The representation of episodic and autobiographical events in working memory: evidence for different Mental Time Lines

Humans from different cultures tend to represent time on a spatially oriented Mental Time Line (MTL). This is supported by research showing that response selection is faster when salient features of the stimulus (i.e., past and future) and of the response (i.e., left and right, or back and forward) are congruent to each other in working memory. Yet, whether the spatial frame of reference onto which the MTL is anchored (i.e., horizontal or sagittal) depends on the specific content to be processed (i.e., autobiographical and episodic) is still unknown. The present study aims to investigate whether personal and non-personal events activate different spatial frame of reference in WM. Fifty-one university students performed a computerized stimulus-response compatibility task and they classified as past or future, personal (e.g., First Kiss) and non-personal (e.g., Twin Towers) events with manual movements along the horizontal plane (i.e., leftward/rightward oriented movements) and along the sagittal plane (i.e., by making backward/forward movements). Results showed that the preferential spatial mapping representation depends on the nature of the event. In particular, non-personal events were represented only along the horizontal plane (i.e., past/future events responded faster with leftward/rightward movements compared to the opposite condition). On the contrary, personal events were represented only along the sagittal plane (i.e., past/future events responded faster with backward/forward movements). These findings indicate that the content (i.e., autobiographical, episodic) of a word in working memory may activate different spatial frames of reference onto which the MTL is mapped.