A feature (also characteristic ) is generally a recognizable characteristic that a person , a thing or an abstract context of other different . The term “feature” is also defined in DIN 55350 and DIN EN ISO 9000: 2005 Section 3.5.1.
The term “feature” has been used in the German language since the 17th century. A special role is played the feature when classifying of objects in the taxonomy since the 17th century, for. B. with Carl von Linné (see #Biology )
Philosophy, concept theory
In philosophy , the term characteristic is related to the traditional doctrine of the term , in which a distinction is made between a being , of which the term can be expressed (material object), and the content (formal object) that is included in this term (→ material object and Formal object ). The term content applies to the feature or the entirety of the features. The term is used both in the semantic meaning of marks (→ characters ; differentia specifica ) and in the sense of property . For the philosopher Immanuel Kant (1724–1804) a characteristic was “that in a thing that constitutes part of the knowledge of it”. The philosopher Georg Wilhelm Friedrich Hegel (1770–1831), on the other hand, wrote: "Nothing is so much itself the feature of outwardness and the lack of logic as the popular category of the feature."
In botany , it was Carl von Linné (1707–1778) who, in order to differentiate between the various plant species, took the essential characteristic into the field of view of his classifications. According to him, which resulted in essential feature of "the most careful description of the development of flower and fruit of the first kind. All the other species of the genus are the first compared with all non-uniform features are excluded. After this work you get the essential feature “. Both Linnaeus and the botanist Joseph Pitton de Tournefort (1656–1798) defined a botanical genus with the essential characteristic . With the exception of the somewhat problematic term "essence" (which for many today's readers, if not necessarily for Linnaeus himself, has an essentialist connotation), this corresponds to the work of biologists with differential characteristics to this day.
Today, in biology, characteristics are understood as all properties of species (and other groups) or individuals that can be used to differentiate between them. The species characteristics are mostly morphological characteristics, but others such as physiological , ethological or genetic characteristics can be more important depending on the question. Individual characteristics are, for example, age, experience or status (in the case of social types).
Some characteristics cannot be clearly assigned: for example, body size is a species characteristic that is often used to differentiate between related species, but it is also individually variable within a reaction norm. The expression of a trait often depends on both the genetic makeup and external environmental influences. The genes in their entirety determine the tolerance range in which characteristics can vary due to environmental influences. Mechanisms of self-organization also play a role here (examples: early embryonic networking of the nerve cells of the brain, formation of the trabeculae). The environmentally controlled expression is called a modification . If individual animal species or groups show a special characteristic that does not appear in all other living beings, this is referred to as an exclusive feature (example: hair up to the fur only occurs in mammals ).
Environmental influences play a major role, for example in ethology, when behavioral characteristics in the development of the individual are individually developed differently through imprinting or other forms of learning .
In phylogenetic systematics or cladistics , the term “characteristic” is sometimes used with two different meanings. On the one hand, it is used to mean “a structure of an organism ”. On the other hand, the state in which a structure is located is also called a feature. According to the first approach, for example, “red flower color” would be a characteristic of a plant, according to the second “red” would be an expression of the characteristic “flower color”. The second approach is usually preferred because it '(due to the distinction between feature English. Character ) and feature state' (Engl. Character state ) enables a more accurate description. However, some biologists continue to use the term in the sense of “individual characteristics”.
In the context of differential psychology or psychological diagnostics , the term “characteristic” is also used as a generic term for all psychological “attributes” of a person with regard to which the person can differ from others. One reason is that the concept of trait in the narrower sense is used for persistent personality traits , from which the states or habits of behavior (habit) are to be distinguished.
Statistics and empirical data
In statistics, one speaks of a characteristic in the sense of a surveyed quantity or a statistical variable .
Applied computer science
In applied computer science, characteristics of data in signal form (images, speech data) are used in order to be able to process the data better (examples are the energy of a speech signal or an image, MFCCs or LPCs in speech recognition ). Different features are often combined to feature vectors that facilitate pattern recognition .
Numerous commercially available products are manufactured in a wide variety of variants, which are described by a large number of features. The features are properties that are typical for the respective product and clearly characterize it from both the customer and the manufacturer's point of view. In the case of automobiles in particular, the customer can put together the characteristics of his product himself with the help of a product configurator. The characteristics can either be loosely next to one another or be logically connected to one another and form an ideal Boolean association . This makes it easier to achieve a consistent selection of product features.
Features of a handwriting
In the Schriftvergleichung and graphology are numerous features of manuscripts of interest, eg. B. Special features of the printing, the line quality, the design and movement management, the flow of movement, the direction of movement, as well as the horizontal and vertical expansion and surface structure.
Types of characteristics
Quantitative and qualitative characteristics
- Quantitative characteristics are measured or counted. The characteristic values are given as numerical values plus unit. Possible values are, for example: 30 cm for the “length” characteristic and 5 kg for the “weight” characteristic. Quantitative features can be discrete or continuous features (see below).
- Qualitative features are features that can be described in words or numbers (for example 0 = red, 1 = green). "Qualitative features are always discrete, since they naturally only have a countable set of possible feature values (categories)."
Discrete and continuous features
- Discrete features: “Discrete are those features that can only assume a finite number or a countably infinite number of manifestations. In particular, all features are discrete, the values of which are determined by counting. ”Instead of discrete features, one also speaks of discontinuous features.
- Continuous characteristics: “Continuous are those characteristics which take on any real value at least in a number interval and thus can have an uncountable number of values. [...] Typical continuous characteristics are time, length, weight, volume, etc. "
- Quasi Continuous Features: Discrete features that can accept an extremely high number of possible outcomes are sometimes referred to as quasi constantly referred. This applies, for example, to amounts of money that can be recorded to two decimal places. For reasons of simplification and cost, these are sometimes "clearly discretized" by classification, as is the case with income limits. Conversely, they can also be "stabilized" if they are of particular importance, which is the case, for example, when exchange rates are specified to five decimal places.
Cumulative and non-cumulative characteristics
Depending on whether a feature carrier can have only one or more feature values with regard to a feature dimension, a distinction is made:
- Non-cumulative characteristic: Only one characteristic value can be clearly assigned to each characteristic carrier. For example, everyone is only one size.
- Common characteristic: A characteristic carrier can have several characteristic values. For example, a person can have two professions.
Since a new feature value is uniquely assigned to all possible combinations of a common feature, a common feature can be reduced to a non-common feature.
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