Habituation is the decline in response to a specific stimulus over time, when that stimulus is repeatedly presented to the organism.

The prepositional phrase in response is adjective and modifies the decline,
to a specific stimulus is also an adjective prepositional phrase, and does it modifies response?

By the way, If the prepositional phrase is acting like an adjective , can it only modify the thing in front of it or can it modify something far from it?

Like the example above,
assuming that "to a specific stimulus semantically modifies response" isn't wrong,
grammatically, can to a specific stimulus modify the decline?

  • No; the PP "in decline" can hardly be an adjective can it! Not everything that modifies a noun is an adjective. In any case, the PP "In response" does not modify "decline", but is a complement of it. The PP " to a specific stimulus ..." is complement of "response".
    – BillJ
    Apr 4, 2019 at 17:33

2 Answers 2


Not everything that affects, modifies or refines a noun is an adjective, as BillJ mentions in the comments. Some nouns can take arguments, as a verb does, and these can be called complements. It's not that they are changing the meaning of the noun, as an adjective does, but they are completing it (hence 'complement').

Decline, on its own, raises the question "decline in what?". In this case, that question is answered with "response to a specific stimulus". Likewise, response prompts the question "response to what?" - and that question is answered with "a specific stimulus". Specific, on the other hand, is simply an adjective modifying stimulus. Thus, stimulus is a noun modified with an adjective to form the noun phrase specific stimulus. Response is a noun, completed by the noun phrase a specific stimulus (linked with to), and decline is a noun, completed by the noun phrase response to a specific stimulus (linked with in).

Habituation is the [decline [in [response [to [a specific stimulus]]] [over time]]

  • Thank you , this is the site I visited when learning PP phrase (grammar-monster.com/glossary/prepositional_phrase.htm), it didn't mention anything about complement when introducing the function of PP phrases. Do you recommend this website and is there a better website for english learner for learning PP phrase?
    – jessie
    Apr 5, 2019 at 2:31
  • @jessie: I'm afraid that I don't know much about sites for learners, being a native speaker, but there's a brief explanation of complements of nouns here: englishgrammar.org/complements-verbs-nouns-adjectives
    – SamBC
    Apr 5, 2019 at 9:56
  • Thank you, i will study the provided site :) By the way , can I bother with one more question. Can one argue that "a specific stimulus" can be a complement of "decline"(linked by "to") , but semantically wouldn't make much sense?
    – jessie
    Apr 5, 2019 at 10:10
  • 1
    @Jessie: complements will generally be closest to the noun they are complementing, it's tight binding. If there weren't another noun in between, and you just had "decline to a specific stimulus", then you could parse it as a complement and it wouldn't be semantically valid. It would be more likely that people would parse it as decline being a verb, as decline to is usually a catenative use of to decline, but then that would fail to make sense (or parse properly) either. It would just confuse people.
    – SamBC
    Apr 5, 2019 at 10:30
  • 1
    @jessie That one is semantically ambiguous, because "in the room" could apply to the bag or the boy. Given that, I would tend to read it as applying to "the bag" rather than the boy. Also, those are adjectivals, not complements; they describe the things, rather than completing their meaning.
    – SamBC
    Apr 5, 2019 at 12:10

Habituation is the decline [in response [to a specific stimulus over time]], when that stimulus is repeatedly presented to the organism.

The PPs are not modifiers, but complements.

The outer brackets surround a PP serving as complement of "decline". Within that PP, the inner brackets surround a further PP serving as complement of "response".

Thus, we have one PP functioning within the structure of another.

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