Repetition priming with no antipriming in picture identification

Previous studies have shown that the processing of a stimulus is facilitated when that stimulus is repeated compared to when it appears the first time, and this phenomenon is called repetition priming (RP). One explanation for RP is that initial processing of a stimulus strengthens connections within the visual representation, enabling subsequent processing of the same stimulus to be more efficient. More recently, it has been reported that presenting an object with features that overlap with those in a subsequent stimulus impairs the latter's processing, and this cost is termed antipriming (AP). AP is said to be the natural antithesis of RP, and it manifests when two objects share component features, thereby having overlapping representations. In two experiments, we investigated RP and AP in a picture naming task. Following previous research, we used a 4-phase paradigm, in which RP and AP were measured, respectively, by an increase or a decrease in performance for repeated or novel stimuli in Phase 4 compared with the baseline performance in Phase 2. We used a fully randomized design in Experiment 1, and a pseudo-randomized design in stimulus selection but a randomized design in presentation location in Experiment 2. We found robust RP in both experiments, but neither experiment showed any evidence of AP. Our results indicate that RP and AP do not always manifest within the same experiment, and that the relationship between these two effects may be more complex than previously understood.