In linguistics and in philosophy of language, an indexical behavior or utterance points to (or indicates) some state of affairs. For example, I refers to whoever is speaking; now refers to the time at which that word is uttered; and here refers to the place of utterance. For Charles Sanders Peirce, indexicality is one of three sign modalities (see further down), and is a phenomenon far broader than language; that which, independently of interpretation, points to something — such as smoke (an index of fire) or a pointing finger — works indexically for interpretation. Social indexicality in the human realm has been regarded as including any sign (clothing, speech variety, table manners) that points to, and helps create, social identity.
Pragmatics and indexicality 
Indexicality is often treated as part of the study of language called pragmatics – in contrast to such fields as phonology, syntax, and semantics – in that it concerns the use and effects of language. Indexicality is sometimes seen as an alternative way of understanding reference (a concept of semantics) since it allows for an expansion of the way we understand language, and communication in general, to work. Scholars in linguistic anthropology, Elinor Ochs for example, note how gender can be indexed by the stances one adopts, whether physical or linguistic. This can be accomplished by the way one stands (e.g., the conventionally feminine: "hand on hip with body bent"; in contrast to the conventionally masculine: "thumb in pocket, standing straight with legs apart"). Gender can also be indexed by the language styles one uses (e.g., the conventionally feminine: "large variable range in speaking tones, favoring higher pitches" or "lisping, soft tones"; in contrast to the conventionally masculine: "deep tones within a narrow range of low pitches"). Indexicality is closely related to deixis, which denotes a behavior or an utterance whose meaning varies according to certain features of the context in which it is uttered. Now, here, and I are also typical examples of deictic terms, as well as examples of indexical terms.
Indexicals are closely related to demonstratives (this, that), in that both vary in meaning depending on context. Demonstratives may be thought of as forming a subset of indexicals: they are often accompanied, in ordinary usage, by pointing gestures or other non-verbal expressions of their sense. Many but not all indexicals are also egocentric, which means that in order to successfully interpret them the hearer must have knowledge of the respective speaker, time, and place of utterance.
Peirce's trichotomy of signs 
C.S. Peirce elaborated three central trichotomies that classify different sign-relations, and that are themselves differentiated, on the basis of Peirce's three universal categories (loosely described as Possibility, Actuality, and Law-likeness). The first trichotomy of sign relations relates to a category that Peirce found to be epitomized in possibility and, as with each trichotomy, is split into three kinds, according to whether the sign in question is a quality, an actual thing, or a matter of habit (tone, token, type, also called qualisign, sinsign, legisign). The second (icon, index, symbol) depends on the kind of relation the sign bears to some object, whether merely imagined (e.g., the idea of a cat when a human says, "Meow"), actual and causally efficacious (e.g., actual wind blowing a weathervane), or a constant and regular force (e.g., convention). Semiotic elements and classes of signs (Peirce)#Rheme, dicisign, argument. The third depends on the kind of significance which the sign will be interpreted as making, to be distinguished from the reference-oriented (sign-to-object) relation of the second trichotomy. Most famous is the second trichotomy:
- Icon, also called a likeness or semblance: a sign that is linked to its represented object by some shared quality (which may vary from physical appearances, common actions, distinct sounds, etc.). An example of this would be the stick-figure pictorial representations of men and women on the door of a public restroom. This is iconic because it is meant to signify a man or woman through a simplified visual representation. An icon does not depend on an actual connection to its object (which may fail to exist) or on a habit of interpretation.
- Index: a sign that is linked to its object by an actual connection or real relation (irrespectively of interpretation), for instance, by a reaction, so as to compel attention, in a definite place and time. A simple example is an "Exit" sign which has an arrow pointing towards the exit. Smoke billowing from a house is an index for a fire inside.
- Symbol: A symbol represents its denoted object by virtue of an interpretive habit or rule that is independent of any shared physical quality, contextual contiguity, or lack thereof, with that which it denotes. A symbol consists in that rule. A word such as "horse" is an example of a symbol which, additionally, is specific to a particular language and prescribes the qualities of its instances, which, then, are noticeably arbitrary with respect to iconic qualities and indexical connections. Most spoken language (with the exception of instances of onomatopoeia like 'hiccup' and 'roar') is symbolic because it is arbitrary in those senses. For example, the English word "window" has no relation to any actual physical window. Peirce usually considered personal names and demonstratives like "this" to be indices, not symbols.
