TY  - JOUR
A1  - Hartmann, Matthias
A1  - Fischer, Martin H.
A1  - Mast, Fred Walter
T1  - Sharing a mental number line across individuals? The role of body position and empathy in joint numerical cognition
JF  - The quarterly journal of experimental psychology
N2  - A growing body of research shows that the human brain acts differently when performing a task together with another person than when performing the same task alone. In this study, we investigated the influence of a co-actor on numerical cognition using a joint random number generation (RNG) task. We found that participants generated relatively smaller numbers when they were located to the left (vs. right) of a co-actor (Experiment 1), as if the two individuals shared a mental number line and predominantly selected numbers corresponding to their relative body position. Moreover, the mere presence of another person on the left or right side or the processing of numbers from loudspeaker on the left or right side had no influence on the magnitude of generated numbers (Experiment 2), suggesting that a bias in RNG only emerged during interpersonal interactions. Interestingly, the effect of relative body position on RNG was driven by participants with high trait empathic concern towards others, pointing towards a mediating role of feelings of sympathy for joint compatibility effects. Finally, the spatial bias emerged only after the co-actors swapped their spatial position, suggesting that joint spatial representations are constructed only after the spatial reference frame became salient. In contrast to previous studies, our findings cannot be explained by action co-representation because the consecutive production of numbers does not involve conflict at the motor response level. Our results therefore suggest that spatial reference coding, rather than motor mirroring, can determine joint compatibility effects. Our results demonstrate how physical properties of interpersonal situations, such as the relative body position, shape seemingly abstract cognition.
KW  - Mental number line
KW  - random number generation
KW  - joint action
KW  - joint Simon effect
KW  - empathy
KW  - Interpersonal Reactivity Index
Y1  - 2019
U6  - https://doi.org/10.1177/1747021818809254
SN  - 1747-0218
SN  - 1747-0226
VL  - 72
IS  - 7
SP  - 1732
EP  - 1740
PB  - Sage Publ.
CY  - London
ER  - 
TY  - INPR
A1  - Shaki, Samuel
A1  - Fischer, Martin H.
T1  - Removing spatial responses reveals spatial concepts even in a culture with mixed reading habits
T2  - Frontiers in human neuroscienc
KW  - cross-cultural
KW  - random number generation
KW  - mental number line
KW  - embodied numerical cognition
KW  - automatic processing
Y1  - 2014
U6  - https://doi.org/10.3389/fnhum.2014.00966
SN  - 1662-5161
VL  - 8
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  -