# Spatial Response Discrimination May Elicit a Simon Effect on a Non-Complementary Task

## TL;DR

This study explores how spatial response discrimination affects the Simon effect in a two-person non-complementary task setting.

## Contribution

The study introduces a novel framework to test the role of spatial response discrimination in eliciting a Simon effect in non-complementary tasks.

## Key findings

- A weak but marginally significant Simon effect was found in the OK group with opposite task keys.
- No Simon effect was observed in the SK group with the same task keys.
- The joint setting (TS group) replicated the joint Simon effect more robustly.

## Abstract

When paired participants are each assigned a complementary half of the Simon task, a joint Simon effect (JSE) has been observed. Co-representation, a cognitive representation of not only one’s own task but also that of the co-actor, has been one of several proposed mechanisms in the JSE. Using the response-discrimination hypothesis as a framework, we tested whether it was sufficient to highlight alternative task keys in a two-person setting in which a non-complementary task was completed to elicit a Simon effect (SE). In our design, the participant’s role was to perform the Go/No-Go Simon task and the co-actor’s role was to initiate each trial for the participant. In one two-person setting participant group (SK group), the same task key was assigned to both the participant and the co-actor; another group (OK) was assigned spatially opposite task keys. In a third group (joint setting, TS group), the standard joint Simon task was also completed to verify that a JSE could be replicated. We hypothesized that an SE would be elicited in the OK group, since opposite task keys would uniquely promote spatial coding. We found a weak but marginally significant SE in the OK group but not in the SK group. These results suggest that, on a non-complementary task, response discrimination may contribute to the emergence of a SE in a two-person setting, while it does not have the same impact as a complementary task completed in a joint setting (TS group) that may afford more robust response representations that reveal the enhanced so-called JSE.