Increased cognitive load during pseudoword processing

Pseudowords (words without semantic meaning) are often used as a control condition in linguistic cognitive experiments, with the expectation that such words, unlike real words, do not activate higher cognitive processes in the brain. However, other theories assume that pseudowords are perceived as new words, leading to an even higher cognitive response. The aim of this study was to investigate the cognitive load of processing a pseudoword by observing event-related potentials in a 3-stimulus oddball paradigm using real target words, real non-target words, and pseudowords as oddball stimuli. The results show a clear task-related P3b triggered by target words, but also a prominent P600 component triggered by pseudowords, indicating difficulty in the classification task due to unknown words. Surprisingly, N400 was decreased for pseudowords compared to target and non-target words at the locations where P3b and P600 were observed, suggesting that task-related effects might inhibit other aspects of cognitive processing. These results could lead to better understanding of the components that may overlap temporally and topographically, and to the more precise control of different cognitive generators involved in event-related potential experiments in pseudowords.