Time Is -Ending: Sublexical Information Activates the Horizontal Mental Time Line in Word Processing

The mental time line (MTL) is a spatial continuum on which earlier events are generally associated with the left space and later events with the right space. Accordingly, past- and future-related words receive faster responses with, respectively, the left and the right hand. Yet, it is currently unclear whether the MTL is activated by the whole word or whether it can be triggered by more subtle sublexical cues, such as verb-endings, and whether the activation of this spatial continuum is an automatic phenomenon. The aim of this study is to test whether verb-endings do bring conceptual information that is in turn capable to activate the MTL and whether this activation holds also when the temporal information is not explicitly processed. We designed three experiments. In Experiment 1, consisting of a temporal categorization task, and in Experiment 2, consisting of a lexical decision task, we tested Italian tensed verbs (trov-avo "I found," trov-ero "I will find") and pseudo-verbs (trop-avo, trop-ero). Results of Experiment 1 showed that both tensed verbs and pseudo-verbs were spatially coded on the MTL. Results from Experiment 2 showed that the MTL is activated by the verb-endings also when temporal information was task-irrelevant (i.e., lexical decision task). Experiment 3 further clarified that the spatial-temporal congruency effect does not emerge during the evaluation of an inhomogeneous set of stimuli (i.e., when adding to the stimuli time-unrelated fillers). Overall, the present findings indicate that sublexical strings carry specific semantic information that comes into play in the generation of spatial-temporal associations.