Sharing Different Reference Frames: How Stimulus Setup and Task Setup Shape Egocentric and Allocentric Simon Effects

Abstract

Different reference frames are used in daily life in order to structure the environment. The two-choice Simon task setting has been used to investigate how task-irrelevant spatial information influences human cognitive control. In recent studies, a Go/NoGo Simon task setting was used in order to divide the Simon task between a pair of participants. Yet, not only a human co-actor, but also even an attention-grabbing object can provide sufficient reference in order to reintroduce a Simon effect (SE) indicating cognitive conflict in Go/NoGo task settings. Interestingly, the SE could only occur when a reference point outside of the stimulus setup was available. The current studies exploited the dependency between different spatial reference frames (egocentric and allocentric) offered by the stimulus setup itself and the task setup (individual vs. joint Go/NoGot task setting). Two studies (Experiments 1 and 2) were carried out along with a human co-actor. Experiment 3 used an attention-grabbing object instead. The egocentric and allocentric SEs triggered by different features of the stimulus setup (global vs. local) were modulated by the task setup. When interacting with a human co-actor, an egocentric SE was found for global features of the stimulus setup (i.e., stimulus position on the screen). In contrast, an allocentric SE was yielded in the individual task setup illustrating the relevance of more local features of the stimulus setup (i.e., the manikin's ball position). Results point toward salience shifts between different spatial reference frames depending on the nature of the task setup.

Keywords: Simon effect; allocentric frame of reference; egocentric frame of reference; joint action; task sharing.

FIGURE 1

(A) Left column: Experimental setup used in Experiments 1 and 2. A variant of the Simon task was split between two participants in such a way that each one responded to one particular stimulus color (here: Participant A to blue stimuli and Participant B to yellow stimuli). The experimental task was carried out under a joint (as shown here) and an individual Go/NoGo Task setting. The seating position and stimulus color assignment to each participant remained the same during the whole experimental session. Right column: Shown is the stimulus layout visible on the screen, separately for the one-element and nine-element condition. In the one-element condition, one stimulus was shown at a time occurring randomly at any out of 16 possible locations centered around the midline of the screen. Nine identical stimuli were shown simultaneously in the nine-element condition (note: due to the use of two midline stimulus locations, the set of nine stimuli occurred pseudo-randomly involving 9 of 18 possible stimulus locations). (B) Abstract geometrical patterns used as stimulus material in Experiment 2. (C) Task setup for Experiment 3. Participants performed the Go/NoGo task setting with (left part, individual Go/NoGo task setting with Japanese waving cat) or without (right part, individual Go/NoGo task setting without Japanese waving cat) an unrelated Japanese waving cat. Different visual angles in the pictures served only to illustrate the layout of the Experiment 3 better.

FIGURE 2

This figure displays all four possible combinations of the experimental factors Stimulus Ball Position (compatible, incompatible) and Stimulus Screen Position (compatible, incompatible) separately for the one-element and nine-element condition. Compatibility labeling refers to the case where a response of the left button is required for a blue stimulus, however, the color-response button associations were alternated across all participants. Transparent stimuli were not visible on the screen and are only displayed for illustrative purpose. In the one-element condition (A), the given stimulus in a trial occurred at any of the 16 lateral positions on the screen (eight left positions, eight right positions). In the nine-element condition (B), 9 of the 18 possible stimuli positions (16 lateral stimulus positions and 2 midline stimulus positions) were filled with the actual stimulus. The majority of the stimuli were on either the left or right side of the screen marking either Stimulus Screen Position compatible or incompatible trials. As shown, the amount of stimuli on the left or right side varied (between 4 and 7, as shown in the examples of the upper and lower panel).

FIGURE 3

Mean reaction times and SEM for Experiment 1, separated for the one-element and the nine-element condition. Solid bars represent conditions, in which manikin’s position at the screen and participant’s seating position are compatible (i.e., SR compatible), dashed bars display conditions, in which the manikin’s position at the screen and the participant’s seating position are incompatible (i.e., SR incompatible). Gray bars show conditions, in which the ball’s position and the participant’s seating position are compatible, green bars illustrate conditions, in which the ball’s position and the participant’s seating position are incompatible. Bars are given separately for the individual and joint Go/NoGo task setting.

FIGURE 4

Mean reaction times and SEM for Experiment 2, separated for the one-element and the nine-element condition. Solid bars represent conditions, in which the abstract pattern’s position and the participant’s seating position are compatible (SR compatible), dashed bars display the conditions, in which the abstract pattern’s position and the participant’s seating position are incompatible (SR incompatible). Gray bars show conditions, in which the ball’s position and the participant’s seating position are compatible, green bars illustrate conditions in which the ball’s position and the participant’s seating position are incompatible. Bars are given separately for the individual and joint Go/NoGo task setting.

FIGURE 5

Mean reaction times and SEM for Experiment 3. Solid bars represent conditions in which the manikin’s position and the participant’s seating position are compatible (SR compatible), dashed bars display conditions in which the manikin’s position and participant’s seating position are incompatible (SR incompatible). Gray bars show conditions in which the ball’s position and the participant’s seating position are compatible, green bars illustrate conditions in which the ball’s position and the participant’s seating position are incompatible. Bars are given separately for the individual Go/NoGo task setting with and without Japanese waving cat.