Search Results
Results 401 - 450 of 952
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Wilken Patrick - - 2004
Previous studies have suggested that visual short-term memory (VSTM) has a storage limit of approximately four items. However, the type of high-threshold (HT) model used to derive this estimate is based on a number of assumptions that have been criticized in other experimental paradigms (e.g., visual search). Here we report ...
Ulrich Rolf - - 2006
Three experiments assessed whether perceived stimulus duration depends on whether participants process an expected or an unexpected visual stimulus. Participants compared the duration of a constant standard stimulus with a variable comparison stimulus. Changes in expectancy were induced by presenting one type of comparison more frequently than another type. Experiment ...
Liem David A - - 2005
Clinical studies on cardioprotection by preinfarct angina are ambiguous, which may involve development of tolerance to repeated episodes of ischemia. Not all preconditioning stimuli use identical signaling pathways, and because patients likely experience varying numbers of episodes of preinfarct angina of different degrees and durations, it is important to know ...
Treue Stefan - - 2004
Allocating spatial attention to a visual stimulus or increasing stimulus contrast both enhance neuronal responses. In a recent study Carrasco et al. demonstrated that attention itself changes perceived contrast. Using an elegant experimental manipulation, they showed that the contrast of an attended stimulus was perceived to be higher than when ...
Norman C - - 2004
Strain differences in perception, cognition and affect have been found to interact with the effect of experimental treatments on learning. The present study tested Dark Agouti (DA) and Wistar rats in conditioning to discrete and contextual stimuli, for strain differences in conditioned emotional response (CER) and effects of stimulus modality. ...
Huettel Scott A - - 2004
Functional magnetic resonance imaging (fMRI) studies have demonstrated that the blood oxygenation level-dependent (BOLD) hemodynamic response (HDR) to a stimulus is reduced by the previous presentation of a similar stimulus. We investigated the dependence of this refractory effect upon stimulus characteristics using a novel adaptation paradigm while scanning subjects using ...
Willemssen Rita - - 2004
Recently Wascher et al. (1999) reported that in a flanker task with arrow stimuli not only the known lateralized readiness potential (LRP) that reflects lateralized response activation was induced, but also a parietal lateralized activation (direction encoding lateralization; DEL) that was interpreted as reflecting an earlier coding of a response ...
Kremers Jan - - 2004
The perception of flicker strength in a center stimulus can be affected by the presence of a surrounding stimulus. We correlated this effect with the interactions between centers and surrounds of the receptive fields (RFs) of neurons in the retino-geniculate pathways. The responses of cells in the lateral geniculate nucleus ...
David Stephen V - - 2004
Studies of the primary visual cortex (V1) have produced models that account for neuronal responses to synthetic stimuli such as sinusoidal gratings. Little is known about how these models generalize to activity during natural vision. We recorded neural responses in area V1 of awake macaques to a stimulus with natural ...
Cho Yang Seok - - 2004
When up-down stimuli are mapped to left-right responses, an up-right/down-left mapping advantage is found that is modified by response eccentricity and hand posture. These effects can be attributed to correspondence of asymmetric stimulus and response codes formed relative to multiple reference frames. We examined the influence of stimulus-set location on ...
Barry Robert J - - 2004
Phasic and tonic measures of electrodermal activity were examined in a simple habituation paradigm, using innocuous visual stimuli. Separate groups were used to investigate the effects of stimulus significance, as manipulated by instructions. One group had no stimulus-related task (indifferent group), while the other was asked to silently count the ...
Dolu Nazan - - 2004
In this study, using auditory sequences, the authors designed an examination with three phases of stimulus-driven attention that is based on the possibility that involuntarily time shifts of attention are caused by nonunique stimulus properties. The purpose was to investigate whether attending and temporal expectancies are influenced by stimulus's properties ...
