Space-Time Interdependence and Sensory Modalities: Time Affects Space in the Hand But Not in the Eye

Space-Time Interdependence and Sensory Modalities: Time Affects Space in the Hand But Not in the Eye Zhenguang G. Cai (zhenguangcai@gmail.com) Louise Connell (louise.connell@manchester.ac.uk) School of Psychological Sciences, University of Manchester, Coupland 1, Oxford Road Manchester, M13 9PL, UK Abstract 2007), and with a longer line than a shorter one (Casasanto & Boroditsky, 2008). There are two alternative accounts of the relationship between time and space representations. According to the spatial metaphor account, people employ spatial metaphors in thinking or talking about time such that they use their concrete spatial experience to support their understanding of abstract time processing (Boroditsky, 2000; Gibbs, 2006; Lakoff & Johnson, 1980, 1999). The temporal relation of two events can be expressed metaphorically as a relation between two locations in space (e.g., tomorrow is ahead of yesterday). Similarly, a temporal duration can be metaphorically envisioned as the distance from a spatial location representing the onset of the duration and a spatial location representing the offset of the duration. Critically, the spatial metaphor account assumes that time and space remain two separate representational systems with an asymmetric mapping between them: concurrent spatial information should always affect its dependent domain of time to a greater extent than concurrent temporal information can affect space (Casasanto & Boroditsky, 2008; Casasanto, Fotakopoulou, & Boroditsky, 2010; Merritt, Casasanto, & Brannon, 2010). Alternatively, according to the spatial representation account of time, temporal and spatial information are processed in a common neural substrate and share representational and attentional resources. Time is closely related to space in action and perception (e.g., Walsh, 2003): space and time are often coordinated in action and correspond to each other in movement (e.g., things travel a certain distance in a certain time). Thus, temporal duration and spatial distance may share a representational format (e.g., Locke, 1689/1995), such that two events are separated by a particular duration in the same way that two locations are separated by a particular distance. Some stronger versions of spatial representation theories have argued that time, space and number all share a common magnitude representation (Burr, Ross, Binda & Morrone, 2010; Walsh, 2003), but a weaker version of the spatial representation theory of time does not necessarily require the magnitude assumption. Critically, rather than comprising separate representational domains, time and space occupy an overlapping temporo-spatial representation that may be affected by concurrent temporal or spatial information. Since the same representation can subserve both temporal and spatial processing, the spatial representation account thus differs from the spatial metaphor account in allowing Time and space are intimately related, but what is the real nature of this relationship? Is time mapped metaphorically onto space, or do the two domains share a common representational format? In the present paper, participants touched (but could not see) physical sticks while listening to an auditory note. Judgements of stick length were affected by concurrent note duration, but not vice versa. When participants were allowed to see as well as touch the sticks, however, the effects reversed. These findings run counter to the spatial metaphor account of time, which claims that effects of space on time should always be stronger than those of time on space. Rather, our findings support the spatial representation account, in which time and space share a common neural substrate that may be affected by concurrent temporal or spatial information, depending on the perceptual acuity of the modality used to perceive space. Keywords: Time; space; representation; haptic perception; visual perception; sensory dominance; metaphor Though our immediate perception of the world is limited to our senses such as vision and hearing, we use these senses to perceive and represent other dimensions of the world besides colours and sounds. For instance, we can perceive the spatial information of an object (e.g., its length, height and size) by looking at it or touching it. How we perceive and represent more abstract domains such as time, however, has been a perennial philosophical question. Many researchers have suggested that abstract domains are grounded to some extent in more familiar concrete domains that we develop through sensorimotor experience (e.g., Barsalou & Wiemer-Hastings, 2005; Gibbs, 2006; Lakoff & Johnson, 1980, 1999). Time, for example, can be understood through the domain of space, as reflected in our use of language. Speakers of English often talk about time in spatial terms (e.g., a long/short time) and sometimes space in temporal terms (e.g., I am 5 minutes from the airport). A range of studies has provided evidence that these linguistic expressions reflect a deeper conceptual bridge between time and space. For example, people perceive the passage of time either as if they are moving in space towards the future, or as if the future is moving towards them (e.g., Boroditsky & Ramscar, 2002; McGlone & Harding, 1998). Other studies have shown that space affects the perception of temporal durations such that people experience longer subjective time when they imagine themselves inside a larger scale model of a room than inside a smaller one (DeLong, 1981), with a larger square than a smaller one (Xuan, Zhang, He, & Chen,