The effect of chromatic and luminance information on reaction times

2010 ◽  
Vol 27 (3-4) ◽  
pp. 119-129 ◽  
Author(s):  
BEATRIZ M. O’DONELL ◽  
JOSE F. BARRAZA ◽  
ELISA M. COLOMBO
Keyword(s):  
Reaction Time ◽  
Stimulus Intensity ◽  
Color Space ◽  
Reaction Times ◽  
Luminance Contrast ◽  
Stimulus Size ◽  
Square Root ◽  
Chromatic Stimulus ◽  
Cone Pathway ◽  
Series Of Experiments

AbstractWe present a series of experiments exploring the effect of chromaticity on reaction time (RT) for a variety of stimulus conditions, including chromatic and luminance contrast, luminance, and size. The chromaticity of these stimuli was varied along a series of vectors in color space that included the two chromatic-opponent-cone axes, a red–green (L–M) axis and a blue–yellow [S − (L + M)] axis, and intermediate noncardinal orientations, as well as the luminance axis (L + M). For Weber luminance contrasts above 10–20%, RTs tend to the same asymptote, irrespective of chromatic direction. At lower luminance contrast, the addition of chromatic information shortens the RT. RTs are strongly influenced by stimulus size when the chromatic stimulus is modulated along the [S − (L + M)] pathway and by stimulus size and adaptation luminance for the (L–M) pathway. RTs are independent of stimulus size for stimuli larger than 0.5 deg. Data are modeled with a modified version of Pieron’s formula with an exponent close to 2, in which the stimulus intensity term is replaced by a factor that considers the relative effects of chromatic and achromatic information, as indexed by the RMS (square-root of the cone contrast) value at isoluminance and the Weber luminance contrast, respectively. The parameters of the model reveal how RT is linked to stimulus size, chromatic channels, and adaptation luminance and how they can be interpreted in terms of two chromatic mechanisms. This equation predicts that, for isoluminance, RTs for a stimulus lying on the S-cone pathway are higher than those for a stimulus lying on the L–M-cone pathway, for a given RMS cone contrast. The equation also predicts an asymptotic trend to the RT for an achromatic stimulus when the luminance contrast is sufficiently large.

Reaction Speed as a Function of Stimulus Intensity in Normals and Retardates

1965 ◽  
Vol 20 (2) ◽  
pp. 649-652 ◽  
Author(s):  
Alfred A. Baumeister ◽  
William F. Hawkins ◽  
George Kellas
Keyword(s):  
Reaction Time ◽  
Stimulus Intensity ◽  
Reaction Times ◽  
Reaction Time Task ◽  
Time Task ◽  
Motor Set ◽  
Reaction Speed

The reaction times of retardates and normals were compared as a function of intensity of the reaction signal. Three intensity levels of a 1000-cycle tone were used: 5, 15, and 25 db above threshold. Each S was presented all tones in a completely counterbalanced order. The results revealed that both intelligence groups reacted faster with each increase in intensity of the signal. Since no significant interactions emerged, it cannot be concluded that the groups benefited differentially from increases in intensity of reaction signal. It is suggested that retardates may have a sensory set whereas normals have a motor set in the reaction time task.

Reaction Time and Visual Brightness: Within-Subject Correlations

1979 ◽  
Vol 48 (1) ◽  
pp. 107-115 ◽  
Author(s):  
Armand V. Cardello
Keyword(s):  
Reaction Time ◽  
Stimulus Intensity ◽  
Reaction Times ◽  
Visual Reaction Time ◽  
Visual Reaction ◽  
Two Measures ◽  
The Relationship ◽  
Linear Correlations ◽  
Visual Brightness ◽  
Magnitude Estimates

An experiment was conducted to compare visual reaction time and visual brightness within the same subjects. Simple reaction times and magnitude estimates of brightness were obtained in response to 1000-msec. flashes of 60.7, 67.5, 76.4, 85.1, and 93.4 dB re 10−10L white light. The relationship between reaction time and stimulus intensity was best described by a negative logarithmic function, while the relationship between magnitude estimates of brightness and stimulus intensity was best described by a power function. Linear correlations between reaction times and magnitude estimates indicated that visual reaction time and brightness are not proportional within all subjects. Previous reports of proportionality between these two measures were discussed as possibly being the result of inappropriate cross-experiment comparisons.

Reaction Time as a Function of Peripheral Retinal Locus around Fovea: Effect of Stimulus Size

1976 ◽  
Vol 43 (2) ◽  
pp. 603-606 ◽  
Author(s):  
Naoyuki Osaka
Keyword(s):  
Reaction Time ◽  
Reaction Times ◽  
Stimulus Size ◽  
Target Size ◽  
Retinal Locus ◽  
Visual Reaction

Using targets of four sizes between 18' and 116' at a fixed luminance of 5.8 cd/m2, human visual reaction times (RT) were measured on a circle at 30° eccentric to the fovea. A foveal and 12 peripheral retinal loci were explored, covering the range between 0° and 330° in steps of 30° units on a circle about the fovea. RT decreased significantly by the stimulation to the quadrant retinal loci between nasal and superior side. RT decreased as a function of increasing target size and the amount of decrement was relatively larger in the periphery than in the fovea.

