Ginsburg, V. 1 , Van Dijck, J. 2 , Van Opstal, F. 2 , Majerus, S. 3 , Fias, W. 2 & Gevers, W. 1
1 Unité de recherche en Neurosciences Cognitives, Université Libre de Bruxelles, Brussels, Belgium
2 Department of Experimental Psychology, University of Ghent, Ghent, Belgium
3 Département de Sciences Cognitives, Université de Liège, Liège, Belgium
Recently, a lateralized position effect in working memory was observed (Van Dijck & Fias, 2011). Words (fruits/vegetables) were sequentially presented and were to be remembered for later recall. During the retention interval, participants performed a categorization task with lateralized responses embedded in a go-nogo procedure such that participants only responded to the words inside the WM sequence but not to the words outside the WM sequence. Words presented early in the sequence were faster responded to with the left hand whereas words later in the sequence were responded to faster with the right hand.
First, we replicated this lateralized position effect using the same go-nogo paradigm but with different categories of words on each sequence (e.g. with 10 different categories of words instead of one) and with a smaller working memory load. In the second experiment, participants responded to all words, both inside and outside the WM sequence. This manner, the WM sequence was no longer relevant for the categorization task. The results show that in this case the lateralized position effect disappeared. We conclude that the lateralized position effect is a robust observation that crucially depends on the relevance of the working memory sequence for the lateralized response categorization.