Effects of intensity, contrast and novelty, on selective attention and choice reaction time.

by Paul Michael McDonnell in [Toronto]

Written in English
Published: Pages: 122 Downloads: 952
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  • Edition Notes

    ContributionsToronto, Ont. University.
    The Physical Object
    Pagination122, [9] leaves.
    Number of Pages122
    ID Numbers
    Open LibraryOL19179372M

Affect. At each trial, participants reported their current intensity of NA and PA. Using a 4-point scale (not at all=0, little=1, much=2, a great deal=3), participants indicated the intensity with which they were currently feeling each of 11 each prompt, NA was computed as the mean of seven negative emotions (sad, anxious, angry, frustrated, ashamed, disgusted, and guilty. Adverse effects in children. Children have a lower incidence of contrast reactions. The reactions that they experience tend to be anaphylaxis-like and/or involve the airway. 6 Children have strong hearts, so cardiovascular-type reactions are very uncommon. Nonvascular routes of administration and acute contrast reaction. the interpretation of reaction time measurement is based. It is hoped that the juxtaposition of these sets of issues will lead to the more care- ful use and interpretation of reaction time measures in the understanding of human information processing. 'Die use of reaction time as a .   The average level of intensity, the study found, drops with each decade of life, with the most pronounced drop between early adulthood - roughly the 20's -and early middle-age in the 40's.

On intensity. Simply said, it's hard to talk about "intensity" of an image. Every pixel has its intensity (for greyscale images, they are usual allowed range is [0, ]), but the concept of image intensity does not exist. If you are doing some kind of image analysis, you could be interested in a parameter describing image intensities, e.g. mean intensity (like @geometrikal said) or. attention. The neural response to contrast increases over a limited range then saturates (black curve). Effect of attention: The red curve shows the effect of attention on the contrast response function of a hypothetical neuron: Less contrast is needed to attain the same response level (Points 1 to 4), and the same contrast elicits a higher.

Effects of intensity, contrast and novelty, on selective attention and choice reaction time. by Paul Michael McDonnell Download PDF EPUB FB2

Attention - Attention - The intensity of attention: These theories have been criticized for dealing with only the passive aspects of attention—certainly there is more to attention than mere selection. Such critics point out that there is also the question of the degree or intensity with which attention is applied to a particular task or situation.

By directly comparing contrast sensitivity at cued and uncued locations, we found a relatively high contrast and novelty constant attentional effect.

We assessed the overall attentional effect (black vertical lines) and found that on average, the valid:invalid ratio was at parafovea (ranges – for individual observers) and at periphery (ranges – for individual observers).Cited by: The analysis of the MRI contrast effect (measured at T) indicates that the pristine Fe NPs are strong contrast agents due to their higher relaxivity ( mM − 1 s − 1) of pristine Fe NPs, compared with IONPs with a similar size (Hadjipanayis et al., ).

Seo and coworkers have reported an improvement on metallic alloy NPs for MRI. However, no significant differences were noted across intensity (medium effect size) or duration (small effect size). The fastest choice reaction time occurred at 75% of PWC, which was near the.

fastest choice reaction time occurred at 75% of PWC, which was near the ventila-tory threshold (% of VO 2 max). Aerobic fi tness was average on selective attention and choice reaction time. book college-aged men ( ml/kg/min.) and was poorly correlated with choice reaction time across exercise intensity.

Further research is needed to compare choice reaction. The contrast effect is a cognitive bias that distorts our perception of something when we compare it to something else, by enhancing the differences between them.

This comparison can be either explicit or implicit, simultaneous or at separate points in time, and can apply to various traits, ranging from physical qualities, such as color and taste, to more abstract qualities, such as price and.

Chromatic contrast occurs in a way that is similar to the lightness contrast effects discussed and illustrated in Chapter 3. Figure shows a color contrast illusion. It has been shown that contrast effects can distort readings from color-coded maps (Cleveland & McGill, ; Ware, ).Contrast effects can be theoretically accounted for by activity in the color opponent channels (Ware.

Possible effects of attention on the contrast response function. The left panel depicts a contrast gain model for attention.

Contrast gain predicts an increase in sensitivity that is a function of stimulus intensity, and is characterized by a leftward threshold (C50) shift in the contrast. Adverse reactions to contrast agents range from a mild inconvenience, such as itching associated with hives, to a life-threatening emergency.

Renal toxicity is a well known adverse reaction. A relevant experimental effect that has been studied for almost a century is the redundant target effect.

When multiple copies of the same stimulus are presented to subjects, in choice, go no-go, and even a simple reaction time task, reaction times (RT) tend to be faster, compared to RT to a.

In simple auditory reaction time, Grice and Hunter () obtained a significant interaction between signal intensity and the manner of intensity manipulation-between or within subjects.

In a reanalysis by more recently developed methods of variable criterion theory, estimates of criterion level have been obtained for each subject in each condition. Specifically, Reynolds et al.

() demonstrated that attention enhances the weak response of neurons in area V4 evoked by low-contrast stimuli but that it has only little influence on the stronger response evoked by high-contrast stimuli (Fig.

1B).Attention thus appeared to shift the neurons’ contrast response function to the left as if it increased the effective contrast of the stimulus. The Correa paper, which was published in Nobre and Coull's () book Attention and Time, also neglects to cite Kingstone.

