The role of context and task demands in Spatial-Numerical Associations

The Spatial-Numerical Association of Response Codes (SNARC effect; Dehaene et al., 1993) is perhaps the most studied phenomenon in the field of Spatial-Numerical Associations (SNAs). Due to this effect participants respond faster to small numbers with a left key, and faster to large numbers with a right key. This phenomenon has been replicated with different experimental paradigms, employing various forms of stimuli and tasks. The robust evidence drawn from this past research unequivocally indicates that numbers are mapped spatially in our minds, and that this mapping is not univocal, but rather flexible. Flexibility in SNAs has been studied extensively. Several studies reported that participants exhibit different SNAs depending on their scanning habits (Dehaene et al., 1993; Zebian, 2005). Other research revealed participants, when trained to conceive numbers in unusual ways, for instance by memorizing random numerical sequences (van Dijck & Fias, 2011) or by spatializing numbers in unusual directions (Pitt & Casasanto, 2020; Bächtold et al., 1998), they exhibit temporary alterations in SNAs. Despite the approach used, these studies manipulated the context in which numbers are processed in similar ways. The general objective of this thesis is to investigate how context alters the SNARC effect and SNAs in general. Another goal is to clarify if these alterations can be attributed to the context alone, or, if not, to understand which role task demands play in this process. To this end, the three studies presented here used alternative spatial-numerical configurations as contexts and distinct tasks that could reinforce the context or not. In this way, the action of the context could be observed in isolation or in interaction with task demands. The first study investigates how an atypical spatial numerical context can alter the SNARC effect. Each experiment used distinct task demands, which could be either consistent, inconsistent, or unrelated to the context. Results suggest that the context can shape a SNA only when task demands and context are consistent. The second study reveals that the interaction between context and task demands observed in the first study is modulated by the salience of the context elicited by task demands. In the third study, the paradigm outlined in the previous studies was used to investigate the role of order and magnitude in the SNARC effect using a context in which people represent numbers in two different orders. The results that emerged are in line with stimuli’s magnitude, but order could have played a role as well. Taken together, the present studies help clarify the mechanisms underlying the influence of context and task on SNAs. From a theorical perspective, such findings give insights about the fact that the connection between number and space in our minds is probably due to a strategical adjustment to the task, rather than an innate feature of number processing.