Effect of interstimulus interval on acquisition and expression of associative learning with masked stimuli.

Abstract

The present research investigates the effect of interstimulus interval (ISI) during the acquisition and testing phases on associative learning with masked stimuli. 84 participants received repeated presentations of two stimulus sequences (S1A àS2A and S1B à S2B), S1 being a masked stimulus. S2 were imperative stimuli for a reaction time (RT) task. The ISI was 23 ms for the half of subjects and 305 ms for the other half. All participants were then tested with 14 presentations of compatible (S1A à S2A and S1B à S2B) and incompatible (S1A à S2B and S1B à S2A) stimulus sequences, using an ISI of 23 ms or 305 ms. The results showed that the ISI used during acquisition did not affected the RTs, but unconscious learning, detected as a positive compatibility effect, was obtained with a short ISI during the testing phase.