The time course of age-of-acquisition effects on eye movements during reading: Evidence from survival analyses

Adults process words that are rated as being learned earlier in life faster than words that are rated as being acquired later in life. This age-of-acquisition (AoA) effect has been observed in a variety of word-recognition tasks when word frequency is controlled. AoA has also previously been found to influence fixation durations when words are embedded into sentences and eye movements are recorded. However, the time course of AoA effects during reading has been inconsistent across studies. The current study further explored the time course of AoA effects on distributions of first-fixation durations during reading. Early and late acquired words were embedded into matched neutral sentence frames. Participants read the sentences while their eye movements were recorded. AoA effects were observed in both early and late fixation duration measures, suggesting that AoA has an early and long-lasting effect on word-recognition processes during reading. Survival analysis revealed that the earliest discernable effect of AoA on distributions of first-fixation durations emerged beginning at 158 ms. This rapid influence of AoA was confirmed through the use of Vincentile plots, which demonstrated that the effect of AoA occurred early and was relatively consistent across the distribution of fixations. This pattern of results provides support for the direct lexical-control hypothesis, as well as the viewpoint that AoA may exert an influence at multiple loci within the mental lexicon.