There is ongoing interest and debate on whether the language we speak influences the way we think or perceive of the world. Indeed, there are considerable differences in how languages segment and package events or actions into sentences (Talmy, 2001). An intriguing question is whether these linguistic differences affect how speakers attend to different aspects of the visual world when speaking. According to Slobinʼs (1996) thinking-for-speaking formulation, the grammatical categories of the language that one speaks shape or filter the way that aspects of the world are expressed. It is argued that obligatory, grammaticalized categories have a special channeling effect on the attention of the speaker towards particular functions of these forms (Berman & Slobin, 1994; Slobin, 1996; Strömqvist & Verhoeven, 2004).
Winskel and Luksaneeyanwin (2009) investigated if obligatoriness of grammatical categories in Thai and English affects the expression of temporal events depicted in short animations in children and adults. Thai and English differ in the degree of obligatoriness of grammatical categories of imperfective aspect and the expression of deictic motion events. English has obligatory grammaticized imperfective aspectual marking on the verb, whereas Thai has verb final deictic-path verbs that form a closed class set. The speech produced by participants was analysed in terms of explicit expression of ongoingness of the two events and entrance and exit of protagonists depicted in the animations. Results supported the notion that obligatory grammatical categories shape how Thai and English speakers express temporal events or actions. English speakers explicitly expressed the ongoingness of the events more than Thai speakers, whereas Thai speakers expressed the entrance and exit of protagonists depicted in the animations significantly more than English speakers.
However, this type of research has its methodological limitations as linguistic behaviour is being used as evidence to support the ʻchanneling of attentionʼ hypothesis. An innovative approach to empirically test this claim that obligatory categories have a channeling effect on ʻattentionʼ, is to monitor eye movements while participants observe animations, as the pattern of eye fixations and the trajectory of the eye are an indicator of visual attention (Rayner, 1998). In the current study participants watched short animations depicting two overlapping actions in a linguistic and a non-linguistic condition and their eye movements were recorded using the latest eye tracking technology (EyeLink 2000). In the linguistic task participants were required to describe what happens in the animations. In the memory task participants were required to select the matching picture to the animation out of a set of three. If event perception is only affected by thinking-for-speaking, but otherwise is independent of language, we would expect differences in distribution of visual attention between English and Thai speakers only in the linguistic condition. However, if cross-linguistic differences in grammatical marking more profoundly affect event perception, we would expect to find differences in visual attention