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Ideal Observer Analysis
Ideal observer analysis is a method for investigating how information is processed in a perceptual system. It is also a basic principle that guides modern research in perception. The ''ideal observer'' is a theoretical system that performs a specific task in an optimal way. If there is uncertainty in the task, then perfect performance is impossible and the ideal observer will make errors. ''Ideal performance'' is the theoretical upper limit of performance. It is theoretically impossible for a real system to perform better than ideal. Typically, real systems are only capable of sub-ideal performance. This technique is useful for analyzing psychophysical data (see psychophysics). Definition Many definitions of this term have been offered. Geisler (2003) (slightly reworded): The central concept in ideal observer analysis is the ''ideal observer'', a theoretical device that performs a given task in an optimal fashion given the available information and some specified constrain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perceptual System
A perceptual system is a computational system (biological or artificial) designed to make inferences about properties of a physical environment based on senses. Other definitions may exist. In this context, a scene is defined as information that can flow from a physical environment into a computational system via sensory transduction. A sensory organ (biological or artificial) is used to capture this information. Therefore, any perceptual system must incorporate input from at least one sensory organ. Examples of perceptual systems include: * The visual system * The auditory system * The olfactory system * The somatosensory system * A bat's sonar/ echolocation system * A man-made light meter * A man-made motion detector Research in the field of perceptual systems focuses on computational aspects of perception. For this reason, there is significant overlap with neuroscience, sensor design, natural scene statistics, and computer science. References Further reading * {{cite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scene Statistics
Scene statistics is a discipline within the field of perception. It is concerned with the statistical regularities related to scenes. It is based on the premise that a perceptual system is designed to interpret scenes. Biological perceptual systems have evolved in response to physical properties of natural environments. Therefore natural scenes receive a great deal of attention. Natural scene statistics are useful for defining the behavior of an ideal observer in a natural task, typically by incorporating signal detection theory, information theory, or estimation theory Estimation theory is a branch of statistics that deals with estimating the values of parameters based on measured empirical data that has a random component. The parameters describe an underlying physical setting in such a way that their valu .... One of the most successful applications of Natural Scenes Statistics Models has been perceptual picture and video quality prediction. For example, the Vi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Receiver Operating Characteristic
A receiver operating characteristic curve, or ROC curve, is a graphical plot that illustrates the diagnostic ability of a binary classifier system as its discrimination threshold is varied. The method was originally developed for operators of military radar receivers starting in 1941, which led to its name. The ROC curve is created by plotting the true positive rate (TPR) against the false positive rate (FPR) at various threshold settings. The true-positive rate is also known as sensitivity, recall or ''probability of detection''. The false-positive rate is also known as ''probability of false alarm'' and can be calculated as (1 − specificity). The ROC can also be thought of as a plot of the power as a function of the Type I Error of the decision rule (when the performance is calculated from just a sample of the population, it can be thought of as estimators of these quantities). The ROC curve is thus the sensitivity or recall as a function of fall-out. In general, if the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensitivity Index
The sensitivity index or discriminability index or detectability index is a dimensionless statistic used in signal detection theory. A higher index indicates that the signal can be more readily detected. Definition The discriminability index is the separation between the means of two distributions (typically the signal and the noise distributions), in units of the standard deviation. Equal variances/covariances For two univariate distributions a and b with the same standard deviation, it is denoted by d' ('dee-prime'): : d' = \frac. In higher dimensions, i.e. with two multivariate distributions with the same variance-covariance matrix \mathbf, (whose symmetric square-root, the standard deviation matrix, is \mathbf), this generalizes to the Mahalanobis distance between the two distributions: : d'=\sqrt = \lVert \mathbf^(\boldsymbol_a-\boldsymbol_b) \rVert = \lVert \boldsymbol_a-\boldsymbol_b \rVert /\sigma_, where \sigma_ = 1/ \lVert\mathbf^\boldsymbol\rVert is the 1d slice of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-alternative Forced Choice
Two-alternative forced choice (2AFC) is a method for measuring the sensitivity of a person, child or infant, or animal to some particular sensory input, stimulus, through that observer's pattern of choices and response times to two versions of the sensory input. For example, to determine a person's sensitivity to dim light, the observer would be presented with a series of trials in which a dim light was randomly either in the top or bottom of the display. After each trial, the observer responds "top" or "bottom". The observer is not allowed to say "I do not know", or "I am not sure", or "I did not see anything". In that sense the observer's choice is forced between the two alternatives. Both options can be presented concurrently (as in the above example) or sequentially in two intervals (also known as two-interval forced choice, 2IFC). For example, to determine sensisitivity to a dim light in a two-interval forced choice procedure, an observer could be presented with series of trials ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Confusion Matrix
