Age-of-acquisition affects object recognition and compound word identification: Evidence from visual duration thresholds and progressive demasking

Items acquired during childhood are processed more quickly and accurately than those acquired during adulthood, a phenomenon known as the age of acquisition (AoA) effect. One explanation is that the AoA effect results from the arbitrary nature of the input-output mapping during the development of a lexical-semantic representation. However, previous behavioural studies have not directly compared the AoA effects in pictures and word processing. To investigate this, 48 British English students completed a visual duration threshold task and four variations of progressive demasking experiments. In these tasks, participants were shown 150 compound words, either unspaced or spaced, while attempting to identify the modifier, head, or the full compound word. In addition, in Experiment 4, we used a visual duration threshold task (VDT) for 150 objects that represented 150 compound words to assess the mapping theory. We observed that early-acquired items were identified more quickly than late-acquired items across all tasks, including the VDT. The AoA effect was strongest for a progressive demasking task (PDT) with unspaced and spaced compound words, followed by the VDT for pictures and PDT with component identification for spaced compound words. The only exception was the PDT with component identification of unspaced compound words, where the effect was not present. These results align with the integrated account, as the AoA effect is rooted in semantic representation during word identification but is also influenced by the connection between perception and semantics in the VDT.