Referential indexicality 
It is possible for signs to have two kinds of meaning, referred to as indexical and referential. Indexical meaning is meaning that is context-dependent. For examples, consider the traditional deictic categories of person, place, and time. Some frequently-used English examples are pronouns, demonstratives, and tense markings. Referential meaning, also called 'semantico-referential function', is when a word functions to describe events or states of affairs in the world independent of the context of the utterance. An example of this could be
- A cat is on a mat
because the meaning that it conveys is independent of who says it, when they say it, etc.
A referential indexical, also called a 'shifter', is a sign which contains both referential and indexical meaning. So for example, the word 'I', as in
- I went to the store.
is a referential indexical. It has referential content, in that it refers to the singular first person, and indexical content, in that its meaning depends on who uttered the word.
Indexical presupposition and performativity 
Indexical sign types are defined by rules of use that state that there exists a relationship between mutually implied existence of sign vehicle token (i.e. icon, index or symbol) and certain aspects of the context of discourse. The indexical sign token presupposes the aspect of the speech situation and is referentially uninterpretable without some knowledge of context. In other words, some aspect of the context is spelled out in the rules of use, fixed and presupposed, and must be understood for the referential contribution to be made. In the use of pure indexical tokens the sign can also have a creative or performative aspect in that rather than change the context, it creates boundaries to the structure of the event. For example in the case of English indexical pronouns, I and we (as opposed to he/she/it/they) create parameters that specify the parties to whom one is referring. Indexes, both referential and non-referential, therefore exist on a sliding scale, some more presupposing, some more creative, and some containing clear aspects of both.
Non-referential indexicality 
Non-referential indices or "Pure" indices do not contribute to the semantico-referential value of a speech event yet "signal some particular value of one or more contextual variables." Non-referential indices encode certain metapragmatic elements of a speech event's context through linguistic variations. The degree of variation in non-referential indices is considerable and serves to infuse the speech event with, at times, multiple levels of pragmatic "meaning." Of particular note are: sex/gender indices, deference indices (including the affinal taboo index), affect indices, as well as the phenomena of phonological hypercorrection and social identity indexicality.
First, second, and higher orders of non-referential indexicality 
In much of the research currently conducted upon various phenomena of non-referential indexicality, there is an increased interest in not only what is called first-order indexicality, but subsequent second-order as well as "higher-order" levels of indexical meaning. First-order indexicality can be defined as the first level of pragmatic meaning that is drawn from an utterance. For example, instances of deference indexicality such as the variation between informal "Tu" and the more formal "Vous" in French (See T/V deference indexes) indicate a speaker/addressee communicative relationship built upon the values of 'power' and 'solidarity' possessed by the interlocutors. When a speaker addresses somebody using the V form instead of the T form, they index (via first-order indexicality) their understanding of the need for deference to the addressee. In other words, they perceive/ recognize an incongruence between their level of 'power' and/or 'solidarity', and that of their interlocutor and employ a more formal way of addressing that person to suit the contextual constraints of the speech event.
Second-Order Indexicality is concerned with the connection between linguistic variables and the metapragmatic meanings that they encode. For example, a woman is walking down the street in Manhattan and she stops to ask somebody where a McDonalds is. He responds to her talking in a heavy "Brooklyn" accent. She notices this accent and considers a set of possible personal characteristics that might be indexed by it (such as the man's intelligence, economic situation, and other non-linguistic aspects of his life). The power of language to encode these preconceived "stereotypes" based solely on accent is an example of second-order indexicality (representative of a more complex and subtle system of indexical form than that of first-order indexicality).
Michael Silverstein has also argued that indexical order can transcend levels such as second-order indexicality and discusses higher-order indexicality in terms of what he calls "oinoglossia" or "wine talk".(For discussion see below)
Non-referential indexical phenomena 
Examples of non-referential forms of indexicality include sex/gender, affect, deference, social class, and social identity indices. Many scholars, notably Silverstein, argue that occurrences of non-referential indexicality entail not only the context-dependent variability of the speech event, but also increasingly subtle forms of indexical meaning (first, second, and higher-orders)as well.
