Effects of frequency of presentation and stimulus length on retention in the Brown-Peterson paradigm.

1974 ◽  
Vol 103 (4) ◽  
pp. 629-637 ◽  
Author(s):  
Alfred H. Fuchs ◽  
Arthur W. Melton
Keyword(s):  
Stimulus Length

Relationships Between Subjective Ratings and Objective Measures of Performance in Speechreading Sentences

1997 ◽  
Vol 40 (4) ◽  
pp. 900-911 ◽  
Author(s):  
Marilyn E. Demorest ◽  
Lynne E. Bernstein
Keyword(s):  
Hearing Impairment ◽  
Performance Evaluations ◽  
Objective Measures ◽  
Large Individual ◽  
Subjective Ratings ◽  
Objective Performance ◽  
Phonetic Distance ◽  
Stimulus Length ◽  
Measures Of Performance ◽  
Confidence Scale

Ninety-six participants with normal hearing and 63 with severe-to-profound hearing impairment viewed 100 CID Sentences (Davis & Silverman, 1970) and 100 B-E Sentences (Bernstein & Eberhardt, 1986b). Objective measures included words correct, phonemes correct, and visual-phonetic distance between the stimulus and response. Subjective ratings were made on a 7-point confidence scale. Magnitude of validity coefficients ranged from .34 to .76 across materials, measures, and groups. Participants with hearing impairment had higher levels of objective performance, higher subjective ratings, and higher validity coefficients, although there were large individual differences. Regression analyses revealed that subjective ratings are predictable from stimulus length, response length, and objective performance. The ability of speechreaders to make valid performance evaluations was interpreted in terms of contemporary word recognition models.

The Impact of Lexical and Articulatory Factors in the Automatic Selection of Test Materials for a Web-Based Assessment of Intelligibility in Dysarthria

2021 ◽  
pp. 1-17
Author(s):  
Katharina Lehner ◽  
Wolfram Ziegler
Keyword(s):  
Clinical Examination ◽  
Clinical Assessment ◽  
Large Scale ◽  
Assessment Tool ◽  
Word Class ◽  
Neighborhood Structure ◽  
Test Materials ◽  
Stimulus Length ◽  
The Impact ◽  
Target Words

Purpose The clinical assessment of intelligibility must be based on a large repository and extensive variation of test materials, to render test stimuli unpredictable and thereby avoid expectancies and familiarity effects in the listeners. At the same time, it is essential that test materials are systematically controlled for factors influencing intelligibility. This study investigated the impact of lexical and articulatory characteristics of quasirandomly selected target words on intelligibility in a large sample of dysarthric speakers under clinical examination conditions. Method Using the clinical assessment tool KommPaS , a total of 2,700 sentence-embedded target words, quasirandomly drawn from a large corpus, were spoken by a group of 100 dysarthric patients and later transcribed by listeners recruited via online crowdsourcing. Transcription accuracy was analyzed for influences of lexical frequency, phonological neighborhood structure, articulatory complexity, lexical familiarity, word class, stimulus length, and embedding position. Classification and regression analyses were performed using random forests and generalized linear mixed models. Results Across all degrees of severity, target words with higher frequency, fewer and less frequent phonological neighbors, higher articulatory complexity, and higher lexical familiarity received significantly higher intelligibility scores. In addition, target words were more challenging sentence-initially than in medial or final position. Stimulus length had mixed effects; word length and word class had no effect. Conclusions In a large-scale clinical examination of intelligibility in speakers with dysarthria, several well-established influences of lexical and articulatory parameters could be replicated, and the roles of new factors were discussed. This study provides clues about how experimental rigor can be combined with clinical requirements in the diagnostics of communication impairment in patients with dysarthria.

