Individual Differences in Implicit Learning: Current Problems and Issues for Research

Background

Implicit learning, learning without awareness of learning processes and/or learning outcomes, has been extensively studied in cognitive psychology (see Perruchet, 2008; Pothos, 2007; Shanks, 2005 for recent reviews). Two learning tasks have been employed in the implicit learning literature: artificial grammar (AG) learning and serial reaction time (SRT) tasks (see Nissen & Bullemer, 1987and Reber, 1967 for representative studies). Since participants typically cannot verbalise the contents of rules or regularities underlying stimuli but nevertheless show learning in both tasks, the nature of their learning is argued to be implicit.

In the typical AG learning task, participants are presented with a series of digits (e.g., XVXXV) without information on the existence of rules, or “grammar”, that underlie such digits. They are just asked to memorise the digits. After training, they are told of the existence of the rules and asked to judge the grammaticality of test digits as well as to indicate the content of such rules. Participants’ performance on the grammaticality judgment is above chance (thus showing evidence of learning).

In the typical SRT task, the screen is divided into quadrants and a stimulus appears in one of the quadrants. Participants are required to press keys corresponding to each location. A sequence of a stimulus follows a fixed pattern and participants do not know of its existence. After repeated exposure to this fixed pattern, reaction time (RT) on the fixed pattern decreases. Later a random sequence of a stimulus is inserted into the key-pressing trial. Since participants’ RTs on this random pattern significantly increases, it is argued that they have learned the fixed pattern of the stimulus sequence.