Specificity condition

Definition
Specificity Condition is a condition on movement which states that movement out of specific NPs leads to worse results than movement out of non-specific NPs. This is shown by the contrast in (i) (showing wh-movement out of a definite NP) and (ii) (wh-movement out of a non-specific indefinite NP). Also known as Specificity Constraint.

(i) a	 *who did you see [that picture of t]      b	 *who did you see [John's picture of t] (ii) a	  who did you see [three pictures of t]      b	  who did you see [more pictures of t]

Links
Utrecht Lexicon of Linguistics