Averbeck Bruno B - - 2004
Neurons in high-level sensory cortical areas respond to complex features in sensory stimuli. Feature elimination is a useful technique for studying these responses. In this approach, a complex stimulus, which evokes a neuronal response, is simplified, and if the cell responds to the reduced stimulus, it is considered selective for ...
Werka Tomasz - - 2004
Shuttle activity during repeated presentation of irrelevant auditory (white band noise) and visual (darkness) stimuli was studied in 32 male Möll-Wistar rats. The subjects were randomly divided into two groups. In Group ND the auditory stimulus was used in the first habituation session, and the visual stimulus in the second ...
Tass Peter A - - 2004
A model of two n:m coupled phase oscillators is studied, where both oscillators are subject to random forces, but only one oscillator is repetitively stimulated with a pulsatile stimulus. The focus of the paper is on transmission of transient responses as well as transient synchronization and desynchronization, which are stimulus ...
Bigman Zehavah - - 2004
Category induction involves abstraction of features common to two or more stimuli. We predicted that category induction affects processing of each stimulus, before completion of perceptual analysis. Event-related potentials (ERPs) were recorded from ten 11-13-year olds while they were performing visual category-induction tasks. Subjects viewed a series of two geometric ...
Rospars Jean Pierre - - 2004
Orientation towards food and mate, especially in insects, is an olfactory-controlled behavior which relies on the detection of small amounts of odorant molecules delivered in turbulent atmospheric conditions, so that randomness in magnitude and time is a major feature of the natural stimulus. The effect of random delivery on the ...
Simmons Andrea Megela - - 2004
Male bullfrogs emit multicroak, quasiharmonic advertisement calls that function in mate attraction and neighbor recognition. The degree of variability of acoustic features in these calls can influence perceptual decisions by conspecific receivers. Analysis of duration of individual croaks in spontaneous advertisement calls of a sample of males shows considerable intraindividual ...
Ashkenazi Amir - - 2004
We describe a new, open flow device for presenting taste stimuli to human subjects under controlled conditions of timing. The device delivers each stimulus as a mist to the participant's tongue through one of 16 nozzles attached to a linear slide. Software controls the position of the slide, the duration ...
Bachmann Talis - - 2004
When two objects are presented in rapid succession, observers find it difficult to discriminate their temporal order. Below certain limit (e.g., 20-70 ms), the rate of correct temporal order judgement is reported to be about 50% (i.e., close to chance level). However we have found stimulus conditions where order discrimination ...
Read Lenore E - - 2004
According to Kornblum's (1992) dimensional overlap model, when an incongruent response to a stimulus is required, automatic activation of the congruent response must first be inhibited. Shiu and Kornblum (1996a) provided evidence for such inhibition in an incongruent symbolic negative priming task. Reaction time was longer when a trial's correct ...
Lesica Nicholas N Division of Engineering and Applied Science, Harvard University, Cambridge, MA, - - 2004
Traditional approaches to characterizing the transformation from a visual stimulus to neural response assume that 1) the stimulus is stationary and uncorrelated, and 2) the functional properties of the encoding do not change over time. However, recent studies of sensory function under natural stimulus conditions have demonstrated important features of ...
Cowey Alan - - 2004
When visual stimuli are presented in the cortically blind visual field of patients or monkeys with verified destruction of striate cortex, many subjects can voluntarily respond to them. In studies of this blindsight, the on- and/or offset of the visual stimulus is usually known to the subject, either because it ...
Samuel Arthur G - - 2003
Immediately after a stimulus appears in the visual field, there is often a short period of facilitated processing of stimuli at or near this location. This period is followed by one in which processing is impaired, rather than facilitated. This impairment has been termed inhibition of return (IOR). In the ...
Persinger M A - - 2003
Four pairs of adult siblings served once as either the stimulus or the response person in two sessions separated by one week. While the brain of the stimulus person, who was seated in a closed chamber, was exposed successively to six different complex magnetic fields for 5 min. each quantitative ...
