Abstract:

The object-based Correspondence effect (also called object-based Simon effect), is a special spatial Correspondence effect, which refers to the phenomenon that responses are faster and more accurate when a handle of the graspable object and the response position or the responding hand are consistent than inconsistent. Tucker and Ellis (1998) first found the object-based Correspondence effect, and attributed the effect to the functional affordance of handles. In other words, when participants watch the graspable object, they automatically activate the tendency to grasp the handle of the object with their corresponding hands. Therefore, when the responding hand which is automatically activated by the handle is consistent that required by the task, responses are faster. In addition to the functional affordance, many researchers have also used the spatial position coding account to explain this effect. The account held the view that the generation of the object-based Correspondence effect was related to the position of the asymmetric handle of the stimuli, which automatically activated the response of the ipsilateral position, leading to the object-based Correspondence effect (Cho & Proctor, 2010). It's uncertain that the generation of object-based Correspondence effect is due to affordance coding or spatial coding hypothesis.

In the present study, three experiments were conducted to investigate the generation mechanism of the object-based Correspondence effect. The stimulus materials were the silhouettes and photographs of the frying pans. In Experiment 1 the frying pan was located at the center of the screen, participants were asked to judge the stimulus to be upright or inverted, and responded with the responding hand. The aim of it was to examine whether the silhouettes and photographs of the frying pan would exist the object-based Correspondence effect without significant spatial position. In Experiment 2, the base of the frying pan was placed at the center of the screen, which made the left and right position of the handle more significant, and continue to examine whether the object-based Correspondence effect would appear when there existed the significant spatial coding. In Experiment 3, a crossed-hand response paradigm was adopted to separate response position from responding hand coding, in other words, participants pressed the right key with the left hand and the left key with the right hand, and to further explore the generation mechanism of the object-based Correspondence effect.

The results suggested that there existed the object-based Correspondence effect in Experiment 1 when spatial location of the stimulus was not significant for silhouette stimuli, but not photograph stimuli. In Experiment 2 when the spatial position of the stimuli was more significant, silhouette and photograph stimuli both showed the Correspondence effect and the effect size was similar. The RT combined analysis of Experiment 1 and 2 suggested that the Correspondence effect size of Experimental 2 was larger than Experiment 1 for silhouette stimuli, and similar for photograph stimuli. In Experiment 3 when the hands were crossed there was Correspondence effect between the handle and the response position for both silhouette and photograph stimuli, but not the Correspondence effect between the handle and the responding hand. The combined analysis with the Experiment 2 suggested that the effect size of Experiment 3 was smaller than Experiment 2 for both silhouette and photograph stimuli.

Based on these results, it is concluded that the spatial coding hypothesis plays an important role in the generation of the object-based Correspondence effect during a two key-pressing selection task, the affordance coding or other explanations are much smaller than that.

Key words: object-based Correspondence effect, grasping, affordance coding account, spatial location coding account, crossed-hand response