Sex/gender indices 
One common system of non-referential indexicality is sex/gender indices. These indices index the gender or "female/male" social status of the interlocutor. There are a multitude of linguistic variants that act to index sex and gender such as:
- word-final or sentence-final particles:many languages employ the suffixation of word-final particles to index the gender of the speaker. These particles vary from phonological alterations such as the one explored by William Labov in his work on postvocalic /r/ employment in words that had no word final "r" (which is claimed, among other things, to index the "female" social sex status by virtue of the statistical fact that women tend to hypercorrect their speech more often than men); suffixation of single phonemes, such as /-s/ in Muskogean languages of the southeastern United States; or particle suffixation (such as the Japanese sentence-final use of -wa with rising intonation to indicate increasing affect and, via second-order indexicality, the gender of the speaker (in this case, female))
- morphological and phonological mechanisms: such as in Yana, a language where one form of all major words are spoken by sociological male to sociological male, and another form (which is constructed around phonological changes in word forms) is used for all other combination of interlocutors; or the Japanese prefix-affixation of o- to indicate politeness and, consequently, feminine social identity.
Many instances of sex/gender indices incorporate multiple levels of indexicality (also referred to as indexical order). In fact, some, such as the prefix-affixation of o- in Japanese, demonstrate complex higher-order indexical forms. In this example, the first order indexes politeness and the second order indexes affiliation with a certain gender class. It is argued that there is an even higher level of indexical order evidenced by the fact that many jobs use the o- prefix to attract female applicants. This notion of higher-order indexicality is similar to Silverstein's discussion of "wine talk" (see below) in that it indexes "an identity-by-visible-consumption [here, employment]" that is an inherent of a certain social register, (i.e. social gender indexicality).
Affect indices 
Affective meaning is seen as "the encoding, or indexing of speakers emotions into speech events." The interlocutor of the event "decodes" these verbal messages of affect by giving "precedence to intentionality"; that is, by assuming that the affective form intentionally indexes emotional meaning.
Some examples of affective forms are: diminutives (for example, diminutive affixes in Indo-European and Amerindian languages indicate sympathy, endearment, emotional closeness, or antipathy, condescension, and emotional distance); ideophones and onomatopoeias; expletives, exclamations, interjections, curses, insults, and imprecations (said to be "dramatizations of actions or states"); intonation change (common in tone languages such as Japanese); address terms, kinship terms, and pronouns which often display clear affective dimensions (ranging from the complex address-form systems found languages such a Javanese to inversions of vocative kin terms found in Rural Italy); lexical processes such as synecdoche and metonymy involved in affect meaning manipulation; certain categories of meaning like evidentiality; reduplication, quantifiers, and comparative structures; as well as inflectional morphology.
Affective forms are a means by which a speaker indexes emotional states through different linguistic mechanisms. These indices become important when applied to other forms of non-referential indexicality, such as sex indices and social identity indices, because of the innate relationship between first-order indexicality and subsequent second-order (or higher) indexical forms. (See multiple indices section for Japanese example).
Deference indices 
Deference indices encode deference from one interlocutor to another (usually representing inequalities of status, rank, age, sex, etc.). Some examples of deference indices are:
T/V deference entitlement 
The T/V deference entitlement system of European languages was famously detailed by linguists Brown and Gilman. As previously mentioned, T/V deference entitlement is a system by which a speaker/addressee speech event is determined by perceived disparities of 'power' and 'solidarity' between interlocutors. Brown and Gilman organized the possible relationships between the speaker and the addressee into six categories:
- Superior and solidary
- Superior and not solidary
- Equal and solidary
- Equal and not solidary
- Inferior and solidary
- Inferior and not solidary
The 'power semantic' indicates that the speaker in a superior position uses T and the speaker in an inferior position uses V. The 'solidarity semantic' indicates that speakers use T for close relationships and V for more formal relationships. These two principles conflict in categories 2 and 5, allowing either T or V in those cases:
- Superior and solidary: T
- Superior and not solidary: T/V
- Equal and solidary: T
- Equal and not solidary: V
- Inferior and solidary: T/V
- Inferior and not solidary: V
Brown and Gilman observed that as the solidarity semantic becomes more important than the power semantic in various cultures, the proportion of T to V use in the two ambiguous categories changes accordingly.
Silverstein comments that while exhibiting a basic level of first-order indexicality, the T/V system also employs second-order indexicality vis-à-vis 'enregistered honorification'. He cites that the V form can also function as an index of valued "public" register and the standards of good behavior that are entailed by use of V forms over T forms in public contexts. Therefore, people will use T/V deference entailment in 1) a first-order indexical sense that distinguishes between speaker/addressee interpersonal values of 'power' and 'solidarity' and 2) a second-order indexical sense that indexes an interlocutor's inherent "honor" or social merit in employing V forms over T forms in public contexts.
