EEG Correlates of Old/New Discrimination Performance Involving Abstract Figures and Non-Words.

Monika Toth,Anke Sambeth,Arjan Blokland

doi:10.3390/brainsci11060719

Abstract

The processing of pre-experimentally unfamiliar stimuli such as abstract figures and non-words is poorly understood. Here, we considered the role of memory strength in the discrimination process of such stimuli using a three-phase old/new recognition memory paradigm. Memory strength was manipulated as a function of the levels of processing (deep vs. shallow) and repetition. Behavioral results were matched to brain responses using EEG. We found that correct identification of the new abstract figures and non-words was superior to old item recognition when they were merely studied without repetition, but not when they were semantically processed or drawn. EEG results indicated that successful new item identification was marked by a combination of the absence of familiarity (N400) and recollection (P600) for the studied figures. For both the abstract figures and the non-words, the parietal P600 was found to differentiate between the old and new items (late old/new effects). The present study extends current knowledge on the processing of pre-experimentally unfamiliar figurative and verbal stimuli by showing that their discrimination depends on experimentally induced memory strength and that the underlying brain processes differ. Nevertheless, the P600, similar to pre-experimentally familiar figures and words, likely reflects improved recognition memory of meaningless pictorial and verbal items.

Highlights

We considered the role of memory strength in the discrimination process of meaningless abstract figures and non-words using a three-phase old/new recognition memory paradigm
The present study shows that the discrimination performance of pre-experimentally unfamiliar abstract figures and non-words depends on memory strength induced by deeper
New abstract figures and non-words were more accurately identified than the old ones that relied on weak memories

Summary

Introduction

An efficient memory system requires the ability to detect and incorporate new information and to readily retrieve familiar information [1,2,3,4]. Information-processing theories define recognition as a predicament of discrimination between what is known (familiar) and what is not known (new) [5,6,7,8]. Discrimination performance is typically tested with paradigms that assess recognition memory. In such paradigms, participants are required to recognize previously studied stimuli (e.g., typically well-known and meaningful figures and words) as old correctly and to identify previously not seen items as new [9]. The decision process determines how we respond: whether a stimulus is judged as old or new

Objectives

Results

Discussion

Conclusion