Reaction time measures of adaptation to chromatic contrast

2008 ◽  
Vol 25 (3) ◽  
pp. 405-410 ◽  
Author(s):  
N.R.A. PARRY ◽  
I.J. MURRAY ◽  
D.J. McKEEFRY
Keyword(s):  
Reaction Time ◽  
Time Course ◽  
Color Space ◽  
Reaction Times ◽  
Full Recovery ◽  
Adaptation Period ◽  
Chromatic Contrast ◽  
Simple Reaction

Simple reaction times (RTs) were measured to brief temporally blurred (total onset 570 ms) Gaussian isoluminant chromatic patches (s.d. 0.5°) whose chromaticities lay along the cardinal chromatic axes (0°, 90°, 180°, and 270° in MBDKL color space). Bipolar adapting stimuli were employed (0° versus 180° or 90° versus 270°). These were larger Gaussian blobs (s.d. 1°), modulating sinusoidally between the two hues at 1 Hz. Throughout, the background was illuminant “C” (x = 0.31, y = 0.316, L = 12.5). In a single run, a series of 64 or 32 stimuli were presented without adaptation, followed by 64 or 32 stimuli each of which was preceded by 3 s of adaptation, either along the same or the orthogonal chromatic axis. Finally, 192 or 128 RTs were recorded to measure the time course of recovery from adaptation. Both adapting and test stimuli were presented at fixed supra-threshold contrasts. The effect of adaptation was seen as a lengthening of the RT, which occurred in the first few seconds of the adaptation period. After cessation of adaptation, there was a similarly rapid shortening of RT, although full recovery took 60–90 s. Adaptation gain functions suggested that the S-(L + M) system was less prone to adaptation than L-M.

Disparity Information in the Peripheral Visual Field for Pattern Perception

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 203-203
Author(s):  
H Kaneko ◽  
C Bourgoin
Keyword(s):  
Reaction Time ◽  
Visual Field ◽  
Tracking System ◽  
Reaction Times ◽  
Window Size ◽  
Luminance Contrast ◽  
Pattern Perception ◽  
Peripheral Visual Field ◽  
Specific Information ◽  
Real Time Control

Although it is known that stereo-acuity declines with increasing eccentricity of the targets, it is not clear how we use disparity information in the peripheral visual field for pattern perception. To examine this question, we investigated pattern perception by restricting the area that presented stereo or luminance information in the periphery. We measured the reaction time for recognising a letter defined by binocular disparity or by luminance in a random-dot display. We restricted the area containing the specific information (disparity or luminance) using an eye-contingent window technique. Disparity or luminance information was thus present only inside a window centred on the fixation point. Observers viewed the display with free eye movement. The magnitudes of the disparity and luminance contrast were chosen so as to give the same reaction times when the area containing the pattern information was not restricted. Eye movements were measured by a limbus-tracking system and the signal was fed into a computer for real-time control of the window position. The reaction time increased as the window size decreased. The increase in reaction time, however, was steeper for the stimuli defined by disparity than for the stimuli defined by luminance. We conclude that disparity information in the periphery is used for recognising a pattern and is more effective than luminance information for a given window size.

Modeling Within-Person Variance in Reaction Time Data of Older Adults

GeroPsych ◽  
2011 ◽  
Vol 24 (4) ◽  
pp. 169-176 ◽  
Author(s):  
Philippe Rast ◽  
Daniel Zimprich
Keyword(s):  
Reaction Time ◽  
Cognitive Aging ◽  
Reaction Times ◽  
Reaction Time Task ◽  
Reaction Time Data ◽  
Scale Model ◽  
Time Data ◽  
Time Task ◽  
The Mean ◽  
Second Wave

In order to model within-person (WP) variance in a reaction time task, we applied a mixed location scale model using 335 participants from the second wave of the Zurich Longitudinal Study on Cognitive Aging. The age of the respondents and the performance in another reaction time task were used to explain individual differences in the WP variance. To account for larger variances due to slower reaction times, we also used the average of the predicted individual reaction time (RT) as a predictor for the WP variability. Here, the WP variability was a function of the mean. At the same time, older participants were more variable and those with better performance in another RT task were more consistent in their responses.