Apparent diffusion time of oxygen from blood to tissue in rat cerebral cortex: implication for tissue oxygen dynamics during brain functions

2007 ◽  
Vol 103 (4) ◽  
pp. 1352-1358 ◽  
Author(s):  
Kazuto Masamoto ◽  
Jeff Kershaw ◽  
Masakatsu Ureshi ◽  
Naosada Takizawa ◽  
Hirosuke Kobayashi ◽  
...  
Keyword(s):  
Time Course ◽  
Oxygen Demand ◽  
Excess Demand ◽  
Tissue Oxygen ◽  
Doppler Flowmetry ◽  
Demand And Supply ◽  
Brain Functions ◽  
Apparent Diffusion ◽  
Time Required ◽  
Stimulus Length

To investigate the dynamics of tissue oxygen demand and supply during brain functions, we simultaneously recorded Po2 and local cerebral blood flow (LCBF) with an oxygen microelectrode and laser Doppler flowmetry, respectively, in rat somatosensory cortex. Electrical hindlimb stimuli were applied for 1, 2, and 5 s to vary the duration of evoked cerebral metabolic rate of oxygen (CMRO2). The electrical stimulation induced a robust increase in Po2 (4–9 Torr at peak) after an increase in LCBF (14–26% at peak). A consistent lag of ∼1.2 s (0.6–2.3 s for individual animals) in the Po2 relative to LCBF was found, irrespective of stimulus length. It is argued that the lag in Po2 was predominantly caused by the time required for oxygen to diffuse through tissue. During brain functions, the supply of fresh oxygen further lagged because of the latency of LCBF onset (∼0.4 s). The results indicate that the tissue oxygen supports excess demand until the arrival of fresh oxygen. However, a large drop in Po2 was not observed, indicating that the evoked neural activity demands little extra oxygen or that the time course of excess demand is as slow as the increase in supply. Thus the dynamics of Po2 during brain functions predominantly depend on the time course of LCBF. Possible factors influencing the lag between demand and supply are discussed, including vascular spacing, reactivity of the vessels, and diffusivity of oxygen.

Stimulus Length and Orientation Variables Interact in Peripheral Motion Perception

1976 ◽  
Vol 43 (1) ◽  
pp. 95-98 ◽  
Author(s):  
Dorothy L. Mattson
Keyword(s):  
Reaction Time ◽  
Motion Perception ◽  
Simple Reaction Time ◽  
Significant Interaction ◽  
Peripheral Vision ◽  
Line Length ◽  
Horizontal Motion ◽  
Simple Reaction ◽  
Cathode Ray Tube ◽  
Stimulus Length

To determine the effects of stimulus length and orientation on the perception of motion, 5 experienced subjects responded with a simple reaction to accelerating lines in peripheral vision while fixating on a reference cross at the center of a cathode-ray tube. Three experimental variables were involved: (a) line length, (b) direction of motion, and (c) orientation of the line with respect to the motion. Simple reaction time (RT) was significantly longer for vertical than for horizontal motion and for lines oriented in-line with the direction of motion than for lines oriented perpendicular to the direction of motion. A significant interaction was found between line length and orientation. The results show that the generalization that RT is shorter for small objects than for large objects must be modified in terms of the orientation of the object.

Inference of Mode in Melodies

1999 ◽  
Vol 17 (2) ◽  
pp. 223-239 ◽  
Author(s):  
Piet G. Vos ◽  
Paul P. Verkaart
Keyword(s):  
Temporal Structure ◽  
Stimulus Presentation ◽  
Music History ◽  
Western Music ◽  
Tonal Music ◽  
Continuous Scale ◽  
Gevolgd Door ◽  
Stimulus Length ◽  
Musical Genres ◽  
The Impact