Cho Yang Seok - - 2004
In two-choice tasks for which stimuli and responses vary along orthogonal dimensions, one stimulus-response mapping typically yields better performance than another. For unimanual movement responses, the hand used to respond, hand posture (prone or supine), and response eccentricity influence this orthogonal stimulus-response compatibility (SRC) effect. All accounts of these phenomena ...
Eisinger William R - - 2003
Stomatal opening exhibits two main peaks of activity in the visible range-a red peak, mediated by photosynthesis, and a blue peak, mediated by one or more blue light (BL) photoreceptors. In addition, a pronounced peak in the UV-B region has been characterized, as has a smaller UV-A peak. The BL-induced ...
García-Hoz Víctor - - 2003
The concept of conditioning as signalization proposed by Ivan P. Pavlov (1927, 1928) is studied in relation to the theory of stimulus-substitution, which is also attributed to him. In the so-called theory of stimulus-substitution a distinction must be made between an empirical principle of substitution and an actual theory of ...
Op de Beeck Hans - - 2003
Similarity is a core concept in theories of object recognition, categorization, and reasoning. It is often conceptualized as a geometric distance in a multidimensional stimulus space. However, research in humans has revealed that similarity judgments involve more than a simple distance calculation and tend to be asymmetric when stimuli differ ...
Johnson Chad R - - 2003
Extracellular Stimuli in an Atrial Reentrant Loop. INTRODUCTION: The interactions between extracellular stimuli and excitation waves propagating in a reentrant loop are a complex function of stimulus parameters, structural properties, membrane state, and timing. Here the goal was a comprehensive understanding of the mechanisms and frequencies of the major interactions ...
Cholewiak Roger W - - 2003
Although tactile acuity has been explored for touch stimuli, vibrotactile resolution on the skin has not. In the present experiments, we explored the ability to localize vibrotactile stimuli on a linear array of tactors on the forearm. We examined the influence of a number of stimulus parameters, including the frequency ...
Hellström Ake - - 2003
In five experiments, participants made comparative judgments of paired successive or simultaneous stimuli. Time- or space-order errors were obtained, which varied with the interstimulus interval (ISI) or stimulus duration, as well as with the stimulus level. The results, in terms of scaled subjective differences, are well described by Hellström's (1979) ...
Bohn Ines - - 2003
The orbital prefrontal cortex (OPFC) is suggested to be part of a circuitry mediating the perception of reward and the initiation of adaptive behavioural responses. In the present study, we investigated in rats changes of goal-directed behaviour after bilateral OPFC-lesions by N-methyl-D-aspartate (NMDA) in more detail. A reaction time (RT) ...
Bee Mark A - - 2003
Territorial male bullfrogs ( Rana catesbeiana) display lower levels of aggression toward familiar territorial neighbors compared to unfamiliar individuals based on the perception of individual differences in vocalizations. Stimulus-specific habituation elicited by repeated exposures to a neighbor's vocalizations is believed to play a role in mediating the low levels of ...
Hommel Bernhard - - 2004
Recent studies have shown that the effects of irrelevant spatial stimulus-response (S-R) correspondence (i.e., the Simon effect) occur only after trials in which the stimulus and response locations corresponded. This has been attributed to the gating of irrelevant information or the suppression of an automatic S-R route after experiencing a ...
Cho Yang Seok - - 2003
One of the most important findings in recent years regarding response selection is that stimulus-response compatibility (SRC) effects occur for situations in which stimulus and response sets vary along orthogonal dimensions. For two-choice tasks, two types of orthogonal SRC effects are found: an overall advantage for the up-right/down-left mapping, and ...
Tass Peter A - - 2003
Transient phase dynamics, synchronization, and desynchronization which are stimulus-locked (i.e., tightly time-locked to a repetitively administered stimulus) are studied in two coupled phase oscillators in the presence of noise. The presented method makes it possible to detect such processes in numerical and experimental signals. The time resolution is enormous, since ...
