Search Results
Results 501 - 550 of 952
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Gage N M - - 2000
Previous work investigating temporal integration in the formation of the auditory evoked field component, M100, indicates an accumulation of stimulus attribute information in the processes underlying the M100 response with a temporal window for this integration of approximately 25-32 ms. We investigate the influence of stimulus duration on M100 amplitude ...
Westheimer G - - 2000
Thresholds for the detection of differences in the duration of visual stimuli were determined for a variety of programs of stimulus onset and offset. Performance suffers when a time interval begins with an ON step and ends with another ON stimulus, compared to the standard ON-OFF stimulation, but the decrement ...
Chen A H - - 2000
PURPOSE: The purpose of this study was to investigate and compare the accommodative accuracy of pre-school children between free-space accommodative stimulus and minus lens-induced accommodative stimulus. METHODS: The accommodative responses of 59 pre-school children, ages 2 to 5 years, were measured objectively with a Canon Autoref R-1 under two different ...
Drösler J - - 2000
Weber's law of 1834, DeltaS/S=c for the just noticeable difference (jnd), can be written as S+DeltaS=kS, k=1+c. It follows that the stimulus decrement required to elicit one jnd of sensation is S-DeltaS*=k(-1)S. If generalized for two stimulus dimensions and two corresponding response dimensions, Weber's law would have to state such ...
Stins J F - - 2000
Three experiments tested whether stimulus-response (S-R) compatibility might be a function of absolute (as opposed to relative) spatial correspondence--that is, the distance between a stimulus and the place of response. Experiment 1 studied reaching movements toward one of two targets in response to one of six visual stimuli. Stimulus-response pairs ...
Krantz J H - - 2000
Most psychology experiments start with a stimulus, and, for an increasing number of studies, the stimulus is presented on a computer monitor. Usually, that monitor is a CRT, although other technologies are becoming available. The monitor is a sampling device; the sampling occurs in four dimensions: spatial, temporal, luminance, and ...
Higgs S S Department of Psychology, Oxford University, South Parks Road, Oxford, OX1 3UD, - - 2000
Rats were trained on a novel attentional task adapted from the five-choice serial reaction time test first developed by Carli et al. [1983; Behav. Brain. Res., 9, 361-80]. The novel task required rats to detect the occurrence of brief light flashes in one of two spatial locations following trial initiation ...
Mead T P - - 2000
Research has indicated that negative and positive thoughts may affect sport performance. The purpose of this analogue study was to assess whether negative and positive stimuli influenced tennis performance similar to positive and negative thought. The reaction time (RT) of 40 competitive tennis players was measured during a timed response ...
Tlauka M - - 2000
The influence of spatial stimulus grouping on stimulus-response compatibility effects was investigated in three experiments. Stimuli were grouped as part of a superordinate unit BY (1) perceptually organizing them (Experiment 1), (2) organizing them on the basis of semantic links (Experiment 2), or (3) arbitrary links (Experiment 3). In some ...
Ransom C B - - 2000
1. We measured activity-dependent changes in [K+]o with K(+)-selective microelectrodes in adult rat optic nerve, a CNS white matter tract, to investigate the factors responsible for post-stimulus recovery of [K+]o. 2. Post-stimulus recovery of [K+]o followed a double-exponential time course with an initial, fast time constant, tau fast, of 0.9 ...
Sinclair R J - - 2000
This study examined selective attention to tactile dimensions by combining a selective cueing paradigm with a test of integrality. In Experiment 1, subjects selectively attended to changes in the frequency or duration of pairs of vibrotactile stimuli and identified the higher frequency or longer duration stimulus. In Experiment 2, using ...
Charman W N - - 2000
Available experimental data on the gain and phase lags in the closed-loop accommodation responses to stimuli whose dioptric vergence changes sinusoidally with time are examined. It is shown that both phase lags and gain change almost linearly with the temporal frequency of the stimulus. This implies that the phase lags ...
