Heed the signs: Operation signs have spatial associations

Abstract

Mental arithmetic shows systematic spatial biases. The association between numbers and space is well documented, but it is unknown whether arithmetic operation signs also have spatial associations and whether or not they contribute to spatial biases found in arithmetic. Adult participants classified plus and minus signs with left and right button presses under two counterbalanced response rules. Results from two experiments showed that spatially congruent responses (i.e., right-side responses for the plus sign and left-side responses for the minus sign) were responded to faster than spatially incongruent ones (i.e., left-side responses for the plus sign and right-side responses for the minus sign). We also report correlations between this novel operation sign spatial association (OSSA) effect and other spatial biases in number processing. In a control experiment with no explicit processing requirements for the operation signs there were no sign-related spatial biases. Overall, the results suggest that (a) arithmetic operation signs can evoke spatial associations (OSSA), (b) experience with arithmetic operations probably underlies the OSSA, and (c) the OSSA only partially contributes to spatial biases in arithmetic.

Keywords:

• Mental arithmetic
• Mental number line
• Operational momentum
• Pointing
• Spatial–numerical association of response codes effect

We thank Gavin Revie and Clare Kirtley for their help with data collection.

M.P. was supported by a Visiting Researcher's Grant from the UK's Experimental Psychology Society. M.H.F. was supported by the British Academy [grant number SG 46947] while working at the University of Dundee.