Japanese honorifics 
Japanese provides an excellent case study of honorifics. Honorifics in Japanese can be divided into two categories: addressee honorifics, which index deference to the addressee of the utterance; and referent honorifics, which index deference to the referent of the utterance. Cynthia Dunn claims that "almost every utterance in Japanese requires a choice between direct and distal forms of the predicate." The direct form indexes intimacy and "spontaneous self-expression" in contexts involving family and close friends. Contrarily, distal form index social contexts of a more formal, public nature such as distant acquaintances, business settings, or other formal settings.
Japanese also contains a set of humble forms (Japanese kenjyoogo 謙譲語) which are employed by the speaker to index their deference to someone else. There are also suppletive forms that can be used in lieu of regular honorific endings (for example, the subject honorific form of taberu (食べる?, to eat): meshiagaru 召し上がる). Verbs that involve human subjects must choose between distal or direct forms (towards the addressee) as well as a distinguish between either no use of referent honorifics, use of subject honorific (for others), or use of humble form (for self). The Japanese model for non-referential indexicality demonstrates a very subtle and complicated system that encodes social context into almost every utterance.
Affinal taboo index 
Dyirbal, a language of the Cairns rain forest in Northern Queensland, employs a system known as the affinal taboo index. Speakers of the language maintain two sets of lexical items: 1) an "everyday" or common interaction set of lexical items and 2) a "mother-in-law" set that is employed when the speaker is in the very distinct context of interaction with their mother-in-law. In this particular system of deference indices, speakers have developed an entirely separate lexicon (there are roughly four "everyday" lexical entries for every one "mother-in-law" lexical entry; 4:1) to index deference exigent of contexts inclusive of the mother-in-law.
Hypercorrection is defined by Wolfram as "the use of speech form on the basis of false analogy." DeCamp defines hypercorrection in a more precise fashion claiming that "hypercorrection is an incorrect analogy with a form in a prestige dialect which the speaker has imperfectly mastered." Many scholars argue that hypercorrection provides both an index of "social class" and an "Index of Linguistic insecurity". The latter index can be defined as a speaker's attempts at self-correction in areas of perceived linguistic insufficiencies which denote their lower social standing and minimal social mobility.
Donald Winford conducted a study that measured the phonological hypercorrection in creolization of English speakers in Trinidad. He claims that the ability to use prestigious norms goes "hand-in-hand" with knowledge of stigmatization afforded to use of "lesser" phonological variants. He concluded that sociologically "lesser" individuals would try to increase the frequency of certain vowels that were frequent in the high prestige dialect, but they ended up using those vowels even more than their target dialect. This hypercorrection of vowels is an example of non-referential indexicality that indexes, by virtue of innate urges forcing lower class civilians to hypercorrect phonological variants, the actual social class of the speaker. As Silverstein claims, this also conveys an "Index of Linguistic insecurity" in which a speaker not only indexes their actual social class (via first-order indexicality) but also the insecurities about class constraints and subsequent linguistic effects that encourage hypercorrection in the first place (an incidence of second-order indexicality).
William Labov and many others have also studied how hypercorrection in African American Vernacular English demonstrates similar social class non-referential indexicality.
Multiple non-referential indices can be employed to index the social identity of a speaker. An example of how multiple indexes can constitute social identity is exemplified by Ochs discussion of copula deletion: "That Bad" in American English can index a speaker to be a child, foreigner, medical patient, or elderly person. Use of multiple non-referential indices at once (for example copula deletion and raising intonation), helps further index the social identity of the speaker as that of a child.
Linguistic and non-linguistic indices are also an important ways of indexing social identity. For example, the Japanese utterance -wa in conjunction with raising intonation (indexical of increasing affect) by one person who "looks like a woman" and another who looks "like a man" may index different affective dispositions which, in turn, can index gender difference. Ochs and Schieffilen also claim that facial features, gestures, as well as other non-linguistic indices may actually help specify the general information provided by the linguistic features and augment the pragmatic meaning of the utterance.