Brown I E - - 2000
The interactive effects of length and stimulus frequency on rise and fall times and on sag were investigated in fast-twitch feline caudofemoralis at normal body temperature. The length and stimulus frequency ranges studied were 0.8 1.2 L0 and 15 60 pps. Isometric rise times were shortest under two sets of ...
Proctor R W - - 2000
When location-relevant trials with an incompatible spatial stimulus-response mapping are mixed with location-irrelevant trials, responses on the latter trials are faster when stimulus and response locations do not correspond than when they do. Experiments 1 and 2 showed that this reverse "Simon effect" also occurs when the location information is ...
Higbee T S - - 2000
Previously researchers have shown that multiple-stimulus preference assessments can produce results comparable to those achieved using the paired-stimulus presentation format. However, extensive experimental validation of this procedure has not yet been accomplished. The purpose of this study was to provide a systematic extension of a study reported by DeLeon and ...
Farroni T - - 2000
We report a series of ten experiments aimed to investigate the newborn's ability to discriminate the components of a visual pattern and to process the visual information that specifies the global configuration of a stimulus. The results reveal that: (i) newborn babies are able to distinguish individual elements of a ...
Lee M D - - 2000
MacGregor and Ormerod (1996) have presented results purporting to show that human performance on visually presented traveling salesman problems, as indexed by a measure of response uncertainty, is strongly determined by the number of points in the stimulus array falling inside the convex hull, as distinct from the total number ...
Awiszus F F Neuromuscular Research Group at the Department of Orthopaedics, Otto-von-Guericke University, Leipziger Strasse 44, D-39120 Magdeburg, Germany. - - 1999
Short-interval, paired-pulse transcranial magnetic stimulation (TMS) is usually used to demonstrate intracortical inhibition. It was shown recently that with short-interval, paired-pulse TMS a facilitation - called intracortical I-wave facilitation - can also be demonstrated. It was the aim of this study to investigate which stimulus conditions lead to intracortical inhibition ...
Shiu L P - - 1999
According to the automatic response activation hypothesis of the dimensional overlap (DO) model (Kornblum, Stevens, Whipple, & Requin, 1999), stimulus-response compatibility effects are expected to occur in go-no-go tasks. This prediction is confirmed in two experiments in which subjects moved a hand to one side of the field on presentation ...
Ghirlanda S - - 1999
Many studies, both in ethology and comparative psychology, have shown that animals react to modifications of familiar stimuli. This phenomenon is often referred to as generalization. The majority of modifications lead to a decrease in responding, but to certain new stimuli an increase in responding is observed. This holds for ...
Keen R - - 1999
This study examined how pigeons discriminate the relative frequencies of events when the events occur serially. In a discrete-trials procedure, 6 pigeons were shown one light nf times and then another nl times. Next, they received food for choosing the light that had occurred the least number of times during ...
Hebhardt P - - 1999
A fully programmable and portable automated regional taste-testing system is described. This system utilizes a glass stimulator held to the surface of the tongue by a mild vacuum. Temporally and spatially discrete trains of stimuli, delivered from a bank of glass reservoirs through microprocessor-controlled Teflon solenoid valves and both glass ...
Turpin G - - 1999
The effects of stimulus intensity, duration, and risetime on the autonomic and behavioral components of orienting, startle, and defense responses were investigated. Six groups of 10 students were presented with 15 white noise stimuli at either 60 or 100 dB, with controlled risetimes of either 5 or 200 ms, and ...
Dietl T - - 1999
OBJECTIVE: Brain electric activity in the theta frequency band has been associated with the encoding of new, and the retrieving of previously stored, information. We studied the time course of stimulus-to-stimulus changes of theta activity under repetitive somatosensory stimulation. MATERIALS AND METHODS: Twelve healthy subjects participated in the study. Repetitive ...
Hultsch H - - 1999
In many oscine birds, song learning is affected by social variables, for example the behaviour of a tutor. This implies that both auditory and visual perceptual systems should be involved in the acquisition process. To examine whether and how particular visual stimuli can affect song acquisition, we tested the impact ...