Listeners' ability to infer the mode (major vs. minor) of a piece of Western tonal music was examined. Twenty-four subjects, divided into two groups according to their level of musical expertise, evaluated 11 musical stimuli, selected from J. S. Bach's "Well-Tempered Clavier". The stimuli included both unambiguous and ambiguous examples of the two modes, as well as one example of a modulation (from minor into major). The stimuli consisted of unaccompanied melodic openings of compositions, each containing 10 tones. Stimulus presentation and evaluation took place in nine progressively longer steps, starting with presentation of the first two tones, followed by their evaluation on a continuous scale, with 0 = "extremely minor" and 100 = "extremely major," and ending with evaluation of the complete stimulus. The results showed that mode inference followed the prescribed modes and tended to become more definite with increasing stimulus length. Experts were generally more definite in their inferences than were nonexperts. Surprisingly, the temporal structure of stimuli also appeared to affect mode inference. The degree of definiteness of mode judgments did not systematically differ between the two modes. It was concluded that listeners are able to infer the mode of a piece of music in the absence of explicit harmonic cues. The generalizability of the results with respect to music pieces of late periods in Western music history and the impact of different musical genres on mode inference are discussed. /// Onderwerp van onderzoek betrof het perceptuele onderscheid tussen majeur en mineur. Vierentwintig proefpersonen, verdeeld in twee groepen die verschilden in nivo van muzikale expertise, evalueerden 11 hen onbekende muziek stimuli, gekozen uit J. S. Bach's "Wohltemperierte Klavier". De stimuli bevatten zowel ondubbelzinnige als ambigue voorbeelden van de twee toonsoort geslachten, alsmede een voorbeeld van modulatie (in dit geval van mineur naar majeur). De stimuli bestonden uit ongeharmonizeerde melodische openingen van composities, elk 10 tonen lang. Stimulus aanbieding en (majeur/mineur) evaluatie vonden plaats in negen toenemend langere stappen, beginnend met de aanbieding van de eerste twee tonen van een stimulus, gevolgd door een evaluatie daarvan (op een continue schaal met 0 = "uitgesproken mineur" en 100 = "uitgesproken majeur"), en eindigend met de evaluatie van de complete stimulus. De resultaten lieten zien dat de evaluaties de profilering der voorgeschreven toonsoortgeslachten volgden en stelliger werden met toenemende stimulus lengte. De experts bleken doorgaans zekerder in hun kwalificaties dan de nonexperts. Verrassend genoeg bleek ook de temporele struktuur der stimuli de beoordeling te beïnvloeden. Geconcludeerd werd dat luisteraars in staat zijn om het geslacht van de toonsoort waarin een muziekstuk staat te identificeren in afwezigheid van expliciete harmonische informatie. De generalizeerbaarheid der resultaten met betrekking tot muziekstukken uit latere perioden in de Westerse tonale muziekgeschiedenis alswel de mogelijke invloed van verschillende muzikale genres op de majeur/mineur interpretatie werden ter discussie gesteld.

Effect of Stimulus Length on Nasalance Scores

1999 ◽  
Vol 36 (3) ◽  
pp. 243-247 ◽  
Author(s):  
Thomas Watterson ◽  
Kerry E. Lewis ◽  
Niamh Foley-Homan
Keyword(s):  
Stimulus Length

Cortical Synchronization and Perceptual Framing

1997 ◽  
Vol 9 (1) ◽  
pp. 117-132 ◽  
Author(s):  
Stephen Grossberg ◽  
Alexander Grunewald
Keyword(s):  
Object Representation ◽  
Receptive Fields ◽  
Shape From Shading ◽  
Visual Object ◽  
Nonlinear Feedback ◽  
Object A ◽  
Stimulus Length ◽  
Cortical Receptive Fields ◽  
The Brain ◽  
Different Parts

How does the brain group together different parts of an object into a coherent visual object representation? Different parts of an object may be processed by the brain at different rates and may thus become desynchronized. Perceptual framing is a process that resynchronizes cortical activities corresponding to the same retinal object. A neural network model is presented that is able to rapidly resynchronize desynchronized neural activities. The model provides a link between perceptual and brain data. Model properties quantitatively simulate perceptual framing data, including psychophysical data about temporal order judgments and the reduction of threshold contrast as a function of stimulus length. Such a model has earlier been used to explain data about illusory contour formation, texture segregation, shape-from-shading, 3-D vision, and cortical receptive fields. The model hereby shows how many data may be understood as manifestations of a cortical grouping process that can rapidly resynchronize image parts that belong together in visual object representations. The model exhibits better synchronization in the presence of noise than without noise, a type of stochastic resonance, and synchronizes robustly when cells that represent different stimulus orientations compete. These properties arise when fast long-range cooperation and slow short-range competition interact via nonlinear feedback interactions with cells that obey shunting equations.

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