Oinoglossia ('wine talk') 
For demonstrations of higher (or rarefied) indexical orders, Michael Silverstein discusses the particularities of "life-style emblematization" or "convention-dependent-indexical iconicity" which, as he claims, is prototypical of a phenomenon he dubs "wine talk." Professional wine critics use a certain "technical vocabulary" that are "metaphorical of prestige realms of traditional English gentlemanly horticulture." Thus, a certain "lingo" is created for this wine that indexically entails certain notions of prestigious social classes or genres. When "yuppies" use the lingo for wine flavors created by these critics in the actual context of drinking wine, Silverstein argues that they become the "well-bred, interesting (subtle, balanced, intriguing, winning, etc.) person" that is iconic of the metaphorical "fashion of speaking" employed by people of higher social registers, demanding notoriety as a result of this high level of connoisseurship. In other words, the wine drinker becomes a refined, gentlemanly critic and, in doing so, adopts a similar level of connoisseurship and social refinement. Silverstein defines this as an example of higher-order indexical "authorization" in which the indexical order of this "wine talk" exists in a "complex, interlocking set of institutionally formed macro-sociological interests." A speaker of English metaphorically transfers him- or herself into the social structure of the "wine world" that is encoded by the oinoglossia of elite critics using a very particular "technical" terminology.
The use of "wine talk" or similar "fine-cheeses talk", "perfume talk", "Hegelian-dialectics talk", "particle-physics talk", "DNA-sequencing talk", "semiotics talk" etc. confers upon an individual an identity-by-visible-consumption indexical of a certain macro-sociological elite identity and is, as such, an instance of higher-order indexicality.
Deixis and indexicality 
The terms deixis and indexicality are frequently used near-interchangeably, and both concern essentially the same idea; contextually-dependant references. However, each has a different history and tradition associated with it. In the past, deixis was associated specifically with spatio-temporal reference, while indexicality was used more broadly. More importantly, each is associated with a different field of study; deixis is associated with linguistics, while indexicality is associated with philosophy.
There are various extensions of the basic idea of indexicality, some of which arise outside of linguistics and philosophy of language. One notorious example is David Lewis's indexicality of actuality, according to which actual is itself an indexical term, and the ontological distinction between merely possible worlds and the actual world is just that the actual world is this world (see Modal realism, Modal logic).
See also 
- Charles Sanders Peirce#Classes of signs
- Semiotic elements and classes of signs (Peirce)
- Yehoshua Bar-Hillel
- Speech act theory
- Rudolf Lingens
- Peirce, C.S., "Division of Signs" in Collected Papers, 1932 . OCLC 783138
- Commens Dictionary of Peirce's Terms, see especially under "Icon", "Index", and "Symbol", Eprint.
- Silverstein, Michael. "Shifters, Linguistic Categories, and Cultural Description." In Meaning in Anthropology. K. Basso and H.A. Selby, eds. Albuquerque: School of American Research, University of New Mexico Press, 1976.
- Silverstein, Michael. "Indexical order and the dialectics of sociolinguistic life". Elsevier Ltd., 2003.
- Brown, R., Gilman, A. "The pronouns of power and solidarity, IN: Sebeok, T.A. (ed.) Style in Language. Cambridge: MIT Press, 1960.
- Wake, Naoko. Indexicality, Gender, and Social Identity.
- Kamei, Takashi.Covering and Covered Forms of women's language in Japanese.'Hitotsubashi JOurnal of Arts of Sciences' 19:1-7.
- Besnier, Niko. Language and Affect. Annual Reviews, Inc., 1990.
- Dunn, Cynthia. "Pragmatic Functions of Humble Forms in Japanese Ceremonial Discourse. 'Journal of Linguistic Anthropology', Vol. 15, Issue 2, pp. 218–238, 2005
- Wolfram, W. Phonological Variation and change in Trinidadian English-the evolution of the vowel system. Washington: Center for Applied Linguistics, 1969.
- DeCamp, D. 'Hypercorrection and Rule Generalization. 1972
- Winford, Donald. 'Hypercorrection in the Process of Decreolization: The Case of Trinidadian English. Cambridge, England: Cambridge Univserity Press, 1978.
- Ochs, Elinor. "Indexicality and Socialization". In J. Stigler, R. Shweder & G. Herdt (eds.) 'Cultural Psychology: Essays on Comparative Human Development'. Cambridge: Cambridge University Press, 1990.
- Ochs, Elinor and Shieffelin, Banbi. "Language has a heart". 'Text 9': 7-25.
- Silverstein, Michael. (1976) "Shifters, linguistic categories, and cultural description". In K. Basso and H. Selby (eds.), Meaning in Anthropology. SAR pp.25
- Levinson, Stephen C. (2006) "Deixis". In Laurence R. Horn, Gregory L. Ward (eds.) The Handbook of Pragmatics, pp. 978–120. Blackwell Publishing.