1 Whereas endogenous control is top down and volitional, exogenous. Attentional effects on neuronal contrast-response function. Response gain (a), contrast gain (b), and input-baseline shift (c) models of attentions on a.

We refer to stimulus intensity modulation in the emotional domain as affect intensity, and we consider affect intensity to be a stable individual difference dimension. Larsen and Diener () have developed two methods for assessing an individual's characteristic magnitude of emotional responsiveness, affect intensity.

This suggests that attention affects the normalized signal once the effect of contrast adaptation has taken place and that these two mechanisms act separately to change contrast sensitivity.

Investigated the effects of duration and intensity of light flashes and momentary interruptions in a prevailing light stimulus, i.e., dark stimuli, on RT. RTs to both light and dark stimuli decreased when the duration of low-luminance stimuli was increased.

This temporal summation extended over approximately msec. This suggests that the physiological mechanisms that limit the temporal. Divided Attention In signal detection and selective attention, the attentional system must coordinate a search for the simultaneous presence of many features.

Divided attention occurs when we are required to perform two (or more) tasks at the same time and attention is required for the performance of both (all) the tasks. The contrast effect is a magnification or diminishment of perception as a result of previous exposure to something of lesser or greater quality, but of the same base characteristics.

For example. Background: Inversion recovery (IR) pulse sequences can generate T1-weighted images with a different range of inversion time (TI) to suppress or null the signal intensity (SI) for a specified tissue.

In this study, we aimed to investigate the effect of TI values on the concentration of the contrast agent, which leads to a minimum signal intensity, using an inversion recovery T1-weighted 3. Evoked unit activity in auditory cortex of monkeys performing a selective attention task.

Brain Research. ; – Hubel DH, Henson CO, Rupert A, Galambos R. “Attention” units in the auditory cortex. Science. ; – Hugdahl K, et al. Effects of attention. Event-related brain potentials in the study of visual selective attention. Proceedings of the National Academy of Sciences of the United States of America, 95 (3), – Hillyard, S.

A., Vogel, E. K., & Luck, S. Sensory gain control (amplification) as a mechanism of selective attention: Electrophysiological and neuroimaging. Percept Mot Skills. Oct;39(2) Reaction time as a measure of the effect of selective attention.

Flaherty EW, Coren S. PMID: that attention increases contrast sensitivity. Grow-ing evidence supports the idea that this effect is me-diated by contrast gain, an effect akin to a change in the physical contrast stimulus.

In the first section, I introduce the construct of selective attention, and discuss the idea that it arises from the high bioenergetic cost of cortical. Using a photosynthetic organism of your choice, choose only ONE of the three variables (temperature, wavelength of light, or light intensity) and for this variable.

• Design a scientific experiment to determine the effect of the variable on the rate of photosynthesis for the organism •. Early differential ERP activity: posterior negative potentials. In selective attention studies, the effect of task relevance associated with target compared with nontarget processing is best observed as differential ERP activity in a time interval between and ms (Hillyard and Anllo-Vento, ).Across widely differing overall ERP topographies, the signature of this early selective.

Contrast agent–related nephropathy is an elevation of the serum creatinine level by more than mg/dL or more than 50% of baseline 1–3 d after contrast injection.

The incidence of contrast agent–related nephropathy is estimated to be 2%–7% (33,34). Causes for contrast-induced nephrotoxicity include renal hemodynamic changes resulting. REACTION-TIME AS AN INDICATOR OF ATTENTION-VALUE used as a criterion with varying success, by Wundt,8 Swift," Cattell,'o Geissler," and Dallenbach Woodrow, in a very thorough study of the relation of reaction-time to attention stated that the evidence that reaction-time does vary with degree of attention is "so overwhelming that it is un.

Davenport MS, Cohan RH, Caoili EM, Ellis JH. Repeat contrast medium reactions in premedicated patients: frequency and severity.

Radiology. Nov. (2) Kolbe AB, Hartman RP, Hoskin TL, Carter RE, Maddox DE, Hunt CH, et al. Premedication of patients for prior urticarial reaction to iodinated contrast medium.

The consequences of varying contrast dose ‘determined by contrast volume and concentration’ and flow rate can be graphically depicted using a time density curve. The ‘I” axis of the graph depicts the time elapsed in seconds, after the start in injections, whereas the ‘Y’ axis chart the relative enhancement levels achieved, in.

Effect of retinal illuminance and field size on the time constants Flicker sensitivity: Ferry-Porter law Temporal impulse response Summary and conclusions References 6 Effect of nonwhite spatial noise on contrast sensitivity Introduction completion of the d2.

Selective attention, as assessed by the d2 test of attention was significantly greater following a bout of HIIE compared to the control condition. Effect size analysis revealed a moderate effect in favour of HIIE compared to control (d = [, ]).

Study #2: 23 university students (17 females; age = ±The idea that the effects of attention are similar to an increase in stimulus contrast is not undisputed, however, as other psychophysical studies reported that attention has only little influence on perceived contrast (Prinzmetal et al.

; Liston and Stone ; Schneider and Komlos ), whereas another study demonstrated that attention.