Skilled readers begin processing sub-phonemic features by 80 ms during visual word recognition: evidence from ERPs

Abstract

Two masked priming experiments investigated the time-course of the activation of sub-phonemic information during visual word recognition. EEG was recorded as participants read targets with voiced and unvoiced final consonants (e.g., fad and fat), preceded by nonword primes that were incongruent or congruent in voicing and vowel duration (e.g., fap or faz). Experiment 1 used a long duration mask (100 ms) between prime and target, whereas Experiment 2 used a short mask (22 ms). Phonological feature congruency began modulating the amplitude of brain potentials by 80 ms; the feature incongruent condition evoked greater negativity than the feature congruent condition in both experiments. The early onset of the congruency effect indicates that skilled readers initially activate sub-phonemic feature information during word identification. Congruency effects also appeared in the middle and late periods of word recognition, suggesting that readers use phonological representations in multiple aspects of visual word recognition.

Fig. 1

The masked priming paradigm. A fixation point was followed by a forward mask, a nonword prime, a backward mask, and a word target. All images were shown in cyan on a black background. The duration of the backward mask for Experiment 2 was 22 ms (prime-target SOA = 66 ms) and for Experiment 1 was 100 ms (prime-target SOA = 144 ms).

Fig. 2

Approximate location of 64 scalp electrodes. Data from electrodes shown in black were included in analyses. ANOVAs included two electrode position factors: Rows (5 levels) and Columns (7 levels).

Fig. 3

Feature congruency effects in Experiment 1. Targets preceded by congruent primes (solid line) evoke a smaller negativity than those in the incongruent condition (dotted line) between 80 –180 ms.

Fig. 4

Feature congruency effects in Experiment 2. Targets preceded by congruent primes (solid line) evoke a smaller negativity than those in the incongruent condition (dotted line) between 80 –120 ms.

Fig. 5

Feature congruency effects in Experiment 1 (shown in red) and 2 (shown in blue). Waveforms in the congruent conditions are drawn in solid lines. Main effects of Experiment are evident 0 – 320 ms after target onset, but no Experiment by Congruency interaction appeared until after this window.

Fig. 6

Topographic maps illustrate the early congruency effect in Experiments 1 and 2. The longer duration of the congruency effect in the long SOA experiment, relative to the short SOA experiment, is evident.

Fig. 7

N1 peak times for participants in Experiments 1 and 2. The distribution of the N1 peak times shifted to the left in the short SOA experiment (shown in black) as compared to the distribution of N1 peak times in the long SOA experiment (shown in grey).

Fig. 8

Significance tests for the early congruency effects. The feature congruency effect onset around 80 ms in both experiments. In Experiment 2 (66 ms SOA), the effect was significant for a narrower time window (80 – 120 ms) relative to Experiment 1 (80 – 180 ms). In Experiment 1, the main effect of congruency was marginal between 100 – 120 ms, F(1,19) = 3.82, p=.066, and a congruency by electrode position interaction was significant between 120 –140 ms, F(6,114) = 2.99, p=.046.