In the field of machine learning and specifically the problem of statistical classification, a confusion matrix, also known as an error matrix, is a specific table layout that allows visualization of the performance of an algorithm, typically a supervised learning one (in unsupervised learning it is usually called a matching matrix). Each row of the matrix represents the instances in an actual class while each column represents the instances in a predicted class, or vice versa – both variants are found in the literature. The name stems from the fact that it makes it easy to see whether the system is confusing two classes (i.e. commonly mislabeling one as another). It is a special kind of contingency table, with two dimensions ("actual" and "predicted"), and identical sets of "classes" in both dimensions (each combination of dimension and class is a variable in the contingency table). __TOC__ Example Given a sample of 12 individuals, 8 that have been diagnosed with cancer an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Estimation Theory
Estimation theory is a branch of statistics that deals with estimating the values of parameters based on measured empirical data that has a random component. The parameters describe an underlying physical setting in such a way that their value affects the distribution of the measured data. An ''estimator'' attempts to approximate the unknown parameters using the measurements. In estimation theory, two approaches are generally considered: * The probabilistic approach (described in this article) assumes that the measured data is random with probability distribution dependent on the parameters of interest * The set-membership approach assumes that the measured data vector belongs to a set which depends on the parameter vector. Examples For example, it is desired to estimate the proportion of a population of voters who will vote for a particular candidate. That proportion is the parameter sought; the estimate is based on a small random sample of voters. Alternatively, it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Information Theory
Information theory is the scientific study of the quantification (science), quantification, computer data storage, storage, and telecommunication, communication of information. The field was originally established by the works of Harry Nyquist and Ralph Hartley, in the 1920s, and Claude Shannon in the 1940s. The field is at the intersection of probability theory, statistics, computer science, statistical mechanics, information engineering (field), information engineering, and electrical engineering. A key measure in information theory is information entropy, entropy. Entropy quantifies the amount of uncertainty involved in the value of a random variable or the outcome of a random process. For example, identifying the outcome of a fair coin flip (with two equally likely outcomes) provides less information (lower entropy) than specifying the outcome from a roll of a dice, die (with six equally likely outcomes). Some other important measures in information theory are mutual informat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Detection Theory
Detection theory or signal detection theory is a means to measure the ability to differentiate between information-bearing patterns (called stimulus in living organisms, signal in machines) and random patterns that distract from the information (called noise, consisting of background stimuli and random activity of the detection machine and of the nervous system of the operator). In the field of electronics, signal recovery is the separation of such patterns from a disguising background. According to the theory, there are a number of determiners of how a detecting system will detect a signal, and where its threshold levels will be. The theory can explain how changing the threshold will affect the ability to discern, often exposing how adapted the system is to the task, purpose or goal at which it is aimed. When the detecting system is a human being, characteristics such as experience, expectations, physiological state (e.g., fatigue) and other factors can affect the threshold app ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scene (perception)
In the field of perception, a scene is information that can flow from a physical environment into a perceptual system via sensory transduction. A perceptual system is designed to interpret scenes. Examples of scenes include * Still images * Binocular still images * Moving images (movies) * Binocular moving images (~ 3D movies) * Sounds of a local environment (audio recordings) * Tactile Tactile may refer to: * Tactile, related to the sense of touch * Haptics (other) * Tactile (device), a text-to-braille translation device See also * Tangibility, in law * Somatosensory system, where sensations are processed * CD96 CD ... properties of a local environment. A natural scene is a scene that a perceptual system would typically encounter in a natural mode of operation. Therefore, a very relevant area of research is natural scene statistics. References Perception {{psych-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of The Acoustical Society Of America
The ''Journal of the Acoustical Society of America'' is a monthly peer-reviewed scientific journal covering all aspects of acoustics. It is published by the Acoustical Society of America and the editor-in-chief is James F. Lynch (Woods Hole Oceanographic Institution The Woods Hole Oceanographic Institution (WHOI, acronym pronounced ) is a private, nonprofit research and higher education facility dedicated to the study of marine science and engineering. Established in 1930 in Woods Hole, Massachusetts, it i ...). References External links * Acoustical Society of America Acoustics journals Publications established in 1929 Monthly journals English-language journals {{acoustics-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
External Validity
External validity is the validity of applying the conclusions of a scientific study outside the context of that study. In other words, it is the extent to which the results of a study can be generalized to and across other situations, people, stimuli, and times.Aronson, E., Wilson, T. D., Akert, R. M., & Fehr, B. (2007). Social psychology. (4 ed.). Toronto, ON: Pearson Education. In contrast, internal validity is the validity of conclusions drawn ''within'' the context of a particular study. Because general conclusions are almost always a goal in research, external validity is an important property of any study. Mathematical analysis of external validity concerns a determination of whether generalization across heterogeneous populations is feasible, and devising statistical and computational methods that produce valid generalizations. Threats "A threat to external validity is an explanation of how you might be wrong in making a generalization from the findings of a particular study ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
