Chapter 1. Introduction and Background
Figure 1.11: Probability vs. fixation position for seven letter words.
at the different fixation positions are recorded. All words of different length were divided into five zones into which a fixation could fall (see for example figure 1.10). By comparing the probability that a word was recognised to the location at which it was fixated, it can be seen that there is a preferred viewing position slightly left of the centre of the word (figure 1.11. This effect is fairly small for short words (i.e. four letter words), but increases with the length of the word. Figure 1.11 shows a curve of the probability of correct pronunciation against the fixation position for seven letter words. It can clearly be seen that words are more easily recognised if they are fixated left of centre and the probability drops sharply on both sides of this optimal viewing position. Note that for a four letter word, their is only a very slight difference in the recognition probability. This might at first look counterintuitive because if the word were presented exclusively to one hemisphere, it could be processed immediately since all the information would be present. But according to Shillcock et al. (2000) the division of labour between the two hemispheres due to the Corpus Callosum is beneficial for the task of visual word recognition rather than hindering it. They show