Left visual-field advantage in the dual-stream RSVP task and reading-direction: a study in three nations.

In the dual-stream Rapid Serial Visual Presentation task, a stream of stimuli containing two target stimuli is rapidly presented left and right. In previous studies, the second target was better identified in the left than in the right hemifield. In all those studies, alphanumeric stimuli were used both as targets and distracters. We examined to what extent this left visual-field advantage is dependent on reading-direction. The task was performed by Germans (with Latin characters), Israelis (with Latin and Hebrew characters) and Taiwanese (with Latin and Chinese characters). If caused by overlearnt associative links between Latin characters and left-to-right reading, the prominent left visual-field bias should be reversed in Hebrew and disappear in Chinese. Furthermore, if caused by direction of reading in the participant's native language, the left visual-field advantage in Latin conditions should be larger in Germans than in Israelis and Taiwanese. A left visual-field advantage was always observed, though slightly smaller in Hebrew and in Chinese, and there was no difference in the Latin conditions between the three nations. Therefore, it seems that the left visual-field advantage in speeded target identification is not primarily caused by the left-to-right reading-direction, but may be a combined effect resulting from the asymmetric organization of general mechanisms of visual processing and from stimulus-induced preferences.