Search Results
Results 351 - 400 of 952
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Heckman Genevieve M - - 2007
Because of well-known nonlinearities in fMRI, responses measured with rapid event-related designs are smaller than responses measured with spaced designs. Surprisingly, no study to date has tested whether rapid designs also change the pattern of responses across different stimulus conditions. Here we report the results of such a test. We ...
Bezzi Michele - - 2007
Information theory - in particular mutual information- has been widely used to investigate neural processing in various brain areas. Shannon mutual information quantifies how much information is, on average, contained in a set of neural activities about a set of stimuli. To extend a similar approach to single stimulus encoding, ...
Volberg Gregor - - 2006
Several studies have demonstrated that hemispheric differences for the processing of hierarchical letter stimuli are more likely to occur when the letters at the levels are associated with conflicting responses. Typically, a single stimulus is presented, so that the conflict occurs between the global and the local levels of the ...
Atkins Stephen G - - 2006
When people must respond discriminatively to 1 or 2 stimuli by making 1 or 2 taps of a response key, they initiate the response more rapidly when the correct number of taps matches the number of stimuli (compatible condition) than when it mismatches (incompatible condition; J. O. Miller, S. G. ...
Sobral G A GA - - 2006
Extending a model due to Derrida, Gardner, and Zippelius, we have studied the recognition ability of an extreme and asymmetrically diluted version of the Hopfield model for associative memory by including the effect of a stimulus in the dynamics of the system. We obtain exact results for the dynamic evolution ...
Lancioni G E - - 2006
This study assessed microswitch and computer technology to enable two participants with multiple disabilities, 32 and 19 years of age, to choose among environmental stimuli and request their repetition whenever they so desired. Within each session, 18 stimuli (12 preferred and 6 nonpreferred) were available. For each stimulus, a computer ...
Freeman Elliot D - - 2006
Two ambiguous transparent structure-from-motion (SFM) stimuli often appear to co-rotate. Grossmann & Dobbins (2003) reported breakdown of such perceptual coupling when one stimulus was made unambiguous (by rendering it opaque), leading them to propose that coupling depends generally on differential stimulus ambiguity. In contrast, we demonstrate robust stimulus-driven coupling even ...
Williams Dean C - - 2006
Two experiments compared delayed matching-to-sample (DMTS) accuracy under 2 procedures in adults with mental retardation. In the trial-unique procedure, every trial in a session contained different stimuli. Thus, comparison stimuli that were correct on one trial were never incorrect on other trials in that session (or vice versa). In the ...
Spackman L A LA Department of Clinical Neurophysiology, Great Ormond Street Hospital, London, UK. - - 2007
Somatosensory processing of duration and frequency changes was investigated using event-related potentials to vibrotactile stimuli. Intermittent vibration to the fingertips of either hand was presented using a two-stimulus odd-ball paradigm (deviant P = 0.10). One group (N = 12, 18-38 years) was presented with stimulus pairs of 20/70, 50/150 and ...
Pan Fei F Glaucoma Institute, State University of New York, State College of Optometry, New York, NY, - - 2006
The purpose of this study is to model perimetric defect and variability and identify stimulus conditions that can reduce variability while retaining good ability to detect glaucomatous defects. The two-stage neural model of Swanson et al. was extended to explore relations among perimetric defect, response variability, and heterogeneous glaucomatous ganglion ...
Marzilli Thomas S - - 2006
Recent evidence has indicated that nicotine, the active agent in tobacco, may affect mental abilities of smokers. To better understand the effects of nicotine on central processing, we used a basic chronometric approach to studying information processing. This chronometric approach allowed for the independent examination of nicotine's effects on two ...
Smits Roel - - 2006
The authors conducted 4 experiments to test the decision-bound, prototype, and distribution theories for the categorization of sounds. They used as stimuli sounds varying in either resonance frequency or duration. They created different experimental conditions by varying the variance and overlap of 2 stimulus distributions used in a training phase ...
