2 mg/kg buspirone in combination with the training dose of CDP resulted in complete response rate suppression, additional combination tests were conducted with 3 mg/kg CDP, a dose which reliably engendered > 90% CDP-appropriate responding, and various doses of buspirone. Similar to the CDP-caffeine interactions, buspirone blocked the cueing properties of 3 mg/kg CDP with a parallel reduction in response rates. Interaction test sessions conducted with Ro 15-1788 and CDP resulted in rightward shifts in both the discriminative and rate functions of CDP. We suggest that the interactions between CDP and both caffeine and buspirone resulted from the perceptual masking of the interoceptive (subjective) effects of CDP, whereas the interaction between Ro 15-1788 and CDP reflect pharmacological antagonism.

Animals↗
PubMed2002

Associative priming in a masked perceptual identification task: evidence for automatic processes.

Two experiments investigated the influence of automatic and strategic processes on associative priming effects in a perceptual identification task in which prime-target pairs are briefly presented and masked. In this paradigm, priming is defined as a higher percentage of correctly identified targets for related pairs than for unrelated pairs. In Experiment 1, priming was obtained for mediated word pairs. This mediated priming effect was affected neither by the presence of direct associations nor by the presentation time of the primes, indicating that automatic priming effects play a role in perceptual identification. Experiment 2 showed that the priming effect was not affected by the proportion (.90 vs. .10) of related pairs if primes were presented briefly to prevent their identification. However, a large proportion effect was found when primes were presented for 1000 ms so that they were clearly visible. These results indicate that priming in a masked perceptual identification task is the result of automatic processes and is not affected by strategies. The present paradigm provides a valuable alternative to more commonly used tasks such as lexical decision.

Association↗
PubMed1996

[Somatosensory evoked potentials: interference and perceptual masking of cutaneous afferents in man].

Somatosensory evoked potentials (SEP) are attenuated following double electrical stimulation of the fingers (II + III). This effect is observed at cervical (N13), parietal (N20-P27) and frontal (P22-N30) levels. We simultaneously observed in the same subjects that cutaneous perception of the test-shock is completely suppressed with interstimulus intervals (ISI) within a 0-10 msec range. With 25-30 msec ISI, the perceptive function totally recovers, but SEP inhibition remains at 50 % of the control. The SEP reduction does not result in a perception deficit as long as the cortical-test response exceeds 50% of control. These results suggest that: SEP inhibition could be a local but durable phenomenon occurring at both cervical and cortical levels. Cutaneous perception does not necessitate a maximal SEP development. The perceptive process involves other associative areas (5,7...) and is activated when the primary cortical activation exceeds a certain threshold which was found at 50% of the unconditioned response voltage.

Adult↗
PubMed2002

Frontal and striatal brain lesions increase susceptibility to masking in perceptual decisions.

Recent data suggest that perceptual decisions on masked stimuli involve neural activity in frontal cortex. We examined the effect of damage to frontal and striatal brain regions in man on the susceptibility to backward masking in rapid stimulus streams. Patients with unilateral frontal excisions and patients with early Huntington's disease were compared to controls in the identification of a brief white letter embedded in short streams of black letters at two presentation rates: (a) 9 letters/s; (b) 12.5 letters/s and also in a control condition in which the first post-target masking letter was absent. Patients could identify the target when the post-target mask was absent, but reducing the delay between stimuli significantly increased the error rates in patients. Intrusion errors often involved reporting post-target or pre-target distractors instead of the target. These results suggest that fronto-striatal lesions increase the period during which perceptual decisions are susceptible to perturbation. This deficit is compatible with a functional role of frontal systems in the cognitive control of brief perceptual decisions.

Adult↗
PubMed1988

Babble and random-noise masking of speech in high and low context cue conditions.

"Perceptual" masking of speech by multitalker speech (babble) has been widely reported but poorly quantified. Furthermore, the validity of the construct of perceptual masking is questionable. This report describes an experiment using a newly standardized test of speech perception in noise (SPIN) with both babble and spectrally matched random-noise maskers. Classical psychophysical ogive curves were used to model speech recognition as a function of signal-to-noise ratio (S/N). The two maskers yielded speech recognition functions of the same steepness but different locations on the S/N axis. The high-context items of SPIN yielded speech recognition curves with steeper slope and different locations on the S/N axis than the low-context items. These data are used to argue that perceptual masking was not documented (under certain assumptions) and that the superior masking of babble may be explained in purely acoustical terms. Speculations are offered about the possible acoustical differences that could be responsible for the differences in masking effect.

Acoustics↗
PubMed1990

Stimulus repetition effects and the dimension-feature distinction in alternative targets.

The negative repetition effect (NRE) refers to a poorer perception of the target in noise-same-as-target than in noise-alternative-target displays. Using the parenthesis as target and noise that are either identical or different in orientation, we tested predictions derived from a feature-specific inhibition model (Bjork & Murray, 1977) that explains the NRE as arising from inhibitory interactions among channels handling identical inputs. Contrary to our expectation of evidence for orientation-specific inhibition, a positive repetition effect (PRE) was observed. We also found a PRE for the dimension target sets whose stimuli differ only in orientation and an NRE for the feature target sets whose stimuli differ in the number of elements. Further experiments that systematically varied relationships between alternative targets indicate that these basic findings, termed the stimulus attributes effects, do not arise from pattern masking, perceptual strategies, or response bias.

