Age of acquisition (AoA) refers to the age at which a language is acquired (Hernandez & Li, 2007). Hence, for second language learners, age at which the first language is acquired would be different from when the second language is acquired.

The Two Views of AoA: Order of Acquisition VS. Critical period

There are two different types of view of AoA. One view is that AoA effects would reflect the order in which language is acquired (early or late) while the other view is that AoA effects would reflect whether a language is acquired before or after a critical period (also known as the sensitive period).

Research has shown that words learned early may result in faster recognition and production than words learned late (Hernandez & Li, 2007). This has been exhibited in various types of tasks, such as visual lexical decision and picture naming.

Meanwhile, according to Marinova-Todd, Marshall and Snow (as cited in Izura & Ellis, 2002), critical period refers to the “time when language can be acquired much more easily than when the critical period has passed.” However, there has been no fixed time frame for this critical period. According to Pinker (as cited in Seidenberg & Zevin, 2006), the critical period is up to 5 or 6 years old while according to Lenneberg (as cited in Seidenberg & Zevin, 2006), it is up to puberty. Based on this concept of critical period, the difficulty of learning a second language would then be attributed to the age at which the second language was learnt.

However, current views of AoA effects seem to be leaning towards the view that AoA effects reflect the order in which language is acquired since AoA effects have been seen even after the critical period has passed. For instance, experiments conducted on adults on early and late learning show AoA effects even though these adults have passed the critical period (Izura & Ellis, 2002).

The factors and theories discussed below are therefore with the assumption that AoA refers to the order of acquisition rather than a critical period.

First created by Christina Amrita Arul, Nur Ayesha Bte Solehan, Nur Atiqah Binte Othman, AY2014/15 Semester 1