McLeod J S - - 1999
This study explored how the type of pictorial stimulus affects the quality of an individual's written expression. Cole, Muenz, Ouchi, Kaufman, and Kaufman in 1997 furnished initial evidence supporting Hooper, et al.'s 1994 theory. A pictorial stimulus different from that used by Cole, et al. was developed from Hooper, et ...
Moore A B - - 1999
While acquisition of the eyeblink conditioned response to a variety of stimuli has been widely studied, it has yet to be established that humans will demonstrate a conditioned response to an olfactory stimulus. In this study we present data to show that humans will demonstrate a classically conditioned eyeblink response ...
Zahn T P - - 1999
The nature of deficits in attention in closed head injury (CHI) was studied by three reaction time (RT) paradigms given to 20 patients who had a CHI 2 or more years previously and to 25 controls. We studied the effects of temporal uncertainty by varying the length and regularity of ...
Krüger G - - 1999
We studied the effect of stimulus quality on the basic physiological response characteristics of oxygenation-sensitive MRI signals. Paradigms comprised a contrast-reversing checkerboard vs. darkness or vs. gray light as well as gray light vs. darkness in a 2 s/52 s protocol (nine subjects). MRI was performed at 2.0 T using ...
Mohan K M - - 1999
PURPOSE: To evaluate the effect of stimulus presentation rate on the measurement of visual field extent in infants and toddlers. METHODS: Visual field extent was measured for 300 children (N = 60 at 3.5, 7, 11, 17, and 30 months) and 24 adults using hybrid static-kinetic perimetry. Flickering light-emitting diode ...
Friedman H S - - 1999
Stimulus response latency is the delay between stimulus onset and the evoked modulation in neural activity. A common technique to estimate latencies involves binning the spike arrival times to form a peri-stimulus histogram. This histogram is smoothed using a fixed bandwidth. The estimated latency is the first time following stimulus ...
Nakamura S - - 1999
The effects of a foreground stimulus on vection (illusory perception of self-motion induced by a moving background stimulus) were examined in two experiments. The experiments reveal that the presentation of a foreground pattern with a moving background stimulus may affect vection. The foreground stimulus facilitated vection strength when it remained ...
Fransson P - - 1999
The temporal and spatial characteristics of oxygenation-sensitive MRI responses to very brief visual stimuli (five Hz reversing black and white checkerboard pattern versus darkness) were investigated (nine subjects) by means of serial single-shot gradient-echo echo-planar imaging (2.0 T, TR=400 ms, mean TE=54 ms, flip angle 30 degrees). The use of ...
Dassonville P - - 1999
In general, for movements to visual targets, response times increase with the number of possible response choices. However, this rule only seems to hold when an incompatibility exists between the stimulus and response, and is absent when stimulus and response are highly compatible (e.g., when reaching toward the location of ...
Zhou S - - 1999
Fuzzy c-mean algorithm was applied to segment spatiotemporal patterns of brainwave into microstates and memberships. The optimal clustering number was estimated with both the trends of objective function and the eigenvalue number of microstates. Comparable spatial patterns may occur at different temporal moments in consideration of fuzzy index that is ...
Michimata Chikashi - - 1999
Recent studies have shown that (1) the global precedence effects in processing the hierarchically organized stimulus can be attenuated by eliminating the low spatial frequencies contained in the stimulus and (2) the human magnocellular pathway is responsible for processing low spatial frequencies and the pathway can be attenuated by imposing ...
Marks L E - - 1998
Attentional processes can modulate the detectability of weak stimuli; for example, the detectability of visual or auditory signals can depend on whether attention is allocated to the appropriate spatial location (vision) or acoustic frequency (hearing). Earlier attempts in the first author's laboratory to find analogous effects of focused attention on ...