Borst Alexander - - 2003
In the quest for deciphering the neural code, theoretical advances were made which allow for the determination of the information rate inherent in the spike trains of nerve cells. However, up to now, the dependence of the information rate on stimulus parameters has not been studied in any neuron in ...
Ben-Shakhar Gershon - - 2003
Two factors that might affect the novelty value of a test stimulus (the frequency of appearance of features common to the test stimulus and the set of preceding stimuli, and the serial position of these features) were systematically manipulated, and their effects on the electrodermal component of the orienting response ...
Jaƛkowski Piotr - - 2003
Romaiguère et al. (1993) reported an stimulus-response (S-R) experiment in which the participants had to respond to bright or dim stimuli by pressing a key strongly or weakly. Reaction time (RT) for a compatible S-R assignment (bright-strong; dim-weak) was substantially shorter than for an incompatible S-R assignment (dim-strong; bright-weak). This ...
Grabauskas Gintautas - - 2003
To explore the parameters that define the characteristics of either inhibitory postsynaptic potentials (IPSP) or currents (IPSC) in the gustatory nucleus of the solitary tract (rNST), whole cell patch-clamp recordings were made in horizontal brain stem slices of newborn rats. Neurons were labeled with biocytin to confirm both their location ...
Veltman Dick J - - 2002
In this study we demonstrate the importance of distributed sampling of peristimulus time in blocked design fMRI studies. Distributed sampling ensures all the components of an event-related hemodynamic response are sampled and avoids the bias incurred when stimulus presentation is time-locked to data acquisition. We found that differences in the ...
Sanders A F - - 2002
Most additive factors method (AFM) analyses of choice reaction time (CRT) have used alphanumerics whereas tests of single process models have often used line length or line orientation. The suggestion is raised that commonly observed additive effects of variables on CRT might not apply to stimuli of the latter category. ...
Hübner Ronald - - 2002
It is widely assumed that the cerebral hemispheres differ in their capacity for processing the global and local levels of hierarchical stimuli. However, corresponding visual-field (VF) effects in response time studies did not show up under all circumstances. In the present article the role of response conflict between the levels ...
Markham Rebecca G - - 2002
This experiment investigated whether directly trained covarying functions are necessary for stimulus class formation and transfer of function in humans. Initial class training was designed to establish two respondent-based stimulus classes by pairing two visual stimuli with shock and two other visual stimuli with no shock. Next, two operant discrimination ...
Griffee Karen - - 2002
The purpose of this study was to determine whether hierarchical categorization would result from a combination of contextually controlled conditional discrimination training, stimulus generalization, and stimulus equivalence. First, differential selection responses to a specific stimulus feature were brought under contextual control. This contextual control was hierarchical in that stimuli at ...
Fields Lanny - - 2002
The present experiment explored the effects of three variables on the spontaneous categorization of stimuli in perceptually distinct and novel domains. Each of six stimulus domains was created by morphing two images that were the domain endpoints. The endpoints of the domains were male and female faces, two abstract drawings, ...
Nakano Yoshiki - - 2002
The present study examined the facilitation effects of an auditory accessory stimulus that was irrelevant to a visual reaction time (RT) task as a function of stimulus onset asynchrony between the accessory stimulus and the visual target stimulus. Results of the present experiment showed that the auditory accessory stimulus caused ...
Eger Marcus - - 2002
To estimate the information transmitted across a neuronal sensory system one has to deal with serial dependence among consecutive samples of the stimulus and the response signal. Common methods usually require a huge amount of data, or are restricted to Gaussian stimuli. Here, we describe stimulus and response as stochastic ...
Ord Terry - - 2002
Video playback has been used to explore many issues in animal communication, but the scope of this work has been constrained by the lack of stimulus-subject interaction. In many natural contexts, each participant's signalling behaviour is dependent from moment-to-moment on that of the other. Analyses of acoustic communication demonstrate the ...
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