Do Spatial Numerical Associations (SNAs) Emerge in the Absence of Compatible Response Codes? A Mouse-Tracking Experiment

Previous research has consistently shown that people respond faster with left responses to small numbers than to large numbers, while the opposite holds for right responses (i.e., the SNARC effect; Dehaene et al., 1993). The SNARC is taken as evidence for inherent spatial-numerical associations (SNAs). Most research on SNAs used responses that owned a left-to-right code, such as left versus right buttons, mouse movements, or line bisection tasks. However, some other research already attempted to avoid left-to-right spatial response codes to isolate SNAs effects, for example by examining biases in spatial attention (att-SNARC). In the present experiment, we address whether numerical processing inherently elicits spatial left-to-right representations using a different approach. To this aim, we adopt top versus bottom responses to assess whether numerical processing naturally elicits spatial representations. Participants respond to the digits’ magnitude by moving their mouse to the top or the bottom of their screen. Such spatial representation should bias participants’ movements toward the left or the right, while participants are instructed to perform vertical movements. The results may shed light on the automatic association of digits’ magnitude to left-to-right spatial dimensions.

Previous research has consistently shown that people respond faster with left responses to small numbers than to large numbers, while the opposite holds for right responses (i.e., the SNARC effect; Dehaene et al., 1993). The SNARC is taken as evidence for inherent spatial-numerical associations (SNAs). Most research on SNAs used responses that owned a left-to-right code, such as left versus right buttons, mouse movements, or line bisection tasks. However, if numbers elicit spatial representations, these might emerge also in different settings, for example when responses do not own a left-to-right code. Previous research attempted to avoid left-to-right spatial response codes to isolate SNAs effects, for example by examining digits-elicited biases in spatial attention (att-SNARC). In the present experiment, we address whether numerical processing inherently elicits spatial left-to-right representations using a different approach. Participants respond to the digits’ magnitude by moving their mouse to the top or the bottom of their screen. Digits-elicited spatial representation might then bias participants’ movements toward the left or the right. The results may shed light on the automatic association of digits’ magnitude to left-to-right spatial dimensions.