Masked antipriming: a behavioral and event-related potential examination of short-term antipriming effects

Abstract

Antipriming is a new implicit-memory effect of prior processing of stimuli measured as impaired identification of objects following recent encoding of other objects (e.g.,identifying a piano is impaired by having recently viewed objects that are not pianos; Marsolek et al., 2006). Antipriming effects have been established in several behavioral experiments (with young adults, amnesic patients, and age-matched controls),neurocomputational models, and studies measuring neural activity. In this series of studies, I extended the prior findings by establishing a new masked antipriming paradigm. This new paradigm allowed examination of the antipriming effect in a task where the prime and target are only separated by milliseconds (a short-term memory task) as opposed to the minutes of separation between prime and target in the original task (measuring long-term memory). Experiment 1 demonstrated both repetition priming (faster response times for repetition primed objects compared to objects in a baseline condition) and antipriming (decreased accuracy as compared to baseline identification). In Experiment 2, speed was emphasized in an effort to detect both priming and antipriming in one measure. Experiment 3 was the first experiment to directly examine the role of visual similarity in antipriming and it demonstrated that high visual similarity between objects could result in increased antipriming. An ERP masked antipriming task revealed two main effects. There were no very early effects and the first effect occurred around 500-600 ms as a positive deflection for antiprimed objects compared to baseline and repetition primed items. The second effect began around 1100 ms also as a positive deflection for antiprimed objects compared to baseline (and sometimes repetition primed items). This effect extends out through 1600 ms and has both a posterior and a frontal location. These effects could be explained by the same theory applied to the long-term memory effects, or they could be due to more immediate effects of competition between object representations.