Wolfsen Herbert H Divisions of Gastroenterology and Hepatology, Mayo Clinic, 6A Davis Bldg., 4500 San Pablo Road, Jacksonville, FL 32224, USA; Divisions of Gastroenterology and Hepatology, Johns Hopkins University, Baltimore, MD, USA; Divisions of Gastroenterology and Hepatology, Ochsner Clinic, New Orleans, LA, USA; Divisions of Gastroenterology and Hepatology, University of Maryland, Baltimore, MD, USA; Divisions of Gastroenterology and Hepatology, Duke University, Durham, NC, USA; Divisions of Gastroenterology and Hepatology, Virginia Mason Medical Center, Seattle, WA, USA; Divisions of Gastroenterology and Hepatology, University of California, San Francisco, CA, USA; Divisions of Gastroenterology and Hepatology, University of Miami, Miami, FL, USA; Divisions of Gastroenterology and Hepatology, Mayo Clinic, Scottsdale, AZ, USA; Divisions of Gastroenterology and Hepatology, University of Pennsylvania, Philadelphia, PA, - - 2006
During Digestive Disease Week 2005 in Chicago, Illinois, our group of 10 gastrointestinal photodynamic therapists met to discuss variations in procedural technique and treatment protocols. An extensive review of the use of photodynamic therapy (PDT) for esophageal disease has recently been published elsewhere [Wolfsen HC. Present status of photodynamic therapy ...
Noppeney Uta - - 2006
Repetition suppression refers to the phenomenon that prior processing of stimuli (or stimulus attributes) decreases activation elicited by processing subsequent stimuli with identical attributes. We present two complementary approaches to identify regions that show repetition suppression for subsequent sentences with either identical: (1) sentence forms or (2) speakers. The first ...
Scharlau Ingrid - - 2007
The present paper reviews recent research on perceptual latency priming (PLP). PLP is the relative latency advantage-earlier perception-of a visual stimulus that is preceded by another, masked stimulus at its location. The first stimulus attracts attention which accelerates perception of the second stimulus. This facilitation arises even if the first ...
Rach Stefan S School of Humanities and Social Sciences, International University Bremen, Bremen, Germany. - - 2006
Responses to multiple stimuli from different modalities tend to be faster compared to responses to each of these stimuli alone. Neurophysiological studies on higher mammals and behavioral studies on humans suggest that the relative amount of enhancement is inversely related to stimuli intensity. In two experiments the duration of visual ...
Derenne Adam - - 2006
Following single stimulus training, responding during a generalization test tends to be distributed around the positive stimulus (S+). However, if participants are trained instead to discriminate the S+ from a negative stimulus (S-), the response gradient often shifts away from the S- and toward the opposite end of the stimulus ...
Nakamura Shinji - - 2006
Static visual stimulus presented behind a moving pattern inhibits vection. On the other hand, the same static stimulus facilitates vection if it is located in front of the moving pattern. In this study, the effects of depth, eccentricity and size of the additional static stimulus on inhibition and facilitation of ...
Smyth Sinéad - - 2006
Two experiments investigated the derived transfer of functions through equivalence relations established using a stimulus pairing observation procedure. In Experiment 1, participants were trained on a simple discrimination (A1+/A2-) and then a stimulus pairing observation procedure was used to establish 4 stimulus pairings (A1-B1, A2-B2, B1-C1, B2-C2). Subsequently, a transfer ...
Ichikawa Makoto - - 2006
We investigated how observers' control of the stimulus change affects temporal aspects of visual perception. We compared the flash-lag effects for motion (Experiment 1) and for luminance (Experiment 2) under several conditions that differed in the degree of the observers' control of change in a stimulus. The flash-lag effect was ...
Melzer Peter P Department of Psychology, Vanderbilt University, 301 Wilson Hall, 111 21st Ave. S, Nashville, TN 37203, USA. - - 2006
We recorded responses to frequencies of whisker stimulation from 479 neurons in primary (S1) and secondary (S2) somatic sensory cortex of 26 urethane-anesthetized rats. Five whiskers on the right side of the snout were deflected with air puffs at seven frequencies between 1 and 18/s. In left S1 (barrels and ...
Abràmoff Michael D - - 2006
Imaging studies from anesthetized feline, primate, and human retinas have revealed near-infrared fundus reflectance changes induced by visible light stimulation. In the present study, the spatial and temporal properties of similar changes were characterized in normal, awake humans. Five normal human subjects were studied. A modified fundus camera was used ...
