Memory for normal and distorted pictures: Modulation of the ERP repetition effect

Previous investigations of how ERP repetition effects are modulated by stimulus content have typically used words or non-words as stimuli. The extent to which these findings can be generalized to pictorial stimuli was examined in the present study. ERPs were recorded while participants viewed a series of pictures repeated over 5-7 intervening items. One set of pictures comprised colored depictions of a variety of objects and scenes, while other similar pictures were distorted to appear as abstract patterns of colored blocks. Repeated items were characterized by two main modulations of the ERP. An early positivity for second presentations as compared to first presentations appeared at around 200-300 ms, and was present for normal and distorted picture stimuli. A later, more sustained positivity emerged for the second presentations of normal pictures only. This later component had an onset latency of about 300 ms, lasting for some 400 ms, The results suggest that previously observed modulations of ERP repetition effects reflect the operation of processes which are not specific to verbal memory but may be observed for a wider range of visual stimuli.