Are time-space synaesthetes superior at event recall because they are high visual imagers?

Abstract

Individuals with time-space synaesthesia report experiencing time sequences (e.g. days of the week, months of the year) as explicit spatial structures located either within their mind’s eye or in the space outside their body. These synaesthetes are also recognised by their exceptional ability to recall past events (Simner et al., 2009) and their high visual imagery (Price, 2009). To better understand the relationship between time-space synaesthesia and visual imagery, we tested visual imagery (Object-Spatial Imagery Questionnaire; Blajenkova et al., 2006) and memory for past events (Edinburgh [Public and Autobiographical] Events Battery; Simner et al., 2009) in 67 non-synaesthetes. Object imagery correlated positively with the recall of autobiographical events; further investigation revealed that it is specifically involved in remembering the content, rather than the dates of memories. We then compared the EEB scores of our high object imagery non-synaesthetes to those of the synaesthetes in Simner et al. (2009). We found the latter group remembered yet more personal memories in a shorter period of time. It is likely that their superior memory for events (Simner et al., 2009) is due in part to their high imagery but also to retrieval strategies involving their explicit visuo-spatial forms. We conclude that although high visual imagery may give superior event recall, it may not be sufficient to account for the exceptional memories of time-space synaesthetes.