Kveraga Kestutis - - 2006
Studies of the relationship between stimulus-response uncertainty and reaction times indicate three qualitatively different functions: Hick's law, simple-choice step function, or flat curve (no effect at all). The extent of stimulus-response S-R) compatibility appears to interact with the effects of uncertainty on response times. One possible hypothesis regarding these various ...
Miller Jeff - - 2006
Three choice reaction time experiments documented a Simon-type congruence effect involving the numbers of stimuli and responses. In Experiment 1 the stimulus consisted of one or two high- or low-pitch tones, and participants were required to respond with one or two taps of a response key depending on stimulus pitch. ...
Harris Justin A - - 2006
Neurological reports of "tactile blindsight" suggest that the human somatosensory system can extract behaviorally useful information about the location of a tactile stimulus in the absence of conscious awareness that the stimulus occurred (Paillard et al., 1983; Rossetti et al., 1995). However, in a series of psychophysical experiments with neurologically ...
Rossi Heather L - - 2006
A hallmark of many orofacial pain disorders is cold sensitivity, but relative to heat-related pain, mechanisms of cold perception and the development of cold allodynia are not clearly understood. Molecular mediators of cold sensation such as TRPM8 have been recently identified and characterized using in vitro studies. In this study ...
Basole Amit - - 2006
Viewed in the plane of the cortical surface, the visual cortex is composed of overlapping functional maps that represent stimulus features such as edge orientation, direction of motion, and spatial frequency. Spatial relationships between these maps are thought to ensure that all combinations of stimulus features are represented uniformly across ...
Vervliet Bram - - 2006
Two experiments investigated the perceptual generalization of acquisition and extinction in human contingency learning. In Experiment 1, the degree of perceptual similarity between the acquisition stimulus and the generalization stimulus was manipulated over five groups. This successfully generated a generalization gradient of acquisition. In the subsequent phase, the response to ...
Panfilov A V - - 2005
Using a computational model of a coupled reaction-diffusion-mechanics system, we find that mechanical deformation can induce automatic pacemaking activity. Pacemaking is shown to occur after a single electrical or mechanical stimulus in an otherwise nonoscillatory medium. We study the mechanisms underpinning this effect and conditions for its existence. We show ...
Hommel Bernhard - - 2007
Five experiments investigated the spontaneous integration of stimulus and response features. Participants performed simple, prepared responses (R1) to the mere presence of Go signals (S1) before carrying out another, freely chosen response (R2) to another stimulus (S2), the main question being whether the likelihood of repeating a response depends on ...
Jackson Anne - - 2005
Gender differences in the discriminative stimulus properties of drugs of abuse have sometimes been reported, although we have previously found no differences in subjective or discriminative responses in human subjects acquiring an alcohol discrimination. The aim of the present work was to determine if there were gender differences in the ...
Ambe Mioko - - 2005
Mediated communication involves a form of intimate partnership where, as in the case of face-to-face intimate relationships, parties have a strong desire to exchange emotion and ensure a connection by way of receiving and responding to personal messages. So, in mediated communication, although partners have an effective means of conveying ...
Miller Jeff - - 2006
A simple reaction time (RT) experiment was conducted to test the hypothesis that redundancy gain arises partly because of hemispheric coactivation. Stimuli were presented to the left or right of fixation, or redundantly to both, and the participants had to make keypress responses as rapidly as possible to stimulus onset. ...
Birn Rasmus M - - 2005
An ongoing question in functional MRI is precisely how measured signal changes relate to neuronal activity. While this question has been probed using animal models and electrophysiologic measures of neuronal activity, it has also been probed by examining, in humans, the spatial location, magnitude, and temporal dynamics of signal changes ...
Bensma?a Sliman - - 2005
The objective of the study was to characterize the Pacinian representation of stimulus waveform. Subjects were presented with pairs of high-frequency vibrotactile stimuli that varied in intensity and/or frequency content and made same-different judgments under conditions of low-frequency adaptation designed to minimize the contribution of the RA system. We wished ...
Cho Yang Seok - - 2005
Two types of stimulus-response compatibility (SRC) effect occur with orthogonal stimulus and response sets, an overall up-right/down-left advantage and mapping preferences that vary with response position. Researchers agree that the former type is due to asymmetric coding of the stimulus and response alternatives, but disagree as to whether the latter ...
