Horizontal spatial representations of number and time : continuous number and categorical time lines

In daily-life situations, such as working at a desk or operating a computer for example, we usually use the left hand to take an object (or to press a key) that is placed to the left side of our body, whereas we use the right hand for objects (or keys) placed to the right of the body. Such behavior is cognitively and biomechanicatly reasonable and motor responses to targets at compatible locations tend to be faster and more accurate than responses to incompatible targets (e.g., Berlucchi et al. (1977) in key pressing, Ishihara and lmanaka (2007) in manual aiming). In psychology, this is known generally as the stimulus-response (S-R) compatibility effect (Berlucchi et al., 1977; Fitts and Seeger, 1953; see also Borghi, this volume). Compatibility has been found to facilitate actions to a certain degree or allow especially efficient action (Prinz and Hommel, 2002; Proctor and Reeve, 1990).