Category Ratings of Visual Velocity Support Haubensak's Consistency Model

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 42-42
Author(s):  
W H Ehrenstein ◽  
A N Sokolov
Keyword(s):  
Computer Simulation ◽  
Human Perception ◽  
Presentation Order ◽  
Skewed Distribution ◽  
Frequency Effect ◽  
Order Effects ◽  
Equal Frequency ◽  
Underlying Assumption ◽  
Consistency Model ◽  
Good Agreement

Identical stimuli receive higher category ratings when presented in a positively skewed distribution (smaller stimuli occur more often than larger) and lower ratings in a negatively-skewed distribution (larger stimuli occur more often). This frequency effect has been explained by a tendency to assign the same categories to the same stimuli (‘consistency model’ by Haubensak, 1992 Journal of Experimental Psychology: Human Perception and Performance18 303) rather than by a tendency to assign the same number of stimuli to each category. The consistency model postulates the prime importance of stimuli that occur early in a sequence, with the underlying assumption that more frequent stimuli have higher probability of occurring earlier. Thus, presentation order rather than frequency of stimuli might be decisive. We asked whether a ‘frequency’ effect would still obtain when stimuli are in fact presented with equal frequency, but in a sequence derived from positively or negatively skewed source samples. Ratings of visual velocity were obtained for a dot that started to move at 0.5 deg below fixation in leftward or rightward direction for 2, 2.5, or 3 deg. Five velocities (3.0, 4.5, 6.0, 7.5, 9.0 deg s−1) were presented 10 times each (in a balanced combination of stimulus duration and displacement) and were rated by 32 subjects using three categories (slow, medium, fast). Our results clearly support Haubensak's model: identical velocities were rated higher/lower in presentation sequences that mimicked the order effects of positive/negative skewing, respectively. Moreover, computer simulation of the Haubensak model reveals good agreement between predicted and observed results.

Rating Visual Velocities: Presentation Order versus Frequency of Occurrence

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 363-363
Author(s):  
A N Sokolov ◽  
W H Ehrenstein ◽  
M A Pavlova
Keyword(s):  
Order Effect ◽  
Frequency Theory ◽  
Presentation Order ◽  
Frequency Effect ◽  
Frequency Of Occurrence ◽  
Frequency Distributions ◽  
Frequency Effects ◽  
Consistency Model ◽  
Group 2 ◽  
Group 1

Given equal frequencies of occurrence of stimuli, identical velocities receive higher or lower ratings depending on whether slow or fast velocities happen to occur on the early trials of a run (Ehrenstein and Sokolov, 1996 Perception25 Supplement, 34 – 35). When stimuli vary in their frequency of occurrence, this presentation-order effect might enhance or substitute the well-known frequency effect (Parducci's range - frequency theory) on category ratings. The aim of the present study was to contrast these two effects for ratings of visual velocities. Two groups of observers had to rate five stimulus velocities (3, 4.5, 6, 7.5, and 9 deg s−1) of a single luminous dot using three categories (slow, medium, fast). Respective frequencies of occurrence for these velocities were either 4 - 4 - 8 - 14 - 20 (group 1, negative skewing for frequency) or 20 - 14 - 8 - 4 - 4 (group 2, positive skewing). The quasi-random presentation order of each set, on the contrary, corresponded to either positively skewed (group 1) or negatively skewed (group 2) frequency distributions. No significant differences in the ratings of two groups (other than a slight preference for the presentation-order effect beyond 6 deg s−1) were found, as if the presentation order and frequency effects had cancelled each other. This suggests that the presentation order of velocities is at least as powerful as their frequency of occurrence. Lack of agreement between our results and predictions of computer-simulated Haubensak's consistency model as well as of Parducci's range - frequency theory requires a model which accounts for an interaction of the two effects.

Feedback versus an Illusion in Time

Perception ◽  
1978 ◽  
Vol 7 (1) ◽  
pp. 91-96 ◽  
Author(s):  
Donald G Jamieson ◽  
William M Petrusic
Keyword(s):  
Presentation Order ◽  
Order Effects ◽  
Information Feedback ◽  
Response Accuracy ◽  
Time Order ◽  
Extended Practice ◽  
Duration Comparison ◽  
Response Biases

The accuracy of many perceptual comparisons depends greatly on the order in which the to-be-compared stimuli are presented. With comparisons of durations around 300 ms, these presentation-order effects do not diminish, even with extended practice, when feedback about response accuracy is withheld. Providing such feedback greatly diminishes presentation-order effects and coincidentally produces substantial increases in response accuracy. The feedback acts in part through inducing response biases and in part through changes in sensitivity. The contradiction between studies which report time-order errors in duration comparison and those which do not is attributable to differences in the use of information feedback.