Adult↗
PubMed2004

High-level effects of masking on perceptual identification.

The extent to which visual form versus higher-level information is used to identify briefly flashed words is assessed in a perceptual identification task. In this task, a word is briefly flashed, post-masked, and a decision is made between two alternatives. The availability of visual (e.g., case or color) and higher-level information (e.g., abstract letter codes, phonology, and meaning) was manipulated by varying the information that discriminates the alternatives. Performance was better with higher-level than with visual information when pattern post-masks were used, but the reverse occurred without masking. The authors conclude that both higher-level and visual-form information can be used to identify words with the strategy depending on the information available at the time of the choice.

Cognition↗
PubMed2002

Spondee recognition in a two-talker masker and a speech-shaped noise masker in adults and children.

OBJECTIVE: The objective of the study was to examine developmental effects for perceptual masking due a two-talker masker. Both continuous and gated maskers were employed in order to determine the importance of masker continuity for perceptual masking. DESIGN: A repeated measures design compared the spondee recognition performance of adults and children using both a speech-shaped noise and a two-talker masker. The masker was either presented continuously, or was gated on and off at about the same time as the target spondee. The ages of the listeners were 19 to 48 yr (adults) and 5 to 10 yr (children). RESULTS: The results for the continuous masker indicated higher thresholds for the two-talker masker than for the speech-shaped noise masker. This effect was greater in the children than in the adults. In the gated masking condition, the greater masking effect associated with the two-talker masker was either diminished (children) or eliminated (adults). CONCLUSIONS: These results suggest a masking effect for two-talker speech competition that is greater in children than in adults. Perceptual masking is greater for continuous than for gated masking.

Adult↗
PubMed1984

Interactions between target and masking stimuli: perceptual and event-related potential effects.

TWo separate experiments were conducted to determinge the nature of the visual event related potential (ERP) at two different cortical areas under conditions of backward visual masking and to see the effects of varied inter-stimulus-intervals (ISIs) upon both masking and the ERP. The results of the first experiment clearly demonstrated visual ERP attenuation at a target-mask ISI of 40 ms, an ISI which consistently produced masking. Both experiments showed that this effect was specific for the occipital recording site since amplitude reductions were not observed at the vertex under this condition. The mask alone condition produced the largest amplitude ERPs in both experiments. Again, this was specific for Oz. In the second experiment target-mask ISIs which did not produce backward masking (i.e., 10 ms and 100 ms) were not accompanied by ERP amplitude reductions. The results may be explained by a cortical excitatory-inhibitory model. That is, when successive stimuli are presented to the visual system, the visual cortical excitation produced by the initial stimuli is inhibited by the presentation of subsequent stimuli when temporal and spatial intervals are appropriate.

Evoked Potentials, Visual↗
PubMed1996

Gratings that induce perceptual distortions mask superimposed targets.

Masking is known to depend upon the relationship between the spatial-frequency content of target and mask. This relationship has been held constant in three experiments in order to investigate the separate contribution of the spatial parameters of the mask, in this case a grating with square-wave luminance profile. Thresholds for the detection of a probe target were highest when the background grating upon which the probe was superimposed had a spatial frequency of about 4 cycles deg-1 (experiment 1) and a duty cycle of 50% (experiment 3). In experiment 2, the thresholds were strongly affected by the size of the background grating even though the size of the target was small in proportion to the grating and remained constant. The increase in threshold was linearly related to the area of visual cortex to which the grating projected. The spatial parameters of gratings that maximise masking are therefore the same as those that have been shown to be optimal for the induction of perceptual distortions, suggesting a possible physiological mechanism for both the masking and the distortions.

Adult↗
PubMed2005

Latency facilitation in temporal-order judgments: time course of facilitation as a function of judgment type.

The paper is concerned with two models of early visual processing which predict that priming of a visual mask by a preceding masked stimulus speeds up conscious perception of the mask (perceptual latency priming). One model ascribes this speed-up to facilitation by visuo-spatial attention [Scharlau, I., & Neumann, O. (2003a). Perceptual latency priming by masked and unmasked stimuli: Evidence for an attentional explanation. Psychological Research 67, 184-197], the other attributes it to nonspecific upgrading mediated by retino-thalamic and thalamo-cortical pathways [Bachmann, T. (1994). Psychophysiology of visual masking: The fine structure of conscious experience. Commack, NY: Nova Science Publishers]. The models make different predictions about the time course of perceptual latency priming. Four experiments test these predictions. The results provide more support for the attentional than for the upgrading model. The experiments further demonstrate that testing latency facilitation with temporal-order judgments may induce a methodological problem resulting in fairly low estimates. A method which provides a more exhaustive measure is suggested and tested.

Adult↗