The Effects of Word Frequency, Age of Acquisition, Animacy, and Grammatical Class on Picture Naming by Volunteers and People with Aphasia.

Numerous studies have investigated the effects of word frequency (WF), age of acquisition (AoA), and animacy on picture naming in volunteers and those with aphasia. But none have controlled for any possible interactions among these three variables during noun retrieval and whether WF and AoA influence verb retrieval in ways that are similar to that observed during noun retrieval. The main purpose of this study was to examine the influences of WF, AoA, and animacy on noun retrieval in both volunteers and participants with aphasia and to compare these results to the effects of AoA and WF in both groups during verb retrieval. A factorial approach was used to study the effects of (a) WF, AoA, and animacy on picture naming for 249 nouns, and (b) the effects of WF and AoA on picture naming for 88 verbs. Fifteen volunteers with no history of neurologic or psychiatric impairment and 13 people with aphasia participated in this study. Naming latencies using key press procedures were used to assess the effects of the independent variables. Linear mixed effects with random intercepts were modeled to analyze the results. Nouns with early AoA and high WF were named significantly faster than all nouns with late AoA. There were no differences between naming speeds for animate vs. inanimate nouns. Animate nouns with early AoA and high frequency were named significantly faster than early, animate nouns with low frequency. Low word frequency facilitated naming by the participants with aphasia for early AoA verbs but slowed the volunteers' naming for these verbs. Participants responded significantly faster to nouns versus verbs regardless of AoA and WF. Controlling for animacy in noun picture naming produces novel findings regarding the effects of WF and AoA on word retrieval. The interaction among WF, AoA, and animacy is more consequential for picture naming speed than the specific effects of any one of these variables alone. [ABSTRACT FROM AUTHOR]