masked priming

Masked priming has become a very popular technique in psycholinguistics and other areas of cognitive psychology. In this paradigm a stimulus (the prime) is presented for a very short presentation duration and is immediately followed by the target, which causes backward masking of the prime. The combined action of the two masking stimuli and the short presentation duration of the prime result in a consciously imperceptible stimulus. 

The advantage of masked priming is that it allows one to investigate the effect of a particular prime-target relationship without participants’ awareness of the manipulation, such that they cannot develop response strategies. Thus considered the technique is a relatively pure way to probe into the machinery of lexical processing (Forster, Mohan & Hector, 2003; Forster & Davis, 1984). Accordingly, masked priming effects are interpreted as the reflection of residual activation caused by the prime at a particular stage of target processing. 

Bodner and Masson have questioned the received wisdom that masked priming reflects lexical preactivation (Bodner & Masson, 1997, 2001, 2003; Masson & Isaak, 1999). In their view, masked priming effects are due to the fact that the prime leaves a trace in episodic memory and that the target subsequently accesses this episodic trace. Hence, the effects are informative on episodic memory rather than the mental lexicon.

Given the wide use of the technique it is important to find out what exactly it measures. Needless to say, the answer to this question can have major consequences for the interpretation of experiments and, hence, for theories of the mental lexicon that hinge on these results.

Masked priming is a commonly used technique in psycholinguistics to investigate how words are stored in our Mental Lexicon. This technique, developed by Forster & Davis (1984), investigates the effect of one word on another without participants’ awareness. Preceding a target in uppercase, a prime in lowercase is presented for a very short duration. Participants have to respond to the target, but the prime, which cannot be seen consciously, can influence the processing of the target. An existing prime-target connection (cat-DOG) causes faster responses than when there is no connection (hat-DOG), because the related prime preactivates the target in our mental lexicon. This is the general assumption. In several publications, Bodner and Masson criticized this interpretation. They claim that the prime creates a trace in episodic memory and that the target is not preactivated by the prime. Instead an unconscious checking mechanism detects that the target is related to the prime, causing faster responses. Hence, priming effects inform us on episodic memory instead of the mental lexicon. If masked priming data provide more information on episodic representations than on lexical ones, many research findings have to be revised. 
The purpose of this project  is to find out whether Bodner & Masson's view can be upheld. The general rationale that will guide all experiments is the question whether masked priming effects activate episodic memory traces when access to lexical memory (the mental lexicon) is sufficient for performing the experimental task. This general question will be approached in two ways: (i) can masked primes access episodic traces that were created in a training phase prior to the experiment and (ii) do masked primes themselves leave episodic traces?