Carbo-Nitride Precipitation in Tempered Martensite - Computer Simulation and Experiment

2012 ◽  
Vol 706-709 ◽  
pp. 1586-1591 ◽  
Author(s):  
Sabine Zamberger ◽  
Ernst Kozeschnik
Keyword(s):  
Computer Simulation ◽  
Precipitation Behavior ◽  
Tempered Martensite ◽  
Extraction Replica ◽  
Transmission Electron ◽  
Simulation And Experiment ◽  
Precipitate Microstructure ◽  
Means Of Transmission ◽  
Quenched And Tempered Steel ◽  
Good Agreement

In the present work, the precipitation behavior of a V-microalloyed, quenched and tempered steel with 0.3wt % C is investigated experimentally and by computer simulation. The specimens are analyzed by means of transmission electron microscopy using selected area diffraction (SAD) and energy dispersive x-ray spectroscopy (EDX). The analysis is done on electropolished foils and on extraction replica. The numerical simulation is performed with the thermokinetic software package MatCalc, where the precipitation kinetics is examined for the experimentally applied thermo-mechanical cycles. Good agreement between experiment and simulation is obtained and the experimentally observed precipitate microstructure can be well explained on the basis of these simulations.

Cooling System for a Portable Bio-Industry Centrifuge

2005 ◽  
Author(s):  
Shahla Vatannia ◽  
Fred Barez
Keyword(s):  
Computer Simulation ◽  
Cooling System ◽  
Model Simulation ◽  
Primary Sources ◽  
Experimental Measurements ◽  
Cfd Model ◽  
Separate Species ◽  
Zero Degree ◽  
Reduced Temperature ◽  
Good Agreement

A centrifuge is used in bio-industry to separate species in blood and other chemicals. Bio-industry requires a temperature of zero degree centigrade in the rotor compartment of a centrifuge where samples are placed. In general, the current portable centrifuge systems generate a temperature of about 22 °C in the rotor compartment when operating at 3000 RPM. The motor and the electronics are the primary sources of the heat generation in such centrifuge. The aim of this study is to develop an appropriate cooling system for a specific portable centrifuge used in separating bioparticles that generates a total heat of approximately 43 W. Experimental, analytical and computer simulation were employed to achieve the project objective of reducing and maintaining the rotor compartment temperature at zero degree C. The CFD code Simulation model predicted rotor compartment temperatures that were in good agreement with those of the experimental measurements within 3%. Having confidence in the CFD model, simulation was carried out to incorporate four TEC units that are embedded on the surface of the rotor compartment resulting in reduced temperature to zero degree C.

The calculation of spin-orbit splitting and g tensors for small molecules and radicals

1973 ◽  
Vol 332 (1590) ◽  
pp. 365-384 ◽  
Keyword(s):  
Order Effects ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Orbit Splitting ◽  
First Order ◽  
Spin Orbit Splitting ◽  
Approximate Form ◽  
Firm Basis ◽  
Semi Empirical ◽  
Good Agreement

The spin-orbit coupling terms in the molecular electronic Hamiltonian have important, spectroscopically observable, effects. In states possessing an orbital degeneracy (e.g. II states of diatomic molecules) they produce a first-order splitting of the various multiplet levels; and in states which are degenerate in spin only the y give second-order effects embodied in a n effective g tensor. Owing to the complexity of the spin-orbit operators, such effects are usually discussed using simple approximate form s and semi-empirical wave-functions. In this paper, the complete operators are employed in ab initio calculations of (i) the spin-orb it splitting of the 2 II ground states of NO and CH, and (ii) the g tensors of CN and NO 2 . The results are in good agreement with experiment. Detailed analysis of the calculations indicates a firm basis for semi-empirical procedures which could easily be applied to larger molecules. The evaluation of new integrals, involving the spin-orbit operators, is discussed in an appendix.

Computer Simulation of Channeling Profile Analysis of Implantation Damage

1998 ◽  
Vol 532 ◽  
Author(s):  
Matthias Posselt
Keyword(s):  
Experimental Data ◽  
Computer Simulation ◽  
Depth Profile ◽  
Profile Analysis ◽  
Binary Collision ◽  
Comparison Of Results ◽  
Implantation Damage ◽  
Good Agreement

ABSTRACTChanneling profile analysis is simulated using the dynamic binary collision code Crystal- TRIM. A good agreement between theoretical and experimental data is found for silicon targets which were predamaged by Si+ ions of different energies and analyzed by 140 keV B+ ions. For each example the depth profile of the defects relevant for the dechanneling of the analyzing ions is given. An estimate of the annealing of such defects is obtained by comparison of results for as-implanted and annealed samples.

A Quantitative Model of Surface Segregation in III-V Ternary Compounds

2000 ◽  
Vol 618 ◽  
Author(s):  
Sergey Yu. Karpov ◽  
Yuri N. Makarov
Keyword(s):  
Surface Segregation ◽  
Quantitative Model ◽  
Model Verification ◽  
Key Factors ◽  
Underlying Assumption ◽  
Factors Affecting ◽  
Surface Population ◽  
Theoretical Predictions ◽  
Good Agreement ◽  
Crystal Bulk

ABSTRACTA quantitative model of surface segregation free from adjustable parameters is suggested for the growth of ternary III-V compounds. In contrast to previous approaches, the model considers the dynamics of surface population by the three elements producing the ternary alloy. The underlying assumption is that the atoms in the adsorption layer are in equilibrium with the crystal bulk. Elastic strain arising in the epitaxial layer due to the lattice constant mismatch with the substrate is found to be one of the key factors affecting segregation. Along with growth temperature, it controls the segregation efficiency and the composition profile evolution in a growing heterostructure. The effect of the V/III ratio, growth rate and other parameters is accounted for. Here, we apply the model to analyze the InGaAs growth by molecular beam epitaxy owing to the vast experimental data available for the model verification. The theoretical predictions show a good agreement with the experimental observations

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