The Level of Reaction Time Determines the ERP Correlates of Auditory Negative Priming

2006 ◽  
Vol 20 (3) ◽  
pp. 186-194 ◽  
Author(s):  
Susanne Mayr ◽  
Michael Niedeggen ◽  
Axel Buchner ◽  
Guido Orgs
Keyword(s):  
Reaction Time ◽  
Negative Priming ◽  
Effect Size ◽  
Priming Effect ◽  
Reaction Times ◽  
Negative Priming Effect ◽  
Episodic Retrieval ◽  
Time Level ◽  
Fast Reactions ◽  
Priming Condition

Responding to a stimulus that had to be ignored previously is usually slowed-down (negative priming effect). This study investigates the reaction time and ERP effects of the negative priming phenomenon in the auditory domain. Thirty participants had to categorize sounds as musical instruments or animal voices. Reaction times were slowed-down in the negative priming condition relative to two control conditions. This effect was stronger for slow reactions (above intraindividual median) than for fast reactions (below intraindividual median). ERP analysis revealed a parietally located negativity of the negative priming condition compared to the control conditions between 550-730 ms poststimulus. This replicates the findings of Mayr, Niedeggen, Buchner, and Pietrowsky (2003) . The ERP correlate was more pronounced for slow trials (above intraindividual median) than for fast trials (below intraindividual median). The dependency of the negative priming effect size on the reaction time level found in the reaction time analysis as well as in the ERP analysis is consistent with both the inhibition as well as the episodic retrieval account of negative priming. A methodological artifact explanation of this effect-size dependency is discussed and discarded.

The Effect of Retest Practice on the Speed-Ability Relationship

2004 ◽  
Vol 9 (1) ◽  
pp. 24-31 ◽  
Author(s):  
Sybille Rockstroh ◽  
Karl Schweizer
Keyword(s):  
Reaction Time ◽  
Skill Acquisition ◽  
Reaction Times ◽  
Cognitive Tasks ◽  
General Intelligence ◽  
Attention Switching ◽  
Letter Comparison ◽  
Sternberg Paradigm ◽  
The Relationship ◽  
Elementary Cognitive Tasks

Effects of four retest-practice sessions separated by 2 h intervals on the relationship between general intelligence and four reaction time tasks (two memory tests: Sternberg's memory scanning, Posner's letter comparison; and two attention tests: continuous attention, attention switching) were examined in a sample of 83 male participants. Reaction times on all tasks were shortened significantly. The effects were most pronounced with respect to the Posner paradigm and smallest with respect to the Sternberg paradigm. The relationship to general intelligence changed after practice for two reaction time tasks. It increased to significance for continuous attention and decreased for the Posner paradigm. These results indicate that the relationship between psychometric intelligence and elementary cognitive tasks depends on the ability of skill acquisition. In the search for the cognitive roots of intelligence the concept of learning seems to be of importance.

How Useful is the Power Law of Practice for Recognizing Practice in Concentration Tests?

2007 ◽  
Vol 23 (3) ◽  
pp. 157-165 ◽  
Author(s):  
Carmen Hagemeister
Keyword(s):  
Logistic Regression ◽  
Reaction Time ◽  
Power Law ◽  
Error Rate ◽  
Reaction Times ◽  
Practice Effect ◽  
Practice Effects ◽  
Rate Decrease ◽  
Small Practice

Abstract. When concentration tests are completed repeatedly, reaction time and error rate decrease considerably, but the underlying ability does not improve. In order to overcome this validity problem this study aimed to test if the practice effect between tests and within tests can be useful in determining whether persons have already completed this test. The power law of practice postulates that practice effects are greater in unpracticed than in practiced persons. Two experiments were carried out in which the participants completed the same tests at the beginning and at the end of two test sessions set about 3 days apart. In both experiments, the logistic regression could indeed classify persons according to previous practice through the practice effect between the tests at the beginning and at the end of the session, and, less well but still significantly, through the practice effect within the first test of the session. Further analyses showed that the practice effects correlated more highly with the initial performance than was to be expected for mathematical reasons; typically persons with long reaction times have larger practice effects. Thus, small practice effects alone do not allow one to conclude that a person has worked on the test before.

Porous Gel Coatings Obtained by Phase Separation in ORMOSIL System

2000 ◽  
Vol 628 ◽  
Author(s):  
Kazuki Nakanishi ◽  
Souichi Kumon ◽  
Kazuyuki Hirao ◽  
Hiroshi Jinnai
Keyword(s):  
Phase Separation ◽  
Reaction Time ◽  
Volume Fraction ◽  
Sol Gel ◽  
Reaction Times ◽  
Dip Coating ◽  
Coating Solution ◽  
Coating Method ◽  
Gel Phase ◽  
Dip Coating Method

ABSTRACTMacroporous silicate thick films were prepared by a sol-gel dip-coating method accompanied by the phase separation using methyl-trimethoxysilane (MTMS), nitric acid and dimethylformamide (DMF) as starting components. The morphology of the film varied to a large extent depending on the time elapsed after the hydrolysis until the dipping of the coating solution. On a glass substrate, the films prepared by early dipping had inhomogeneous submicrometer-sized pores on the surface of the film. At increased reaction times, relatively narrow sized isolated macropores were observed and their size gradually decreased with the increase of reaction time. On a polyester substrate, in contrast, micrometer-sized isolated spherical gel domains were homogeneously deposited by earlier dippings. With an increase of reaction time, the volume fraction of the gel phase increased, then the morphology of the coating transformed into co-continuous gel domains and macropores, and finally inverted into the continuous gel domains with isolated macropores. The overall morphological variation with the reaction time was explained in terms of the phase separation and the structure freezing by the forced gelation, both of which were induced by the evaporation of methanol during the dipping operation.

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