Human Eye Color and Reaction Time

1978 ◽  
Vol 47 (2) ◽  
pp. 503-506 ◽  
Author(s):  
W. H. Tedford ◽  
W. R. Hill ◽  
Lynn Hensley
Keyword(s):  
Reaction Time ◽  
Visual Stimulus ◽  
Reaction Times ◽  
Nonsignificant Trend ◽  
Response Latencies ◽  
Eye Color ◽  
Human Eye ◽  
Trend Data ◽  
Iris Pigmentation ◽  
Reaction Task

Response latencies to a visual stimulus were determined for 44 male and 82 female Caucasians. Those with dark eyes had significantly shorter simple (one stimulus) reaction times. Complex (one of four stimuli) reaction times showed a similar, but nonsignificant, trend. Data from an additional 206 male Caucasians on a one-trial non-practiced reaction task followed the same nonsignificant trend. Darker iris pigmentation apparently correlates with shorter reaction times but more strongly on practiced tasks and on those which do not involve accuracy.

Impending Electrical Shock Can Affect Response Force in a Simple Reaction Task

1994 ◽  
Vol 79 (2) ◽  
pp. 995-1002 ◽  
Author(s):  
Piotr Jaśkowski ◽  
Marek Wróblewski ◽  
Dorota Hojan-Jezierska
Keyword(s):  
Reaction Time ◽  
Simple Reaction Time ◽  
Visual Stimuli ◽  
Reaction Times ◽  
Reaction Time Task ◽  
Response Force ◽  
Simple Reaction Time Task ◽  
Electrical Shock ◽  
Simple Reaction ◽  
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' mode! of stress.

scholarly journals Crowdsourced Measurement of Reaction Times to Audiovisual Stimuli With Various Degrees of Asynchrony

2018 ◽  
Vol 60 (8) ◽  
pp. 1192-1206 ◽  
Author(s):  
Pavlo Bazilinskyy ◽  
Joost de Winter
Keyword(s):  
Reaction Time ◽  
Visual Stimulus ◽  
Reaction Times ◽  
Stimulus Presentation ◽  
Past Research ◽  
Stimulus Onset ◽  
Task Instructions ◽  
Audiovisual Stimuli ◽  
The Right ◽  
Onset Asynchrony

Objective: This study was designed to replicate past research concerning reaction times to audiovisual stimuli with different stimulus onset asynchrony (SOA) using a large sample of crowdsourcing respondents. Background: Research has shown that reaction times are fastest when an auditory and a visual stimulus are presented simultaneously and that SOA causes an increase in reaction time, this increase being dependent on stimulus intensity. Research on audiovisual SOA has been conducted with small numbers of participants. Method: Participants ( N = 1,823) each performed 176 reaction time trials consisting of 29 SOA levels and three visual intensity levels, using CrowdFlower, with a compensation of US$0.20 per participant. Results were verified with a local Web-in-lab study ( N = 34). Results: The results replicated past research, with a V shape of mean reaction time as a function of SOA, the V shape being stronger for lower-intensity visual stimuli. The level of SOA affected mainly the right side of the reaction time distribution, whereas the fastest 5% was hardly affected. The variability of reaction times was higher for the crowdsourcing study than for the Web-in-lab study. Conclusion: Crowdsourcing is a promising medium for reaction time research that involves small temporal differences in stimulus presentation. The observed effects of SOA can be explained by an independent-channels mechanism and also by some participants not perceiving the auditory or visual stimulus, hardware variability, misinterpretation of the task instructions, or lapses in attention. Application: The obtained knowledge on the distribution of reaction times may benefit the design of warning systems.

The Influence of an Intermittent Visual Stimulus on Perceptual Motor Skills in Aviation

1966 ◽  
Vol 8 (6) ◽  
pp. 569-572
Author(s):  
Ross E. Ailslieger ◽  
R. Dale Dick
Keyword(s):  
Reaction Time ◽  
Motor Skills ◽  
Visual Stimulus ◽  
Digit Span ◽  
Reaction Times ◽  
Pursuit Rotor ◽  
Flashing Light ◽  
Perceptual Motor Skills

The effect of a light flashing at 5 fps on performance of tasks representative of those required of a pilot was studied. The tasks were digit span, pursuit rotor, reaction time, and a combination of all three. Reaction time was longer in the combined task, and pursuit rotor performance was degraded by the flashing light. It was concluded that the longer reaction times were due to lowered vigilance, and the degradation of pursuit rotor performance was attributed to interference in the central processes by the flashing light.

The Effects of Alcohol on Four Choice Serial Reaction Time

1982 ◽  
Vol 22 (3) ◽  
pp. 181-188 ◽  
Author(s):  
Daniel Antebi
Keyword(s):  
Reaction Time ◽  
Reaction Times ◽  
Serial Reaction Time ◽  
Serial Reaction ◽  
The Mean ◽  
Reaction Task

Sixteen subjects were asked to perform a 4 choice serial reaction task, 8 of whom were given 140 ml of 65.5° vodka before performing the task. The subjects were all asked to complete the test every half an hour for 2 1/2 hours. The results showed that: Although the mean number of errors was increased this was not significant. The total number of responses and total number of correct responses were both increased. This again was not statistically significant. The mean number of gaps, i.e. reaction times greater than 1.000 seconds, was increased significantly. The mean reaction times were also significantly increased.

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.

scholarly journals Genome-wide association study in almost 195,000 individuals identifies 50 previously unidentified genetic loci for eye color

2021 ◽  
Vol 7 (11) ◽  
pp. eabd1239
Author(s):  
Mark Simcoe ◽  
Ana Valdes ◽  
Fan Liu ◽  
Nicholas A. Furlotte ◽  
David M. Evans ◽  
...  
Keyword(s):  
Association Study ◽  
Genome Wide Association Study ◽  
Color Variation ◽  
Genome Wide Association ◽  
Nucleotide Polymorphisms ◽  
Melanin Pigmentation ◽  
Eye Color ◽  
Human Eye ◽  
Genome Wide ◽  
Genomic Regions

Human eye color is highly heritable, but its genetic architecture is not yet fully understood. We report the results of the largest genome-wide association study for eye color to date, involving up to 192,986 European participants from 10 populations. We identify 124 independent associations arising from 61 discrete genomic regions, including 50 previously unidentified. We find evidence for genes involved in melanin pigmentation, but we also find associations with genes involved in iris morphology and structure. Further analyses in 1636 Asian participants from two populations suggest that iris pigmentation variation in Asians is genetically similar to Europeans, albeit with smaller effect sizes. Our findings collectively explain 53.2% (95% confidence interval, 45.4 to 61.0%) of eye color variation using common single-nucleotide polymorphisms. Overall, our study outcomes demonstrate that the genetic complexity of human eye color considerably exceeds previous knowledge and expectations, highlighting eye color as a genetically highly complex human trait.

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