Search

BACKGROUND One of the most widely replicated findings in cognitive psychology is the existence of spatial-numerical associations (SNAs). This finding suggests that numbers are mentally represented through spatial formats (Fischer & Shaki, 2014). A horizontal left-to-right oriented line (i.e., mental number line, MNL), with small numbers positioned relatively on the left and large numbers on the right, has been the spatial format most extensively studied across cultures, developmental ages, and even species (for a review, see Toomarian & Hubbard, 2018). Recently, it has been argued that numbers might be represented also along down-to-up (i.e., vertical) and near-to-far (i.e., sagittal) oriented mental lines, even though the investigation of SNAs along the vertical and sagittal axes is much more limited (Winter, Matlock, Shaki, & Fischer, 2015). Despite the limited number of studies, the available evidence suggests the existence of three independent and equally strong SNAs, one for each axis. Specifically, small numbers were found to be associated with the left, down, and near sides of space, whereas large numbers were found to be associated with the right, up, and far sides of space (Aleotti et al., 2020; Winter, Matlock, Shaki, & Fischer, 2015). Furthermore, a recent study has shown that the SNAs elicited along the three Cartesian axes, when assessed in combination, can interact with each other (Aleotti et al., 2021; preprint). Because lateralized response codes (i.e., horizontally, vertically, and sagittally aligned buttons) were used, from the findings of Aleotti et al. (2021; preprint) it is impossible to disentangle whether the interaction among multiple SNAs arises only at the response selection level or also at the semantic one. Likely, both options are possible. Basso Moro et al. (2018), indeed, have suggested that the horizontal SNA origins at both response selection and semantic stages. The same might be observed for the vertical and sagittal SNAs, as well as for the interaction among the three SNAs. Nonetheless, as far as we know, no studies have investigated the interaction among the three Cartesian axes at the level of semantic representations. Grounding on the findings of Aleotti et al. (2021; preprint), in the present study we will test whether the three Cartesian axes can interact also at the semantic stage, by lateralizing the position of the target numbers on the screen, while keeping the response button fixed in a central position (i.e., non-lateralized). Our hypothesis is that if the multiple SNAs interact only at the response selection level, then the interaction among the three Cartesian axes should disappear. On the contrary, if the multiple SNAs interact (also) at the semantic stage, then the interaction should be observed. AIM This study aims to investigate the SNAs in the three-dimensional mental space (i.e., horizontal, vertical, and sagittal axes) by varying the spatial location occupied by numbers in a simulated 3D environment, created by means of a picture of a corridor and cues of perspective. To avoid lateralized response codes, all responses will be collected by one, centrally placed response button. The spatial locations of the stimuli (i.e., Arabic digits) will result by combining the three Cartesian axes (i.e., horizontal: left vs. right; vertical: down vs. up; sagittal: near vs. far), so that eight spatial locations will be obtained (see Figure 1 in the attached file "Stimuli_and_Procedure"): • Spatial Location 1 will be defined by the left-down-near space; • Spatial Location 2 will be defined by the left-down-far space; • Spatial Location 3 will be defined by the left-up-far space; • Spatial Location 4 will be defined by the left-up-near space; • Spatial Location 5 will be defined by the right-down-far space; • Spatial Location 6 will be defined by the right-down-near space; • Spatial Location 7 will be defined by the right-up-near space; • Spatial Location 8 will be defined by the right-up-far space. The opposite spatial locations will be considered as the two extremities of a Plane (i.e., one in the left-sided space and one in the right-sided space). Hence, four Planes will result: • Plane 1: Spatial Location 1 (i.e., left-sided extremity) linked to Spatial Location 8 (i.e., right-sided extremity). Horizontal SNA: compatible; Vertical SNA: compatible; Sagittal SNA: compatible (see Table 1 in the attached file "Tables"). Hence, number magnitude on Plane 1 can be compatible along three axes. • Plane 2: Spatial Location 2 (i.e., left-sided extremity) linked to Spatial Location 7 (i.e., right-sided extremity). Horizontal SNA: compatible; Vertical SNA: compatible; Sagittal: SNA incompatible (see Table 1 in the attached file "Tables"). Hence, number magnitude on Plane 2 can be compatible along two axes. • Plane 3: Spatial Location 3 (i.e., left-sided extremity) linked to Spatial Location 6 (i.e., right-sided extremity). Horizontal SNA: compatible; Vertical SNA: incompatible; Sagittal: SNA incompatible (see Table 1 in the attached file "Tables"). Hence, number magnitude on Plane 3 can be compatible along one axis. • Plane 4: Spatial Location 4 (i.e., left-sided extremity) linked to Spatial Location 5 (i.e., right-sided extremity). Horizontal SNA: compatible; Vertical SNA: incompatible; Sagittal: SNA compatible (see Table 1 in the attached file "Tables"). Hence, number magnitude on Plane 4 can be compatible along two axes.