The combination of the horizontal and vertical dimensions in mental time representation: the existence of a spatial mental map of time.

Horizontal and vertical representations of time (past-left or down and future-right or top) have been demonstrated. However, only a few studies have investigated the existence of a spatial map of time, considering it as the interaction of different spatial dimensions in space. The aim of this study was to investigate the existence of a mental time representation along the diagonal axes, intended as the combination of the horizontal and the vertical dimensions. Seventy-nine Italian participants (85% females; mean age = 25.11 ± 4.86 years; 77 right-handed) performed an online temporal judgment task using 20 Italian temporal expressions presented either always in the center (Experiment 1) or in the four corners of the screen (Experiment 2) and two pairs of response keys ("C" and "U" for the positive diagonal; "R" and "N" for the negative diagonal). Results showed spatial-temporal associations in positive (i.e., time was represented from left-bottom to right-top) and negative (i.e., time was represented from left-top to right-bottom) diagonals, although in Experiment 2 these associations were weak for the negative diagonal. These spatial-temporal associations along both diagonals were confirmed even when participants were free to place different temporal stimuli along a diagonally drawn line, in a Time-to-Position task, indicating that the temporal expressions could be ordered linearly along the diagonal spaces. Finally, these data indicated that the horizontal information was mainly used for determining the spatial-temporal associations along both diagonals, whereas the vertical information was flexible with a bottom-to-top (for positive diagonal) and top-to-bottom (for negative diagonal) temporal representation.

Following the aridity: Historical biogeography and diversification of the Philodromidae spider genus Petrichus in South America.

Aridity conditions and expansion of arid biomes in South America are closely linked to the onset of Andean orogeny since at least 30 Mya. Among arid-associated taxa, spiders belonging to the genus Petrichus are found along the Andes mountains and across the diagonal of open formations of the Chaco and Cerrado domains. In this contribution, we asked whether Petrichus originated prior to the central Andean uplift and what historical processes have promoted their diversification. We time-calibrated the phylogenetic tree of Philodromidae and estimated the divergence times of Petrichus. Considering phylogenetic uncertainty, we assessed biogeographical hypotheses of the historical events associated with the diversification of these spiders in South America. Petrichus originated along the Pacific coastal deserts in the Central Andes during the Early Miocene. The species likely dispersed from the western to the eastern side of the Andes coincidently with the central Andean uplift. The diversification of these spiders is coeval with the expansion of open grassland formations during the Late Miocene and Early Pliocene. Multiple dispersal events occurred from the Monte desert to southern South America and eastward to Chaco between âˆ¼ 8 and 2.5 Mya. The Andes might have played a role as a corridor favoring geographical range expansions and colonization of new environments. In addition, we also suggest that Philodromidae might have an Oligocene origin or earlier. Future analyses based on further evidence and larger taxon sampling should be carried out to corroborate our findings.