Table 3.

Different patterns of successful and impaired object naming

Group	Reaction times (ms): Match/Rel/Unrel	N400c	N400m	N400m timing
Control	630/722/705	+	+	Normal
PPA: recognized & named (P11–P19)	915/1087/1016	−	+	Prolonged
PPA: recognized & unnamed (P11–P19)	1113/1175/1058	−	−	Not present
PPA: recognized & unnamed(Postsemantic, P20)	543/676/647	−	+	Normal

Patterns are classified according to three parameters: whether the target word is accurately recognized as a match or mismatch for the pictured object, whether it can be produced during naming aloud, and whether a name that cannot be produced during naming aloud can be produced in written form (postsemantic, as in the case of P20). Two of the patterns in this table are derived from a subset of patients, P11–P19, for reasons described in the text. Another pattern, not shown in this table, is one where anomia occurs on a background of severe word comprehension deficits where recognition of the word as a match or mismatch is also impaired. Patients with significant numbers of such recognition errors were not included in this study since they were unable to understand task instructions. This table illustrates the multiple patterns of impairment that can contribute to the object naming impairments of PPA.