Burrell B D - - 1998
Using the shortening reflex of the medicinal leech Hirudo medicinalis we examined stimulus generalization of habituation learning. Preparations received mechanosensory stimulus at two positions on the leech body wall, one site used to carry out habituation training and a second novel site to test for generalization of habituation. After training, ...
Blakemore S J - - 1998
A self-produced tactile stimulus is perceived as less ticklish than the same stimulus generated externally. We used fMRI to examine neural responses when subjects experienced a tactile stimulus that was either self-produced or externally produced. More activity was found in somatosensory cortex when the stimulus was externally produced. In the ...
Trevena J A - - 1998
Two experiments using a probe-RT paradigm showed that partial information about the size of a stimulus can influence response processes before complete size information is available. Contrary to the asynchronous discrete coding model, these results suggest that the perceptual system may transmit to the response system information that only partially ...
Roberts T P - - 1998
The latency of components of the auditory evoked neuromagnetic field has been shown to reflect, or encode, stimulus attributes. In particular, the M100 component, occurring approximately 100 ms post stimulus onset has a latency that depends on stimulus pitch, spectral complexity and presentation level. This study used magnetoencephalography to record ...
Rainey Bill B - - 1998
BACKGROUND: Clinicians frequently assess the accommodative convergence to accommodation (AC/A) ratio using near phoria measurements and accommodative stimuli. The purpose of this study was to evaluate the repeatability of AC/A ratio measurements and to compare the response AC/A ratio to stimulus AC/A ratios determined two different ways. METHODS: Heterophorias and ...
Mennemeier M - - 1998
How do stimulus size and item number relate to the magnitude and direction of error on center estimation and line cancellation tests? How might this relationship inform theories concerning spatial neglect? These questions were addressed by testing twenty patients with right hemisphere lesions, eleven with left hemisphere lesions and eleven ...
Ioannides A A - - 1998
The real-time, single-trial activity in the human auditory cortex was extracted from magnetoencephalographic signals. A predictor of single-trial activity was defined as the sum of the average response and a mean-free base level computed over a range of base times. For simple stimuli the residual (predicted-actual) activity had a stimulus-independent ...
Thorpe S J - - 1998
Many previous information processing studies have noted that people with severe anxiety selectively attend to threat stimuli. The experiment reported here tests the hypothesis that, when real threat stimuli are used instead of semantic stimuli, attention may be divided between threat and safety. Spider phobics and controls participated in a ...
Müsseler J - - 1998
When subjects are asked to determine where a fast-moving stimulus enters a window, they typically do not localize the stimulus at the edge, but at some later position within that window (Fröhlich effect). We report five experiments that explored this illusion. An attentional account is tested, assuming that the entrance ...
McFarland D J - - 1998
Thresholds for the discrimination of temporal order were determined for selected auditory and visual stimulus dimensions in 10 normal-adult volunteers. Auditory stimuli consisted of binary pure tones varying in frequency or sound pressure level, and visual stimuli consisted of binary geometric forms varying in size, orientation, or color. We determined ...
Krüger G - - 1998
Oxygenation-sensitive MRI responses to repetitive and sustained visual activation were compared for stimuli with different temporal, spatial, and luminance contrasts, i.e. reversing checkerboard, flashing diffuse red light, and stationary diffuse gray light with darkness as a control. All paradigms elicited an initial oxygenation 'overshoot' as well as a post-stimulus 'undershoot'. ...
Jordan W P - - 1998
Two experiments examined the frequency specificity of habituation of the acoustic startle response in the rat. Following the long-term habituation of startle to one of two pure tone stimuli in Experiment 1, animals were presented with the other stimulus. Startle response asymptotes were unaffected by this change in stimulus frequency. ...
Lages M - - 1998
A long-term sensory memory is believed to account for spatial frequency discrimination when reference and test stimuli are separated by long intervals. We test an alternative proposal: that discrimination is determined by the range of test stimuli, through their entrainment of criterion-setting processes. Experiments 1 and 2 show that the ...
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