Vu Kim-Phuong L - - 2005
The present study confirmed that there is no overall right-left prevalence effect for Simon tasks, in which stimulus location is irrelevant, when (1) the stimulus and response sets vary along both horizontal and vertical dimensions simultaneously, (2) the stimulus set varies along both dimensions, but the response set varies along ...
Junius Dirk - - 2005
The present study investigates the relationship between evoked responses to transient broadband chirps and responses to the same chirps when embedded in longer-duration stimuli. It examines to what extent the responses to the composite stimuli can be explained by a linear superposition of the responses to the single components, as ...
Coker Cheryl A - - 2005
The purpose of this study was to explore the influence of stimulus direction and velocity on the coincident timing performance of a ballistic striking task. 26 subjects randomly performed 20 trials at each of two stimulus velocities (4 and 8 mph) and two striking variations (moving with an approaching stimulus ...
Lesica Nicholas A - - 2005
Traditional approaches to characterizing the transformation from stimulus to response in sensory systems assume both stationarity of the stimulus and time-invariance of the stimulus/response mapping. However, recent studies of sensory function under natural stimulus conditions have demonstrated important features of neural encoding that are in violation of these assumptions. Many ...
Wühr Peter - - 2005
The present study investigates sequential modulations of the Simon effect. The Simon effect involves faster responses to spatially corresponding than to noncorresponding stimuli, even when stimulus position is irrelevant. Recently, the Simon effect has been shown to decrease or to disappear after noncorresponding predecessor trials. Possible explanations for these sequential ...
Xie Shuiqing - - 2005
A widely adopted approach in cognitive psychology research is to analyze changes in the response time to a stimulus onset in order to infer information about the cognitive functioning of a subject being tested. But current techniques have inherent variations in the timing between stimulus activation and stimulus display of ...
Miller Jeff - - 2005
Four choice reaction time experiments documented a stimulus-response (S-R) compatibility effect involving the numbers of stimuli and responses. In Experiment 1, the stimulus consisted of one or two tones, and the correct response was either one or two taps of a response key. Responses were much faster with a compatible ...
Wühr Peter - - 2005
The Simon effect denotes faster responses when the task-irrelevant stimulus position corresponds to the response position than when it does not. Accounts of this effect assume that stimulus position automatically activates a spatially corresponding response while the correct response is being computed. Yet the Simon effect has been found to ...
Lingnau Angelika - - 2005
In two experiments, we studied the temporal dynamics of the response time effects of masked visual prime stimuli, as a function of stimulus eccentricity and size. Experiment 1 factorially varied prime-target congruency, eccentricity, and mask-target stimulus onset asynchrony. Early facilitative and late inhibitory effects of congruency were observed at all ...
Lidierth Malcolm - - 2005
This paper describes software that runs in the Spike2 for Windows environment and provides a versatile tool for generating stimuli during data acquisition from the 1401 family of interfaces (CED, UK). A graphical user interface (GUI) is used to provide dynamic control of stimulus timing. Both single stimuli and trains ...
Ling Li L School of life science and technology, University of electronics science and technology of China, Chengdu 610054, - - 2005
The alpha wave (8~13 Hz) phase resetting from pre-stimulus to post-stimulus is investigated for eight healthy subjects in a visual and auditory synchronously oddball stimuli experiment. Six parameters are considered: pre-stimulus amplitude and phase angle, post-stimulus amplitude and latency of first positive and negative peak. The results show that the ...
Vitevitch Michael S - - 2005
Lipinski and Gupta (2005) report the results of 12 experiments and numerous analyses that attempted to examine further the effects of phonotactic probability originally reported in Vitevitch and Luce (1998, & further explored in Vitevitch & Luce 1999). They suggested that Vitevitch and Luce's results were due to differences in ...
Mediavilla Cristina - - 2005
Taste aversion learning (TAL) consists of the avoidance of a taste previously associated with a noxious visceral stimulus. Clinical and experimental studies suggest that this adaptive process can be established by different procedures that imply distinct forms of learning and memory, although the final result is analogous, i.e. avoidance of ...
Bulatov Aleksandr - - 2005
In psychophysical experiments, subjects matched two spatial intervals of a three-spot stimulus into what appeared to them to be equal. The stimulus was flanked by stripes. The length matching errors increased in proportion to the referent interval of the stimulus and approached 6-12 percent of its length. Also, the error ...
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