On the flexibility of letter position coding during lexical processing: evidence from eye movements when reading Thai

Previous research supports the view that initial letter position has a privileged role in comparison to internal letters for visual-word recognition in Roman script. The current study examines whether this is the case for Thai. Thai is an alphabetic script in which ordering of the letters does not necessarily correspond to the ordering of a word\u27s phonemes. Furthermore, Thai does not normally have interword spaces. We examined whether the position of transposed letters (internal, e.g., porblem, vs. initial, e.g., rpoblem) within a word influences how readily those words are processed when interword spacing and demarcation of word boundaries (using alternatingbold text) is manipulated. The eye movements of 54 participants were recorded while they were reading sentences silently. There was no apparent difference in degree of disruption caused when reading initial and internal transposed-letter nonwords. These findings give support to the view that letter position encoding in Thai is relatively flexible and that actual identity of the letter is more critical than letter position. This flexible encoding strategy is in line with the characteristics of Thai—that is, the flexibility in the ordering of the letters and the lack of interword spaces, which creates a certain level of ambiguity in relation to the demarcation of word boundaries. These findings point to script-specific effects operating in letter encoding in visual-word recognition and reading

Sources of individual differences in the speed of naming objects and actions: The contribution of executive control

Item does not contain fulltextWe examined the contribution of executive control to individual differences in response time (RT) for naming objects and actions. Following Miyake et al., executive control was assumed to include updating, shifting, and inhibiting abilities, which were assessed using operation span, task-switching, and stop-signal tasks, respectively. Experiment 1 showed that updating ability was significantly correlated with the mean RT of action naming, but not of object naming. This finding was replicated in Experiment 2 using a larger stimulus set. Inhibiting ability was significantly correlated with the mean RT of both action and object naming, whereas shifting ability was not correlated with the mean naming RTs. Ex-Gaussian analyses of the RT distributions revealed that updating ability was correlated with the distribution tail of both action and object naming, whereas inhibiting ability was correlated with the leading edge of the distribution for action naming and the tail for object naming. Shifting ability provided no independent contribution. These results indicate that the executive control abilities of updating and inhibiting contribute to the speed of naming objects and actions, although there are differences in the way and extent these abilities are involved