Phonological facilitation effects on naming latencies and viewing times during noun and verb naming in agrammatic and anomic aphasia

Abstract

Background: Phonological priming has been shown to facilitate naming in individuals with aphasia as well as healthy speakers, resulting in faster naming latencies. However, the mechanisms of phonological facilitation (PF) in aphasia remain unclear.

Aims: Within discrete vs. interactive models of lexical access, this study examined whether PF occurs via the sub-lexical or lexical route during noun and verb naming in agrammatic and anomic aphasia.

Methods and procedures: Thirteen participants with agrammatic aphasia and 10 participants with anomic aphasia and their young and age-matched controls (n=20/each) were tested. Experiment 1 examined noun and verb naming deficit patterns in an off-line confrontation naming task. Experiment 2 examined PF effects on naming both word categories using eyetracking priming paradigm.

Results: Results of Experiment 1 showed greater naming difficulty for verbs than for nouns in the agrammatic group, with no difference between the two word categories in the anomic group. For both participant groups, errors were dominated by semantic paraphasias, indicating impaired lexical selection. In the phonological priming task (Experiment 2), young and age-matched control groups showed PF in both noun and verb naming. Interestingly, the agrammatic group showed PF when naming verbs, but not nouns, whereas the anomic group showed PF for nouns only.

Conclusions: Consistent with lexically mediated PF in interactive models of lexical access, selective PF for different word categories in our agrammatic and anomic groups suggest that phonological primes facilitate lexical selection via feedback activation, resulting in greater PF for more difficult (i.e., verbs in agrammatic and possibly nouns in anomic group) lexical items.

Keywords: aphasia; eyetracking; lexical access; noun and verb naming; phonological priming.

Figures

Figure 1

The mechanisms of phonological facilitation: sub-lexical PF within the discrete models (a) and lexically-mediated PF within the interactive models (b). The bolded boxes and arrows indicate the level(s) and directions of PF. Only the interactive models allow for PF to affect lexical selection via feedback from the phonological encoding level.

Figure 2

Sample experimental trials for phonological priming during noun (a) and verb naming (b)

Figure 3

Phonological facilitation effects in noun naming (** p < .01, * p < .05)

Figure 4

Phonological facilitation effects in verb naming (*** p < .001, ** p < .01).

Figure 5

Phonological facilitation (PF) for nouns and verbs for individual participants in Experiment 2 as a function of performance in Experiment 1 (G = Agrammatic participants; A = Anomic participants). Positive bars indicated facilitation and negative bars indicate inhibition. Participants who show greater verb naming deficits in Experiment 1 are indicated by ‘*’ and those who showed greater noun deficits in Experiment 1 are indicated by “^”.