Compatibility effects between the physical size of stimulus objects and response locations.

• Applicant: Professor Dr. Peter Wühr
• Subject Area: General, Cognitive and Mathematical Psychology
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426561782

In „A Theory Of Magnitude“ (ATOM), Walsh (2003, 2015) postulates a generalized (brain) system for the processing of different “magnitudes” (e.g., size, space, time) that are relevant for the control of action. ATOM predicts that the concurrent processing of these magnitudes should lead to compatibility or interference effects. Whereas previous research has extensively studied compatibility and interference effects for numerical magnitude and spatial position, and for numerical magnitude and physical size, previous research has neglected the possible consequences of the concurrent processing of physical size and spatial position. In pilot work, we showed a compatibility effect between physical stimulus size and horizontal response position: Participants responded faster to (relatively) small stimuli with the left response (hand) than with the right response (hand), whereas the reverse pattern was observed for (relatively) large stimuli. This stimulus-size response-location compatibility effect (henceforth called: size-location effect) not only occurred when stimulus size was task relevant, but also when stimulus size was task irrelevant (Seegelke & Wühr, 2018; Wühr & Seegelke, 2018). Moreover, preliminary results suggests that the effect occurs for right-handed, but not for left-handed participants. The research project, proposed here, has three general aims. The first aim is to empirically evaluate two possible explanations for the size-location compatibility effect. The first explanation arises from the polarity-correspondence principle proposed by Proctor and colleagues (e.g., Proctor & Xiong, 2015). The second explanation arises from the fact that the dominant hand is usually stronger than the non-dominant hand (at least in right-handed individuals), which might have caused a preference for grasping larger (and often heavier) objects with the dominant hand. The second aim of the project is to uncover similarities and differences between the size-location compatibility effect and the SNARC effect. Therefore, it is planned to directly compare different compatibility effects in different spatial dimensions. Commonalities and differences between the effects might be informative with regard to whether the effects have common or different sources, and whether the effects arise at similar or different stages of processing. The third aim of the project is to further develop ATOM. In its present form (e.g., Walsh, 2015), ATOM merely predicts the existence of (mutual) interference when stimulus size and response location are concurrently processed. But because empirical research on this issue is lacking, ATOM cannot tell much about the causes and characteristics of the interference effects. Moreover, ATOM cannot explain the direction of compatibility (or congruency) effects between non-spatial magnitudes and spatial (location) information. The results of our research project might be useful in filling these empirical and theoretical gaps.

• DFG Programme: Research Grants