biology

Head-directionality parameter

Head-directionality parameter is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Head-directionality parameter rather than just read about it. In short: In linguistics, head directionality is a proposed parameter that classifies languages according to whether they are head-initial (the head of a phrase precedes its complements) or head-final (the head follows its complements). The head is the element that determines the category of a phrase: for example, in a verb phrase, the head is a verb.

Key takeaways

Head-directionality parameter belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Head-directionality parameter to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Head-directionality parameter from memory before moving on to harder problems.

Reference excerpt

In linguistics, head directionality is a proposed parameter that classifies languages according to whether they are head-initial (the head of a phrase precedes its complements) or head-final (the head follows its complements). The head is the element that determines the category of a phrase: for example, in a verb phrase, the head is a verb. Therefore, head initial would be "VO" languages and head final would be "OV" languages. Some languages are consistently head-initial or head-final at all phrasal levels. English is considered to be mainly head-initial (verbs precede their objects, for example), while Japanese is an example of a language that is consistently head-final. In certain other languages, such as German and Gbe, examples of both types of head directionality occur. Various theories have been proposed to explain such variation. Head directionality is connected with the type of branching that predominates in a language: head-initial structures are right-branching, while head-final structures are left-branching. On the basis of these criteria, languages can be divided into head-final (rigid and non-rigid) and head-initial types. The identification of headedness is based on the following:

the order of subject, object, and verb the relationship between the order of the object and verb the order of an adposition and its complement the order of relative clause and head noun.

Types of phrase In some cases, particularly with noun and adjective phrases, it is not always clear which dependents are to be classed as complements, and which as adjuncts. Although in principle the head-directionality parameter concerns the order of heads and complements only, considerations of head-initiality and head-finality sometimes take account of the position of the head in the phrase as a whole, including adjuncts. The structure of the various types of phrase is analyzed below in relation to specific languages, with a focus on the ordering of head and complement. In some cases (such as English and Japanese) this ordering is found to be the same in practically all types of phrase, whereas in others (such as German and Gbe) the pattern is less consistent. Different theoretical explanations of these inconsistencies are discussed later in the article. There are various types of phrase in which the ordering of head and complement(s) may be considered when attempting to determine the head directionality of a language, including:

Verb Phrase: the head of verb phrase (VP) is a verb, and the complement(s) are most commonly objects of various types. The ordering here is related to one of the chief questions in the word order typology of languages, namely the normal order of subject, verb and object within a clause (languages are classed on this basis as SVO, SOV, VSO, etc.).

Noun Phrase: the head of a noun phrase (NP) is a noun; various kinds of complementizer phrases (CPs) and adpositional phrases (PPs) can be complements.

Adjective Phrase: the head of an adjective phrase (AP) is an adjective, which can take as a complement, for example, an adverbial phrase or adpositional phrase (PP).

Adpositional Phrase: the head of an adpositional phrase (PP) is an adposition. Such phrases are called prepositional phrases if they are head-initial (i.e. headed by a preposition), or postpositional phrases if they are head-final (i.e. headed by a postposition). The complement is a determiner phrase (or noun phrase, depending on analytical scheme followed).

Determiner Phrase: the head of a determiner phrase (DP) is a determiner. DPs were proposed under generative syntax; not all theories of syntax agree that they exist. Complementizer Phrase: the head of a complementizer phrase (CP) is a complementizer, like that in English. In some cases the C head is covert (not overtly present). The complement of C is generally agreed to be a tense phrase (TP).

Tense Phrase: the head of a tense phrase (TP) is tense; these are phrases in which the head is an abstract category representing tense; the complement is a verb phrase. Aspect Phrase: the head of an aspect phrase (AspP) is aspect; these are phrases in which the head is an abstract syntactic category representing aspect. In more traditional analysis the entire phrase (including any elements denoting tense or aspect) is considered to be simply a verb phrase.

Head-initial languages

English English is a mainly head-initial language. In a typical verb phrase, for example, the verb precedes its complements, as in the following example:

eat an apple [VP [V eat] [DP an apple]] The head of the phrase (the verb eat) precedes its complement (the determiner phrase an apple). Switching the order to "[VP [DP an apple] [V eat]]" would be ungrammatical. Nouns also tend to precede any complements, as in the following example, where the relative clause (or complementizer phrase) that follows the noun may be considered to be a complement:

He married a girl who is from Texas. [NP [N girl] [CP who is from Texas]] Nouns do not necessarily begin their phrase; they may be preceded by attributive adjectives, but these are regarded as adjuncts rather than complements. Adjectives themselves may be preceded by adjuncts, namely adverbs, as in extremely happy. However, when an adjective phrase contains a true complement, such as a prepositional phrase, the head adjective precedes it:

a person happy about her work [AP [A happy] [PP about her work]] English adpositional phrases are also head-initial; that is, English has prepositions rather than postpositions:

a majority of eligible voters [PP [P of] [DP eligible voters]] On the determiner phrase (DP) view, where a determiner is taken to be the head of its phrase (rather than the associated noun), English can be seen to be head-initial in this type of phrase too. In the following example the head is taken to be the determiner any, and the complement is the noun (phrase) book:

any book [DP [D any] [NP book]] English also has head-initial complementizer phrases, as in this example where the complementizer that precedes its complement, the tense phrase Mary did not swim:

… excerpt ends here. Continue reading the full article.

Illustrations

Head-directionality parameter: English VP structure — English VP structure

Worked examples

Example 1 — a first encounter with Head-directionality parameter

Start with the simplest possible case. Write down what Head-directionality parameter claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Head-directionality parameter before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Head-directionality parameter ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Head-directionality parameter

In research: Head-directionality parameter appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Head-directionality parameter in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Head-directionality parameter is common in secondary-school and first-year university syllabi. It links to neighbouring topics Generative syntax, Linguistic typology, Word order, so understanding it makes those chapters shorter.
In everyday life: Look for Head-directionality parameter outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Head-directionality parameter in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Head-directionality parameter means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Head-directionality parameter out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Head-directionality parameter in simple terms?

Why does Head-directionality parameter matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Head-directionality parameter?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Head-directionality parameter.