You will be presented with a collection of medical randomized controlled trial (RCT) reports addressing a shared clinical question -- for instance, the efficacy of a medical intervention on a disease or condition. Given the titles and abstracts of these reports, your task is to generate the conclusion of the systematic review article synthesizing the key findings. Your conclusion should be a few sentences long. In your response, include only the conclusion and no other text. The RCT reports are below.



Title 1:
The Cognitive Mechanisms of the SNARC Effect: An Individual Differences Approach
Abstract 1:
Access to mental representations of smaller vs. larger number symbols is associated with leftward vs. rightward spatial locations , as represented on a number line . The well-replicated SNARC effect ( Spatial-Numerical Association of Response Codes ) reveals that simple decisions about small numbers are facilitated when stimuli are presented on the left , and large numbers facilitated when on the right . We present novel evidence that the size of the SNARC effect is relatively stable within individuals over time . This enables us to take an individual differences approach to investigate how the SNARC effect is modulated by spatial and numerical cognition . Are number-space associations linked to spatial operations , such that those who have greater facility in spatial computations show the stronger SNARC effects , or are they linked to number semantics , such that those showing stronger influence of magnitude associations on number symbol decisions show stronger SNARC effects ? Our results indicate a significant correlation between the SNARC effect and a  2D mental rotation task  , suggesting that spatial operations are at play in the expression of this effect . We also uncover a significant correlation between the SNARC effect and the distance effect , suggesting that the SNARC is also related to access to number semantics . A multiple regression analysis reveals that the relative contributions of spatial cognition and distance effects represent significant , yet distinct , contributions in explaining variation in the size of the SNARC effect from one individual to the next . Overall , these results shed new light on how the spatial-numerical associations of response codes are influenced by both number semantics and spatial operations
Additional analyses revealed a significant effect size advantage for explicit instruction tasks compared with implicit instructions , yet yielded no difference for the role of expertise on SNARC-like effects .
The similarities in the response properties for the spatial mappings of numerical and non-numerical domains support the concept of a general higher order magnitude system .