Look up contiguity in Wiktionary, the free dictionary.

A contiguity is a continuous mass, or a series of things in contact or in proximity. In a different meaning, contiguity is the state of being contiguous.^[1] The concept was first set out in the Law of Contiguity, one of Aristotle's Laws of Association, which states that things which occur in proximity to each other in time or space are readily associated.

Biology[link]

A cluster of genes that are located close to one another at a chromosome locus are termed contiguous. Contiguous gene disorders result from deletions or duplications of a chromosome segment, thus causing a contiguous gene imbalance. Also, Contiguity refers to the way Taxonomy is ordered and formed after Charles Darwin wrote his famous, Theory of the Origins of Species in 1859. Prior to this a more strict taxonomy based upon an organisms locomotion and mobility was used. Now, we still use a type which is based on contiguity where the changes in an organism's anatomy are tracked and classed over time, thus showing a contiguous shaping over time.

Computer science[link]

Elements of memory are contiguous if they are adjacent to one another and appear to be connected, but may in fact be disconnected. A computer file or other data stored on a mass storage system, particularly hard disk-based, is said to be contiguous—sometimes, ungramatically, to be composed of one fragment—if the file data is in one continuous region without intervening extraneous data. A non-contiguous file is said to be fragmented, and can usually be defragmented with appropriate software.

Geography[link]

Land which are in physical contact with one another. In the United States, for example, the "48 contiguous states" exclude the states of Hawaii and Alaska, which do not share borders with other U.S. states.^[2]

Two or more contiguous municipalities can be consolidated into one, or one municipality can consist of many noncontiguous elements. For example, the Financially Distressed Municipalities Act allows the commonwealth of Pennsylvania to merge contiguous municipalities to reduce financial distress.

Geographic contiguity is important in biology, especially animal ranges. For a particular species, its habitat may be a 'contiguous range', or it might be broken, requiring periodic, typically seasonal migrations; (see: Disjunct distribution). The same concept of contiguous range is true for human transportation studies in an attempt to understand census geography.^[3] It also comes into play with electoral geography and politics.^[4]

Interaction design[link]

Contiguous data is recognized by the fact that it needs to be in a particular order to keep its meaning: if you would scramble the letters, words or even the paragraphs in a text it wouldn't be the same text anymore.^[5]

Management[link]

The concept of close operational context is an approach to determine the co-operation of entities, e.g. persons or persons with equipment, to monitor the usage of equipment just by an fuzzy metrics for lateral distance, as else the events of coooperation or, in healthcare, especially the events of service by staff to patients.^[6]

Mathematics[link]

The ideas of closeness are inherent in the concept of a contiguity space or proximity space. See also Law of Continuity. In addition, the Law of Continuity can be applied to conceptual computational abstract ideas.

Philosophy[link]

Philosophers speak of contiguity when they assume two events or objects lying directly side by side in space and time without being connected by causality or any other principle.^[7]

Physics[link]

Contiguity is a metallurgical property used to characterize microstructure of materials. It is computed by finding the ratio of solid–solid length to the sum of solid–solid and solid–liquid length of the microstructure.

Probability theory[link]

The contiguity of a pair of sequences of probability measures is a property that relates to the commonality of the sets which have zero measure as the index in the sequence increases: see Contiguity (probability theory).

Psychology[link]

Association by contiguity is the principle that ideas, memories, and experiences are linked when one is frequently experienced with the other. For example, if you constantly see a knife and a fork together they become linked (associated). The more these two items (stimuli) are perceived together the stronger the link between them. When one of the memories becomes activated later on, the linked (contiguously associated) memory becomes temporarily more activated and thus easier to be called into working memory. This process is known as priming, and the initial memory that primed the other is known as the retrieval cue.

Association by contiguity is the root of association by similarity. Association by similarity is the idea that one memory primes another through their common property or properties. Thus, an apple may prime a memory of a rose through the common property of red. These two become associated even though you may have never experienced an apple and a rose together (consistent with association by contiguity).

In the study of human memory, the contiguity effect has been found in studies of free recall. Analyses of free recall data indicates that there tends to be the greatest number of +/- 1 transitions between words, suggesting that words that are closer together in a list are more likely to be recalled together (^{[Syracuse University 1]}). This is shown in a graph of conditional response probability as a function of lag as originated by Dr. Michael Kahana. The probability of recall (y-axis) is plotted against the lag, or separation between subsequently recalled words (^[8] ) also see figure http://memory.psych.upenn.edu/Research?action=AttachFile&do=get&target=crp2a_square.jpg. For example, if two items A and B are learned together, when cued with B, A is retrieved and vice-versa due to their temporal contiguity, although there will be a stronger forward association (when cued with A, B is recalled) (^[9]).

The contiguity effect appears relatively constant, and has been predicted to have long-term effects according to the temporal context model proposed by Howard and Kahana (^[10]). This model explains the contiguity effect in the following manner: when an item is presented, it activates the temporal context that was active when the item was originally studied. Since contexts of neighboring items overlap, and that overlap increases with decreasing lag between items, a contiguity effect results (^{[Syracuse University 2]}). The contiguity effect has even been found between items in different lists, although it has been speculated that these items could simply be intrusions ( ^{[Syracuse University 3]}

When one associated memory, a group of associated memories, or a whole line of associated memories becomes primed, this is known as spreading activation.

In conditioning, contiguity refers to how associated a reinforcer is with behaviour. The higher the contiguity between events the greater the strength of the behavioural relationship.

Edwin Ray Guthrie's contiguity theory deals with patterned movements.^[11]

References[link]

See also[link]

• Closeness
• Cohesion
• Connectedness
• Contact
• Continuity
• Neighbourhood
• Proximity
• Vicinity