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Biomedical subjects

P Jaśkowski

Publications and source records attributed to P Jaśkowski.

18 recordsLinked to original sources
PubMed1997

Effect of sleep deficit, knowledge of results, and stimulus quality on reaction time and response force.

Some recent findings suggested that response force measured during reaction time experiments might reflect changes in activation. We performed an experiment in which the effect of sleep deprivation, knowledge of results, and stimulus quality on response force was studied in simple and choice reaction tasks. As expected, both simple and choice reaction times increased with sleep deficit. Further, simple and choice reactions were faster with knowledge of results and slowed down when stimulus quality was degraded. As sleep deprivation affects both arousal and activation, we expected a detrimental effect of sleep on force amplitude. On the other hand, knowledge of results was expected to increase force by its compensatory effect on arousal and activation. No effect of sleep deprivation on response force was found. Knowledge of results increased response force independently of sleep deprivation.

Adult↗
PubMed1996

Simple reaction time and perception of temporal order: dissociations and hypotheses.

Simple motor reaction time and judgment of temporal order are commonly recognized as two methods for estimation of perceptual latency. Unfortunately, the results obtained by the methods under the same conditions do not agree. We review hypotheses attempting to explain the disagreement. Although some of these seem to be promising, no one at present could be fully accepted.

Arousal↗
PubMed1995

The effect of stimulus intensity on force output in simple reaction time task in humans.

The force needed to press the key in a simple reaction time task was measured as a function of stimulus intensity for visual and auditory stimuli in three experiments using a total 45 male and female human subjects. Intensity ranged from 0.316 to 1995 cd/m2 for visual stimuli and from ranged from 47 to 102 dB for auditory stimuli. We found, in agreement with Angel's (1973) original study, that for auditory stimuli higher intensity is accompanied by a larger force. Surprisingly, in the case of visual stimuli the intensity does not influence the force. These findings are explained by the assumption that the changes of force reflect the changes of unspecific activation level evoked by immediate arousal. Thus, the different behaviour of force for these two modalities is in agreement with the common view that loud auditory stimuli are arousing while intense visual ones are not.

Adult↗
PubMed1994

Impending electrical shock can affect response force in a simple reaction task.

For 20 subjects reaction times and force of response were measured on a simple reaction time task to visual stimuli while activation was manipulated by occasionally delivering a noninformative electrical shock. In blocks in which shocks were delivered, forces of response were larger than those in control blocks without shocks. The results are discussed in terms of Sanders' model of stress.

Adult↗
PubMed1994

Response force and reaction time in a simple reaction task under time pressure.

The aim of this study was to examine the effect of effort on timing and force of simple reactions. To do this, we performed an experiment, arranged like a video-game, in which these variables were measured under different time-pressure conditions. In accordance with our expectations reaction time was shorter and force amplitude larger when the time for responses was limited. These findings are discussed within the framework of Sanders' (1983) model of stress.

Adolescent↗
PubMed1993

Selective attention and temporal-order judgment.

A procedure originally introduced by Sternberg and coworkers was used to examine the effect of selective attention on temporal-order judgment. Two-response and three-response paradigms were employed. As in Sternberg et al's work, a shift of psychometric functions for the two-response paradigm was found that suggested shorter latency for the stimulus to which attention was directed. However, no shift was noted for the three-response paradigm. This discrepancy can be explained by the assumption that the shift obtained for the two-response paradigm results from an artifact caused by a specific task. The artifact occurs because the instruction to attend to a particular stimulus induces a response bias when the subject is forced to guess in situations where he/she cannot recognize the temporal order of stimuli. The artifact disappears with the three-response paradigm where the subject has the additional option to respond "simultaneous".

Artifacts↗
PubMed1993

Temporal-order judgment and reaction time to stimuli of different rise times.

Point of subjective simultaneity and simple reaction time were compared for stimuli with different rise times. It was found that these measures behave differently. To explain the result it is suggested that in the case of temporal-order judgment the subject takes into account not only the stimulus onset but also other events connected with stimulus presentation.

Fixation, Ocular↗
PubMed1992

Temporal-order judgment and reaction time for short and long stimuli.

The effect of intensity on visual latency was investigated. Visual latency was measured by two methods: simple motor reaction time (RT) and temporal-order judgment (TOJ). It was found, in accordance with previous studies, that the changes in RT were larger than TOJ latency when measured in the same range of intensity. Moreover, the relationship between TOJ latency and intensity was compared in two conditions: under so-called "with-offset", the information about offset order was available for the subject, while under "without-offset" conditions it was not. It was hypothesized on the ground of Jáskowski's 1991 study that the TOJ latency-intensity relation should differ for these two conditions because of the effect of intensity on visual persistence. We were unable to find any such effect.

