Editing Wh-movement (section)

===Left branch islands===
A ''left branch island'' occurs where a modifier precedes the noun that it modifies. The modifier cannot be extracted, a constraint which Ross identified as the ''Left Branch Condition''.<ref>Ross (1967/86) gives his left branch condition on page 127: "No NP which is the leftmost constituent of a larger NP can be reordered out of this NP by a transformational rule".</ref> Possessive determiners and attributive adjectives form left branch islands. Fronting of these phrases necessitates pied-piping of the entire noun phrase, for example:

::a. Susan likes <u>'''Fred's''' account</u>.
::b. *'''Whose''' does Susan like __ account? <small>– Attempt to extract from a left branch under a noun fails</small>
::c. <u>'''Whose''' account</u> does Susan like __? <small>– Extraction succeeds if the entire noun phrase is pied-piped</small>

::a. He bought <u>an '''expensive''' boat</u>.
::b. *How '''expensive''' did he buy a __ boat? <small>– Attempt to extract from a left branch under a noun fails</small>
::c. <u>How '''expensive''' a boat</u> did he buy? <small>– Extraction succeeds if the entire noun phrase is pied-piped</small>

Extraction fails in the b. sentences because the extracted expression corresponds to a left-branch modifier of a noun.

While left branch islands exist in English, they are absent from many other languages, most notably from the Slavic languages.<ref>Concerning the lack of left branch islands in Slavic languages, see Ross (1967/86:145), Grosu (1973), Roberts (1997:189).</ref>