Adult↗
PubMed1991

Perceived onset simultaneity of stimuli with unequal durations.

Temporal-order judgment was investigated for a pair of visual stimuli with different durations in order to check whether offset asynchrony can disturb the perception of the order/simultaneity of onset. In experiment 1 the point of subjective simultaneity was estimated by the method of adjustment. The difference in duration of the two stimuli in the pair was either 0 or 50 ms. It was found that the subject shifts the onset of the shorter stimulus towards the offset of the longer one to obtain a satisfying impression of simultaneity even though the subject was asked to ignore the events concerning the stimulus offset. In experiments 2 and 3 the method of constant stimulus was applied. Both experiments indicate that subjects, in spite of instruction, take into account the offset asynchrony in their judgment.

Attention↗
PubMed1991

Two-stage model for order discrimination.

Ulrich (1987), exploring the shapes of psychometric functions obtained in the ternary-response paradigm, indicated several inconsistencies between observed and predicted relationships providing evidence against most popular models of temporal-order judgment. In this paper, a new model is presented. It assumes that there are two mechanisms involved in the order discrimination task: one is responsible for the recognition of whether or not the stimuli are successive, and the second is able to determine their order. The model was tested using Allan's (1975a, 1975b) and Ulrich's (1987) data; the model predictions were found to be consistent with the experimental results.

Attention↗
PubMed1990

VEP latency and some properties of simple motor reaction-time distribution.

The median of simple motor reaction (RT) to a flash parallels the latencies of visually evoked potential (VEP) deflections if flash intensity is varied. However, mean and median reaction times are not equal because of the skewness of RT distribution. It therefore seemed plausible that the mean reaction time--intensity relationship would be steeper than that for VEP latency. Such divergence would account for the intensity-dependent motor component of RT revealed by other psychophysical studies. The latencies of VEP deflections were measured as a function of intensity and the results were compared with mean and median RTs. The difference between mean and median RT is constant and independent of flash intensity. Moreover, both values are parallel to VEP latency. The general pattern of results remains the same after a change in the distribution from which the foreperiod is sampled.

Arousal↗
PubMed1990

Temporal-order judgments and reaction time for stimuli of different modalities.

Reaction times and the relative latency evaluated by the temporal-order-judgment method for two stimuli of different modalities (visual and auditory) were measured. The difference between reaction times for visual and auditory stimuli was about 40 ms. The relative latency was slightly shorter, however; in conflict with Rutschmann and Link's (1964) previous result, the auditory stimulus must be delayed to be perceived simultaneously with the visual one.

Adult↗
PubMed1990

[Use of Pulfrich's phenomenon in ophthalmological diagnosis].

The Pulfrich effect is a simply observable visual stereo phenomenon arising when the visual latency for one eye is longer than for the another. In the paper the review of the literature devoted to the application of this phenomenon for the ophthalmological diagnosis is presented. The authors come to the conclusion that the Pulfrich effect can be successfully used in clinical practice as an indicator of many ophthalmological disorders especially of optic neuritis.

Functional Laterality↗
PubMed1984

Human reaction time to negative contrast stimuli.

Simple motor reaction time (RT) to 100 percent negative contrast stimuli was measured for various background luminances as well as after bleaching a fraction of retinal photopigments. RT decreased to asymptotical value with the increase of background intensity. The intensity-dependent portion of RT behaved identically for 100 percent positive and negative contrast. Moreover, RT to 100 percent negative contrast was extended by bleaching and falls down during the adaptation to the lower background luminance. The results were discussed on the basis of the Pulfrich latency researches.

Cues↗
PubMed1983

Distribution of the human reaction time measurements.

Simple motor reaction time to, visual stimuli in dependence of stimulus intensity was measured and the histograms representing the distribution of reaction time were constructed. It was found that the reaction time distributions are positively skewed for all stimulus intensities used. The mean value, the standard deviation as well as the coefficient of skewness increases as the stimulus intensity decreases.

Humans↗
PubMedDate not supplied

[Spontaneous Pulfrich's effect in patients with dysfunction of the optic nerve].

Twenty patients with various dysfunctions of the optic nerve were subjected to examinations by means of a test based on the Pulfrich's phenomenon. The Pulfrich's effect was observed in 18 among them. The survey of the phenomenon was continued in 5 patients in the course of the treatment. It was detected that the dimension of the spontaneous Pulfrich's illusion diminishes gradually tending towards norm. The results obtained assure us of the usefulness of the application of the Pulfrich's effect as a diagnostic test in ophthalmology and neurology.

Evoked Potentials, Visual↗